Facies associations of the Bathonian Hamam Formation from ...

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Nov 21, 2013 - Two stratigraphic sections of the Hamam Formation (Bathonian Stage, Middle Jurassic) exposed in the western part of Wadi Zarqa region, ...
Arab J Geosci (2014) 7:4861–4875 DOI 10.1007/s12517-013-1137-5

ORIGINAL PAPER

Facies associations of the Bathonian Hamam Formation from Northwestern Jordan Fayez Ahmad & Sherif Farouk & Abdelmohsen Ziko

Received: 17 June 2013 / Accepted: 20 September 2013 / Published online: 21 November 2013 # Saudi Society for Geosciences 2013

Abstract Two stratigraphic sections of the Hamam Formation (Bathonian Stage, Middle Jurassic) exposed in the western part of Wadi Zarqa region, northwestern Jordan, are described and interpreted on the basis of palynoflora and facies analysis in order to reconstruct their depositional environments and sequence stratigraphic framework, which not discussed before. Five facies associations have been identified in the Hamam Formation characterized by a mixed carbonate–siliciclastic ramp setting, ranging from incised fluvial valley fill facies, beach foreshore restricted inner ramp to high-energy shoals and mid-ramp settings. The palynoflora includes wellpreserved miospore assemblages which are recorded only from the incised fluvial valley fill facies for the first time and yielded 64 miospore species belonging to 40 genera. Most of these taxa are long-ranging and have been reported from Jurassic and Cretaceous rocks worldwide, except Callialasporites dampieri, Murospora florida , Granulatisporites jurassicus , Piceites expositus , Pityosporites parvisaccatus , Leptolepidites verrucatus, and Protopinus scanicus which have short ranges in the Middle Jurassic. Furthermore, these rocks are rich in shallow-marine Neo-Tethys macro-invertebrates supporting a Bathonian age. Two third-order depositional sequences bounded by three regional unconformities at the Bajocian–Bathonian F. Ahmad (*) Department of Earth and Environmental Sciences, The Hashemite University, Zarqa 13115, Jordan e-mail: [email protected] S. Farouk Exploration Department, Egyptian Petroleum Research Institute, Nasr City 11727, Egypt e-mail: [email protected] A. Ziko Geology Department, Faculty of Science, Zagazig University, Zagazig, Egypt e-mail: [email protected]

and Bathonian–Callovian stage boundaries as well as within the Bathonian are defined based upon facies characteristics and stratal geometries. A regional correlation of sequence boundaries of similar age indicates that they are eustatic in origin. Keywords Jurassic . Bathonian . Hamam Formation . Palynoflora . Mixed carbonate and siliciclastic ramp . Wadi Zarqa . Northwestern Jordan

Introduction The Jurassic successions are widely distributed and have economic importance for hydrocarbon reservoirs in the Middle East region (Rousseau et al. 2005). They are composed mainly of mixed shallow-marine carbonate–siliciclastic deposits. The Jurassic system in Jordan was discussed by various geologists from different aspects. Detailed paleontological studies based upon brachiopods and mollusks carried out on the Jordanian Middle Jurassic strata (Cox 1925; MuirWood’s 1925; Ahmad 1998; 1999; Basha and Aqrabawi 1994; Pandey et al. 2000; Feldman et al. 2012). The scarcity of the cosmopolitan ammonite species in the Jordanian Jurassic coupled with the few published studies of the microfauna (Basha 1980; Al-Harithi 1993); complicated the conclusion concerning the precise age of such strata. No detailed age determination is available for the Ramla and Hamam formations in the subsurface (Andrews 1992). In fact, the sequence stratigraphic framework and the floral content of the Hamam Formation are not known until now. The aims of this paper are three-fold; (1) to determine the facies characteristics in order to understand relative sea level and paleoenvironmental changes during the Bathonian, (2) to record, for the first time, the palynoflora of the Hamam Formation, and (3) to establish a sequence stratigraphic framework and compare its depositional

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sequences and boundaries with those previously published especially for the Arabian Platform.

Material and methods Two exposed stratigraphic sections of the Hamam Formation at Arda (32°08′30″N, 35°40′45″E) and Tal el Dhahab (32°12′ 37″N, 35°44′47″E) in the western part of Wadi Zarqa have been measured and sampled in great detail (Fig. 1). The facies descriptions are based on field observations, faunal content, lithological samples, and 50 thin-sections. The sandstone and

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limestone microfacies have been described following the classification of Pettijohn et al. (1987) and Dunham (1962), respectively. For their palynomorphic content, each sample has been tested for the presence of carbonate by the addition of a few drops of dilute hydrochloric acid; 50 g is then crushed in a mortar. Hydrofluoric acid (70 %) is added for 72 h. The insoluble fluorides are eliminated by boiling the residue in 10 % hydrochloric acid and then washing three times with distilled water. The organic residue is poured into a test tube with 10 % nitric acid for oxidation, heated in a double boiler for 1–2 min, then washed and centrifuged. The organic

Fig. 1 Geological map of the study area in northwestern Jordan modified from Muneizel and Khalil (1993) and Swarieh and Barjous (1993)

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residue is sieved through a mesh sieve to remove the large (larger than 100 μm) and small debris (less than 5 μm), then the 5–100 μm fraction is washed with distilled water, and concentrated by centrifuging. The final residue mixed with cellusize (hydroxyl ethyl cellulose) is strewn on a coverslip, dried, and mounted by overturning the coverslip on a couple of drops of Canada balsam on a microscope slide.

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Geological setting and lithostratigraphy During the Jurassic Period, the Levant was a part of the Gondwanian Tethys shelf that extended from Morocco in the west to the Arabian Peninsula in the east and southward to the horn of Africa. The opening of the Neo-Tethys in the Late Permian and the inception of the Gondwana rifts

Fig. 2 Stratigraphic columns of the Bathonian Hamam Formation showing microfacies types, components, and depositional sequences

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Table 1 List of the palynomorph taxa Devision

Family

Taxa of pollen and spores

Lycopsida Arthrophyta Pteridophyta

Pleuromeiaceae Equisetites unknown (Cyatheaceae/Dicksoniaceae)

Aratrisporite coryliseminis Klaus 1960 Calamospora tener Leschik 1955 Conbaculatisporites sp. Concavissimisporites montuosus Döring 1965 Concavissimisporites cf. potoniei Pocock 1964 Concavissimisporites verrucosus Delcourt and Sprumont 1955 emend. Delcourt et al. 1963 Cyathidites asper Bolkhovitina 1953 Cyathidites concavus Bolkhovitina 1953 Cyathidites minor Couper, 1953 Cyathidites punctatus Delcourt and Sprumont 1955 emend. Delcourt et al. 1963 Deltoidospora hallii Miner, 1953 Deltoidospora mesozoica (Thiergart) Schuurman 1977 Verrucosisporites contactus Clarke 1965 Verrucosisporites obscurilaesuratus Pocock 1962 Verrucosisporites triassicus Bharadwaj and Tiwari 1977 Trilobosporites hannonicus (Delcourt and Sprumont) Potonié 1956 Trilobosporites marylandensis Brenner 1963 Trilobosporites purverulentus (Verbitskaya) Dettmann 1963 Trilobosporites tenuiparietalisDöring 1965 Impardecispora trioreticulosus Cookson and Dettmann 1958 Ischyosporites variegates Couper 1958 Trilites tuberculiformis Cookson, 1947

?Dicksoniaceae

Schizaeaceae

Filicopsida

Lycopsida Polypodiales

Selaginellaceae Lycopodiaceae Dennstaedtiaceae

Filicopsida

Lycopodiaceae

Lycopodiaceae

Dipteridaceae Bryophytes

Dipteridaceae Hepatics or Anthocerotaceae

Coniferophyta

Araucariaceae

Osmundales

Osmundaceae

Cycadophyta

Cheirolepidiaceae

Klukisporites pseudoreticulatus Couper 1958 Klukisporites variegates Couper 1958 Klukisporites sp. Leptolepidites verrucatus Couper 1953 Lundbladispora densispinosa Bharadwaj and Tiwari 1977 Lycopodiumsporites clavatoides Couper 1958 Microreticulatisporites fuscus (Nilsson) Morbey 1975 Microreticulatisporites uniformis Singh 1964 Punctatisporites couperi Ravn 1995 Punctatisporites crassiradiata De Jersey 1960 Punctatisporites globosus (Leschik) Lund 1977 Punctatisporites gretensis Balme and Hennelly 1956 Densoisporites microrugulatus Brenner 1963 Densoisporites sp. Granulatisporites jurassicus Pocock 1970 Foraminisporis jurassicus Schulz 1967 Foraminisporis paucispinosus Döring 1973 Gemmatriletes clavatus Brenner 1968 Araucariacites australis Cookson 1947 Callialasporites dampieri Balme 1957 Callialasporites microvelatus Schulz 1966 Callialasporites trilobatus (Balme 1957) Sukh 1967 Callialasporites sp. Osmundacidites wellmanii Couper 1953 Osmundacidites sp. Couper 1953 Cerebropollenites thiergartii Schulz 1967

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Table 1 (continued) Devision

Coniferopsida

Family

Taxa of pollen and spores

Cycadaceae

Corollina torosa (Reissinger) Klaus emend. Cornet & Traverse 1975 Cycadopites sp. Ovalipollis pseudoalatus (Krutzsch 1955) Schuurman 1976

Pinaceae ?Coniferales Podocarpaceae Coniferophyta

Ovoidites spriggii (Cookson & Dettmann) Zippi 1983 Piceites expositus Pityosporites parvisaccatus De Jersey 1960 ?Podocarpidites sp. Protopinus scanicus Nilsson 1958 Quadraeculina anellaformis Maljavkina 1949

introduced a fundamental plate reorganization that was associated with the Mesozoic break-up of Pangaea (Badalini et al. 2002). The study area is part of the elevated platform terrain of the Arabian Nubian Shield, which is covered by intermittent Paleozoic to Cenozoic sedimentary successions consisting mainly of siliciclastic units with marine carbonates increasing upward (Rybakov and Segev 2005). At the beginning of the Jurassic, emergence led to subaerial exposure that was accompanied by extensive freshwater runoff and subaerial weathering (Goldberg and Friedman 1974). Subsequent subsidence allowed the formation of shallow and marginal shelf environments interrupted by lagoons resulting in the deposition of thick, partly calcareous sandstones that were overlain by thick, partly gypsiferous carbonates, marls, and sandy marls (Basha 1980). In northwestern Jordan, Jurassic outcrops can be found along the western part of Wadi Zarqa beginning near the old Jerash Bridge and extending westward to Deir-Alla, a distance of about 20 km; toward the south the outcrop belt passes through Ain-Khuneizir, Subeihi, and Arda Road (Ahmad 2002). The Jurassic succession decreases in thickness from the Zarqa River and Wadi Huni eastward toward the Zarqa Bridge and from there southeast toward Suweileh-1 and Safra-1. All siliciclastic and carbonate Jurassic rocks outcropping in Jordan are represented by the Azab Group and attain of a thickness of about 350 m on average. In Jordan, it is subdivided into seven formations from older to younger: Hihi, Nimr, Silal, Dhahab, Ramla, Hamam, and Mughanniyya (Khalil and Muneizel 1992). The Azab Group unconformably overlies Triassic strata; while its top (Mughanniyya Formation) represents the youngest exposed Jurassic unit in Jordan and crops out consistently below the Lower Cretaceous Kurnub Sandstone Group. During the Late Jurassic, Jordan was probably subjected to orogenic movements leading to strong erosion, where Upper Jurassic rocks are absent (Moullade and Nair 1978). The present study deals with the Bathonian Hamam Formation and its boundaries. It consists mainly of mixed siliciclastic–carbonate rocks and is

divided into three informal members with a combined thickness ranging from 35 m in the Tal el Dhahab section to 52 m in the Arda section (Fig. 2). The lower member of the Hamam Formation is composed of massive fossiliferous limestone with calcareous algae, bivalves and brachiopods overlying the Ramla Formation, which consists of fine- to very finegrained quartz sandstones with a mud-rich matrix, contains a fully marine fauna (echinoid spines) and documents a vertical facies change with a sharp contact. The middle member with thickness of about 5 to 10 m consists of terrestrial sandy mudstone, rich in pollen and spores but lacking dinoflagellates and thus represents a nonmarine environment. The upper member with a thickness of 25 m consists of a highly fossiliferous oolitic limestone capped by a massive sandstone containing trace fossils. This sandstone is overlain by the Mughanniyya Formation, which represents the upper part of the Jurassic succession in Jordan. It consists mainly of moderately indurated limestone with bivalves, gastropods, brachiopods, and echinoids indicating deposition in a shallow, open-marine environment with periodically strong siliciclastic influx. The presence of calcareous algae suggests deposition within the photic zone. Up-section the limestones pass into dolomitic limestone that normally delimit the top of the Mughanniyya Formation (Fig. 2). The limestones of the Hamam Formation are characterized by a macrofauna indicative of a Bathonian age. They include the brachiopods Cererithyis jabbokensis, Cererithyis africana , Cererithyis jordanensis , Daghanirhynchia sp. A, Monsardithyris ventricosa , Monsardithyris sp., Tubithyris chouberti , Burmirhynchia moulani , Burmirhynchia termierae, Eudesia (Sphriganaria) angulocostata, Eudesia (Sphriganaria ) magharensis , Eudesia (Sphriganaria ) modesta , Eudesia (Sphriganaria ) subcircularis , Eudesia (Sphriganaria ) bicostata , and Eudesia (Sphriganaria ) bramkampi, and the bivalves Arca (Eonavicula) trisulcata, Acromytilus laitmairensis, Modiolus imbricatus, Bakevellia waltoni , Eligmus asiaticus , Eligmus rollandi , Eligmus rollandi var. jabbokensis, Eopecten velatus, Ceratomyopsia striata , Gryphaeligmus jabbokensis , Pholadomya (P.)

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Fig. 3 LM microphotographs ×1,000 unless otherwise specified. (1) Aratrisporite coryliseminis Klaus 1960, (2–3) Araucariacites australis Cookson 1947, (4) Corollina torosa (Reissinger) Klaus emend. Cornet & Traverse, 1975, (5) Conbaculatisporites sp., (6 and 10–11). Concavissimisporites montuosus (Döring 1965) Fensome 1987, (7) Apetodinium granulatum Eisenack 1958, (8) Calamospora tener (Leschik 1955) Mädler 1964, (9 and 13) Callialasporites dampieri Balme 1957 (12, 16, and 18) Concavissimisporites cf. potoniei Pocock 1964, (14–15) Callialasporites microvelatus Schulz 1966, (17) Concavissimisporites

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verrucosus Delcourt and Sprumont 1955 emend. Delcourt et al. 1963, (19) Callialasporites trilobatus (Balme 1957) Sukh 1967, (20) Cerebropollenites thiergartii Schulz 1967, (21) Cyathidites asper Bolkhovitina 1953, Dettmann 1963, (22–23) Osmundasporites othmani Klaus 1960, (24–26) Cyathidites minor Couper 1953, (27–29) Triplanosporites sp., (30) Cyathidites concavus Bolkhovitina 1953, (31– 32) Cyathidites punctatus Delcourt and Sprumont 1955 emend. Delcourt et al. 1963, (33–34) Densoisporite smicrorugulatus Brenner 1963

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Fig. 4 (1) Deltoidospora hallii Miner 1953, (2) Deltoidospora mesozoica (Thiergart) Schuurman 1977, (3) Densoisporites sp., (4–6) Foraminisporis jurassicus Schulz 1967, (7) Foraminisporis paucispinosus Döring 1973, (8 and 11) Granulatisporites jurassicus Pocock 1970, (9) Gemmatriletes clavatus Brenner 1968, (10) Ischyosporites variegatus Couper (1958) Schulz 1967, (12 and 14–17). Klukisporites pseudoreticulatus Couper 1958, (13) Impardecispora trioreticulosus (Cookson and Dettmann 1958), (18–19) Klukisporites

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sp., (20–21) Klukisporites variegatus Couper 1958, (22–25) Lycopodiumsporites clavatoides Couper (26–27) Lundbladispora densispinosa Bharadwaj and Tiwari 1977, (28–29) Osmundacidites wellmanii Couper1953, (30) Ovoidites spriggii (Cookson & Dettmann) Zippi, 1983 (31) ?Podocarpidites sp., (32–33) Punctatisporites couperi Ravn 1995 (34) Punctatisporites crassiradiata De Jersey 1960, (35) Punctatisporites globosus (Leschik) Lund 1977

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Fig. 5 (1–2) Leptolepidites verrucatus Couper 1953, (3–4) Microreticulatisporites fuscus (Nilsson) Morbey1975, (5) Murospora florida (Balme) Pocock 1961, (6) Microreticulatisporites uniformis Singh 1964, (7) Osmundacidites sp., (8–9 and 12) Ovalipollis pseudoalatus (Krutzsch 1955) Schuurman 1976, (10) Punctatisporites gretensis Balme and Hennelly 1956, (11) Piceites expositus Bolchovitina 1956, (13) Triplanosporites sp., (14–15) Pityosporites parvisaccatus De Jersey 1960, (16) Protopinus scanicus Nilsson 1958, (17) Quadraeculina anellaformis Maljavkina 1949, (18) Quadraeculina canadensis Pocock 1970, (19) Rugulatisporites ramosus De Jersey, 1960, (20) Sestrosporites

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pseudoalveolatus (Couper 1958) Dettmann 1963, (21–22) Tricolpites vulgaris (Pierce) Srivastava 1969, (23 and 30) Trilites tuberculiformis Cookson 1947, (24–25) Trilobosporites marylandensis Brenner 1963, (26–28) Trilobosporites purverulentus (Verbitskaya) Dettmann 1963, (29) Trilobosporites hannonicus (Delcourt and Sprumont) Potonié 1956, (30–31) Trilobosporite stenuiparietalis Döring 1965, (32) Verrucosisporites contactus Clarke 1965, (33) Verrucosisporites obscurilaesuratus Pocock 1962, (34) Verrucosisporites triassicus Bharadwaj and Tiwari (1977), (35) cf. Uvaesporites sp.

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acuminate , Pholadomya (P.) lirata , Pholadomya (P.). kachchhensis, Mactromya aequalia, Integricardium triboleti , Acromytilus laitmairensis , E. asiaticus , E . rollandi , E . rollandi var. jabbokensis , Chlamys (C .) textoria , Africogrypha costellata, and Thracia viceliacensis.

Palynology The present study was aimed to shed some light on the dating of the non-marine rocks of the Hamam Formation based upon their palynological content. This will be of great value for dating Jordanian Jurassic strata. The palynoflora with well-preserved miospore assemblages is described only from the incised fluvial valley fill facies of the Hamam Formation and contains the species Callialasporites dampieri , Callialasporites trilobatus , Murospora florida , Corollina torosa, Osmundacidites wellmanii, Granulatisporites jurassicus, Cyathidites australis, Cyathidites minor, Protopinus scanicus, Klukisporites variegatus (the palynomorphs are listed in Table 1 and photographed in Figs. 3, 4, 5). Together with many other diagnostic Jurassic species the taxa form a palynological assemblage named the Middle Jurassic C. dampieri–M. florida assemblage (Table 2).

Age of the Hamam Formation Many different authors working worldwide agreed that Jurassic sporomorphs have a limited role in large-scale correlations, as many are long-ranging with disparate ranges in different areas (Backhouse 1988; Batten and Koppelhus 1996; Truswell et al. 1999; Schrank 2010). Despite these difficulties, the commonly cited Australian palynozones (Helby et al. 1987) have been used widely, also in the current study. The genus Callialasporites first appeared worldwide in the Early Jurassic (Saad 1963; Helal 1965; Filatoff 1975; Sultan and Soliman 1978; Davies 1985; Sultan 1985; Tiwari and Vijaya 1988; Shahin and El-Beialy 1989; Ibrahim et al. 2001), and toward the Middle Jurassic became dominant and more diversified. Ibrahim et al. (2002), in their study of the Jurassic rock from Qatar, recorded Callialasporites trilobatus , from the Izhara Formation dated as Hettangian to Sinemurian, whereas its upper part is Bajocian in age, and from Araej Formation dated as Middle Jurassic (late Bajocian/Bathonian to early Callovian) by means of strontium isotopes. Vijaya and Bhattacharji (2003) reported the first occurrence of M. florida in the Oxfordian with a phase of non-deposition between the Middle Triassic and Middle Jurassic in west Bengal, India.

Table 2 Comparison of palynozonations with different parts of the world

Helby et al. 1987

florida

verrucatus Zone

Dictyotosporites complex Zone

Leptolepidirites

Association Contignisporites Zone (in cooksoniae Zone part)

Contignisporites glebulentus Association Zone

Contignisporites glebulentus Zone

Aequitriradites norrisii Association Zone

Not zoned

Callialasporites dampieri Superzone

Bathonian

Callovian

Murospora

Jordan

Ibrahim

The present study

et al. 2001

Not studied

McKellar 1998

Egypt

Callialasporites dampieri-Murospora florida Zone

De Jersey and Raine 2002

Australia

Verrucosisporites spp. –Converrucosisporites spp. –Trilobosporites spp. Assemblage Zone

Age

New Zealand

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McKellar (1998) and Helby et al. (1987) recorded the M. florida Association Zone from the late Middle Callovian to Early–Middle Oxfordian (Table 2). Stefanowicz (2008) recorded the dominance of the cooler element Araucariacites australis as well as all Callialasporites species present here (C. dampieri, C. turbatus, and C. minus) in coastal assemblages in the Bajocian and Bathonian of Scotland. The presence of the mentioned pollen grains in the Jordanian Jurassic, may indicate the dominance of a cooler climate throughout the Middle Jurassic.

In contrast, the Hamam Formation is characterized by an abundant macrofauna indicative of a Bathonian age, based on which Ahmad (1998) described two biozones; the Cererithyris jabbokensis–Daghanirhynchia Biozone and the Cererithyris –Eligmus –Gryphaeligmus –Africogryphaea Biozone. The ammonite Micromphalites (Jordaniceras ) jordanicum and the brachiopod Eudesia cardium occurring in the Hamam Formation at Arda indicate a Bathonian age (Bandel K and Zeiss 1987). Aqrabawi (1987) dated the Ramla and Hamam Formation as Bajocian to Bathonian in age,

Table 3 Facies types of the Hamam Formation FT Name

Description

1

Quartz wacke

2

Echinoid quartz wacke (Fig. 8a)

3

Bioclastic glauconitic quartz wacke Pel-bio-packstone (Fig. 8g)

Very fine to fine quartz sandstone, well sorted, grains angular, The abundant pollen and spores and the absence of finely laminated, mud cemented. With occasional clay and dinoflagellates reflect deposition in a terrestrial silt inter-beds with plant remains environment as incised valley fill deposits Well-sorted fine-to medium-grained sandstones with lowHigh-energy lower shoreface angle stratification, moderate sorting, angular to subangular grains, glauconitic, echinoid fragments; cemented by mud Consisting of quartz grains, lithic fragments, and glauconite Beach facies grains with ferruginous patches in a calcareous mud matrix

4

Depositional environments and remarks

Bioclastic, grain-supported, dominated by calcareous algae, Protected, fully marine mid-ramp environment below the fairforaminifera, and rounded to ellipsoidal peloids cemented weather wave-base, with moderately high water-energy in a micrite to microsparite matrix (packstone fabrics) 5 Algal foraminiferal Mainly molluscan shell fragments and bioclastic grains of The low-diversity foraminifera and sponge spicules in wackestone juvenile brachiopods, bivalves, gastropods, red algae, addition to the juvenile brachiopods in a micritic matrix (Fig. 8d) ostracods, and foraminifera. They are loosely packed in a indicates a mid-ramp position below the fair-weather wavedense micritic matrix, which due to aggrading base with low-energy conditions and open circulation neomorphism becomes granular as well as mosaic sparry in (Wilson, 1975; Flügel, 2004; Hughes 2006) parts 6 Brachiopod Major components are bioclasts, mainly brachiopods. The brachiopod fauna characterizes somewhat deeper parts of packstone Fragments of thin bivalves are abundant, ostracods and the subtidal zone (Flügel, 2004). The predominance of (Fig. 8e) echinoderms are rare, sponge spicules are common mud-supported textures as well as the well-preserved infaunal and epifaunal associations suggests a mid-ramp environment 7 Bioclastic lime Rare skeletal particles closely packed in a dark dense micrite Restricted inner ramp environments in quiet water condition. mudstone/ matrix with black spots of organic material. Skeletal Comparable to the standard ramp microfacies 20 of Flügel wackestone particles are represented by low diversity of poorly (2004) (Fig. 8b) preserved foraminiferal tests, well rounded micritic pellets, ostracods oyster shell fragments and juvenile brachiopods. Some of these skeletal particles are replaced by microspar by aggrading neomorphism while their internal structure is still well preserved 8 Miliolid-textulariid Benthic foraminifera (miliolids and textulariids) and peloids Such recorded shallow-water biota of reduced diversity refers wackestone embedded in a micrite matrix to warm water, restricted inner ramp above the fair-weather (Fig. 8f) wave-base 9 Bio-grainstone/bio- Mainly skeletal debris of crinoid stems, bivalves and High-energy sand shoals packstone gastropods embedded in a sparry calcite cement. Most of (Fig. 8c) shell debris is rounded to sub-rounded, coarse- to mediumgrained and subjected to complete micritization High-energy intertidal shoal 10 Onco-ooMainly well sorted, rounded peloids (diameter: 0.05– 0.27 mm) with elongated to rounded algal oncoids (0.48– grainstone 1.7 mm in diameter). The allochems are cemented in a (Fig. 8h) sparry calcite with mosaic cement types; syntaxial types were also recognized in some samples

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although the equivalent Sherif Formation of Palestine is dated as Bathonian (Hirsch and Picard 1988). Therefore, in the present study, we suggest a Bathonian age for the miospore C. dampieri–M. florida Assemblage Biozone based on the correlation with different parts of the world.

Facies analysis and depositional environments Ten different (micro-) facies types could be distinguished in the Bathonian Hamam Formation by thin-section studies of the composition and texture, which are briefly described and illustrated (Table 3). Jordan and its neighboring regions were situated at the margin of the Neo-Tethys during the Middle Jurassic and represented a wide-mixed carbonate–siliciclastic ramp setting (Fig. 6). At the end of the Triassic, the area was uplifted, and consequently subjected to intensive weathering, resulting in a thick pile of sand deposited over an extensive area in Levant to produce a succession of mixed carbonates and siliciclastics (Hirsch 1986).

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The siliciclastic rocks of the Hamam Formation represent three alternating quartz wacke microfacies types (Fig. 2): quartz wacke (FT1), echinoid quartz wacke (FT2), and bioclastic glauconitic quartz wacke (FT2) reflect two deposition environments: the quartz wacke (FT1) reflects fills of marginal river channels and estuaries as is indicated by the dominant pollen and spores and the absence of dinoflagellates, while the other two facies types (FT2 and FT3) were deposited in high-energy lower shoreface of the beach face. The carbonate rocks of the Hamam Formation comprise peloidal bioclastic packstone (FT4), algal foraminiferal wackestone (FT5), brachiopodal packstone (FT6), bioclastic lime mudstone/wackestone (FT7), miliolid-textulariid peloidal wackestone (FT8), bioclastic grainstone/packstone (FT9), and onco-oo-grainstone (FT10). They suggest a depositional environment ranging from inner ramp to mid-ramp, reflecting minor fluctuations in relative sea level (Fig. 7). The sediments are arranged in coarsening-upward depositional cycles. The inner ramp comprises a restricted inner ramp including bioclastic lime mudstone/wakestone (FT7) and miliolidtextulariid peloidal wackestone (FT8) as well as high-energy shoals characterized by bioclastic grainstone/packstone (FT9) and onco-oo-grainstone (FT10). A middle ramp comprises peloidal bioclastic packstone (FT4), algal foraminiferal wackestone (FT5) and brachiopodal packstone (FT6). It reflects the deepest part of the ramp setting in a quieter environment below the fair-weather wave-base with open circulation. In analogy to the lower Bathonian carbonate deposits in Syria with abundant foraminifera, brachiopods, and bivalves (Fig. 8) (Kuznetsova et al. 1996), deposition took place in an open-marine basin with normal salinity related to an outer ramp, which deepened towards the east–northeast, where the siliciclastic facies is missing (Fig. 7).

Sequence stratigraphic framework The Hamam Formation of northwestern Jordan is interpreted in two third-order depositional sequences (Fig. 2). These depositional sequences are bounded by three regional hiatuses at the ?Bajocian–Bathonian stage boundary, within the Bathonian, and at the Bathonian–Callovian stage boundary. Hamam Sequence A

Fig. 6 Paleogeographic position of the study area, modified after Riccardi (1991) and Fürsich et al. (2004)

The Hamam Sequence A is ca. 20 m thick and is represented by the lower part of the Hamam Formation. It is traced between the shallow-marine, mixed siliciclastic–carbonate deposits of the basal part of the Bathonian Hamam Formation and the siliciclastic sandstones of the underlying

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Fig. 7 Lithofacies associations within the Bathonian Hamam Formation showing the ramp inclined towards the east– northeast

?Bajocian Ramla Formation and is associated with a strong vertical facies change (Fig. 2). This sequence boundary (SB1) may be coinciding with the Bajocian Bir Maghara and the Bathonian Safa formational boundary in Sinai, Egypt (El-Araby 2003). It is also recorded in western Iraq between the Bajocian Amij Formation and Lower Muhaiwir Formation (Al-Naqib and Al-Juboury 2013). The Hamam Sequence A includes the following systems tracts. The transgressive systems tract (TST) corresponds to the first appearance of fossiliferous limestone beds overlying the beach deposits (echinoid quartz wacke FT2) of the Ramla Formation to bioclastic lime mudstone/wackestone (FT7), deposited during rising sea level within a hypersaline, lowenergy shallow lagoonal setting. No underlying lowstand systems tract (LST) has been recognized due to the lowrelief ramp setting. In this case, the transgressive systems tract (TST) coincides with the sequence boundary (SB1). The maximum flooding surface (MFS) is represented by the top part of first carbonate beds and includes the maximum occurrence of the macrofauna in this interval. The highstand systems tract (HST) comprises oncoid-ooid grainstone (FT10) characterizing a high-energy intertidal shoal. The Hamam Sequence A is terminated by sequence boundary SB2 separating the incised valleys fill above from the HST below. This boundary can apparently be traced to many countries of the Arabian Plate, including Saudi Arabia, Kuwait,

Bahrain, western Iraq, and Qatar (Al-Husseini and Matthews 2006; Al-Naqib and Al-Juboury 2013). Hamam Sequence B The Hamam Sequence B is ca. 40 m thick and is represented by the middle and upper part of the Hamam Formation (Fig. 2). The LST is related to infilling starting in incised valleys in the late phase of the lowstand. It is represented by the massive, channeled sandstone alternating with 2–10 cm thick silt and clay. It matches well the terrestrial conditions during deposition of the coal seams of the Safa Formation at Gebel Maghara, Egypt. The coal seams of the Sherif Formation in the wells of the Negev are thin (Goldberg and Friedman 1974), which were dated as Bathonian (Hirsch and Picard 1988) and were replaced by terrestrial sandstone in Jordan compared to thicker coal seams in Gebel Maghara, Egypt. The TST is represented by a deepening-upward trend in facies and a decreasing-upward trend in sand/mud ratio are significant within the upper part of the Hamam Formation, documented by the presence of thin bivalves accompanied by monaxon and tetraxon sponge spicules and dwarfed, or juvenile costate brachiopods. This facies corresponds to the transition from the restricted inner ramp to the mid-ramp, bounded above by a MFS, which correlates with the Arabian Plate MFS J30 of Sharland et al. (2001).

Arab J Geosci (2014) 7:4861–4875 Fig. 8 Scale bar 250 μm. (a) Echinoid quartz wackestone consisting of fine sand-sized quartz grains and echinoid plates, sample 12, Arda section. (b) Bioclastic lime mudstone/ wackestone, sample 2, Tal el Dhahab section. (c) Bio-ograinstone dominated by calcareous algae, foraminifera with rounded to ellipsoidal peloidc cemented by micrite to microsparite, sample 7, Tal el Dhahab section. (d) Algal foraminiferal wackestone comprising monaxon and tetraxon sponge spicules, with foraminiferal tests and juvenile brachiopods embedded in lime mud, sample 26, Arda section. (e) Brachiopod packstone composed mainly of brachiopods with few bivalves, sample 18, Arda section. (f) Wackestone rich in benthic forams of miliolids and textulariids, sample 25, Arda section. (g) Pel-bio-packstone comprising rounded circular and elliptical normal and superficial ooids as well as calcareous algae, sample 13, Arda section. (h) Onco-oo- grainstone /rudstone with sparitic cement, sample 20, Arda section

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a

b

c

d

e

f

g

During the HST a progradational package of mixed bioclastic glauconitic quartz wacke (FT2), onco-oograinstone (FT10) and bioclastic grainstone/packstone (FT9) was deposited. The HST is terminated by the sequence boundary (SB3) separating the Hamam Formation from the Mughanniyya Formation.

h

A correlative hiatus coincides with the missing Upper Bathonian–Lower Callovian stage boundary between the Middle and Upper Dhruma Formation in Saudi Arabia (Fischer 2001). During the Lower Callovian, a significant transgressive episode is characterized by widespread shelf carbonate deposition of the Mughanniyya Formation with

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high densities of shelly fossils in Jordan. The base of the Mughanniyya Formation is dominated by miliolid-textulariid peloidal wackestone (FT10) and calcispheres are well developed in this microfacies, which indicates another phase of transgression at the beginning of Callovian. This deepening is observed in many areas of Arabian–African plates such as Egypt, Qatar, Saudi Arabia, Iraq, and Syria (Said 1990; Kuznetsova et al. 1996; Rousseau et al. 2005; Al-Naqib and Al-Juboury 2013).

Conclusions The Bathonian Hamam Formation of northern Jordan was deposited mainly in shallow-marine environments on the shelf of the Neo-Tethys. It consists of mixed carbonate–siliciclastic rocks, assigned to a Bathonian age on the basis of ammonites, brachiopods, and foraminifers. These mixed carbonate– siliciclastic depositional systems were composed of an incised fluvial valley fill facies (FT1), beach foreshore (FT2 and FT3), restricted inner ramp (FT4, FT5, and FT6), high-energy shoals (FT9 and FT10), and mid-ramp facies (FT7 and FT8). Two depositional sequences are recognized in the Bathonian Hamam Formation bounded by three regional hiatus at the Bajocian–Bathonian boundary, within the Bathonian, and at the Bathonian–Callovian stage boundary. These sequence boundaries can be correlated with those of neighboring countries, suggesting a eustatic origin. Three types of stacked systems tracts are defined: LST, TST, and HST. The LST was identified from sequence A only. It consists of quartz wackes, contains abundant and well-preserved spores, pollen grains and other organic debris, and is indicative of an incised fluvial valley fill environment. It yielded 64 miospore species belonging to 40 genera. The miospore C. dampieri–M. florida Assemblage Biozone introduced herein supports the Middle Jurassic (Bathonian) age of the Hamam Formation. The transgressive systems tracts are represented by restricted inner ramp and mid-ramp settings, while the highstand systems tracts are characterized by high-energy shoals followed by siliciclastic sediments. Acknowledgments We are gratefully acknowledging Prof. Dr. Franz T. Fürsich (Friedrich-Alexander Universität Erlangen-Nürnberg) for reading and comments of the revised version of this work.

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