Integrated Ichnological and Sedimentological

ISSN 0869-5938, Stratigraphy and Geological Correlation, 2018, Vol. 26, No. 7, pp. 709–721. © Pleiades Publishing, Ltd., 2018.

Integrated Ichnological and Sedimentological Analysis of the Cambrian Kunzam La (Parahio) Formation, Shian Section, Pin Valley, Spiti, Northwest Himalaya1 R. S. Chaubeya, B. P. Singha, R. Mikulášb, *, O. N. Bhargavac, N. K. Subhaya, and S. K. Prasada aCenter

of Advanced Study in Geology (CAS), Panjab University, Chandigarh, 160014 India of Sciences of the Czech Republic, Institute of Geology, Prague, Czech Republic cINSA Honorary Scientist, Panchkula (Haryana), India *e-mail: [email protected]

bAcademy

Received December 14, 2017; in final form, March 15, 2018

AbstractThe Kunzam La (Parahio) Formation along the Shian section of the Pin Valley was previously interpreted as containing Ediacaran–Cambrian boundary trace fossils, but re-examination of the Shian section shows that the oldest part of the section belongs to the late part of Cambrian Series 2, Stage 4, which contradicts the previous interpretation. The trace fossil assemblage comprises ?Arborichnus isp., Archaeonassa isp., Diplichnites isp., Hormosiroidea isp., Monomorphichnus lineatus, Bergaueria aff. langi, Palaeophycus tubularis, Rusophycus isp., and Treptichnus-like fossils that occur stratigraphically below the Oryctocephalus indicus biozone (Series 3, Stage 5) along the section and belong to the late part of Series 2, Stage 4. Sedimentary structures recorded along the section include hummocky cross-stratification (HCS) with deeply bioturbated tops, trough- and low-angle cross stratification, ball and pillow structures and climbing-ripple cross stratification. Integrated ichnofabric and sedimentological data suggest a storm-dominated, lower to upper shoreface shallow-marine environment of deposition. Keywords: Trace fossils, Ediacaran-Cambrian boundary, Cambrian Kunzam La (Parahio) Formation, storm-dominated, lower to upper shoreface, Pin valley, Spiti, India DOI: 10.1134/S0869593818070079

INTRODUCTION The Cambrian Kunzam La (Parahio) Formation of the Spiti region contains abundant trace fossils and nearly 40 ichnogenera have so far been reported from different sections (Bhargava and Bassi, 1998; Bhargava and Srikantia, 1985; Bhargava et al., 1982, 1986; Hughes et al., 2013; Parcha and Pandey, 2011, 2016; Sudan and Sharma, 2001; Sudan et al., 2000). However, these traces have never been subjected to detailed study in context of the lithological association; therefore, their significance in the Cambrian deposits of the Spiti region remains poorly understood. Moreover, trace fossils are poorly known from the Pin valley which lies in the southeastern part of the Spiti region. Sudan et al. (2000) described a few trace fossils from the Pin valley and used them to (i) define the two trace fossil zones (F1 and F2) in the section and subsequently for the Cambrian of Himalaya, (ii) demarcate the Ediacaran–Cambrian boundary interval (below their F1 zone), and (iii) identify the proliferation of organisms having jointed appendages at the transition from F1 to F2 zones. Later, Hughes (2002) and 1 The article is published in the original.

Hughes et al. (2013) commented broadly on various records of trace fossils from the Himalaya and rejected the view of two trace fossils zones in the Cambrian of Himalaya. Since the Ediacaran–Cambrian boundary in the Spiti region of the Himalaya has not previously been identified using paleontological and geochronological evidences, and the Pin valley does probably preserve a rock record of this interval (see Hayden, 1904; Fuchs, 1982), this encouraged us to explore the Shian (Saybang) section of the Pin valley (Spiti) to recover faunal elements relating Ediacaran–Cambrian boundary, viz., small shelly fauna of the basal Cambrian and the associated First Appearance Datum (FAD) of Treptichnus pedum. Here, we document the stratigraphic occurrence of trace fossils in the Shian (Saybang) section of the Pin valley (Spiti) with respect to the recently proposed trilobite biozonation of the Pin valley by Singh et al. (2017), and also assess their paleoenvironmental context based on interpretation of the physical sedimentology and ichnofabrics. A brief discussion on Ediacaran-Cambrian boundary issue in the Pin valley is provided.

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ad kh gar en em Kh

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Thango

Parahio river

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b

a kh sa

s su tu

Map and image legends re z one

Srinagar K ash nu r

Delhi India

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TF = trace fossils bearing level TB = trilobite bearing level

50 100 km

Muth quartzite Pin (Takche) formation Thango formation Kunzam La(Parahio) formation Batal formation Higher himalayan crystallines (HHC)

Mud

N Muth

0

2 km

TB

Pin

Pin valley

rive r

Saybang

Saybang

Baldur

tent

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Fig. 1. Geological map of the Pin and Parahio valleys of the Spiti region (modified after Bhargava and Bassi, 1998). Inset shows goggle image (looking North) of the location.

GEOLOGICAL SETTING AND LITHOSTRATIGRAPHY

Shian and Baldur localities along the right and left banks of the Pin River.

The Cambrian succession in the Himalaya is known from the two lithotectonic zones, namely the Tethyan Himalayan Zone (THZ) and the Lesser Himalayan Zone (LHZ), which are separated by the high grade metamorphic rocks of the Greater Himalayan Zone (GHZ). The Zanskar-Spiti sub-basin belongs to the THZ and lies north of the GHZ. The Spiti region lies in the northernmost part of the Himachal Pradesh and is bound in the west by Lahaul, in the north by Ladakh and in the east by Kinnaur and Tibet. The Pin Valley lies within the southeastern part of the Spiti region (Tethyan Himalayan Zone, THZ) and constitutes a remote region of the Lahaul and Spiti district of the Himachal Pradesh, India (Fig. 1). In the Pin Valley the outcrops of the Cambrian Kunzam La (Parahio) Formation are exposed between the

Lithostratigraphically, the Cambrian rocks of the Pin valley are included in the Haimanta Group, which consists of the Batal and the Kunzam La formations (Srikantia, 1981). In the Pin Valley, the contact between the Batal and the Kunzam La formations is gradational; it is exposed upstream of Pin River near the Tariya locality (Fuchs, 1982). Recently, Myrow et al. (2006a, 2006b) described 1360 m of Parahio Formation which represent only the top part of the Kunzam La Formation (Srikantia, 1981). The term Parahio Formation for the entire Kunzam La Formation was contested by Bhargava (2008, 2011), Parcha and Pandey (2011) and Virmani et al., (2015). Recently, the term Kunzam La (Parahio) was adopted for easy understanding of old and new names of the same formation (Singh et al., 2014, 2015a, 2015b, 2016a, 2016b, 2017), which is also used herein until the uniform ter-

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Table 1. The generalized stratigraphic classifications of the Cambrian of Spiti region (after Singh et al., 2016a) Stoliczka Greisbach (1865) (1891)

Hayden (1904)

Pascoe (1959)

CAMBRIAN

Parahio series “Bhabeh “Haimanta “Cambrian Series” Series” System”

Upper Haimanta series

Srikantia (1981)

Kunzam La Formation

Batal Formation

minology is not developed. Lithologically, the Batal Formation consists of phyllite, quartzite, sandstone and subordinate shale and conglomerate. No fossils have been found in the Batal Formation from exposures in the Pin Valley. Kunzam La (Parahio) Formation in Pin valley comprises shale, siltstone, sandstone and, less frequently, calcareous sandstone. Fossils from the topmost preserved part of the Kunzam La (Parahio) Formation in the Pin Valley yielded Oryctocephalus indicus, Pagetia significans, Kunmingaspis pervulgata and Bhargavia prakritika, suggesting the early part of the Cambrian Series 3, Stage 5 (Singh et al., 2017). Hayden (1904) recovered Redlichia noetlingi (Cambrian Series 2, Stage 4) from the float in the Pin valley but its stratigraphic horizon is not known (Reed, 1910; Jell and Hughes, 1997).The Thango Formation (Ordovician) is made up of conglomerate, grittysandstone, and quartzite of f luvio-shallow marine origin, unconformably (angular unconformity) lying over the Kunzam La (Parahio) Formation along the Shian section (Bhargava and Bassi, 1998; Fuchs, 1982; Hayden, 1904; Singh et al., 2017). The generalized stratigraphy of the Cambrian of the Spiti region is provided in Table 1. STUDIED SECTION The present study has been carried out along the Saybang (Shian) section in the Pin valley, which is also known as the Pin valley section (Hayden, 1904; Parcha, 1996, 1998; Reed, 1910; Singh et al., 2017; Sudan et al., 2000). The trace fossil bearing outcrops of the Kunzam La (Parahio) Formation are exposed along a slope on the right (east) bank of the Pin River (31°55′81.7′′ N, 78°02′01.2′′ E) and lies nearly 5.26 km south-south-east of the Mud (Muth) village (Fig. 1, TF; Fig. 2). The 164.5 m-thick composite section was measured and its physical sedimentology and ichnofabric analysed in detail (Fig. 3). The Kunzam La (Parahio) Formation along the section consists of thickly bedded, fine- to medium-grained sandstone, thinly laminated reddish-shale and siltstone and thick sandstone intervals. Nearly 0.3 km north of the trace STRATIGRAPHY AND GEOLOGICAL CORRELATION

Kumar et al., Myrow et al., (1984) (2006a) Kunzam La Fm.

Age

Parahio Member Debsa Khad Member

Batal Formation

Parahio Formation

Batal Formation

Bhargava (2008, 2011)

Singh et al., (2014, 2016a)

Kunzam La Formation

Kunzam La (=Parahio) Formation

Batal Formation

Batal Formation

fossil bearing section (Fig. 1, TF), an outcrop of the Kunzam La (Parahio) Formation is exposed along the slope (Fig. 1, TB) that encloses trilobites belonging to the Oryctocephalus indicus biozone and Bhargavia prakritika level of basal Cambrian Series 3, Stage 5 (Singh et al., 2017). A small brook separates the trace fossil-bearing strata from the Oryctocephalus indicus biozone; however, strike extension shows these trace fossil-bearing strata to lie nearly 100 m below the Oryctocephalus indicus biozone. TRACE-FOSSIL DISTRIBUTION, SEDIMENTOLOGY, ICHNOFABRIC AND DEPOSITIONAL ENVIRONMENTS The base of the section is not exposed and is covered under the slope debris (Fig. 3). The exposed section consists of light-green to grey shale and fine- to medium-grained sandstone interbedded with silty shale and fine-grained siltstone. The lower part of the section (upto 60.5 m) exhibits cyclic sedimentation (with cycles from 1.3 to 17.9 m thick);an ideal cycle consists of silty shale (slightly bioturbated, ii1–ii2; ii = ichnofabric index as defined by Bottjer and Droser, 1986) and fine-grained sandstone beds (HCS or tempestites) deposited in a lower-middle shoreface setting and highly bioturbated (ii = 3–4). In the basal part of the section, the 1.3-m thick, thinly laminated, finegrained sandstone exhibits hummocky cross stratification (HCS) (Fig. 4a) and shows moderate bioturbation (ii = 3). These beds indicate deposition under storm activity below the fair-weather wave base and above the storm wave base. Intense bioturbation of Planolites is commonly preserved a top these storm beds. Upward, these beds are followed by a fine- to medium-grained, moderately thick (6–7 cm), unbioturbated sandstone unit (1.2 m), that is characterised by intense interference ripple marks and indicates shallower condition than the underlying deposits. Upward, this unit is followed by a 1.2-m thick, light greenish-grey shale and micaceous siltstone alternation that preserves Planolites and whose ichnofabric index range from 1to3. This unit is followed by a modVol. 26

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Thango formation (Ordovician)

(TB)

rmity onfo r unc la a u Ang

Kun zam La(P arah io) fo rmat ion

(TF)

Angualar unconformity

Kun zam La(P arah io)

form ation Exp osur e (B )on slop e 88 m

Unexposed (~16 m)

Thango formation (Ordovician)

Un (~8expo 0 m sed )

(a)

16.5 Exposum re(A)o n slope

(b) Fig. 2. Field photographs of the trace fossils bearing section below the Cambro-Ordovician angular unconformity. (a) Panoramic view of the Shian section (Pin valley) and marked sections of trilobite (TB) (Singh et al., 2017) and the trace fossils (TF); (b) detail of the trace fossils bearing section at Shian (Saybang) locality on the right bank of the Pin river, Pin Valley (Spiti, Northwest Himalaya).

erately thick (10–12 cm), fine-to medium-grained, 1.3-m thickly bedded sandstone and shale-siltstone unit characterised by climbing ripple cross-stratification showing trough-like or festoon-like interlocking bedding (Fig. 4b). This unit is intensely bioturbated (ii 2 to ii4) and contains the trace fossils of Planolites, Palaeophycus tubularis and Bergaueria aff. langi. At 44.3 to 60.5 m from the base of the section the top of the fine-grained tempestites beds contains abundant traces including of a Treptichnus-like trace, ?Arborichnus, Diplichnites, and Planolites. Nearly 16 m of the section is covered by debris soil and could not be measured. The section is again measured above this soil cover and from 76.5 to 85.1 m an alteration of micaceous siltstone and thick, fine-grained sandstone, the latter of which exhibits ball and pillow structures (Figs. 4c–4e). No soft rocks were observed below or above the ball and pillow structures. These structures have been described mainly from the shallow-marine and deltaic deposits (Goldring, 1971; Pepper et al., 1954; Potter, 1963; Potter and Pettijohn, 1963; Radwański and Roniewicz, 1962; Smith, 1916 ) and can form within rapidly deposited sand due to differential

loading of underlying soft mud or also produced in earthquake (Howard and Lohrengel, 1969; Kaye and Power, 1954; Sims, 1973, 2013). Myrow et al. (2006a, 2006b) also recorded ball and pillow structures in the Parahio Formation in the Parahio valley and Zanskar region, and interpreted these as formed by gravitational action in a shallow-marine deltaic setting. The micaceous siltstone-sandstone unit overlying the finegrained sandstone unit with ball and pillow structures contains trace fossils of Diplichnites, Planolites, Archaeonassa isp., and Monomorphichnus lineatus. The middle part of the section (87.1 to 129 m) is dominated by medium to coarse-grained, massively bedded sandstone with a few intervals of fine shale and siltstone. It contains Hormosiroidea isp. and Planolites isp. The bedded sandstone preserves trough cross stratification (TCS), pebbly sandstone showing rip-up clasts, and graded bedding, and generally shows very low bioturbation (ii = 1). At 93.7 m of the section, fine-grained sandstone shows rip up clasts (mud chips) with erosional base (Fig. 5b) and trough cross stratification (TCS) (Fig. 5a) and abundant ball and pillow structures. This unit is followed upward by


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Bharaavia prakritika Level Oryctocephalus indicus Zone

Thango Formation

Shian (Saybang) section Pin Valley, Spiti (Singh et al., 2016)

Middle Shoreface

Middle Shoreface Lower Shoreface

Lower Shoreface

Upper Shoreface

Lower Shoreface

Upper Shoreface/ Fluvial

Lower Shoreface

Upper Shoreface

Lower Shoreface

Depositional environment

Ichnofabric indices 12345

0m

Planolites isp.

Planolites isp. Palaeophycus tubularis Bergaueria aff. langi Planolites isp. Planolites isp.

Treptichnus-type traces Arborichnus isp.

Trough Cross Stratification (TCS) Gutter Cast Ball and pillow structure Climbing cross-stratification Hummocky Cross Stratification (HCS) Fine-grained sandstone Fine-grained Siltstone Silty-Shale

LEGEND

Diplichnites isp., Planolites isp.

Diplichnites, Monomorphichnus lineatus Archaeonassa isp. Planolites isp.

76.5 m 60.5 m ~16 m scree covered

Planolites isp.

102.1 m

Hormosiroidea isp.

129.1 m

Planolites isp., Hormosiroidea isp. Diplichnites isp., Rusophycus isp., Palaeophycus isp. Planolites isp.

Hormosirojdea isp. Planolites isp.,

~80 m scree covered 164.5 m

Saybang (Shian) Section (Pin Valley) Spiti

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Fig. 3. Stratigraphic column measured at Shian (Saybang) locality in the Pin Valley (Spiti) showing the lithology, trace fossils distribution, ichnofabric indices and the predicted depositional setting.

Kunzam La (Parahio) Formation

Cambrian Series 2 (Stage 4)

Cambrian Series 2 Series 3 Ord.

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B

H

(a)

(b)

Ball & pillow-2

Ball & pillow-1

Fault

(c)

Ball & pillow strucctures

(d)

(e)

(f)

Fig. 4. Sedimentary structures within the Kunzam la (Parahio) Formation recorded from the Shian Section (Pin Valley). (a) A variation of ideal Hummocky cross stratification sequence showing hummocky zone (H) with several second-order truncations and deeply bioturbated top (B); the H zone with several second-order truncations missing F zone and Xb zone (after Dott and Bourgeois, 1979, 1980); (b) combined-flow and climbing ripple cross-stratification showing trough or festoon-like interlocking bedding formed under high energy conditions (Allen, 1971); (c–e) ball and pillow structures and enlarge view of the ball structure; (f) gutter cast preserved in the sole of the bed.

alternating shale, silty-shale and thinly bedded finegrained sandstone beds (129.1 to 164.5 m) with abundant Planolites, Diplichnites, Hormosiroidea, Palaeo-

phycus and Rusophycus exhibiting ichnofabric index 1 to 3. The fine-grained sandstone beds are 10–18 cm thick with low-angle cross stratification and top of


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(a)

(b)

Erosional surface B

B

TCS

Pebbles

(c) Fig. 5. Sedimentary structure recorded from the middle part of the Shiansection within the Kunzam la (Parahio) Formation. (a) Eroded trough cross-stratification (TCS) with erosional surface; (b) pebbly sandstone in the middle part of the section; (c) low angle trough cross stratification (TCS) truncated by an erosional surface with probably fragment of Daedalus? (B).

each sandstone bed is overlapped by highly bioturbated micaceous silty layer contains Diplichnites and Planolites. Silty layers show wavy lamination and lenticular bedding. Bioturbation and occurrences of trace fossils indicate that traces are commonly preserved only above the tempestites and transgressive units of lower shoreface. Middle to upper shoreface deposits are mostly less bioturbated (ii = 1) and contain gutter casts, ball STRATIGRAPHY AND GEOLOGICAL CORRELATION

and pillow structures, pebbly sandstone, trough crossstratification (TCS); these features indicate rapid deposition of these sediments. On the other hand, the lower shoreface deposits are characterised by finegrained hummocky cross-stratified sandstone displaying strong ichnological variability (ii 3–4). At one place a variation of ideal hummocky cross stratification sequence (Fig. 4a) exhibits a hummocky zone (H) with several second-order truncations and a deeply Vol. 26

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a1

(a) a1

(b) Fig. 6. (a, b) Archaeonassa isp., trails (in situ) preserved on bedding plane over the tempestites beds, Shian (Saybang) Section, Pin Valley.

bioturbated top (B). This sequence shows the dominant H zone with several second-order truncations and completely missing the F and Xb zones (after Dott and Bourgeois, 1979, 1982). Abundant Treptichnuslike traces (cf. Wilson et al., 2012) have been recorded in addition to lanolites, Archaeonassa,?Arborichnus, Diplichnites, Monomorphichnus, and Rusophycus from lower shoreface deposits (Figs. 6–8). Based on physical sedimentology and nature of bioturbation we interpret that these deposits indicate a lower to upper shoreface environment of deposition. Trace fossil distribution is essentially controlled by alternating and contrasting energy conditions of lower to upper shoreface setting and frequent storm events. Bioturbation is highly restricted on the top of the event beds (storm beds and tempestites) and ichnofabric index ranges from 1 to 4. DISCUSSION A great variation in the record of stratigraphic thickness of the Cambrian strata along the Shian (Saybang)/Pin section is observed in the published literature (Hayden, 1904; Parcha, 1996, 1998; Sudan et al., 2000). Hayden (1904) stated that some 100 m of Cambrian strata is exposed below the Cambrian–Ordovician angular unconformity at the Shian locality. Parcha (1996, 1998) observed two different thicknesses for the same section, i.e., 765 m (Parcha, 1996, p. 5, Fig. 1)

and 430 m (Parcha, 1998, p. 239, Fig. 3). Sudan et al. (2000) illustrated the thickness of the Kunzum La (Parahio) Formation along the Pin section as 3100 m (Sudan et al., 2000, p. 651, Fig. 2). Our measured thickness in the Pin section is very close to the estimation of Hayden (1904) and is only 164.5 m below the Cambro-Ordovician angular unconformity. Hence, we reject the stratigraphic thicknesses suggested by Parcha (1996, 1998) and Sudan et al. (2000) and confirm those of Hayden (1904). Further southeast of the Shian section (near the Tariya locality) a thick (~1200 m) succession of the Kunzam La (Parahio) Formation is exposed along the high slope. Following the strike and dip of the Kunzam La (Parahio) Formation in the Pin valley, it is likely that rocks between the Shian and Tariya localities in the Pin valley are earliest Cambrian (Terreneuvian to Series 2/Stage 3). Further investigation along the Tariya locality is required for the search of Ediacaran–Cambrian boundary interval in the Pin valley. However, it is constrained that the rocks around the Shian locality are no younger than the early part of the Cambrian Series 3, Stage 5 and no older than late part of the Series 2, Stage 4, which contradicts the view of existence of Ediacaran-Cambrian boundary along the Shian section (Sudan et al., 2000). The physical sedimentological dataset and the trace fossils recovered from the Shian section are interpreted to understand the paleoenvironmental setting of these rocks. In the past 50 years, various general


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(b)

(d)

(c)

(e)

Fig. 7. (a, b) Treptichnus-type trace fossil from the fine-grained micaceous siltstone slab, CAS/PIN/2015/TF-1612; (c–e) Hormosiroidea isp., PIN/2015/TF-1606; PIN/2015/TF-1601 and PIN/2015/TF-1610.

models and approaches have been developed worldwide by using trace fossils in the identification and interpretation of specific sedimentary environments (e.g., Bann et al., 2004; Buatois and Mangano, 2004, 2011; Gingras et al., 1999; Howard and Frey, 1984; STRATIGRAPHY AND GEOLOGICAL CORRELATION

MacEachern and Pemberton, 1992; MacEachern et al., 1999, 2005; Mangano and Buatois, 2004; Pemberton and Wightman, 1992; Pemberton et al., 1992, 2012; Savrda and Bottjer, 1989; Seilacher, 1967; Taylor et al., 2003; Trace Fossils..., 2012). Most of these modVol. 26

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(a)

(b)

(c)

(d)

(e)

(f)

Fig. 8. Cambrian trace fossils from the Shian (Saybang) Section, Pin Valley. (a) Monomorphichnus lineatus, CAS/PIN/2015/TF-1602; (b) Bergaueria aff. langi, PIN/2015/TF-1605; (c) Palaeophycus tubularis, PIN/2015/TF-1607; (d) Rusophycus isp., in situ; (e) ?Arborichnus isp., in situ; (f) Diplichnites isp., in situ.

els are related to the Mesozoic and younger rocks; therefore, a comprehensive sedimentological-ichnological model for the Cambrian succession is poorly understood. Myrow et al., (2006a, 2006b) interpreted that the Cambrian rocks in the Spiti and Zanskar regions are deposited in a deltaic setting, with exceptionally high rate of sedimentation. The Cambrian rocks of the Spiti and Zanskar region throughout contain highly diverse and abundant trace fossils at multiple horizons (Hughes et al., 2013; Singh, 2009). Normally the high rate of sedimentation makes the substrate unstable for colonization (Howard and Reineck, 1981; Monaco, 1995), but overall the Kunzam La (Parahio) Formation contains high diversity and abundant trace fossils. It may be possible that some episodes in which rate of sedimentation may be high within the Cambrian sediments of Zanskar-Spiti region. We have used the models of trace fossil associations in a deltaic setting (MacEachern et al., 1999, 2005) to understand the present studied case from the Pin valley. We have observed that along the Shian section, none of the trace fossils indicative of the deltaic environment (cf. MacEachern et al., 1999). In these deposits, the traces are abundantly found in the lower and middle shoreface strata, whereas the upper shoreface deposits are rarely bioturbated. The occurrence of the ball and pillow structures in the Cambrian of Spiti and Zanskar region, and indicative of deltaic setting (Myrow et al., 2006a, 2006b), may be produced by other mechanisms such as the gravitational sinking of

the sediments under rapid deposition or earthquakes (cf. Plink-Björklund and Steel, 2005; Sims, 1973, 2013). These deposits also cannot be categorized under the delta-front and prodelta setting because the tempestites associated with delta-front and prodelta settings show anomalous impoverishment of Skolithos ichnofacies elements and a predominance of depositfeeding structures (Coates and MacEachern, 1999, 2000; Gingras et al., 1998; MacEachern and Loseth, 2003; Soegaard and MacEachern, 2003). Typical ichnofaunal elements of Skolithos ichnofacies (as understood by Seilacher, 1967) have not yet been recognized in the Kunzam La (Parahio) Formation. The studied part of the Kunzam La (Parahio) Formation shows progradational successions and contains ball and pillow structures, gutter cast, hummocky cross stratification (HCS), climbing ripple cross-stratification, lowangle trough cross stratification (TCS), and collectively indicate a high-energy wave- and storm-dominated upper to lower shoreface environment. Abundance of ball and pillow structure in the middle of the studied section indicates that this part of the Kunzam La (Parahio) Formation was probably deposited under high-energy, gravitationally dominated processes (cf. Plink-Björklund and Steel, 2005). CONCLUSIONS At the Shian locality in the Pin valley, the Cambrian Kunzam La (Parahio) Formation occurs immediately


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below the Cambrian–Ordovician angular unconformity. The Formation represents the interval from the late part of the Cambrian Series 2, Stage 4 to early part of the Series 3, Stage 5, which was previously interpreted spanning the Ediacaran-Cambrian boundary interval. The bioturbation index of these rocks ranges from 1 to 4. Overall, the measured section shows progradational succession deposited in a high-energy wave- and storm-dominated upper to lower shoreface environment. ACKNOWLEDGMENTS BPS is thankful to Prof. Sören Jensen and acknowledges him for discussion of some of the traces described in this article. We are equally thankful to the reviewers A.V. Dronov and A.K. Rindsberg for the constructive reviews and fruitful suggestions. BPS is thankful to University Grant Commissions (UGC) for providing the Startup Grant (no. F.201/2012(BSR)/20-8(12)/2012(BSR)).ONB thanks Indian National Science Academy (New Delhi) for supporting the financial grant. RM acknowledges the Institute of Geology, Czech Academy of Sciences, Prague, for support (Item no. RVO 67985831 and Czech Science Foundation, Project no. 18-05935S). We acknowledge muleteer and porter Chawang and Thinley Ghatak for logistical support. Reviewers A.V. Dronov and A.K. Rindsberg REFERENCES Allen, J.R.L., Mixing at turbidity current heads, and its geological implications, J. Sediment. Petrol., 1971, vol. 41, pp. 97–113. Bann, K.L., Fielding, C.R., MacEachern, J.A., and Tye, S.C., Differentiation of estuarine and offshore marine deposits using integrated ichnology and sedimentology: Permian Pebbley Beach Formation, Sydney Basin, Australia, in The Application of Ichnology to Palaeoenvironmental and Stratigraphic Analysis, McIlroy, D., Ed., Spec. Publ.—Geol. Soc. London, 2004, no. 228, pp. 179–211. Bhargava, O.N., An updated introduction to the Spiti geology, J. Palaeontol. Soc. India, 2008, vol. 53, no. 2, pp. 113– 129. Bhargava, O.N., Early Palaeozoic palaeogeography, basin configuration, palaeoclimate and tectonics in the Indian Plate, Mem. Geol. Soc. India, 2011, no. 78, pp. 69–99. Bhargava, O.N. and Bassi, U.K., Geology of Spiti-Kinnaur Himachal Himalaya, Mem. Geol. Surv. India, 1998, no. 124, pp. 1–210. Bhargava, O.N. and Srikantia, S.V., Trilobite and other trace fossils from the Kunzam La Formation, eastern Lahaul Valley, Himachal Himalaya, J. Geol. Soc. India, 1985, vol. 26, no. 6, pp. 880–886. Bhargava, O.N., Kumar, G., and Gupta, S.S., Cambrian trace fossils from the Spiti valley, Himachal Himalaya, J. Geol. Soc. India, 1982, vol. 23, no. 3, pp. 183–191. Bhargava, O.N., Bhandari, A.K., and Sharma, R.K., Lower Cambrian trace fossils from the Kilung Valley, Lahaul and STRATIGRAPHY AND GEOLOGICAL CORRELATION

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INTEGRATED ICHNOLOGICAL AND SEDIMENTOLOGICAL ANALYSIS Seilacher, A., Bathymetry of trace fossils, Marine Geol., 1967, vol. 5, pp. 413–428. Sims, J.D., Earthquake-induced structures in sediments of Van Norman Lake San Fernando, California, Science, 1973, vol. 182, pp. 162–163. Sims, J.D., Earthquake-induced load casts, pseudonodules, ball-and-pillow structures, and convolute lamination: Additional deformation structures for paleoseismic studies, in Recent Advances in North American Paleoseismology and Neotectonics East of the Rockies, Cox, R.T., Tuttle, M.P., Boyd, O.S., and Locat, J., Eds., Geol. Soc. Am., 2013, vol. 493, doi https://doi.org/10.1130/SPE493 Singh, B.P., Integrated ichnological and sedimentological studies of the Parahio Formation (Cambrian) of the Zanskar Region (Zanskar–Spiti Basin), Northwest Himalaya, J. Geol. Soc. India, 2009, vol. 74, no. 12, pp. 723–737. Singh, B.P., Virmani, N., Bhargava, et al., Yuehsienszella (Cambrian Series 2) trilobite from the Parahio Valley, Spiti region (Zanskar-Spiti Sub-basin), India and its biostratigraphic significance, J. Palaeontol. Soc. India, 2014, vol. 59, no. 1, pp. 81–88. Singh, B.P., Virmani, N., Bhargava, O.N., et al., Trilobite fauna of Cambrian Series 2 (Stage 4)–Series 3 (Stage 5) boundary from the Parahio Valley (Spiti), Northwest Himalaya, India, Himalaya Karakorum Workshop, 2015a, vol. 30, pp. 42–43. Singh, B.P., Bhargava, O.N., Juyal, K.P., et al., Skeletal microfauna from the Cambrian Series 2 (Stage 4) Kunzam La Formation, Parahio valley, Spiti region (Tethyan Himalaya), India, Curr. Sci., 2015b, vol. 109, pp. 2191–2195. Singh, B.P., Virmani, N., Bhargava, O.N., et al., N., Trilobite fauna of basal Cambrian Series 3 (Stage 5) from the Parahio Valley (Spiti), Northwest Himalaya, India and its biostratigraphic significance, Ann. Paléontol., 2016a, vol. 102, pp. 59–67. Singh, B.P., Virmani, N., Bhargava, O.N., and Gill, A., Revision of diagnostic features of the trilobite genus Bhargavia (Ellipsocephaliodea) from the Parahio valley (Spiti), Northwest Himalaya, India, J. Palaeontol. Soc. India, 2016b, vol. 61, no. 1, pp. 9–14.


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