GeoArabia, 2013, v. 18, no. 3, p. 103-130 Gulf PetroLink, Bahrain
MIDDLE EAST GEOLOGIC TIME SCALE 2013 Chrono- and sequence-stratigraphy of the Mid-Permian to Early Triassic Khuff sequences of the Arabian Plate Moujahed I. Al-Husseini and Bastian Koehrer ABSTRACT The Middle Permian (Guadalupian), Upper Permian (Lopingian) and Lower Triassic Khuff and correlative formations in the Arabian Plate consist of six “third-order” sequences, from oldest to youngest KS6 to KS1, and at least 45 “fourth-order” sequences. They are here dated using biostratigraphic constraints and correlated to two independent sequence-stratigraphic time scales: (1) global sequences calibrated in the Geological Time Scale GTS 2012; and (2) orbitalforcing glacio-eustatic sequences that track the 0.405 million year (Myr) orbital eccentricity signal in the M&H-2010 scale (Matthews and Al-Husseini, 2010). The chronostratigraphic calibration of the Khuff sequences provides a reference section and common nomenclature that can be used for regional and global correlations. It permits positioning the hydrocarbon reservoirs of the Khuff and equivalent formations in a sequence-stratigraphic framework that can be used in exploration and reservoir characterization. The lower sequence boundary of the Khuff Formation (Khuff SB) is correlated to global Wordian SB Wor1 near the Roadian/Wordian Boundary at 268.8 ± 0.5 Ma, and correlative SB 19C at 268.9 Ma in the M&H-2010 scale. The upper sequence boundary of the Khuff Formation with the overlying Sudair Formation (Sudair SB) is correlated to Olenekian SB Ole1 near the Induan/Olenekian Boundary at 250.0 ± 0.5 Ma, and correlative SB 17 at 249.5 Ma in the M&H-2010 scale. These calibrations imply the Khuff was deposited in about 19.4 Myr, and consists of 48 “stratons”; i.e. transgressive-regressive (T-R) depositional subsequences with an average duration of 0.405 Myr corresponding to long-eccentricity orbital cycles 664 to 617. The 48 stratons are predicted to form four “dozons” (19C, 18A, 18B and 18C), each consisting of 12 stratons. Individual dozons lasted 4.86 Myr and are separated by regional sequence boundaries (SB 19C to SB 17A). In Oman, Khuff Sequence KS6 on the Saiq Plateau is correlated to the subsurface Lower Khuff Member, and both are interpreted to consist of 12 subsequences that are correlated to stratons 664–653 forming Dozon 19C between 268.9– 264.0 Ma. KS6 is correlated to the four global sequences Wordian Wor1 to Capitanian Cap1 dated between 268.8–264.0 Ma in GTS 2012. Khuff Sequence KS5 corresponds to the Middle Khuff Member up to the top of Middle Khuff Anhydrite in subsurface Oman. On the Saiq Plateau, KS5 potentially consists of 12 cycle sets (Koehrer et al., 2010) that are correlated to stratons 652–641 of Dozon 18A, between 264.0–259.2 Ma. It is correlated to global sequences Capitanian Cap2 and Cap3 dated between 264.0–259.8 Ma in GTS 2012. Khuff Sequence KS4 consists of 11 cycle sets on the Saiq Plateau and other localities in Al Jabal al-Akhdar in Oman (Koehrer et al., 2010, 2012). It is assumed that one cycle set remains unidentified in KS4, completing its correlation to stratons 640–629 of Dozon 18B between 259.2–254.3 Ma. KS4 correlates to the global sequences Wuchiapingian Wuc1 and Wuc2 dated between 259.8–254.2 in GTS 2012. Khuff sequences KS3, KS2 and KS1 combined consist of 10 cycle sets in Al Jabal al-Akhdar (Koehrer et al., 2010, 2012), and two are presumed
103
Al-Husseini and Koehrer
unidentified so as to correlate to the 12 stratons 628–617 of Dozon 18C between 254.3–249.5 Ma. Sequence KS3 correlates to Changhsingian global sequences Cha1 and Cha2 dated between 254.2–252.5, and KS2 and KS1 to latest Permian– Early Triassic global sequences Cha 3 and Induan–Olenekian Ind1 dated between 252.5–249.9 Ma in GTS 2012. The Permian/Triassic Boundary (PTB), dated at 252.2 ± 0.5 Ma in GTS 2012, occurs in lowermost Khuff Sequence KS2, in cycle set KCS 2.3, and based on the orbital calibration of the Upper Permian (Lopingian) Series in South China, it occurs in Straton 623 between 252.3 and 251.9 Ma.
INTRODUCTION The Middle Permian–Lower Triassic Khuff and correlative formations in the Arabian Plate consist mainly of carbonates and evaporites that attain a thickness of more than 1,000 m (Al-Jallal, 1995; Sharland et al., 2001). The formations overlie terrestrial clastics typified by the Gharif Formation of Oman, and their lower boundaries represent the start of the regional transgression of the “Fusulinid Sea” over many parts of the Arabian Plate (Montenat et al., 1976; Le Métour, 1987; Baud et al., 2001a, b; Osterloff et al., 2004; Richoz et al., 2005; Baud and Bernecker, 2010, see references therein, Figure 1). The formations are overlain by the basal shales of the Lower Triassic Sudair Formation in Saudi Arabia (Manivit et al., 1983) and Oman (Osterloff et al., 2004; Forbes et al., 2010), and correlative rock units elsewhere in the Arabian Plate (Figure 2). The Khuff Formation has been interpreted in several regions as one “second-order” super-sequence consisting of six “third-order”, transgressive-regressive (T-R) sequences (Figures 1 and 2; Insalaco et al., 2006; Maurer et al., 2009; Koehrer et al., 2010, 2012): LATE PERMIAN (CHANGHSINGIAN) KHUFF PALEOGEOGRAPHY 45°E
30°N 0
N
250
gr
KUWAIT Kuh-i-Mand
Qibah
Khursaniyah Berri Abqaiq
Abu Sa'fah
BAHRAIN
Ghawar Khurais
Al Fayda Ad Dawadimi
Darma
Wadi Ar Rayn
Arabian Shield
20°
Riyadh SHD-1 Well
Awali
os
Te t
30°
hy
Su
Iran Terranes in Cimmeria
sR
tu
re
ift
Middle and outer shelf carbonates
Kuh-e-Surmeh Kangan IRAN South Fars Figures 7 and 9 South Pars
Ras alAbu Al Khaimah Bukhoosh North Nasr Field Zakum QATAR
Harmaliyah Arzanah
Wadi Al Mulayh
Marginal-marine/ deltaic deposits
Dalan
North Pars Karan
SAUDI ARABIA
Buraydah
o-
Za
Quadrangles with Khuff Outcrops
25°
Ne
Kuh-e-Dena
IRAQ
km
Baq’a’
Inner shelf 55° carbonates
50°
Hail Umm UAE Shaif Wadi Maqam Lekhwair-70 Well
Musandam 25°
Gulf of Oman
Al Jabal al-Akhdar Figure 1b
Yibal
Saiq Plateau Figure 6 and 8
OMAN
Sulayyimah
Al Huqf Hasirah-1 Figure 4
Wadi Tathlith
45°
50°
20°
55°
Sayyala-29 Figure 5
Figure 1a: Late Permian paleogeography showing localities mentioned in the paper, and key oil (green) and gas (red) fields in the Khuff and equivalent formations (compiled by Maurer et al., 2009). The Khuff crops out in several quadrangles in Saudi Arabia and is discussed by Vaslet et al. (2005). 104
Arabian Plate Khuff Sequences
• • • •
Mid-Permian Khuff sequences KS6 and KS5, Late Permian Khuff sequences KS4 and KS3, latest Permian–Early Triassic Khuff Sequence KS2, and Early Triassic Khuff Sequence KS1.
The reservoirs in sequences KS4 to KS1 contain some of the world’s greatest reserves of nonassociated gas in fields in Bahrain, Iran, Saudi Arabia, United Arab Emirates and Qatar, as well as oil in the Yibal Field in Oman (Figure 1a). The age calibration and correlation of these and other T-R sequences across the Arabian Plate is a work-in-progress launched in 2008 as the Middle East Geological Time Scale (Al-Husseini, 2008). This paper presents a revision to the age calibrations of the Khuff T-R sequences that was attempted in 2010 (Al-Husseini and Matthews, 2010). It starts by predicting the ages of the regional sequences of the Mid-Permian to Early Triassic based on a model of orbital-forcing glacio-eustasy, referred to as the M&H-2010 scale (after Matthews and Al-Husseini, 2010; Figure 2, Tables 1 and 2). Next the OUTCROP MAP, OMAN MOUNTAINS 57°E
57°30'
58°
58°30'
59°
Gulf of Oman Q
Jabal Bawshar
Semail Ophiolite
23°30'N
S PTr
Jabal Tayin
Wadi Hedek
J P
JK
Al Jabal al-Akhdar
23°30'
Hulw Wadi Mayh PTr Jabal Abu Da’vd
Pc CO
Wadi Mijlas Tt
CO Ja
ba
Figure 8
Saiq Plateau
25
km
Wadi Aday
Semail Ophiolite
Pc
23°
Muscat
Tt
J
N
0
l AJ by a
Ja
ba
d
lA
J
sw
ad
23°
JK
Semail Ophiolite
Tt Tt
Hamrat ad Duru Range
Ja
S
ba
57°
lH
am
m
ah
57°30'
(Q) Quaternary
Q
Jabal Safra
58°
Kawr Group (Triassic–Cretaceous)
(Tt) Tertiary
Al Aridh Group (Triassic–Late Cretaceous)
(J) Sahtan Group (Jurassic)
Umar Group (Triassic–Cretaceous)
(JK) Kahmah Group (end Jurassic–mid-Cretaceous) Baid Formation (Late Permian–Jurassic) (PTr) Akhdar Group (Late Permian–Triassic (CO) Haima Group (Cambrian–Ordovician) (P) upper Huqf Group (Precambrian–Cambrian)
Hamrat Duru Group (Late Permian–Late Cretaceous)
(Pc) lower Huqf Group (Precambrian)
S
Hawasina Nappes
Wasia Group (mid-Cretaceous)
(S) Semail Ophiolite (mid-Late Cretaceous) Metamorphic sole (mid-Late Cretaceous)
54°
BAHRAIN
Abu Dhabi UAE
N
26°
Gulf of Oman
Location Muscat
OMAN
22°
0
59° 58°
QATAR
22°
SAUDI ARABIA 200
km
Muti Formation (mid-Late Cretaceous) Aruma Group (end Cretaceous)
Q
58°30'
Arabian Sea 18° YEMEN
18° 54°
58°
Figure 1b: Localities of sections of the Permian–Triassic (PTr) formations in Al Jabal al-Akhdar that are discussed in the paper (Koehrer et al., 2010, 2012; Bendias et al., 2013; Walz et al., 2013).
105
Al-Husseini and Koehrer
Table 1 Calibration of Khuff Sequence Stratigraphy (Million Years Before Present Ma) Stage Olenekian Olenekian Induan/Olenekian Olenekian Induan Induan Induan Induan Chang/Induan Changhsingian Changhsingian Changhsingian Changhsingian Changhsingian Wuch/Chang Changhsingian Wuchiapingian Wuchiapingian Wuchiapingian Wuchiapingian Wuchiapingian Wuchiapingian Wuchiapingian Wuchiapingian Wuchiapingian Wuchiapingian Wuchiapingian Wuchiapingian Capitan/Wuchiaping Capitanian? Capitanian? Capitanian? Capitanian Capitanian Capitanian Capitanian Capitanian Capitanian Capitanian Capitanian Capitanian Capitanian Capitanian Capitanian Word/Capitanian Capitanian Wordian Wordian Wordian Wordian Wordian Wordian Wordian Wordian Roadian/Wordian
Global Sequence Boundary (SB)
J. Ogg & Orbital Orbital 405 C. Huang Surface Clock Cycle GTS-12 SB
SB Ole1
249.9
Boundary
250.0
SB In1
250.6
PTB
252.2
SB Cha3
252.5
SB Cha2
253.1
Boundary
254.2
SB Cha1
254.2
SB Wuc2
255.8
SB Wuc1
259.8
Boundary
259.8
SB Cap3
SB Cap2
262.4
264.0
SB Cap1
265.1
Boundary
265.1
SB Wor3
SB Wor2
266.4
267.5
SB Wor1
268.8
Boundary
268.8
Al Jabal al-Akhdar Oman
Iran South Fars
Zhuzang South China
1
2
249.5
616
SB 17
Sudair
Aghar Mbr
3
249.9
617
18C-12
?
KS1c
250.3
618
18C-11
KCS 1.0
KS1b
250.7
619
18C-10
KCS 1.1
KS1a
251.1
620
18C-9
SB KS1
KS2d
251.5
621
18C-8
KCS 2.1
KS2c
251.9
622
18C-7
KCS 2.2
KS2b
252.3
623
18C-6
SB KS2
KS2a
252.7
624
18C-5
?
KS3b
Sequence 16
253.1
625
18C-4
KCS 3.1
KS3a4
Sequence 15
253.5
626
18C-3
KCS 3.2
KS3a3
Sequence 14
253.9
627
18C-2
KCS 3.3
KS3a2
Sequence 13
254.3
628
SB 18C
SB KS3
KS3a1
Sequence 12
254.7
629
18B-12
?
KS4c4
Sequence 11
255.1
630
18B-11
KCS 4.1
KS4c3
Sequence 11
255.5
631
18B-10
KCS 4.2
KS4c2
Sequence 10
255.9
632
18B-9
KCS 4.3
KS4c1
Sequence 9
256.3
633
18B-8
KCS 4.4
KS4b3
Sequence 8
256.7
634
18B-7
KCS 4.5
KS4b2
Sequence 7
257.1
635
18B-6
KCS 4.6
KS4b1
Sequence 6
257.5
636
18B-5
KCS 4.7
KS4a5
Sequence 5
258.0
637
18B-4
KCS 4.8
KS4a4
Sequence 4
258.4
638
18B-3
KCS 4.9
KS4a3
Sequence 3
258.8
639
18B-2
KCS 4.10
KS4a2
Sequence 2
259.2
640
SB 18B
SB KS4
KS4a1
Zhuzang 1
259.6
641
18A-12
KCS 5.1
Nar Mbr
Emeishan
260.0
642
18A-11
KCS 5.2
260.4
643
18A-10
KCS 5.3
260.8
644
18A-9
KCS 5.4
261.2
645
18A-8
KCS 5.5
261.6
646
18A-7
KCS 5.6
262.0
647
18A-6
KCS 5.7
262.4
648
18A-5
KCS 5.8
262.8
649
18A-4
KCS 5.9
263.2
650
18A-3
KCS 5.10
263.6
651
18A-2
KCS 5.11
264.0
652
SB 18
SB KS5
Base Middle Khuff
264.4
653
19C-12
KCS 6.1
Lower Khuff 12
264.8
654
19C-11
KCS 6.2
Lower Khuff 11
265.2
655
19C-10
KCS 6.3
Lower Khuff 10
265.6
656
19C-9
KCS 6.4
Lower Khuff 9
266.1
657
19C-8
KCS 6.5
Lower Khuff 8
266.5
658
19C-7
KCS 6.6
Lower Khuff 7
266.9
659
19C-6
KCS 6.7
Lower Khuff 6
267.3
660
19C-5
KCS 6.8
Lower Khuff 5
267.7
661
19C-4
KCS 6.9
Lower Khuff 4
268.1
662
19C-3
KCS 6.10
Lower Khuff 3
268.5
663
19C-2
KCS 6.11
Lower Khuff 2
268.9
664
SB 19C
Khuff SB
Khuff SB
PTB
GLB Basalt
Oman Sayyala-29 4
1. Koehrer et al. (2010, 2012); 2. Insalaco et al. (2006); 3. Wang et al. (2011) and 4. Matthews and Al-Husseini (2010)
106
Arabian Plate Khuff Sequences
Table 2 Calibration of Global and Arabian Sequence Stratigraphic Surfaces (Million Years Before Present Ma) Stage Olenekian/Anisian Olenekian Olenekian Olenekian Olenekian Induan/Olenekian Induan Induan Induan Permian/Triassic Changhsingian Changhsingian Changhsingian Changhsingian Wuchiaping/Chang Wuchiapingian Wuchiapingian Wuchiapingian Capitan/Wuchiaping Capitanian Capitanian Capitanian Wordian/Capitanian Wordian Wordian Wordian Wordian Roadian/Wordian Roadian Roadian Kungurian/Roadian
Global Surface
GTS-04 GTS-12 Age Linear
J. Ogg & C. Huang
Error
Orbital Clock
405 Cycle
Dozon Boundary
Arabian Plate
249.5
SB 616
SB 17
Sudair SB
250.9
mid-620
MFS Tr20
251.7
mid-622
MFS Tr10
252.3
SB 623
Boundary
247.1
247.1
247.1
SB Ole4
246.6
247.7
247.9
SB Ole3
247.6
248.5
248.3
SB Ole2 SB Ole1
247.9 249.3
248.7 249.8
248.5 249.9
Boundary
249.5
250.0
250.0
SB In1 MFS Cha3
249.9
250.5
250.6 251.3
Boundary
251.0
252.2
252.2
SB Cha3
251.5
252.6
252.5
SB Cha2
252.5
253.3
253.1 253.5
253.3
mid-626
SB Cha1
253.8
254.2
254.2
254.3
SB628
Boundary
253.8
254.2
254.2
SB Wuc2
256.0
256.1
255.8 257.0
256.1
mid-633
SB Wuc1
260.4
259.8
259.8
259.2
SB 640
SB 18B
SB KS4
Boundary
260.4
259.8
259.8
SB Cap3
262.0
261.4
262.4
SB Cap2
263.0
262.4
264.0
264.0
SB 652
SB 18
SB KS5
SB Cap1
265.8
265.1
265.1
Boundary
265.8
265.1
265.1
265.2
655
268.9
SB 664
MFS Ind1
0.50
250.2
MFS Cha1
MFS Wuc1
MFS Wor3
0.50
266.5
266.9
266.4
SB Wor2
267.0
267.5
267.5
SB Wor1
267.5
268.2
268.8
Boundary
268.0
268.8
268.8
SB Roa2
268.4
269.3
269.3
SB Roa1
270.6
272.3
272.3
Boundary
270.6
272.3
272.3
SB KS3
0.30 MFS P30
0.40
0.50
265.8
SB Wor3
MFS P40 SB 18C
MFS P20
SB 19C
Khuff SB
0.50
0.50
model sequences are correlated to the empirical global sequences compiled by Snedden and Liu (2011) from the charts of Hardenbol et al. (1998) and Haq and Schutter (2008) as calibrated in the Geological Time Scale GTS 2012 (Gradstein et al., 2012; Henderson et al., 2012; Ogg, 2012; see www. stratigraphy.org; C. Huang and J. Ogg, written communications, 2012, 2013). The model and global scales are shown to share five Mid-Permian–Early Triassic sequence boundaries that are used to date the six Khuff sequences. The paper also compares the dating of the Upper Permian in South China using radiometric data and the M&H-2010 scale. The results are encouraging, and support using orbital periods to tune empirical scales to as far back as the Mid-Permian.
SEQUENCE-STRATIGRAPHIC TIME SCALES M&H-2010 Orbital Time Scale The dominant periods of the Fourier representation of the eccentricity of the Earth’s orbit around the Sun are ca. 0.1, 0.405 and 2.4 Myr (Laskar et al., 2004, 2011). These periods are predicted by the glacio-eustatic model of Matthews and Frohlich (2002) to be manifested as T-R sequences that have average durations of 0.1, 0.405, and 2.0, 2.4 and 2.8 Myr. They recommended using the term “fourthorder” for the 0.405 Myr sequence, and “third-order” for the 2.0, 2.4 and 2.8 Myr sequences. The application of these recommendations proved impractical because they conflict with the existing definitions of “orders” used in empirical sequence stratigraphy (e.g. Emery and Myers, 1996; Tinker, 1998; Table 3).
107
Al-Husseini and Koehrer
Table 3 Comparison of Nomenclature for Sequence Stratigraphy Cycle Order Reference
Second Order
Third Order
3.0–50 Myr
0.5–3.0 Myr Depositional Sequence
Fourth Order
Fifth Order
0.1–0.5 Myr Emery and Myers (1996)
Parasequence Set
Parasequence
0.1–1.0 Myr Tinker (1998)
10–100 Myr Supersequence
1.0–10 Myr Composite Sequence
M&H-2010 scale and Matthews and Frohlich (2002)
14.58 Myr Orbiton (36 Stratons)
4.86 Myr Dozon (12 Stratons)
High-frequency Sequence HFS)
Cycle Set
0.405 Myr Straton (Long Eccentricity)
0.01–0.10 Myr Cycle
0.1 Myr (Short Eccentricity)
Note: Throughout this paper sequence-stratigraphic terms, such as “third-order”, “parasequence”, “cycle”, etc. (Table 3) are shown in quotation marks as used by the original authors. To circumvent confusion regarding the usage of sequence-stratigraphic terms, Matthews and Al-Husseini (2010) introduced the term “straton” to mean the T-R sequence that has an average duration of 0.405 Myr (Laskar et al., 2004, 2011). In the M&H-2010 scale, stratons are identified by integer numbers with Straton 1 starting at ca. 372,000 years ago (0.372 Ma) and continuing today. The age for the start of any straton (e.g. Straton M) is: Age for start of Straton M = (M-1) x 0.405 + 0.372 Ma For example, Straton 623 (M = 623) is important because it may contain the Permian/Triassic Boundary (PTB) dated in GTS 2012 as 252.2 Ma (Table 1), and between 252.28 ± 0.08 and 252.10 ± 0.06 Ma (Shen et al., 2011). The age for the start of Straton 623 is estimated as: (623-1) x 0.405 + 0.372 = 252.281 = ca. 252.3 Ma The M&H-2010 scale predicts that the Middle Permian to Lower Triassic contains five regional sequence boundaries (SB) that are separated by intervals of 4.86 Myr (12 x 0.405 Myr) and that bound groups of 12 stratons. From youngest to oldest the five regional boundaries are named SB 17A, SB 18C, SB 18B, SB 18A and SB 19C (Figure 2; Tables 1 and 2). The 36 stratons that occur between sequence boundaries denoted by the letter “A” form an “orbiton” (e.g. Orbiton 18 between SB 18A and SB 17A, Figure 2). The sequence boundaries denoted by the letter “A” may, in some cases, be more prominent and the age of their lower sequence boundary (SB without an “A”) is calculated as follows: Age of SB N = 1.586 + N x 14.58 Ma For example, for N = 17, the age of SB 17 (Sudair SB in Figure 2; Tables 1 and 2) is: Age of SB 17 = 1.586 + 17 x 14.58 = 249.446 = ca. 249.5 Ma.
Global Sequence Boundaries in GTS 2012 Table 2 shows the age estimates for the stage boundaries of the Mid-Permian (Guadalupian), Late Permian (Lopingian) and Early Triassic epochs in GTS 2004 (Ogg, 2004; Wardlaw et al., 2004; Gradstein et al., 2004) and their revisions in GTS 2012 (Ogg, 2012; Henderson et al., 2012; Gradstein 108
Arabian Plate Khuff Sequences
Ole4
250.0 ± 0.5
Changhsingian
Tr20
251.3
252.2 ± 0.5
Tr10
252.5
Cha2
MFS P40
253.1 253.5
Cha1 254.2 ± 0.3
Age (Ma)
Sudair Formation
249.9 250.2 250.6
Ind1
Sequence
-100
Ole1
Cha3
Lopingian (Late)
0
247.9 248.3 248.4
Ole3 Ole2
Induan
255
100
MFS
254.2
Dozon
Dozon 17A
Sudair SB
249.5
Khuff Sequences KS2 + KS1
250.9 251.7
SB KS2
252.3
Khuff Sequence KS3
253.3
SB KS3
254.3
Orbiton
1.0
Landward 0.5 0.0
Sea Level (m)
Orbiton 17
Olenekian Early
TRIASSIC
250
Coastal Onlap
Stage/Age (Ma) 247.1 ± 0.5
M&H-2010 Orbital Scale
SB 17
Dozon 18C
SB 18C
Wuc2 255.8
Wuchiapingian
MFS P30
257.0
256.1
Khuff Sequence KS4
Dozon 18B
Orbiton 18
Epoch
Age (Ma)
Period
GTS 2012
Wuc1
SB KS4 259.8 ± 0.4
PERMIAN
?
262.4
MFS P25
Cap2
Guadalupian (Middle)
264.0 265
SB 18B
Khuff Middle Anhydrite
Cap3
Capitanian
259.2
Dozon 18A
Khuff Sequence KS5
262.4
SB KS5
264.0
SB 18
Cap1 265.1 ± 0.5 Wor3
265.8 266.4
Wordian
MFS P20
265.1
Wor2
Presentday sea level
265.2
Khuff Sequence KS6
Dozon 19C
267.5 Wor1 268.8 ± 0.5
Roa2
268.8
Longterm trend
270
Roadian
272.3 ± 0.5
Khuff SB
269.3
Roa1
Gharif Formation
268.9
SB 19C
Orbiton 19
260
259.8
Dozon 19B
272.3
Figure 2: Correlation of the six Khuff sequences KS6 to KS1 to the global T-R sequences compiled by Snedden and Liu (2011) for Triassic (Hardenbol et al., 1998) and Permian (Haq and Schutter, 2008) in the Geological Time Scale GTS 2012 (Henderson et al., 2012; Ogg, 2012; C. Huang and J. Ogg, written communication, 2012, 2013; see also Tables 1 and 2). The global and Khuff sequences are also correlated to the model M&H-2010 orbital scale (Matthews and Al-Husseini, 2010) constructed by dozons (4.86 Myr) and orbitons (14.58 Myr). 109
Al-Husseini and Koehrer
et al., 2012). The stage boundaries in GTS 2012 carry an estimated uncertainty of between ± 0.3 and ± 0.5 Myr) (Figure 2). The global sequences in Figure 2 are compiled in Snedden and Liu (2011) from Hardenbol et al. (1998) for the Cenozoic–Mesozoic (Early Triassic in Figure 2), and Haq and Schutter (2008) for the Paleozoic (Middle and Late Permian in Figure 2). The sequences are named after the first three letters of the stage in which their lower sequence boundary (SB) occurs, followed by an integer. For example, Capitanian Sequence Cap2 occurs between SB Cap2 at 264.0 Ma and base Wuchiapingian SB Wuc1 at 259.8 Ma (Figure 2). Three age estimates for each sequence boundary are given in Table 2. The first is from GTS 2004 (Sneddon and Liu, 2011), and the second is its recalibration in GTS 2012 by linear interpolation between stage boundaries. The third estimate was made by C. Huang and J. Ogg (written communications, 2012, 2013), and differs in some cases from the linear interpolation. For example, the linear interpolation from GTS 2004 to GTS 2012 implies an age of 268.2 Ma for Wordian SB Wor1. In contrast, C. Huang and J. Ogg correlate SB Wor1 to base Wordian at 268.8 + 0.5 Ma. A significant difference occurs for the age of Capitanian SB Cap2 with an age of 262.4 Ma by linear interpolation versus 264.0 Ma taken at the base of Jinogondolella altudaensis Zone in GTS 2012 by C. Huang and J. Ogg (written communications, 2012, 2013). The chronostratigraphic constraints for the global sequences (Hardenbol et al., 1998; Haq and Schutter, 2008), as well as those for Saudi Arabia (Haq and Al-Qahtani, 2005), have not been documented in the public domain. It is therefore not possible to assess their accuracy except possibly where they are shown to correlate to stage boundaries as in the case of the Middle and Upper Permian. As discussed below three stage boundaries are correlated to Khuff sequence boundaries (Figure 2). In contrast to the Permian stage boundaries, the Triassic stage boundaries and the Permian/Triassic Boundary (PTB) are not correlated to global sequence boundaries.
Correlation of Five Key Sequence Boundaries in the GTS 2012 and M&H-2010 Scales The five Middle Permian–Lower Triassic sequence boundaries that separate dozons in the M&H2010 scale can be correlated by numerical age to within + 0.6 Myr to five global sequence boundaries (Figure 2; Tables 1 and 2) as calibrated by C. Huang and J. Ogg (written communications, 2012, 2013): • • •
• •
Orbital SB 17 at 249.5 Ma is about 0.4 Myr younger than SB Ole1 at 249.9 Ma, and is within the + 0.5 Myr uncertainty for estimates in the Early Triassic. Orbital SB 18C at 254.3 Ma correlates to SB Cha1 at 254.2 Ma. Orbital SB 18B at 259.2 Ma is about 0.6 Myr younger than SB Wuc1 corresponding to the Middle/Lower Permian Boundary (Guadalupian/Lopingian Boundary, GLB) at 259.8 + 0.4 Ma. The correlation is adopted because the alternative global correlatives, SB Cap3 or SB Wuc2, result in greater mis-ties. The age of the Middle/Lower Permian Boundary is not well constrained. It was revised from 260.4 + 0.7 in GTS 2004 to 259.8 + 0.4 Ma in GTS 2012 (Table 2), and other estimates range between 262.3 Ma (Menning et al., 2008) and 259.0 Ma (Shen et al., 2010). As discussed on pages 112–113 and in Figure 3, astronomical tuning of the Upper Permian Series in South China, suggests the age of the boundary is close to the orbitally predicted 259.2 Ma. Orbital SB 18 correlates to early Capitanian SB Cap2 at 264.0 Ma. Orbital SB 19C at 268.9 Ma correlates to SB Wor1 and the Roadian/Wordian Boundary dated at 268.8 ± 0.5 Ma.
KHUFF SEQUENCES KS6 TO KS1 This section reviews the sequence and biostratigraphic constraints of the six Khuff sequences KS6 to KS1, mainly in subsurface Oman (Figures 4 and 5, Osterloff et al., 2004), the outcrops in Al Jabal al-Akhdar in Oman (Enclosure, Figures 6 and 8, Koehrer et al., 2010, 2012), as well as
110
Arabian Plate Khuff Sequences
Khuff Sequences KS4 to KS1 in the South Fars region in subsurface Iran (Figures 7 and 9, Insalaco et al., 2006). It starts with the lower boundary of the oldest Khuff Sequence KS6, the Khuff Sequence Boundary (Khuff SB), proceeds upwards through the six Khuff sequences KS6 to KS1, ending with the upper boundary of Khuff Sequence KS1, the Sudair Sequence Boundary (Sudair SB).
Khuff Sequence Boundary (Khuff SB): 268.9 Ma The Khuff SB or correlative Sub-Khuff Unconformity in subsurface Oman separates the terrestrial clastics of the Gharif Formation from the overlying carbonates or mixed clastics-carbonates in the lower part of the Khuff Formation (Figures 4 and 5, Osterloff et al., 2004). On the Saiq Plateau, Permian terrestrial clastics, about 15 m thick, unconformably overlie lower Paleozoic or Proterozoic formations (Enclosure and Figure 6; Koehrer et al., 2010; Bendias et al., 2013). The unconformity is sometimes referred to as “Hercynian unconformity”, “midCarboniferous unconformity” or “pre-Khuff unconformity” (e.g. Sharland et al., 2001). It is here referred to as the “Sub-Permian Unconformity”. The terrestrial clastics are known as the “lower Saiq member”, “Saiq unit A1”, “basal Saiq clastics”, or “basal Khuff clastics”. The latter term is believed to be misleading because by stratigraphic position, lithology and fluvial-estuarine depositional setting the terrestrial clastics correlate to the subsurface Gharif Formation (Figures 4 and 5; Al-Husseini and Matthews, 2010). The Khuff SB on the Saiq Plateau is picked at the boundary between the “lower Saiq member” and the overlying mixed clastics and carbonates of the Khuff-equivalent part of the Saiq Formation (Enclosure and Figure 6). Over paleohighs in Al Jabal al-Akhdar, the terrestrial clastics are absent and the Sub-Khuff Unconformity (Khuff SB) merges with the Sub-Permian Unconformity. The Khuff SB can be traced from the Arabian Peninsula into the Zagros Mountains where it separates the carbonates and evaporites of the Dalan Formation from the underlying terrestrial clastics of the Faraghan Formation or older rocks (Szabo and Kheradpir, 1978; Al-Jallal, 1995; Insalaco et al., 2006). In the Alborz Mountains in North Iran it passes to the base of the Wordian– Capitanian Ruteh Limestone Formation, which overlies the terrestrial clastics of Shah Zeid Formation or Dorud ironstone (Gaetani et al., 2009; Crippa and Angiolini, 2012). Age: The lowermost part of the Khuff Formation is assigned to the Neoschwagerina schuberti Zone implying the start of the transgression that deposited the Khuff Formation and equivalents is mid-Murghabian (Montenat et al., 1976; Rabu et al., 1986). However, the relationship between the Murgabian Stage of the Pamirs Realm and the North American Roadian and Wordian stages in GTS 2012 is not precisely established (Henderson et al., 2012; Davydov and Arefifard, 2013). Most biostratigraphic studies assign the Khuff SB to the Wordian Stage. In the Al Huqf outcrops in Oman (Figure 1), brachiopod fauna found in Khuff Member 3, which occurs about 15 m above the Khuff SB, indicate a Wordian age (Angiolini et al., 1998, 2003, 2004). Palynological studies of the Gharif and Khuff formations in subsurface Oman and Saudi Arabia indicate the Khuff SB occurs at the base of Oman-Saudi Arabia Palynological Zone OSPZ6 in the Wordian (Stephenson et al., 2003; Stephenson, 2006). Baud and Bernecker (2010) confirmed the Wordian age for the basal part of the Khuff-equivalent Maqam Formation in Wadi Maqam (Figure 1) by citing the finding of conodonts Hindeodus excavatus and Hindeodus wordensis by C. Henderson and A. Nicora in 2009. Based on the foraminiferal assemblage found in Al Jabal al-Akhdar (Presumatrina and primitive Afghanella species), H. Forke (written communication, 2012) considered the onset of carbonate deposition to occur between the base of the Murgabian (late Roadian?–Wordian) to the lower part of middle Murgabian (Wordian). Dating of the Khuff Formation using strontium-isotope measurements has been attempted but was inconclusive. Stephenson et al. (2012) measured 87Sr/86Sr ratios from several brachiopods taken from Khuff Member 3 in Al Huqf. They obtained a mean value of 0.7027, which implies a Roadian or even Kungurian age (see their figure 4, and figure 24.9 in GTS 2012; Henderson et al., 2012). They considered the global strontium-isotope dataset to be insufficiently sampled in the Wordian– Roadian interval and retained a Wordian age for the Khuff SB. (Continued on p. 114) 111
Al-Husseini and Koehrer
Limestone, silicalite, muddy algal siltstone, muddy.
K2
Bioclastic micrite, cherty limestone.
Lagoon
Siltstone, fine sandstone, algal limestone and sandy mudstone.
Tidal flat and mire Lagoon Subtidal Mire Tidal flat and tidal channel Lagoon
K3-1 C5
254.2 Ma
K4 C7
250
K5-1 K5-2
Calcarenaceous and lithic sandstone and siltstone.
K6 C14
Muddy fine sandstone and siltstone.
200
C16 C17
Longtan Formation
C18
Wuchiapingian
UPPER PERMIAN (LOPINGIAN)
C11 C12
C19 C20
Mire Distributary channel Interdistributary bay Tidal channel Distal bar Mire Tidal channel Interdistributary bay Mire
Siltstone, sandstone.
Distal bar
Fine sandstone, siltstone and sandy mudstone.
Tidal flat
Calcareous fine sandstone with interbeds of (muddy) siltstone. Muddy siltstone and fine sandstone.
K11 C32 K12
Muddy siltstone, limestone.
259.8 Ma
GTS 2012
Fine sandstone, (muddy) siltstone, with interlayers of mudstone and limestone.
Emeishan Basalt (259-260 Ma)
Figure 3: See facing page for caption and legend. 112
SS
Straton
13
627
12
628
629
630
LSS 10
631
9
632
8
633
7
634
6
635
5
636
4
637
3
638
TSS
2
639
LSS
1
640
HSS
Tidal flat Mire Lagoon
CSII
Mire TSS
Mire Tidal channel Mire Tidal flat Mire Tidal flat Mire Lagoon Mire
C34-1
C34-2 K13 C35
626
11
Tidal flat and mire
C29
14
Distributary channel
K9 C27 C28
625
TSS
Mire
Calcareous siltstone, fine sandstone, mudstone.
K8
15
CSIII
Tidal flat and mire
C23
50
HSS
Lagoon Tidal flat Tidal channel Mouth bar
Muddy siltstone and muddy limestone.
K7-2
100
Mire Lagoon Mire
Muddy siltstone with layers of ferrous limestone.
K7-1
624
Tidal flat
Siltstone, sandy mudstone and bioclastic micrite. Calcarenaceous siltstone, muddy siltstone. Siltstone, fine sandstone, sandy mudstone.
16
Mire
Siltstone, mudstone and algal limestone.
C8 C9
4th order Sequence
Tidal flat and mire
Siltstone, sandy mudstone and algal limestone.
K3-2 C6-1 C6-2
150
Sedimentary Facies
K1 C1
C2
300
Lithological Association
CS
Sedimentary Features
Tidal flat and lagoon
Lithology
Lower deltaic plain
252.2 Ma
Changxing Formation
Changhsingian
EARLY TRIASSIC
Depth (m) Age
Tidal flat and mire Subtidal bar Lagoon Mire and paleosol
LSS
Tidal flat-lagoon
Stratigraphy
MB (K) Coal (C)
ZHUZANG SECTION, GUIZHOU PROVINCE, SOUTH CHINA
HSS CSI
SB 18C (259.2 Ma)
Arabian Plate Khuff Sequences
UPPER PERMIAN (LOPINGIAN) SERIES IN SOUTH CHINA The chronostratigraphy and sequence stratigraphy of the Upper Permian Series in South China provide a good dataset for testing the accuracy of the M&H-2010 scale. Several sections that represent this series in South China contain radiometrically dated volcanic rocks at various stratigraphic levels, as well as the three Global Boundary Stratotype and Section Points (GSSP, Golden Spike) of the Upper Permian: (1) PTB: Permian/Triassic Boundary (Yin et al., 2001) dated 252.3 Ma (Shen et al., 2010) and 252.2 ± 0.5 Ma in GTS 2012; (2) WCB: Wuchiapingian/Changsinghian Boundary (Jin et al., 2006b) dated at 254.0 Ma (Shen et al., 2010) and 254.2 ± 0.3 Ma in GTS 2012; (3) GLB: Guadalupian/Lopingian Boundary (Jin et al., 2006a) corresponding to the Capitanian/ Wuchiapingian Boundary and Middle/Upper Permian Boundary, dated at 259.8 ± 0.4 Ma in GTS 2012 (Henderson et al., 2012). In many localities in South China the Upper Permian Series immediately overlies the Emeishan Basalt dated 259.0 ± 3.0 Ma (Shen et al., 2010), and which also correlates to global Wuchiapingian SB Wuc1 (Figures 2 and 3). One section that is particularly appropriate for testing the M&H-2010 scale is located at Zhuzang in the Zhijin coalfield, western Guizhou Province of South China (Figure 3 and Table 1; Wang et al., 2011). In this section the Upper Permian Series overlies the Emeishan Basalt, consists of 16 “fourth-order” sequences without evidence of significant hiatuses, and is capped by the Permian/Triassic Boundary at the top of Sequence 16 (Wang et al., 2011). With the exception of Sequence 11, the thickness of the sequences ranges between 10 and 30 m and is 21 m on average (Figure 3). Sequence 11 is exceptionally thicker at 55 m and has a mire (bog) sedimentary facies near its interpreted maximum flooding surface, which in several other sequences is interpreted as a sequence boundary. It is therefore likely that Sequence 11 contains two stratons (2 cycles of 0.405 Myr) and that the Upper Permian in Zhuzang consists of the 17 stratons 640 to 624 in Figure 3. Converting the 17 stratons to time at 0.405 Myr/straton gives 6.9 Myr, and subtracting this interval from the age of model SB 18B at 259.2 Ma (Figure 2), implies the PTB at the top of Sequence 16 has an age of 252.3 Ma, just 0.1 Myr older than the estimate in GTS 2012.
SB
Decrease A/S mfs Increase A/S
Sandstone
Chert
Horizontal bedding
Siltstone
Fossils
Wavy bedding
Muddy siltstone
Plant leaves
Bidirectional bedding
Silty mudstone
Rootlets
Siderite
Mudstone
Lenticular bedding
TSS : Transgressive Sequence Set
Basalt
Tabular bedding
HSS : Highstand Sequence Set
Limestone
Small cross bedding
CS : Composite Sequence
Coal
Flaser bedding
MB : Marine band (K)
SB
SS : Sequence Set LSS : Lowstand Sequence Set
Figure 3 (continued): Zhuzang Section from Zhijin coalfield, western Guizhou Province, South China (Wang et al., 2011). The section represents the Upper Permian (Lopingian) starting immediately above the Emishan Basalt and ending at the top of fourth-order Sequence 16 at the Permian/Triassic Boundary (PTB). The section is interpreted in terms of 16 fourth-order sequences by Wang et al. (2011) and 17 stratons (0.405 Myr) in this paper.
113
Al-Husseini and Koehrer (Continued from p. 111) Global and Orbital Correlations: A Wordian age for the Khuff SB implies it is younger than early Wordian SB Wor1 with an estimated age of 268.2 Ma by linear interpolation or 268.8 Ma as estimated by C. Huang and J. Ogg (written communications, 2012, 2013). It may be as young as mid-Wordian SB Wor2 at 267.5 Ma, or late Wordian SB Wor3 at 266.4 Ma. In the M&H-2010 scale the Khuff SB is correlated to SB 18C at 268.9 Ma, close to the Roadian/Wordian Boundary (268.8 ± 0.5 Ma in GTS 2012) and SB Wor1 (Figure 2).
Khuff Sequence KS6: 268.9–264.0 Ma The Lower Khuff Member in subsurface Oman overlies the Gharif Formation and is overlain by the massive carbonates of the Middle Khuff Member (Figures 4 and 5). The thickness of the Lower Khuff Member varies from about 30 m in South Oman to a maximum of 330 m in the Lekhwair-70 Well (Figure 1a, Osterloff et al., 2004). A. Al-Harthy (2000, PDO unpublished report in Osterloff et al., 2004) interpreted the Lower Khuff Member in terms of three regional sequences, denoted P17, P18 and P19, the latter containing the regionally correlative “Khuff Marker Limestone” (KML, Figures 4 and 5), here interpreted to correspond to Wordian MFS P20 (Sharland et al., 2001, 2004). Al-Husseini and Matthews (2010) correlated the Lower Khuff Member to Khuff Sequence KS6 on the basis of stratigraphic position in the lowermost part of the formation. In the Sayyala-29 Well the Lower Khuff Member is 144 m thick, and based on the motif of the density log and carbonateshale cyclicity they interpreted it as 12 subsequences, denoted LK1 to LK12 (LK for Lower Khuff) in ascending order (Figure 5 and Table 2). On the Saiq Plateau in the Oman Mountains, Koehrer et al. (2010) interpreted Khuff Sequence KS6 (167 m thick) between the top of the “lower Saiq member” (possibly Gharif Formation below the Khuff SB) and Microbial Marker 1 (SB KS5) (Enclosure and Figure 6). They divided the sequence into 12 “cycles”, 5–30 m thick, and considered them as “fifth-order”. Bendias et al. (2013) interpreted the same Saiq Plateau KS6 section in terms of 14 “fourth-order” cycle sets of which two occur in the “lower Saiq member”. They interpreted 43 “fifth-order” cycles in Khuff Sequence KS6 (Enclosure). It is here suggested that the 12 “cycles” of Koehrer et al. (2010) are “cycle sets” and may correlate, onefor-one, to the 12 subsequences LK1 to LK12 in the Sayyala-29 Well (Enclosure, Figures 5 and 6). Age: By stratigraphic position above the Khuff SB, the age of the lower part of KS6 is Wordian. The age of its upper part is not constrained, and may be Wordian or early Capitanian (Koehrer et al., 2010, 2012; Forke et al., 2012). Wordian Maximum Flooding Surface MFS P20: Wordian MFS P20 of Sharland et al. (2001, 2004) is here interpreted to correspond to the MFS of Khuff Sequence KS6 (Figures 4 and 5). In Al Jabal al-Akhdar, Koehrer et al. (2010) interpreted one MFS in Sequence KS6 in a 15 m-thick unit named the “Muddy Marker” in cycle set KCS 6.4 (Enclosure). It contains thick stacks of massive dark-blue, bioturbated mudstone. They considered it the lowest energy zone, mainly characterized by suspension setting, starvation and background sedimentation below storm wave base. They suggested its dark blue color may be due to less oxygenated waters in a deeper-water setting. The “Muddy Marker” may correlate to the Khuff Marker Limestone (KML), which is a regionally correlative pure carbonate unit in subsurface Oman (Osterloff et al., 2004; compare Figures 4 to 6, Enclosure). A possible position for MFS P20 may be in Straton 655 (ca. 265.2 Ma) and the late Wordian MFS Wor3 at 265.8 Ma in global Sequence Wor3 (Figure 2). Global and Orbital Correlations: If Sequence KS6 consists of 12 stratons and the Khuff SB occurs near the base Wordian, then KS6 would correlate to Dozon 19C between 268.9–264.0 Ma, and SB KS5 would correlate to SB 18 at 264.0 Ma (Figure 2). In this scenario, Sequence KS6 would correlate to the four global sequences Wor1 to Wor 3 and Cap1 between 268.8–264.0 Ma (Figure 2).
Khuff Sequence KS5: 264.0–259.2 Ma Osterloff et al. (2004) interpreted three sequences, denoted P20, P23 and P27, between the top of the Lower Khuff Member (Sequence KS6) and the top of the “Khuff Middle Anhydrite” (Figure 4). The top of the Khuff Middle Anhydrite is a regional sequence boundary that is readily recognized in
114
Arabian Plate Khuff Sequences
Gamma-Ray (API)
0.0
Sonic
150.0
(μsec/m) 500.0
Compensated Neutron Log
Lithology
Depth (meter)
Sequence
Member
Formation Sudair
45.0
Density
KS1
1.95
UPPER PERMIAN
?
Khuff Formation
1,760
Dominated by limestones and dolomites with thin interbeds of shale and occasional anhydrites.
Tr20
1,800
Limestone-mudstone/ wackestone, variable argillaceous, generally light gray.
1,860 1,880
Tr10
PTB GR Signature
1,900
Key identifying elements:
1,920
(1) The upper boundary is here conformable and picked at the contact of continuous carbonates with the red or gray-green shales of the basal Sudair and marked by a decrease in gamma.
P40
1,940 1,960
P35
2,000
KS4
P30
(2) The lower boundary is conformable marked by a sharp change from carbonates to clastics of the Gharif and an increase in gamma and sonic and a sharp break on the neutron-density.
P27
(3) Occurrence of anhydrite in the Middle Khuff. Uppermost section below the Sudair may be slightly anhydritic.
2,020 2,040
Middle
2,060
Middle Anhydrite
2,080
Khuff Sequence KS5
2,100 2,120 2,140 2,160
P23
2,180 2,200
P20
2,220 2,240
? KML P19
2,260
Khuff Sequence KS6
Lower
2,280
Gharif
Dolomite, anhydritic, often with relict textures. Shale, variable calcareous, varicolored red, green-gray, gray.
1,980
Khuff
2.95
1,840
KS3
Descriptive Lithology
1,740
1,820
KS2
MIDDLE PERMIAN
-15.0
(gm/cc)
100.0
1,780
Upper
LOWER TRIASSIC
Series
HASIRAH-1, KHUFF FORMATION, AKHDAR GROUP, OMAN
2,300 2,320
P18
2,340 2,360
(4) Top of the Middle Khuff coincides with the top occurrence of Permian fauna (benthonic forams, algae) and is always placed at the base of a distinct shale unit (red or gray-green cf. Sudair shales). (5) The boundary between the Middle and Lower Khuff is quite distinctly marked by the change to a sequence of continental mottled red, green and gray shales and marine limestones. To the south the continental deposits predominate. Marked by a sharp increase in gamma and sonic and a sharp break on the neutron-density. (6) A "Marker Limestone" bed is identified in the Lower Khuff of South and Central Oman. It loses its character northwards to Lekhwair.
2,380
P17
2,400 2,420
Khuff SB
2,440
Gharif Formation
Figure 4: Hasirah-1 Well showing positions of Khuff depositional sequences P17 to Tr20 of Osterloff et al. (2004). Note Wordian MFS P20 should be repositioned in the Khuff Marker Limestone (KML). 115
Al-Husseini and Koehrer
KHUFF SEQUENCE KS6, SAYYALA-29, CENTRAL OMAN Density
(API)
150
Sonic
40
Arabian Plate Sequence
2.95
Porosity (%)
0.45
-0.15
Straton
(msec/ft)
(gm/cc)
1.95
Subsequence
Middle Khuff Member
140
Lithology
LK12
653
LK11
654
LK10
655
LK9
656
LK8
657
LK7
658
LK6
659
LK5
660
1,200
LK4
661
1,210
LK3
662
LK2
663
LK1
664
1,070
1,080
Dozon 18A
0
KS5
Gamma-Ray Local Stratigraphy
1,090
1,100
1,110
KML
SB KS5 (ca. 264.0 Ma)
MFS P20
1,160
MFI P18
1,180
1,190
1,220
1,230
Upper Member
Haushi Group
Gharif Formation
Roadian
1,240
Dozon 19C
1,150
Khuff Sequence KS6
1,140
Lower Khuff Member
Khuff Formation
Akhdar Group
Middle
PERMIAN
Wordian−Capitanian
1,130
MFI P17
Khuff Sequence Boundary (ca. 268.9 Ma)
1,250
1,260
Fine clastics Carbonates
1,270 m
Figure 5: Type section of Khuff Sequence KS6 in subsurface Oman is taken in Sayyala-29 Well. A. Al-Harthy (2000, PDO unpublished report in Osterloff et al., 2004) divided the Lower Khuff Member into three transgressive-regressive cycles with maximum flooding intervals (MFI) P17, P18 and P19 (Khuff Marker Limestone, KML). Based on the character of the density log and shale/carbonate lithology, the Lower Khuff Member is interpreted in terms of 12 subsequences (LK for Lower Khuff) and correlated to stratons 664 to 653. Wordian MFS P20 of Sharland et al. (2001, 2004) is here repositioned in the Khuff Marker Limestone (KML). 116
Arabian Plate Khuff Sequences
many regions of the Middle East: top “Khuff Median Anhydrite” in the United Arab Emirates and Qatar, top “Khuff-D Anhydrite” in Saudi Arabia, top Nar Member of Dalan Formation in Iran, and top Satina Member in Iraq (Al-Jallal, 1995; Sharland et al., 2001). Al-Husseini and Matthews (2010) correlated Sequence KS5 to sequences P20, P23 and P27 (Figure 4). Koehrer et al. (2010) interpreted Khuff Sequence KS5, 214 m thick, on the Saiq Plateau between “Microbial Marker 1” (SB KS5) and “Microbial Marker 2” (SB KS4), and divided it into the 12 “cycle sets” KCS 5.1 to KCS 5.12 in descending order (Enclosure and Figure 6). In contrast, Walz et al. (2013) interpreted four “high-frequency” sequences (HFS KS 5-I to HFS KS 5-IV) and 19 “cycle sets” in the same section. The difference between 12 and 19 “cycle sets” in the same Saiq Plateau KS5 section indicates that more rigorous criteria and additional (chrono-) stratigraphic calibration data are required to interpret sequences in terms of sequence hierarchy and order. In the Wadi Hedek Section (272 m thick, Figure 1b), Walz et al. (2013) interpreted 21 medium-scale, “fourth-order” cycle sets and 66 small-scale “fifth-order” cycles. Age: The age of Sequence KS5 is Capitanian based on the presence of Sphairionia sikuoides (Forke et al., 2012). In the uppermost part of the sequence the occurrence of miliolid foraminifer Shanita amosi and several other genera (e.g. Paraglobivalvulina, Rectostipulina) indicate a latest Capitanian age (Insalaco et al., 2006; Forbes et al., 2010; Koehrer et al., 2010, 2012; Forke et al., 2012). These genera occur immediately below the Middle Khuff Anhydrite in the subsurface (Insalaco et al., 2006; Forbes et al., 2010; Koehrer et al., 2010, 2012; Forke et al., 2012). Capitanian Maximum Flooding Surface MFS P25 (?): Sharland et al. (2001, 2004) positioned Wordian MFS P20 in the lower part of the subsurface Middle Khuff Member, which is here interpreted as Capitanian (Figures 4 and 5). It is recommended to re-position MFS P20 into the Lower Khuff Member and use Capitanian MFS P25 (?) instead, corresponding to the “Chert Marker” in outcrops of the Al Jabal al-Akhdar (Koehrer et al., 2010; Walz et al., 2013). Global and Orbital Correlations: As noted above biostratigraphic evidence indicates the upper part of Sequence KS5 is latest Capitanian implying SB KS4 correlates in the global scheme to basal Wuchiapingian SB Wuc1 at 259.8 Ma in GTS 2012 (i.e. Capitanian/Wuchiapingian Boundary, Guadalupian/Lopingian Boundary, GLB, Middle/Upper Permian Boundary) (Figure 2). In the orbital model Sequence KS5 is correlated to Dozon 18A between 264.0 and 259.2 Ma, and the 12 cycle sets KCS 5.1 to KCS 5.12 on the Saiq Plateau to stratons 652–641 (Figure 6). Based on the proposed orbital correlation, Sequence KS5 might correlate to two global Capitanian sequences Cap2 and Cap3 between 264.0–259.8 Ma (Figure 2).
Khuff Sequence KS4: 259.2–254.3 Ma In subsurface Oman (Figure 4), Sequence KS4 corresponds to sequences P30 and P35 and possibly the lower part of P40 of Osterloff et al. (2004). Koehrer et al. (2010, 2012) interpreted Khuff Sequence KS4 on the Saiq Plateau (Enclosure and Figure 6) and correlated it across the outcrops in Al Jabal al-Akhdar in Oman (Figure 1b), where it ranges in thickness from 152 m to 171 m. They considered it a “third-order” sequence and divided it into two “high-frequency” sequences (HFS), HFS KS4b and HFS KS4a (here renamed as HFS KS4-I and HFS KS4-II to avoid confusion with terms used in South Fars by Insalaco et al., 2006; Enclosure), 11 “fourth-order” cycle sets (KCS 4.1–KCS 4.11, in descending order), and 66 “fifth-order” cycles. Insalaco et al. (2006) interpreted Khuff Sequence KS4 above the Nar Member of the Dalan Formation in Iran (Figures 1a and 7). It is ca. 159 m thick in subsurface South Fars, 114 m in Kuh-e Surmeh and 117 m in Kuh-e Dena. They considered it a “third-order” composite sequence, and divided it into three “fourth-order” T-R sequences (KS4a, KS4b, KS4c in ascending order) and 12 “parasequence sets” (KS4a1 to KS4a5, KS4b1 to KS4b3, KS4c1 to KS4c4). Age: Khuff Sequence KS4 is interpreted in both Iran and Al Jabal al-Akhdar as representing the Wuchiapingian Stage (Insalaco et al., 2006; Koehrer et al., 2010, 2012).
117
Al-Husseini and Koehrer
720
4.1
630
4.2
631
4.3
220
280
662
300
663 664
SB 19C ?Roadian–Wordian Khuff SB (268.9 Ma) Gharif Fm Sub-Permian Unconformity
Figure 6: (a) Koehrer et al. (2010) interpreted Khuff Sequence KS6 on the Saiq Plateau above the Basal Saiq Clastics (probably the Gharif Formation) to consist of 12 cycles that are here correlated to stratons 664 to 653 of Dozon 19C between 268.9 (SB 19C, Khuff SB) and 264.0 Ma (SB 18). (b) Koehrer et al. (2010, 2012) interpreted Khuff sequences KS5 and KS4 in terms of 12 and 11 cycle sets, respectively. The 23 cycle sets are here correlated to stratons 652 to 629 of dozons 18A and 18B. Note in Dozon 18B one straton is assumed to be unidentified and arbitrarily shown as Straton 634 in Khuff Cycle Set KCS4.6. (See Figure 1 for location, Figure 2 and Enclosure, Tables 1 and 2 for overview of Khuff sequence stratigraphy).
633
634?
320
340
SB 18B SB KS4
259.2 Ma 360
380
400
420
440
460
480
500
4.4
4.5
MFS P30 635
4.6
636
4.7
637
4.8
638
4.9
639
4.10
640
4.11
641
5.1
642
5.2
643
5.3
644
5.4
645
5.5
646
5.6
647
5.7
MFS 648 P25
5.8
649
5.9
650
5.10
651
5.11
652
5.12
520
540
SB 18 SB KS5 (264.0 Ma)
560
118
3rd KS KS3
Straton 629
632
661 700
Stage
200
260
KCS 4th
Khuff Sequence KS4 (170 m)
660
Chan. 254.3 Ma
240
5th
Khuff Sequence KS5 (214 m)
659
40
Cyclicity
628
Khuff Formation
658
(API)
10
Wuchiapingian (Dozon 18B)
657
GammaRay
SB 18C SB KS3
180
654
MFS 656 P20
(meter)
3rd KS
Capitanian (Dozon 18A)
680
4th
Khuff Sequence KS6 (167 m)
660
160
655
Khuff Formation
640
40
264.0 Ma
Wordian–Capitanian (Dozon 19C)
620
(API)
Cyclicity
SB KS5 653
580
600
10
Straton
Formation
Stage
(meter)
Depth
560
Total GammaRay
Depth
(b)
(a)
Formation
KHUFF SEQUENCES KS6, KS5 AND KS4, SAIQ PLATEAU, OMAN
Arabian Plate Khuff Sequences
KHUFF SEQUENCE KS4, SOUTH FARS, IRAN
South KS4c4 629
Restricted facies, internal sands and lagoons Main reservoir intervals
Sequence KS4c (58 m)
Major exposure surface and breccia unit
KS4c1 thin (~1 m) dolomitic reservoir level
KS4c3 630
Maximum Accommodation Zone (MAZ)
Zone of mouldic bioclastic and oolitic transgressive sandwave complexes
KS4c2 631
SB 18C (254.3 Ma)
North
"Muddy" maximum flooding zone mudstone layer with "open" bioclast elements followed by azoic muds chemical oceanographic event poor oxygenation
MFS P30
Small subtidal oolitic and bioclastic shoals with local lagoons. Deepening-up bioclastic grain-capped cycles.
KS4b3 633
Good mouldic porosity in late aggradational/ retrogradational sands
Mainly limestone intervals
Excellent poroperm dolomitized shoal and lagoon facies
Dominated by shallow-water restricted facies and shallow-water oolitic tidal shoals
Mainly dolomitic intervals
KS4b2 634
KS4b1 635
Dozon 18B
Main reservoir interval
Sequence KS4b (53 m)
Upper Dalan Member
KS4a4 637 Aggradation of grain-supported facies - small shallowwater oolitic tidal shoals. Mud-capped cycles.
KS4a Maximum Accommodation Zone (MAZ)
KS4a3 638
KS4a2 639
Dominated by shallow-water restricted facies (lagoons and sabkhas)
Parasequence set cycles
Capitanian Nar Member, Dalan Formation
KS4a1 640
Major exposure surface and breccia unit
Straton
Figure 7: Khuff Sequence KS4 in subsurface South Fars, Iran (after Insalaco et al., 2006).
119
SB 18B (259.2 Ma)
Minor reservoir intervals
KS4a5 636
Sequence KS4a (48 m)
UPPER PERMIAN (Wuchiapingian)
KS4c1 632
Al-Husseini and Koehrer
Wuchiapingian Maximum Flooding Surface MFS P30: In Al Jabal al-Akhdar, Koehrer et al. (2012) interpreted the main MFS in Sequence KS4 in cycle set KCS 4.6 (Figure 6 and Enclosure) at the maximum thickness of grainstones interbedded with muddy foreshoal textures, indicating the most open-marine conditions. Insalaco et al. (2006) interpreted three MFSs in Sequence KS4 in South Fars and considered the one in KS4c to be the dominant one (Figure 7). Both papers correlated their MFSs to Wuchiapingian MFS P30 of Sharland et al. (2001, 2004). Global and Orbital Correlations: Khuff Sequence KS4 correlates to global Wuchiapingian sequences Wuc1 and Wuc2 between 259.8–254.2 Ma, which in turn may correlate to HFS KS4-I and HFS KS4-II (HFS4a and HFS KS4b of Koehrer et al., 2012). In the M&H-2010 scale KS4 correlates to Dozon 18B between 259.2–254.3 Ma (Figure 2). The 12 “parasequence sets” in Iran and 11 “cycle sets” in Oman (with one presumed unidentified) are correlated to stratons 640–629 and to “fourthorder” sequences 1 to 11 in the Zhuzang Section of South China (Table 1). In the orbital model Straton 633 contains the MFS of HFS KS4-II (KS4a of Koehrer et al., 2012) and the MFS of KS4b of Insalaco et al. (2006) (Figures 6 and 7). In the Zhuzang Section of South China the base of Straton 633 correlates to the surface separating the transgressive and regressive sequence sets (TSS and HSS) corresponding to the MFS of “composite sequence” CSII (Wang et al., 2011). These correlations imply Straton 633 contains the MFS of global sequence Wuc1 and correlative MFS P30 of the Arabian Plate, with an age of ca. 256.1 Ma.
Khuff Sequence KS3: 254.3–252.3 Ma In Al Jabal al-Akhdar in Oman, Khuff Sequence KS3 varies in thickness between 62 to 69 m, and consists of the four “cycle sets” KCS 3.4 to KCS 3.1 (Figures 1b and 8, Enclosure; Koehrer et al., 2010, 2012). It corresponds in part or completely to Late Permian sequence P40 of Osterloff et al. (2004). Insalaco et al. (2006) reported that Khuff Sequence KS3 is ca. 115 m thick in subsurface South Fars (Figures 1a and 9), or about twice as thick as in Kuh-e Surmeh (47 m) and Kuh-e Dena (60 m). They divided it into lower “third-order” Sequence KS3a, which consists of the four “parasequence sets” KS3a1 to KS3a4, and overlying “fourth-order” Sequence KS3b, which consists of the five “depositional units” KS3b0 to KS3b4. Age: On biostratigraphic evidence the lower boundary of Sequence KS3, SB KS3, is correlated to the Wuchiapingian/Changhsingian Boundary (WCB) and its upper boundary, SB KS2, occurs below the Permian/Triassic Boundary (PTB) (Figure 2; Insalaco et al., 2006; Maurer et al., 2009; Koehrer et al., 2010, 2012). In subsurface Oman, the PTB occurs in the transition between the Middle and Upper Khuff members (Figure 4; Osterloff et al., 2004; Vachard and Forbes, 2009; Forke, 2009, unpublished PDO report in Forbes et al., 2010), implying the uppermost Permian SB KS2 occurs near the top of the Middle Khuff Member, possibly the top of P40 of Osterloff et al. (2004). Changhsingian Maximum Flooding Surface MFS P40: In Al Jabal al-Akhdar, Koehrer et al. (2010, 2012) interpreted the MFS of Sequence KS3 in cycle set KCS 3.2 (Figure 8 and Enclosure). It occurs in a distinctive one meter-thick coral-rich floatstone bed informally named the “Coral Marker”. Insalaco et al. (2006) interpreted the MFS of Sequence KS3 in South Fars in KS3a3 (Figure 9). Both studies correlate their MFSs to Late Permian MFS P40 of Sharland et al. (2001, 2004), and both occur in Straton 626 with an orbital age of ca. 253.3 Ma (Figure 2). These correlations imply Changsinghian MFS P40 correlates to the MFS Cha1 of global sequence Cha1, which has an age of ca. 253.5 Ma in GTS 2012. In the Zhuzang Section of South China the MFS of “composite sequence” CSIII is older if it is correlated to the base of Straton 627 at 253.9 Ma. Global and Orbital Correlations: The lower boundary of Khuff Sequence KS3 is correlated to the Wuchiapingian/Changhsingian Boundary (WCB) and therefore to SB Cha1 at 254.2 Ma in GTS 2012 (Figure 2). The upper boundary of KS3 occurs below the Permian/Triassic Boundary and would therefore correlate to SB Cha3 at 252.5 Ma in GTS 2012 (Figure 2). Sequence KS3 is correlated to the five stratons 628–624 in the lower part of Dozon 18C (Figure 2 and Table 1). The five stratons 628– 624 may correspond to the KS3a1 to KS3a4 “parasequence sets” and the “fourth-order” sequence KS3b in South Fars (Figure 9), to “fourth-order” sequences 12–16 in the Zhuzang Section (Figure 3),
120
Arabian Plate Khuff Sequences
Khuff Formation
621
KCS 2.2
623
KCS 2.3
Changhsingian SB 18C SB KS3
254.3 Ma
KCS 1.1
619
KCS 1.2
620
KCS 2.1
621
KCS 2.2
622
KCS 2.3
623
100
KCS 3.1
MFS 626 P40
KCS 3.2
627
KCS 3.3
628
KCS 3.4
629
KCS 4.1
HFS
(meter)
60
249.5 Ma
Khuff Sequence KS1
618
120
140
625
160
180
Depth
?
120
PERMIAN
KCS 2.1
MFS 622 Tr10
SB KS2
KCS 1.0
80
SB KS1
60
140
KCS 1.2
KS
160
Khuff Sequence KS2
620
40
5th 4th
624?
180
KCS 3.1
625
KCS 3.2
626
KCS 3.3
627
KCS 3.4
628
200 KS4
220
Khuff Sequence KS3
Induan
MFS Tr20
KCS 1.1
Cyclicity
Sudair SB SB 17 617?
Khuff Sequence KS1
TRIASSIC
20
100
50
Sudair SB 619
80
0
(API)
10
20
249.5 Ma
40
KS
Gamma-Ray
Straton
4th
HFS
Straton
40
5th
KCS
10
Cyclicity
Khuff Sequence KS2
?
Total GammaRay (API)
Khuff Sequence KS3
0
Sudair Formation Formation
Stage Olenekian
System
(meter)
Depth
KHUFF SEQUENCES KS3, KS2 AND KS1, AL-JABAL AL-AKHDAR, OMAN Saiq Plateau Wadi Hedek
Figure 8: Khuff sequences KS3, KS2 and KS1 in Saiq Plateau and Wadi Hedek, Al Jabal al-Akhdar, Oman (after Koehrer et al., 2010, 2012). Wadi Hedek Cycle Set KCS1.0 is absent in the Saiq Plateau. The orbital time scale M&H-2010 predicts that two stratons remain to be identified, probably 624 and 617. (See Figure 1 for location, Figure 2 and Enclosure, Tables 1 and 2 for overview of Khuff sequence stratigraphy).
121
Al-Husseini and Koehrer
Main reservoir intervals
Sequence KS1 (ca. 107 m)
MFS Tr20
617
KS1b2
618
KS1b1 KS1a4
Peritidal and evaporitic supratidal flats with tidal channels, shallow shoals, local microbial facies, and green shales
Transgressive pulses which generate accommodation which is filled by grainstone shoal facies. Capped by lagoon and mudflat facies.
Main reservoir intervals
KS1c1 KS1b3
Microbial-influenced depositional systems - lagoons, tidal flats and poorly-oxygenated embayments K1 microbial event
KS1a3 KS1a2 619 KS1a1
Anhydritised tidal flats
Sequence KS2 (ca. 57 m)
KS1c2
MFS Tr10
Grainy facies in MFZ
KS2d 620
KS2c 621
Thrombolites
KS2b 622 KS2a 623
Platform flooding surface
Epikarst
Increasing frequency of grainy beds and reappearance of oolites
KS3b3 Appearance of intercalated foram-rich sands
KS3b2
Stacked burrowed rooted lagoonal and tidal flats
KS3b1
Straton 624
Sequence KS3b (ca. 60 m)
Highly aggradation KS3b
KS3b0
Main reservoir intervals
KS3a4 625 Sequence KS3a (ca. 55 m)
Upper Dalan Member
UPPER PERMIAN (Changhsingian)
KS3b4
MFS P40
Maximum Accommodation Zone (MAZ) (thick muddy embayment unit)
Local peloidal and bioclastic tidal shoals
Double anhydrite bands KS4c4 major exposure surface
Restrictive coastal lagoons and shallow-water poorly oxygenated muddy embayments and small grainstone/ packstone levels
KS3a3 626
Local erosion of anhydrite bands
KS3a2 627
KS3a1 628 Flooding surface
Figure 9: Khuff sequences KS3, KS2 and KS1 in subsurface South Fars, Iran (after Insalaco et al., 2006). 122
SB 18C (254.3 Ma)
Kangan Formation
LOWER TRIASSIC (Induan)
Base Aghar Peritidal and evaporitic supratidal flats with tidal Erosively-based oolitic channels, green shales and and peloidal grainstone local microbial facies channels and shallow shoals
South SB 17 (249.5 Ma)
KHUFF SEQUENCES KS3, KS2 AND KS1, SOUTH FARS, IRAN
Dozon 18C
North
Arabian Plate Khuff Sequences
and to “cycle sets” KCS 3.4 to KCS 3.1 with one remaining unidentified in the Oman Mountains (Figure 8 and Table 1). E. Insalaco (written communication, 2013) noted that the correlation of KS3b in South Fars to Straton 624 implies it consists of the five “depositional units” KS3b0 to KS3b4, and is much thicker than other stratons. He speculated that this anomaly might be related to the higher aggradation and possibly better preservation associated with this depositional package, but that this interpretation requires further clarification.
Khuff Sequences KS2 and KS1: 252.3–249.5 Ma In Al Jabal al-Akhdar in Oman, Khuff Sequence KS2 ranges in thickness from 55 to 61 m and consists of the three “cycle sets” KCS 2.3 to KCS 2.1 (Koehrer et al., 2010, 2012, Figure 8 and Enclosure). Sequence KS1 attains a maximum thickness of 84 m in Wadi Hedek, where it consists of three “cycle sets” KCS 1.2 to KCS 1.0. Sequences KS2 and KS1, together, correspond to Triassic sequences Tr10 and Tr20 of Osterloff et al. (2004, Figure 4). Insalaco et al. (2006) reported that Sequence KS2 ranges in thickness from 50 m at Kuh-e Dena to 57 m in subsurface South Fars, and interpreted it as a “fourth-order” sequence, which consists of four “parasequence sets” KS2a to KS2d, Figure 9). Khuff Sequence KS1 is ca. 100 m thick in South Fars and reaches 129 m in Kuh-e Dena. It is interpreted as a “third-order” sequence and divided into three “fourth-order” sequences KS1a, KS1b and KS1c, and 10 “depositional units” (KS1a1 to KS1a4, KS1b1 to KS1b3, and KS1c1 to KS1c3, Figure 9). Age: Sequence KS2 straddles the Changsinghian and Induan stages with the Permian/Triassic Boundary picked in cycle set KCS 2.3 on the Saiq Plateau in Oman and KS2b in Iran (Enclosure, Figures 8 and 9; Table 1). Khuff Sequence KS1 is interpreted as Induan–?early Olenekian by stratigraphic position above the PTB and below the Sudair SB, which occurs near the Induan/ Olenekian Boundary (see below). Induan Maximum Flooding Surfaces MFS Tr10 and Tr20: Sharland et al. (2001) interpreted two maximum flooding surfaces, MFS Tr10 and MFS Tr20, in the Early Triassic (Scythian) and positioned them in the uppermost part of the Khuff Formation. In their revised study, Sharland et al. (2004) interpreted MFS Tr10 as Induan but did not discuss the age or position of MFS Tr20. The youngest two MFSs of the Khuff Formation occur in cycle sets KCS 2.2 and KCS 1.2 on the Saiq Plateau (Koehrer et al., 2010), and they are correlated to stratons 622 and 620, respectively, in the Induan. So it is proposed that MFS Tr10 (ca. 251.7 Ma) and MFS Tr20 (250.9 Ma) be taken as the flooding surfaces of KS2 and KS1, respectively, in global sequences Cha3 and Ind1 (Figure 2 and Table 1). Global and Orbital Correlations: Sequences KS2 and KS1 correlate to global sequences Cha3 and probably Ind1 between SB Cha3 at 252.5 Ma and SB Ole1 at 249.9 Ma (Figure 2). They correlate to the seven stratons 623–617 in the upper part of Dozon 18C (Figure 2 and Table 1). In Oman “cycle sets” KCS 2.3, 2.2 and 2.1 are tentatively correlated to stratons 623, 622 and 621, and KCS 1.2, KCS 1.1 and KCS 1.0 to stratons 620, 619 and 618, with Straton 617 missing, possibly due to erosion and postdepositional tectonics during the Late Cretaceous (Koehrer et al., 2012). “Cycle set” KCS 2.3 contains the Permian/Triassic Boundary (252.2 ± 0.5 Ma) as consistent with the age of Straton 623 between 252.3 and 251.9 Ma. In South Fars the four stratons 623 to 620 may correlate to the four “parasequence sets” KS2a, KS2b, KS2c and KS2d, and the three stratons 619 to 617 to the three “fourth-order” sequences KS1a, KS1b and KS1c (Figure 9 and Table 1).
Sudair Sequence Boundary In the Arabian Peninsula, the Khuff Formation is overlain by the Sudair Formation and equivalent rock units, and the intervening boundary is referred to as the Sudair Sequence Boundary (Sudair SB, Figures 4 and 8, Enclosure). In South Fars in Iran, the Sudair SB passes to the boundary between
123
Al-Husseini and Koehrer
the Kangan Formation and overlying Aghar Shale Member of the Dashtak Formation (Figure 9, Insalaco et al., 2006). In Al Jabal al-Akhdar, Rabu et al. (1986) described the lowermost part of the Sudair-equivalent as: “commonly includes decimeter-thick beds of dolomite with quartz and intra-formational breccia with a sandstone-dolomite cement (Wadi Mu’aydin), beds of maroon siltstone (Wadi Misin), and a close succession of hardgrounds separating the dolomite beds and reflecting periodic emergence.” The Sudair SB represents a regional regression that was dated in the Oman Mountains by chemostratigraphy as late Induan (between the top of the Griesbachian to middle Dienerian) (Richoz, 2006; Baud and Richoz, 2013). Forbes et al. (2010) characterized the Triassic Upper Khuff Member and Sudair Formation in subsurface Oman by Palynozone 2351 of Petroleum Development Oman (PDO) (Densoisporites nejburgii with Endosporites papillatus). They reported that in the lower shale of the Sudair Formation small marine acritarchs, characterized by Veryhachium spp., define PDO Palyno-subzone 1095. They added that the Veryhachium-Micrhystridium acritarch bloom, together with the associated miospores, appears to be an Induan–early Olenekian worldwide event. Palynological analysis of samples taken from the basal shale of the Sudair Formation in the SHD-1 Well in Central Saudi Arabia (Figure 1a) also contain abundant Veryhachium spp. of Early Triassic age (Manivit et al., 1983). Forbes et al. (2010) also reported that a single specimen of Hemigordiellina tenuifistula, noted by Vachard (2007), suggests an Olenekian age at the base of the Sudair Formation outcrop-equivalent, and that Vachard (2007) recognized an Induan biozone (sporadic Hemigordiellina sinensis) in uppermost Khuff-equivalent outcrops in Al Jabal al-Akhdar. In the Musandam Peninsula outcrops (Figure 1), Maurer et al. (2009) reported that a succession that is most likely equivalent to the Sudair Formation yields an association of Hoyenella sinensis and Meandrospira pusilla. They added that morphotypes and association of these foraminifera indicates a late Induan–Olenekian age. They considered the age of the youngest Khuff Sequence KS1 to be Induan. In the Al Jabal al-Akhdar outcrops, Oman (Figure 1), Koehrer et al. (2010) reported that foraminiferal fauna with sporadic occurrences of Hoyenella sinensis and H. tenuifistula occur in the lower part of the Sudair Formation outcrop equivalent on the Saiq Plateau (“Middle Mahil Member”). They considered the Sudair Formation as Olenekian, and Khuff Sequence KS1 as Induan. Pöppelreiter et al. (2011) reported that in the Al Jabal al-Akhdar outcrops Cornuspira mahajeri occurs with shell fragments in the “Claraia beds” in the lowermost Sudair Formation outcrop equivalent. They took the occurrence of this Lower Triassic “disaster fauna” together with a prominent positive δ13CCarb isotope shift to indicate a late Induan–early Olenekian (late Dienerian–early Smithian) age for the lower part of the Sudair Formation. They positioned Olenekian MFS Tr30 in the Sudair Formation, corresponding to the Aghar Shale Member of the Dashtak Formation in South Fars (Insalaco et al., 2006). The above-cited biostratigraphic studies place the Sudair SB near the Induan/Olenekian Boundary dated at 250.0 ± 0.5 Ma in GTS 2012, implying it correlates to either latest Induan SB Ind1 at 250.6 Ma, or earliest Olenekian SB Ole1 at 249.9 Ma (Figure 2 and Table 2). In the M&H-2010 scale the Sudair SB correlates to orbital SB 17 at 249.5 Ma (base Straton 616).
DISCUSSION Putting Sequences in Order The terms used in this paper to categorize sequences are quoted from the original papers. Most authors adopt the term “order” to categorize sequences; for example, a “third-order” sequence consists of several “fourth-order” sequences, which in turn are composed by “fifth-order” sequences (Table 3). The “fifth-order” sequence is generally synonymous with “cycle” and “parasequence”, and the “fourth-order” sequence with “parasequence set” and “cycle set”. Some
124
Arabian Plate Khuff Sequences
Table 4 Proposed new Khuff Sequence Stratigraphic subdivision based on Dozons and Stratons Age M&H-2010 Orbital Scale
Khuff Composite Sequence (CS)
Dozon (4.86 Myr)
High-frequency Sequence (HFS) (GTS 2012)
Straton (0.405 Myr)
254.3–249.5 Ma
Composite Sequence KS1-KS3
Dozon 18C
4 HFS: Cha1 to Ind1
12 stratons: 628–617
259.2–254.3 Ma
Composite Sequence KS4
Dozon 18B
2 HFS: Wuc1 and Wuc2
12 stratons: 640–629
264.0–259.2 Ma
Composite Sequence KS5
Dozon 18A
2 HFS: Cap2 and Cap3
12 stratons: 652–641
268.9–264.0 Ma
Composite Sequence KS6
Dozon 19C
4 HFS: Wor1 to Cap1
12 stratons: 664–653
12 HFS
48 stratons
Complete Khuff
19.4 Myr
4 Composite Sequences
4 dozons
authors use additional terms to subdivide “fourth-order” sequences into longer “high-frequency” sequences (HFS) and shorter “cycle sets” or “parasequence sets” (Tinker, 1998). The calibrations that are made in this paper imply that Khuff sequences KS6, KS5 and KS4 have durations of ca. 5.0 Myr, while the briefest KS1 lasted only ca. 1.2 Myr. The durations of the 12 global sequences that span the same time interval in GTS 2012 vary from about 4.0 Myr for Wuc1 to 0.6 Myr for Cha2 (Figure 2). Thus the durations attributed to empirical “third-order” sequences range from 0.6–5.0 Myr, and do not match the prediction by the model of Matthews and Frohlich (2002) that “third-order” sequences lasted 2.0, 2.4 or 2.8 Myr. Here, the four dozons 19C, 18A, 18B and 18A are interpreted to correspond to the four “composite” sequences KS6, KS5, KS4 and KS3–KS1 (Table 4). The global sequences used in the GTS 2012 (Wor1 to Ind1) are interpreted to represent “high-frequency” sequences rather than classical “third-order” composite sequences (Tables 3 and 4). To avoid confusion regarding the sequence-stratigraphic hierarchy of the Khuff Formation across the Arabian Plate, we recommend using the M&H-2010 orbital scale to subdivide the Khuff Formation into 48 “stratons” and 4 “dozons” (Table 4). The four “dozons” 19C to 18C correspond to the four “composite” sequences KS6, KS5, KS4 and combined KS3 to KS1.
Converting Stratons to Time The “cycle sets” of Koehrer et al. (2010, 2012) and “parasequence sets” of Insalaco et al. (2006) are good candidates for “stratons”. Several pitfalls, however, can occur when converting these sets or “fourth-order” sequences to time. The most common is assuming that the section is without hiatuses. On the Saiq Plateau, this pitfall is evident at the Sudair SB because cycle set KSC1.0, seen in Wadi Hedek, is missing on the Saiq Plateau (Figure 8). Two more stratons are predicted to be missing in Al Jabal al-Akhdar if the count of 12 is to be completed for Dozon 18C in combined “composite” sequence KS3 to KS1 (Table 4). A strategy for recognizing significant hiatuses is to correlate sequence boundaries, maximum flooding surfaces and stratons between several localities. In this paper KS4 to KS1 are shown in Al Jabal al-Akhdar and South Fars, located about 500 km apart and each encompassing a study area of
125
Al-Husseini and Koehrer
more than 100 square km (Figures 1, 6 to 9). A total of 24 stratons are predicted in these sequences, which appears to be the case in South Fars, but not so in Al Jabal al-Akhdar where only 22 are recognized. In the Ghawar Field of Saudi Arabia (Figure 1), 20 “high-frequency” sequences (HFS) have been recognized in KS4 to KS1 (Al-Eid and Tawil, 2011; Al-Dukhayyil et al., 2012; A. Al-Tawil, personal communication, 2012). It is possible that these HFS are rather “stratons” with four stratons missing over this structure that was located in a more proximal setting than South Fars. Another pitfall is suspected to occur in the Zhuzang Section in South China (Figure 3; Wang et al., 2011), where “fourth-order” Sequence 11 may consist of two stratons implying it represents ca. 0.8 Myr. The opposite pitfall is suspected in South Fars where the five “depositional units” in Sequence KS3b may be “fifth-order” sequences with durations of about 0.1 Myr rather than 0.405 Myr (Figure 9). Some of these pitfalls may be avoided by collecting additional stratigraphic data to better constrain the ages of sequence boundaries and maximum flooding surfaces/intervals in terms of stratons. F. Maurer (written communication, 2013) emphasized that the lack of detailed biostratigraphy in many Khuff sections makes a detailed correlation of sequences difficult. He suggested that the use of other proxies, such as carbon isotopes, may provide an alternative tool for correlations. Clarkson et al. (2012, their figure 4) show a correlation of the Triassic part of the Khuff Formation between Musandam and Wadi Sahtan in Al Jabal al-Akhdar. It illustrates that the Musandam Section has a much higher sedimentation rate, implying that in Al Jabal al-Akhdar region not all stratons might be recorded. He thinks it might be beneficial to use the carbonate-isotope signature for a section with high-resolution sequences, such as the Zhuzang Section, and compare it with the Arabian Plate for a better fine-tuning of the straton-to-straton correlation.
Regional, Global and Orbital Isochronous Surfaces Three major sequence boundaries are recognized in Al Jabal al-Akhdar (Koehrer et al., 2010, 2012): (1) Khuff SB marking the start of the marine transgression, (2) SB KS4 at the top of the Middle Anhydrite or its equivalent, and (3) Sudair SB at the breccia level at the top of the Khuff Formation. In the global scheme only two Mid-Permian–Early Triassic sequence boundaries, SB Ole2 and SB Wuc1, are interpreted as “major” in the compilation of Snedden and Liu (2011). Therefore only one sequence boundary is recognized as “major” in both the Arabian and global frameworks: correlative SB KS4 and SB Wuc1. In the orbital M&H-2010 scale, five sequence boundaries are predicted to be regional and these are recognized in both the Arabian and global schemes (Figure 2). Of the five, SB 17A (Sudair SB) and SB 18A (SB KS5) are predicted to be more prominent than the other three (Figure 2). This prediction is true for SB 17A corresponding to the major regression at the Sudair SB, characterized by the influx of terrestrial clastics and exposure above carbonates and evaporites. It is less clear whether SB 18A is a more prominent sequence boundary in comparison to SB KS4 (top Middle Anhydrite) or the Khuff SB. The significance of SB 18A may be that its correlative SB KS5, at the base of Sequence KS5, represents the start of a second transgression of much greater regional extent than KS6. This scenario is suggested by regional correlations from Iran and Oman (Tethys-side) to Saudi Arabia (Al-Jallal, 1995), and the interpretation that the Khuff transgression first reached as far as the Arabian Shield during the Capitanian (Vaslet et al., 2005). This scenario implies that the extent of coastal onlap onto the Arabian Plate of Capitanian Sequence KS5 was far greater than that of Wordian–?early Capitanian KS6, or opposite to that depicted in the global onlap curve (Figure 2).
CONCLUSIONS This study uses biostratigraphic and sequence-stratigraphic constraints to position the Khuff Formation between global Wordian sequence boundary SB Wor1 at ca. 268.8 ± 0.5 Ma and Olenekian sequence boundary SB Ole1 at ca. 249.9 ± 0.5 Ma as calibrated in GTS 2012 (Figure
126
Arabian Plate Khuff Sequences
2; Tables 1 and 2). These two boundaries correlate by numerical age to two model-predicted, regional sequence boundaries at 268.9 and 249.5 Ma in the M&H-2010 orbital scale. The model scale predicts that the Khuff Formation contains 48 T-R sequences with an average duration of 0.405 Myr, corresponding to the long-eccentricity orbital cycle and referred to as “stratons”. Moreover the 48 stratons are predicted to group into four “dozons” each lasting 4.86 Myr (Table 4). The chronostratigraphic framework presented in this paper is believed to have an accuracy of less than one million years, and perhaps approaching 0.405 Myr – the duration of a straton. The Khuff Formation on the Saiq Plateau in Al Jabal al-Akhdar provides a comprehensively documented, reference section at outcrop for the Mid-Permian (Wordian) to Early Triassic (Induan– ?early Olenekian) sequence stratigraphy (Enclosure). A total of 45 transgressive-regressive (T-R) “fourth-order” cycle sets are considered good candidates to represent all but three of the 48 stratons, with three remaining to be identified or absent due to faulting (Enclosure, Figures 6 and 8; Table 1). In the Al Jabal al Akhdar outcrops in Oman, the four dozons correlate closely to composite Khuff sequences KS6, KS5, KS4 and combined KS3 to KS1 (Figure 2; Tables 1, 2 and 4). The M&H-2010 scale was also used to calibrate the Upper Permian (Lopingian) Zhuzang Section in South China (Figure 3 and Table 1). The section is bounded below by the Emeishan Basalt dated at 259.0 ± 3.0 Ma and corresponding to global basal Wuchiapingian sequence boundary SB Wuc1 dated at 259.8 Ma in GTS 2012. It is bounded above by the Permian/Triassic Boundary dated at 252.2 ± 0.5 Ma. The application of the M&H-2010 scale dates the Zhuzang Section between 259.2 and 252.3 Ma. The results from Oman and South China are believed to support the prediction by Laskar et al. (2004, 2011) that the 0.405-Myr clock is stable as far back as the Permian/Triassic Boundary, and that the M&H-2010 scale can be used to estimate the ages of Mid-Permian–Early Triassic T-R sequences. Geoscientists working on the Khuff reservoir in the Middle East are encouraged to use the M&H2010 orbital scale as a sequence-stratigraphic template, instead of empirical cycle definitions and orders. In the M&H-2010 orbital scale, Khuff reservoir zones can be better positioned in a regional chrono- and sequence-stratigraphic framework using time-calibrated “stratons” (0.405 Myr cycles) and “dozons” (4.86 Myr cycles). This may allow correlating the Khuff and its correlative formations in a consistent way from field to field across the Arabian Plate.
ACKNOWLEDGEMENTS The authors thank Jim Ogg and Chunju Huang for sharing their estimates for the ages of the global sequences calibrated in the Geologic Time Scale GTS 2012. Enzo Insalaco, Chunju Huang, Florian Maurer, Mike Stephenson and Daniel Bendias are thanked for their comments and suggestions that have improved the manuscript. Bastian Koehrer would especially like to thank Tom Aigner, Michael Pöppelreiter and his former colleagues of the Sedimentary Geology working group of the University of Tübingen. GeoArabia’s Assistant Editor Kathy Breining is thanked for proofreading the manuscript, and GeoArabia’s Production Co-manager, Arnold Egdane, for designing the paper for press.
REFERENCES Al-Dukhayyil, R.K., J.F. Read and A.A. Al-Tawil 2012. Sequence stratigraphy of the Permian–Triassic Upper Khuff carbonates, Ghawar Field, Saudi Arabia. In The Permo–Triassic Sequence of the Arabian Plate, Abstracts of the EAGE’s Third Arabian Plate Geology Workshop, Kuwait. Abstract, GeoArabia, v. 17, no. 1, p. 212-213. Al-Eid, G.A. and A. Al Tawil 2011. High-resolution sequence stratigraphy of the late Permian Khuff-C in Hawiyah, Ghawar Field. 9th Middle East Geosciences Conference, GEO 2010. GeoArabia, Abstract Part 1, v. 16, no. 1, p. 155. Al-Husseini, M.I. 2008. Launch of the Middle East Geologic Time Scale. GeoArabia, v. 13, no. 4, p. 11 and 185-188. Al-Husseini M.I. and R.K. Matthews 2010. Middle East Geologic Time Scale 2010: Calibrating Mid-Permian to Early Triassic Khuff sequences with orbital clocks. GeoArabia, v. 15, no. 3, p. 171-206. Al-Jallal, I.A. 1995. The Khuff Formation: Its regional reservoir potential in Saudi Arabia and other Gulf countries; depositional and stratigraphic approach. In M.I. Al-Huseini (Ed.), Middle East Petroleum Geosciences Conference, GEO’94. Gulf PetroLink, Bahrain, v. 1, p. 103-119.
127
Al-Husseini and Koehrer
Angiolini, L., A. Nicora, H. Bucher, D. Vachard, A. Pillevuit, J.-P. Platel, J. Roger, J.A. Baud, J. Broutin, H. Al Hashmi and J. Marcoux 1998. Evidence of a Guadalupian age for the Khuff Formation of southeastern Oman: Preliminary report. Rivista Italiana di Paleontologia e Stratigrafia, v. 104, no. 3, p. 329-340. Angiolini, L., M. Balini, E. Garzanti, A. Nicora, A. Tintori, S. Crasquin-Soleau and G. Muttoni 2003. Permian climatic and paleogeographic changes in Northern Gondwana: The Khuff Formation of Interior Oman. Palaeogeography, Palaeoclimatology, Palaeoecology, v. 191, nos. 3-4, p. 269-300. Angiolini, L., S. Crasquin-Soleau, J.-P. Platel, J. Roger, D. Vachard, D. Vaslet and M.I. Al-Husseini 2004. Saiwan, Gharif and Khuff formations, Haushi-Huqf Uplift, Oman. In M.I. Al-Husseini (Ed.), Carboniferous, Permian and Early Triassic Arabian Stratigraphy. GeoArabia Special Publication no. 3, Gulf PetroLink, Bahrain, p. 149-183. Baud, A. and M. Bernecker 2010. The Permian-Triassic transition in the Oman Mountains. GUtech Geoscience Workshop Publication 1, IGCP 572 Field Guide Book 2, 109 p. Baud, A. and S. Richoz 2013. Stratigraphic Note: The Permian–Triassic transition and the Saiq/Mahil Boundary in the Oman Mountains: Proposed correction for lithostratigraphic nomenclature. GeoArabia, v. 18, no. 3, p. 87-98. Baud, A., F. Béchennec, F. Cordey, L. Krystyn, J. Le Métour, J. Marcoux, R. Maury and S. Richoz 2001a. Permo-Triassic Deposits: From the Platform to the Basin and Seamounts, Conference on the Geology of Oman, Field Guidebook, Excursion A01, Muscat, Oman, p. 1-54. Baud, A., F. Béchennec, F. Cordey, J. Le Métour, J. Marcoux, R. Maury and S. Richoz 2001b. Permo-Triassic Deposits: From shallow water to base of slope, Conference on the Geology of Oman, Field guidebook, Excursion B01, Muscat, Oman, 40 p. Baud, A., M. Bernecker, L. Krystyn, S. Richoz, O. Weidlich, B. Beauchamp, F. Cordey, S. Grasby and C. Henderson 2012. The Arabian Plate and the IGC Programme 572 (Permian–Triassic extinction and recovery): Results from the Muscat – Gutech (German University of Technology in Oman) field meeting (February, 2010). In The Permo– Triassic Sequence of the Arabian Plate, Abstracts of the EAGE’s Third Arabian Plate Geology Workshop, Kuwait. Abstract, GeoArabia, v. 17, no. 1, p. 199-202. Bendias, D., B. Koehrer, M. Obermaier and T. Aigner 2013. Mid-Permian Khuff Sequence KS6: Paleorelief-influenced facies and sequence patterns in the Lower Khuff time-equivalent strata, Oman Mountains, Sultanate of Oman. GeoArabia, v. 18, no. 3, p. 135-178. Clarkson, M.O., S. Richoz, R.A. Wood, F. Maurer, L. Krystyn, D.J. McGurty and D. Astratti. 2012. A new highresolution δ13C record for the Early Triassic: Insights from the Arabian Platform. Gondwana Research, http:// dx.doi.org/10.1016/j.gr.2012.10.002. Crippa, G. and L. Angiolini 2012. Guadalupian (Permian) brachiopods from the Ruteh Limestone, North Iran. GeoArabia, v. 17, no. 1, p. 125-176. Davydov, V.I. and S. Arefifard 2013. Middle Permian (Guadalupian) fusulinid taxonomy and biostratigraphy of the mid-latitude Dalan Basin, Zagros, Iran and their applications in paleoclimate dynamics and paleogeography. GeoArabia, v. 18, no. 2, p. 17-62. Emery, D. and K. Myers 1996. Sequence Stratigraphy. Blackwell Publishing Company, 297 p. Forbes, G.A., H.S.M. Jansen and J. Schreurs 2010. Lexicon of Oman subsurface stratigraphy: Reference guide to the stratigraphy of Oman’s hydrocarbon basins. GeoArabia Special Publication 5, Gulf PetroLink, Bahrain, 371 p. Forke, H., M. Pöppelreiter, T. Aigner, B. Koehrer, L. Walz, D. Bendias and M. Haase 2012. Integrated biostratigraphy of the Saiq Formation (Al Jabal al-Akhdar, Oman Mountains) and its implication for the regional correlation of Khuff time-equivalent deposits. In The Permo–Triassic Sequence of the Arabian Plate, Abstracts of the EAGE’s Third Arabian Plate Geology Workshop, Kuwait. Abstract, GeoArabia, v. 17, no.1, p. 230-234. Gaetani, M., L. Angiolini, K. Ueno, A. Nicora, M. Stephenson, D. Sciunnach, R. Rettori, G. Price, and J. Sabouri 2009. Pennsylvanian to Early Triassic stratigraphy in Alborz Mountains (Iran). In M.-F. Brunet, M. Wilmsen and J.W. Granath (Eds.), South Caspian to Central Iran Basins. Geological Society, London, Special Publications, no. 312, p. 79-128. Gradstein, F.M., J.G. Ogg, A.G. Smith, F.P. Agterberg, W. Bleeker, R.A. Cooper, V. Davydov, P. Gibbard, L. Hinnov, M.R. House, L. Lourens, H-P. Luterbacher, J. McArthur, M.J. Melchin, L.J. Robb, J. Shergold, M. Villeneuve, B.R. Wardlaw, J. Ali, H. Brinkhuis, F.J. Hilgen, J. Hooker, R.J. Howarth, A.H. Knoll, J. Laskar, S. Monechi, J. Powell, K.A. Plumb, I. Raffi, U. Röhl, P. Sadler, A. Sanfilippo, B. Schmitz, N.J. Shackleton, G.A. Shields, H. Strauss, J. Van Dam, J. Veizer, Th. van Kolfschoten and D. Wilson 2004. A Geologic Time Scale 2004. Cambridge University Press, 589 p. Gradstein, F.M., J.G. Ogg, M. Schmitz and G. Ogg 2012. (Eds.) The Geological Time Scale 2012. Elsevier, 1,144 p. Hardenbol, J., J. Thierry, M.B. Farley, T. Jacquin, P.-C. de Graciansky and P.R. Vail 1998. The Mesozoic and Cenozoic chronostratigraphic framework of European basins. In P.-C. de Graciansky, J. Hardenbol, T. Jacquin and P.R. Vail (Eds.), Mesozoic and Cenozoic Sequence Stratigraphy of European Basins. Society of Economic Paleontologists and Mineralogists, Special Publication no. 60, p. 1-13. Haq, B.U. and A.M. Al-Qahtani 2005. Phanerozoic cycles of sea-level change on the Arabian Platform. GeoArabia, v. 10, no. 2, p. 127-160. Haq, B.U. and S.R. Schutter 2008. A chronology of Paleozoic sea-level changes. Science, v. 322, p. 64-68. Henderson, C.M., V.I. Davydov, B.R. Wardlaw, F.M. Gradstein and O. Hammer 2012. The Permian Period. In F.M. Gradstein, J.G. Ogg, M. Schmitz and G. Ogg (Eds.), The Geological Time Scale 2012. Elsevier, p. 653-679. Insalaco, E., A. Virgone, B. Courme, J. Gaillot, M. Kamali, A. Moallemi, M. Lotfpour and S. Monibi 2006. Upper Dalan Member and Kangan Formation between the Zagros Mountains and offshore Fars, Iran: Depositional system, biostratigraphy and stratigraphic architecture. GeoArabia, v. 11, no. 2, p. 75-176. Jin, Y., S. Shen, C.M. Henderson, X. Wang, W. Wang, Y. Wang, C. Cao, and Q. Shang 2006a. The Global Stratotype
128
Arabian Plate Khuff Sequences
Section and Point (GSSP) for the boundary between the Capitanian and Wuchiapingian Stange (Permian). Episodes, v. 29, p. 253-262. Jin, Y., Y. Wang, C. Henderson, B.R. Wardlaw, S. Shen and C. Cao 2006b. The Global Stratotype Section and Point (GSSP) for the base of the Changsinghian Stage (Upper Permian). Episodes, v. 24, p. 175-182. Koehrer, B., M. Zeller, T. Aigner, M. Poeppelreiter, P. Milroy, H. Forke and S. Al-Kindi 2010. Facies and stratigraphic framework of a Khuff outcrop equivalent: Saiq and Mahil formations, Al Jabal al-Akhdar, Sultanate of Oman. GeoArabia, v. 15, no. 2, p. 91-156. Koehrer, B., T. Aigner, H. Forke and M. Pöppelreiter 2012. Middle to Upper Khuff (Sequences KS1 to KS4) outcropequivalents in the Oman Mountains: Grainstone architecture on a subregional scale. GeoArabia, v. 17, no. 4, p. 59-104. Laskar, J., P. Robutal, F. Joutel, M. Gastineau, A. Correia and B. Levrard 2004. A long term numerical solution for the insolation quantities of the Earth. Astronomy and Astrophysics, v. 428, p. 261-285. Laskar, J., A. Fienga, M. Gastineau and H. Manche 2011. La2010: A new orbital solution for the long term motion of the Earth. Astronomy and Astrophysics, v. 532, A89, p. 1-15. Le Métour, J. 1987. Géologie de l’autochtone des Montagnes d’Oman: La fenêtre du Saih Hatat. PhD thesis, University Pierre and Marie Curie, Paris VI, France, 425 p. (Document Bureau de Recherches Géologiques et Minières no. 129, Orléans, France, 1988, 430 p.) Manivit, J., D. Vaslet, Y.-M. Le Nindre and F.X. Vaillant 1983. Stratigraphic drill hole SHD-1 through the lower part of the Jilh Formation, Sudair Shale and Khuff Formation in the Durma quadrangle (sheet 24H). Saudi Arabian Directorate General of Mineral Resources, open file report 0F-03-50, p. 1-34. Matthews, R.K. and C. Frohlich 2002. Maximum flooding surface and sequence boundaries: Comparisons between observation and orbital forcing in the Cretaceous and Jurassic (65-190 Ma). GeoArabia, v. 7, no. 3, p. 503-538. Matthews, R.K. and M.I. Al-Husseini 2010. Orbital-forcing glacio-eustasy: A sequence-stratigraphic time scale. GeoArabia, v. 15, no. 3, p. 155-167. Maurer, F., R. Martini, R. Rettori, H. Hillgärtner and S. Cirilli 2009. The geology of Khuff outcrop analogues in the Musandam Peninsula, United Arab Emirates and Oman. GeoArabia, v. 14, no. 3, p. 125-158. Menning, M., J.G. Ogg and R.L. Romer 2008. A Middle and Late Permian time scale calibrated by cycles and radioisotopic age determinations. Abstract 33rd IGC International Congress. Oslo, Norway. Montenat, C., A.F. de Lapparent, M. Lys, H. Termier, G. Termier and D. Vachard 1976. La transgression Permienne et son substratum dans le Jabal Akhdar (Montagnes d’Oman, Péninsule Arabique). Annales de la Société Géologique du Nord, Lille, France, v. 96, no. 3, p. 239-258. Ogg, J.G. 2004. The Triassic Period. In F.M. Gradstein, J.G. Ogg, A.G. Smith (Eds.), A Geologic Time Scale 2004. Cambridge University Press, p. 271-306. Ogg, J.G. 2012. The Triassic Period. In F.M. Gradstein, J.G. Ogg, M. Schmitz and G. Ogg (Eds.) The Geological Time Scale 2012. Elsevier, Chapter 25, p. 681-730. Osterloff, P., A. Al-Harthy, R. Penney, P. Spaak, G. Williams, F. Al-Zadjali, N. Jones, R. Knox, M.H. Stephenson, G. Oliver and M.I. Al-Husseini 2004. Depositional sequence of the Gharif and Khuff formations, subsurface Interior Oman. In M.I. Al-Husseini (Editor), Carboniferous, Permian and Early Triassic Arabian Stratigraphy. GeoArabia Special Publication 3, Gulf PetroLink, Bahrain, p. 83-147. Pöppelreiter, M.C., C.J. Schneider, M. Obermaier, H.C. Forke, B. Koehrer and T. Aigner 2011. Seal turns into reservoir: Sudair equivalents in outcrops, Al Jabal al-Akhdar, Sultanate of Oman. GeoArabia, v. 16, no. 1, p. 69-108. Rabu, D., F. Béchennec, M. Beurrier and G. Hutin 1986. Explanatory notes to the geological map of the Nakhl Quadrangle, Sultanate of Oman. Geoscience map, scale 1:100,000, sheet NF 40-3E. Ministry of Petroleum and Minerals, Directorate General of Minerals, Sultanate of Oman. 42 p. Richoz, S. 2006. Stratigraphie et variations isotopiques du carbone dans le Permien supérieur et le Trias inférieur de quelques localités de la Néo-Téthys (Turquie, Oman et Iran). Mémoire de Géologie de Lausanne, v. 46, 284 p. Richoz, S., A. Baud, L. Krystyn, R. Twitchett and J. Marcoux 2005. Permo-Triassic Deposits of the Oman Mountains from Basin and Slope to the Shallow Platform. In 24th IAS Regional Meeting, Post-Conference Excursion A13, Muscat, Oman, p. 1-57. Sharland, P.R., R. Archer, D.M. Casey, R.B. Davies, S.H. Hall, A.P. Heward, A.D. Horbury and M.D. Simmons 2001. Arabian Plate sequence stratigraphy. GeoArabia Special Publication 2, Gulf PetroLink, Bahrain, 371 p., with 3 charts. Sharland, P.R., D.M. Casey, R.B. Davies, M.D. Simmons and O.E. Sutcliffe 2004. Arabian Plate Sequence Stratigraphy. GeoArabia, v. 9, no. 1, p. 199-214. Shen, S.-Z., C.M. Henderson, S.A. Bowring, C.Q. Cao, Y. Wang, W. Wang, H. Zhang, Y.C. Zhang and L. Mu 2010. High-resolution Lopingian (Late Permian) timescale of South China. Geological Journal, v. 45, p. 122-134. Shen, S.-Z., J.L. Crowley, Y. Wang, S.A. Bowring, D.H. Erwin, P.M. Sadler, C.-Q. Cao, D.H. Rothman, C.M. Henderson, J. Ramezani, H. Zhang, Y. Shen, X.-D. Wang, W. Wang, L. Mu, W.-Z. Li, Y.-G. Tang, X.-L. Liu, L.-J. Liu, Y. Zeng, Y.-F. Jiang and Y.-G. Jin 2011. Calibrating the End-Permian Mass Extinction. Science, v. 334, no. 6061 p. 1367-1372. Snedden, J.W. and C. Liu 2011. Recommendations for a uniform chronostratigraphic designation system for Phanerozoic depositional sequences. Bulletin of the American Association of Petroleum Geologists, v. 95, p. 10951122. Stephenson, M.H. 2006. Stratigraphic Note: Update of the standard Arabian Permian palynological biozonation: Definition and description of OSPZ 5 and 6. GeoArabia, v. 11, no. 3, p. 173-178. Stephenson, M.H., P.L. Osterloff and J. Filatoff 2003. Palynological biozonation of the Permian of Oman and Saudi Arabia: Progress and challenges. GeoArabia, v. 8, no. 3, p. 467-496.
129
Al-Husseini and Koehrer
Stephenson, M.H., L. Angiolini, M.J. Leng and D.P.F. Darbyshire 2012. Geochemistry, and carbon, oxygen and strontium isotope composition of brachiopods from the Khuff Formation of Oman and Saudi Arabia. GeoArabia, v. 17, no. 2, p. 61-76. Szabo, F. and A. Kheradpir 1978. Permian and Triassic stratigraphy, Zagros basin, south-west Iran. Journal of Petroleum Geology, v. 1, no. 2, p. 57-82. Tinker, S.W. 1998. Shelf-to-basin facies distributions and sequence stratigraphy of a steep-rimmed carbonate margin: Capitan depositional system, McKittrick Canyon, New Mexico and Texas. Journal of Sedimentary Research, v. 68, no. 6, p. 1146-1174. Vachard, D.J. 2007. Microfossils and Biostratigraphy of Jebel Akhdar (Oman). Centre National de la Recherche Scientifique, University of Lille, France. Unpublished report for PDO. Vachard, D. and G.A. Forbes 2009. Micropalaeontology and Microfacies study of the Khuff Formation in well Yibal-192. Unpublished PDO Exploration XGL Laboratory Note 2009/23. Vaslet, D., Y.-M. Le Nindre, D. Vachard, J. Broutin, S. Crasquin-Soleau, M. Berthelin, J. Gaillot, M. Halawani and M.I. Al-Husseini 2005. The Permian-Triassic Khuff Formation of central Saudi Arabia. GeoArabia, v. 10, no. 4, p. 77-134. Walz, L., T. Aigner and B. Koehrer 2013. Khuff sequence KS5 outcrop equivalents in the Oman Mountains, Sultanate of Oman: Variations to the simple “layer-cake“ stratigraphy. GeoArabia, v. 18, no. 4, p. 179-218. Wang, H., L. Shao, L.M. Hao, P.F. Zhang, I.J. Glasspool, J.R. Wheeley, P.B. Wignall, T.S. Yi, M.Q. Zhang and J. Hilton 2011. Sedimentology and sequence stratigraphy of the Lopingian (Late Permian) coal measures in southwestern China. International Journal of Coal Geology, v. 85, p. 168-183. Wardlaw, B.R., V.I. Davydov and F.M. Gradstein 2004. The Permian Period. In F.M. Gradstein, J.G. Ogg, A.G. Smith (Eds.), A Geologic Time Scale 2004. Cambridge University Press, p. 249-270. Yin, H., K. Zhang, J. Tong, Z. Yang and S. Wu 2001. The Global Stratotype Section and Point (GSSP) of the PermianTriassic Boundary. Episodes, v. 24, p. 102-114.
ABOUT THE AUTHORS Moujahed I. Al-Husseini founded Gulf PetroLink in 1993 in Manama, Bahrain. Gulf PetroLink is a consultancy aimed at promoting technology in the Middle East petroleum industry. Moujahed received his BSc in Engineering Science from King Fahd University of Petroleum and Minerals in Dhahran (1971), MSc in Operations Research from Stanford University, California (1972), PhD in Earth Sciences from Brown University, Rhode Island (1975) and Program for Management Development from Harvard University, Boston (1987). Moujahed joined Saudi Aramco in 1976 and was the Exploration Manager from 1989 to 1992. In 1996, Gulf PetroLink launched the journal of Middle East Petroleum Geosciences, GeoArabia, for which Moujahed is Editor-in-Chief. Moujahed also represented the GEO Conference Secretariat, Gulf PetroLink-GeoArabia in Bahrain from 1999–2004.
[email protected] Bastian Koehrer is a Development Geologist in Wintershall’s German business unit, working on mature oil field and tight gas sands development in the German North Sea and Lower Saxony. He has more than five years of E&P project experience in Germany, Oman, Qatar and the UAE with a professional track record in both carbonate and clastic reservoirs. Bastian obtained a PhD degree (2011) in Carbonate Sedimentology (Khuff Formation, Oman) from the University of Tübingen (Germany) in research collaboration with Shell (Qatar) and Petroleum Development Oman. Bastian is a member of the EAGE, AAPG and DGMK and has published several papers on carbonate sequence stratigraphy and reservoir outcrop analogs. His work interests include integration of rock, log and test data to improve reservoir characterization and 3-D reservoir modeling during the development and production stages of the field life cycle.
[email protected]
130