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Home , Miaolingian, Serpukhovian, Wuliuan

Proc Indian Natn Sci Acad 86 No. 1 March 2020 pp. 217-226  Printed in India. DOI: 10.16943/ptinsa/2020/49800

Status Report 2016-2019 Contributions to the Palaeozoic and of the Himalaya O N BHARGAVA1,*, BIRENDRA P SINGH1, B PANDEY2, J A GANAI3, G M BHAT3, S K PRASAD1 and R A RASHID4 1Centre of Advanced Studies in Geology, Panjab University, Chandigarh 160 014, India 2 Department of Geology, Banaras Hindu University, Varanasi, India 3Department of Geology, University of Jammu, Jammu and Kashmir, Srinagar, India 4Department of Geology, Aligarh Muslim University, Aligarh, India

(Received on 08 August 2019; Accepted on 10 October 2019)

Introduction Stratigraphic Code of Nomenclature. In the Himalaya both the Palaeozoic and the Mesozoic Craig et al. (2018) considered that the sequences are developed in the Tethyan Himalaya, Palaeozoic setup of the Zanskar basin is rather similar while in the lesser Himalaya only parts of the to that of the Peshawar Basin, which constitutes Palaeozoic (, and ) and hydrocarbon reservoirs. The thick argillaceous Mesozoic (late ) are preserved. The successions of the Palaeozoic and the Mesozoic difficult terrain combined with travel restrictions, successions of the Kashmir, Zanskar, Chamba and which required special administrative clearance Spiti basins are potential hydrocarbon source rock discouraged geological investigations in the Tethyan horizons. The Mesozoic successions include thick area. With improvement in the logistics and removal sequences of organic material rich argillaceous of restrictions, there is a spurt in geological activity in sediments. Some of the shales contain organic matter Spiti. The renewed activity in most instances was and could represent viable hydrocarbon source rocks, restricted to short duration due to limited period of while some of the limestones, dolomites and field work available in the high-altitude terrain. For sandstones have sufficient reservoir characteristics. obvious reasons,the hurried investigations with little appreciation of regional picture besides generating Palaeozoic new data, in some cases created anomalies. Cambrian Hughes et al. (2018) in a review paper The Cambrian of the Tethyan Himalaya in Spiti and suggested Parahio Valley Section as the type section also in the lesser Himalaya has been intensely studied for the Cambrian in India and recommended Parahio during 2016-2020 for refinement of the biostratigraphy Formation as name for the Cambrian sequence of as well as the sedimentology. These are summarised the Tethyan Himalaya. Srikantia and Bhargava (2018) below. contested the claim of Hughes et al. (2018) and stated that the Parahio section is truncated due to a fault Parcha and Pandey (2016) described and represents only late part of the Cambrian Diplichnites, Dimorphichnus, Monomorphichnus, 2, 4 to Wulian Stage, Series, while Palaeophycus, Planolites and Skolithos from the a complete succession is exposed in the Kunzam La Cambrian Kunzam La Formation, Chandra Tal section section after which the formation is named. Srikantia (Lahaul valley) and interpreted a shallow marine and Bhargava (2018) also clarified certain arbitrary environment for the deposition. nomenclature applied to Cambrian, Ordovician and sequences in contravention of the Indian Singh et al. (2016a) precisely demarcated the *Author for Correspondence: E-mail: [email protected] 218 O N Bhargava et al.

Hayden level 2 in the Kunzam La Formation, in Spiti; section immediately below the Cambro-Ordovician it brackets the local stratigraphic range of contact suggests erosion of nearly 1160 m of the indicus - a key taxon considered Cambrian strata (deposited within about 2 My, i.e., for the Global Stratotype and Point Section (GSSP) 509 to 507 Ma) prior to the deposition of the Ordovician for the base of the Wuliaun Stage, Miaolingian Series Thango Formation. (or Middle Cambrian) and possibly, the -Wuliaun Stage, Miaolingian Series boundary. Singh et al. (2017b) described the Cambrian The FAD and LAD of O. indicus are preserved at Stage, Miaolingian Series, fauna 7.74 and 14.61 m respectively, indicating 6.87 m comprising sp., Eosoptychoparia cf. stratigraphic range of the taxon along the Parahio spinosa, Gaotanaspis cf. pingzhaiensis and valley section (Singh et al., 2016a). The FADs of Gaotanaspis cf. transversa immediately above the and Kunmingaspis, together at 7.34 m known Oryctocephalus indicus in the predate the FAD of O. indicus 7.74 m. Pagetia Parahio valley (Spiti). The FAD of Peronopsis and ranges from the Cambrian Series 2 (Stage 4) to the LAD of Gaotanaspis were utilized by these authors base of the Wuliuan Stage, Miaolingian Series and its to establish a Peronopsis-Gaotanaspis concurrent occurrence in Spiti is consistent with the global biozone immediately above the Oryctocephalus occurrences. The taxon, Eosoptychoparia indicus biozone. The first records of cf. pingzhaiensis (Danzhaina) sp. was recorded for the ûrst time from and Peronopsis taijiangensis from the Cambrian of the Indian Himalaya. Spiti together with the other faunal elements were correlated with the biozone of the , Singh et al. (2016b) discovered complete South China. The stratigraphic thickness from the base specimens of ellipsocephalinae trilobite Bhargavia of the O. indicus biozone to the top of the prakritika from the Kunzam La Formation, Peronopsis-Gaotanaspis concurrent biozone in the Parahiovalley section, Spiti. It enabled elaboration of Kunzam La Formation and its comparison to the Kaili its diagnostic characters, which earlier were based Formation indicate a possible stratigraphic only on cranidia and pygidia. B. prakritika now has condensation in the basal part of the Cambrian Series been recorded at 12.1 m above the Oryctocephalus 3, Stage 5 of the Parahio valley (Spiti). indicus Zone (Cambrian Series 3, Stage 5), which becomes the lowest stratigraphic level of this taxon, Singh et al. (2017c) reported the first occurrence reported so far. This level is equated with the upper of Treptichnus pedum and Treptichnus lublinensis part of the Plagiura Zone of the Great basin. Earlier, from the Cambrian succession of the Spiti Valley the type species of B. prakritika were known from (Tethyan Himalaya) and the Nigali Dhar syncline Kaotaia prachina Zone (Stage 5) around 233.4 m (Lesser Himalaya) respectively. These authors above the inferred O. indicus level (Peng et al., discussed the morphological variation, palaeo- 2009). environmental and stratigraphic significance of Ichnogenus Treptichnus and reviewed the known Singh et al. (2017a) for the first time recorded occurrences of Phycodes pedum and Treptichnus, from the Pin Valley (Spiti) the trilobite fauna synonymous and analogous from the Cambrian of comprising Oryctocephalus indicus, Pagetia India and Bhutan and concluded that in the Himalaya significans, Kunmingaspis pervulgata, and (including Bhutan) the known occurrences of Bhargavia prakritika, which ranges from the top Treptichnus pedum show a range from Cambrian part of the Cambrian Series 2 (Stage 4) to the basal Series 2, Stage 4 to () part, hence most part of the Wuliuan Stage, Miaolingian Series. not useful for demarcating the -Cambrian On the bases of the trilobite fauna and their boundary. The late appearance of Treptichnus stratigraphic levels, the Oryctocephalus Zone (5.4 ichnogenus in the Cambrian of the Himalaya was m), interval 1 of no zonation, and the Bhargavia attributed to higher latitudinal position of India during prakritika Level (Wuliuan, Miaolingian) are the Early Cambrian. As a result, possibly, the recognised. The O. indicus Zone is based on the FAD Treptichnus producing organism, i.e. priapulid worms and LAD (local range) of the eponymous species in emerged in the later part of the Cambrian Series 2, the Pin Valley section. The occurrence of fossiliferous Stage 4 in both the regions. Contributions to the Palaeozoic and Mesozoic of the Himalaya 219

Chaubey et al. (2018) described sedimentology Sandstone Member of the Koti Dhaman Formation and trace fossils assemblageofa part of the Kunzam (Cambrian Series 2, Stage 4), Tal Group, Nigali Dhar La Formation exposed along the Shian section of the Syncline, Lesser Himalaya. The trilobite traces Pin Valley. The trace fossil assemblage comprising? Cruziana salomonis, Cruziana fasciculata, Arborichnus isp., Archaeonassa isp., Diplichnites Rusophycus dispar and Rusophycus burjensis of isp., Hormosiroidea isp., Monomorphichnus Gondwana affinity were reported along with lineatus, Bergaueriaaf flangi, Palaeophycus Arenicolites isp., and Skolithos isp. from the Lower tubularis, Rusophycus isp. and Treptichnus-like Quartzite Member. This rich and diverse ichno- fossils, occurring stratigraphically below the assemblage, attributed to the Cruziana ichnofacies, Oryctocephalus indicus biozone (Series 3, Stage 5) is the first record from the Arkosic Sandstone belongs to the late part of Series 2, Stage 4; this finding Member. Seven ichnofossil assemblages, i.e., supersedes the previous Ediacaran–Cambrian Cruziana-Rusophycus, Planolites-Palaeophycus, boundary age assignment. Integrated ichnofabric and Cruziana-problematica, Diplichnites, Cochlichnus sedimentological data of these authors suggest a storm- anguineus, Bergaueria perata and Psammichnites dominated, lower to upper shoreface of shallow- gigas have been recognized in the Lower Quartzite marine environment. to Arkosic Sandstone members. Seven sedimentary facies are identified in the Koti Dhaman Formation, Yin et al. (2018) described low-diversity which indicate shallowing upward parasequences of acritarch assemblages, including Alliumella baltica, a tidal flat complex. Overall, two major events are Bavlinella faveolata, Brocholaminaria nigrita, recognized: i) the break in sedimentation between the Brocholaminaria sp., Eliasum sp., Leiosphaeridia- Lower Quartzite Member and the overlying Shale minutissima, Leiosphaeridia spp., Member, probably related to forced-regressive event Lophosphaeridium sp., Pterospermella solida, and ii) the facies shift from the Arkosic Sandstone Satka colonialica, Siphonophycus sp., and Member represents an erosive transgressive event; Synsphaeridium sp., including a new species the surface is interpreted as wave ravinement surface, Synsphaeridium parahioense together with which is also a sequence boundary. Integrated studies filamentous algae and cryptospore-like microfossils indicate that the Lower Quartzite Member was from 45 rock samples of the Cambrian Kunzam La deposited in a shallow subtidal sand sheet complex Formation around the Oryctocephalus indicus Zone and tidal flat complex, while the Shale Member was (Cambrian Series 3) at the Kaltarbo locality in the deposited in a mud flat setting of a tidal flat complex Parahio valley, Spiti. The acritarch assemblages at and the Arkosic Sandstone Member in a mixed-flat the basal part of the Cambrian Series 3 in the Kunzam (tidal flat complex) to sand sheet complex front and La (Parahio) Formation were dependent on the local margin (subtidal sand sheet complex). Overall, the marine environment. The new discovery of lower to middle part of the Koti Dhaman Formation cryptospore-like microfossils from the Cambrian represents a tide-dominated shallow subtidal–intertidal KunzamLa Formation confirmed the extensive to mud-flat sub-environments of the tidal flat complex. distribution of possible cryptospores in the Cambrian Palaeogeographic reconstruction of lower Cambrian sequences. (516-514Ma) based on the distribution of trilobite Kaur et al. (2019) refined the Cambrian traces from the Lesser Himalaya and the Bikaner- biozonation along a continuous section in the Parahio Nagaur area of Peninsular India (eastern Gondwana), valley and precisely located trilobite faunas of Egypt, Jordan, Turkey (western Gondwana) and Haydenaspis parvatya level and the O. indicus Canada (Avalonia) was also proposed by these Biozone, which are stratigraphically separated by 183.4 authors. m, which is 62 m higher than the level estimated by Ordovician Peng et al. (2009). Sinha and Verniers (2016) recorded chitinozoans Singh et al. (2019) presented an integrated Belonechitina capitata from the Shiala Formation ichnology, sedimentology and sequence stratigraphy of Tethyan Kali Valley, Uttrakhand. The authors have from the Lower Quartzite Member to the Arkosic suggested that B. capitata had a wide latitudinal range 220 O N Bhargava et al. extending from northern Gondwana, over Avalonia to clastic sediments and the and Baltica, and is a useful guide fossilof the middle to granitites from the Himalaya suggest that Tethyan late Ordovician. sediments may have been derived from these granitoid belts. Detrital mineralogy and CIA values postulate Pandey and Parcha (2018) added to the existing that the provenance was affected by low to moderate record of Ordovician algae in the Himalaya by degree of weathering. The high CIA values related reporting calcareous algae Dasyporella silurica, to humid, non- (early Ordovician) and Moniliporella multipora and Vermiporella fragilis the low CIA values related to cold glacial period (late from the Middle Ordovician ( to ) Ordovician). Thango Formation exposed in the Pin Valley of the Spiti. This algal assemblage indicates shallow marine, Singh et al. (2019b) for the first time recorded warm, well-oxygenated and relatively high-energy Ordovician trace fossils from the Lesser Himalaya in environment of deposition. These calcareous algae the NigaliDhar Syncline, Himachal Pradesh. An also known from the Tarim Basin, Kazakhstan, angular unconformity separates Ordovician trace Baltica, North America, Scotland and India indicate fossil bearing horizon with the underlying Lower that all these terrains were located along the 0-30° Cambrian Shale Member of the KotiDhaman latitudinal belt during the Ordovician period, with a Formation (Tal Group). possible link between the Tethyan Himalaya and the Tarim basin. Silurian Chaubey et al. (2019) described warm-water Myrow et al. (2018) reported a lower Silurian Dasycladaceae algae Mastopora and Cyclocrinites ozarkodinid fauna within the upper member of the from the Takche Formation (Upper Ordovician–lower Takche Formation that included Ozarkodina sp. cf. Silurian), Parahio Valley, Spiti. The abundance of hassi, Oulodus sp., Panderodusuni costatus, and cyclocrinitid remains indicates location of the Spiti at Distamodus sp., the latter is a lower Silurian index about 30° South palaeolatitude during the Late fossil, thus confirming a Llandovery, age for the Ordovician and early Silurian. They attributed the uppermost Takche Formation. They provided a extinction of cyclocrinitids at the end of Ordovician high-resolution ~13C curvepossibly indicating latest period is related to cooling and glaciations. Ordovician to earliest Silurian sea to a transition into a major icehouse condition. The curve shows a Cryptostome bryozoan Ptilotrypa bapjaii long-term positive excursion that is capped by a reported from the lower part of the Yong Limestone, conspicuous positive spike, recorded within a thin Tethyan Kumaun Himalaya indicates an Upper calcareous algae-rich shale unit. Directly overlying Ordovician age. The Ordovician-Silurian boundary strata shows an abrupt negative shift (>1.5‰) and thus may lie in the upper part of the Yong Limestone then further negative drift of ~1.3‰. When correlated or in the overlying Variegated Formation (Swami et to other sections globally,it indicated that the pattern al. 2019). represented the Paroveja (= BC-14, Elkhorn) positive excursion, the last major excursion prior to the - Rashid and Ganai (2018) documented boundary interval. They further suggested petrography and sedimentology of the siliciclastc rocks that the Takche Formation also recorded pre- of the Thango Formation, Spiti, which suggest three Hirnantian warming interval and an Hirnantian global major depositional environments, viz., fluvial, cooling (Boda event). transitional and marine representing transgressive and regressive phases. Geochemical and petrographic studies suggest passive margin tectonic setting for these siliciclastic rocks. Petrographic and geochemical Singh et al. (2017d) described an ichnofossils characteristics coupled with some signiûcant immobile assemblage comprising Asteriacites stelliformis, A. elemental ratios and REE patterns and strong negative quinquefolius, Biformites insolitus, Helminthoidi- Eu/Eu* anomaly indicate the derivation of the chnites? isp., Lingulichnus isp., Lockeia siliquaria, Spitisiliciclastic sediments from a more felsic dominant Palaeophycus tubularis, Planolites isp., source. Multi-elemental spider diagrams of the Thango Protovirgularia isp. A, Protovirgularia isp., B, Contributions to the Palaeozoic and Mesozoic of the Himalaya 221

Protovirgularia isp. C, Psammichnites isp., Manigam (Anantnag Kashmir). This assemblage of Rusophycus isp., and Treptichnus isp. from the Po the northern margins of Gondwana, on the shores of Formation (Visean-) exposed at the base the Palaeo-Tethys, is dominated by remains of an of the Ganmachidam Hill near Chichong village, Spiti eligulate, mainly monopodial lycopsid with persistent Valley. Sedimentary structures such as hummocky leaves. The stems show considerable morphological cross-stratification, low-angle planar and trough cross variation that having been assigned to different fossil- beds, and shallow, slightly asymmetrical gutter casts species and genera. Partially the morphological combined with the trace fossil assemblage indicated variation could have been due to variations in growth upper shoreface to lower shoreface of an open shelf rate of the individual plants, which in turn may reflect environment of deposition. stressed growing conditions in a wetland. The systematic position of Spondylodendron however, The geochemical studies carried out by Ganai remains uncertain due to the lack of reproductive et al. (2016) and Ganai and Rashid (2019) suggested structures, though it may have affinity with the that varying Chemical Index of Alteration values Sublepidodendraceae. (CIA) and –4Si% values corresponding to Lipak, Po and Ganmachidam formations of Spiti might have Agnihotri et al. (2018) using a single zircon (U- resulted due to varying weathering conditions in the Pb method) assigned 329 ± 16 Ma age (late Viséan provenance, i.e. warmer (more weathering), to early Serpukhovian) for the Fenestella Shales, gradually becomes cooler during middle Carboniferous which coincides with the earlier observations based and finally leading to ice age during the Permo- on faunal assemblage. The palynoflora of the

Carboniferous interval. Based on high SiO2, Al2O3 Fenestella Shale was compared by these authors to and relatively low MgO values coupled with immobile the Carboniferous-Permian of Pakistan, Yemen, South elemental ratios (SiO2/Al2O3, Al2O3/TiO2) and LREE America, South Africa, Antarctica, Australia and India. enriched and almost flat HREE patterns, Th/Sc, La/ Mega-fossils of pteridophytes and gymnosperms Sc, Cr/Th, La/Th, ratios and strong negative Eu/Eu* monosaccate and bisaccate pollen grains and the suggest derivation of sediments from the Proterozoic trilete spores together with abundant Fenestella and Palaeozoic granitoids of the Himalaya (Rashid specimens indicate a marine coastal environment. and Ganai, 2018). Geochemical palaeo-redox Diverse micro- and megafloral assemblages of the parameters such as Ni/Co (4.0-7.2), V/Cr (1.7-2.8), Fenestella Shales in the Banihal area of Kashmir V/(V+Ni) (0.6-0.9),V/Sc (7.2-29.1) and negative to region suggest warm, temperate climatic conditions. subtle positive Ce anomalies indicate that Devonian- Carboniferous black shales of the Lipak Formation Permian represent an event of anoxia, which can be correlated Ghosh et al. (2016) documented sedimentological and with global events such as Hengenberg Events or the high-resolution trace element concentrations and Lower Alum Shale Event in Germany. The phosphatic carbon, oxygen, lead isotope data across the P-Tr nodules occurring in these black shales show enriched boundary in Atargu and Guling sections in Spiti. Based Y, Sr and REE abundances with high P2O5 contents on framboidal pyrites, fossils and laminated lithology and MREE enrichments, with a “hat-shaped” pattern of the Late Permian shales of the Gungri Formations and subtle positive Ce-anomalies. The hat-shaped deeper anoxic depositional environment was patterns are linked to the formation of authigenic interpreted. δ13C org excursions of 2.4‰ and 3.1‰ apatite caused by microbial decomposition of organic in Atargu and Guling sections, respectively, signify matter (Ganai and Rashid, 2019). the P-Tr transition across a clayey, partly gypsiferous The δ13C values of the Lipak carbonates range ferruginous layer. Sedimentological similarities of this from –8 to +2.6 ‰ and δ18O from –10-14.5%, the layer to other Neo-Tethyan sections from large shift in values may represent facies change Transcaucasia and Iran indicate subaqueous oxidation associated with the regression (Ganai et al., 2016). of shallow marine sediments on a regional scale. Light Rare Earth Element-enriched Late Permian Gungri Cleal et al. (2016) reported rich fossil flora of Shales with conspicuous Ce–Eu anomalies point to Serpukhovian age from the Fenestella Shales of the adjacent Panjal Trap basalts (ca. 289 Ma) of 222 O N Bhargava et al.

Kashmir as source. Continental crustal Nb-Ta and boundary. This global perturbation of the carbon Zr-Hf anomalies appear at the P-Tr boundary isotope signal is linked to a climate change at the sediments, and extend to the overlying Early Griesbachian-Dienerian transition, from a cool and carbonates. Original Pb isotope ratios, along with an dry to a hot and humid climate. This transition could increasing Pb abundance closer to the P-Tr boundary, be the trigger of the migration of neogondolellids distinguish the volcanic source of the Late Permian towards the high latitude, and of the radiation of shales from the continental crustal siliciclastic neospathodids during the Dienerian. signature of the carbonates. The δ13C org, trace element and Pb isotope record from Spiti Petrographic and, major and trace element indicate catastrophic changes in sediment sources and geochemistry and rare earth elements studies of the facies, with effects on carbon cycle, which are late Permian and early Triassic sediments by Pillai et consistent with an abrupt episode of marine regression al. (2017) in the Guryul Ravine revealed a visible and erosion also observed elsewhere along northern change in the lithostratigraphy from argillaceous - Gondwanaland. Simultaneous eruption of Siberian carbonaceous mudstone in the C Member of the volcanics and bolide impacts in the Parana basin of Zewan Formation, to fine grained argillaceous siltstone Brazil and elsewhere implied impact-triggered with quartz in the D Member, (4 m below the Late volcanism that affected sea level, climate, marine Permian Event Horizon. The XRD analysis indicates anoxia and tectonic stability that connected the P-Tr more terrigenous input below the PTB, which is also crisis across global terrestrial and marine realms. supported by the dominance of quartz whereas the dominant clay mineral illiteis followed by chlorite. The

Jasper et al. (2016) recorded fragments of K2 O + Na2 O vs SiO2 plot indicates that the sediments tracheids that show homogenized cell walls, a at the PTB were derived from andesite type of rocks characteristic feature of charcoal in the Late Permian (SiO2 52-63%) of intermediate composition. Major Zewan Formation of the Guryul ravine. This feature oxides SiO2,CaO, Na2O and MnO are most abundant is regarded an evidence of palaeo-wildfire, which in the D Member, whereas the E Member is enriched permits reconstructing environment during the Late in the Co, Ni, Cu, V and Zn signifying reducing Permian Zewan Formation. conditions. Dominance of incompatible elements such as Ti, K, Rb, and Sr in finer shale fraction shows Brosse et al. (2017) studied the increased reworking of sediments. Moderate biochronology and isotopic records of the fifteen weathering is observed at PTB, whereas below the lowermost stratigraphical metres (Member E) of the LPEH, physical weathering is more pronounced. Y/ Khunamuh Formation at the Guryul Ravine, which HO ratio varies from 24-51 indicating that REEs are includes both the Permian-Triassic and the derived from shale source. The Corg :P is < 10:1 in the Griesbachian-Dienerian (Induan) boundaries. The late Permian whereas it is > 10:1 in the early Triassic FAD of Hindeodusparvus occurs in the middle of Period suggesting that the conditions transformed sub-member E bed (GUR09). They established 10 2 from oxidizing to reducing (maximum values noticed conodont Unitary Association zones. The UAZ of 1-2, in sample no. 5 (80:1)) indicating sub-oxic to anoxic Late Permian, identified only in South China, conditions, which may be one of the causes of oceanic UAZ are present both in China and the Guryul 3-10 redox at PTB. Ravine. The Griesbachian-Dienerian boundary is located within the interval of separation between Study by Huang et al. (2019) revealed two

UAZ7 and UAZ8. At the Guryul Ravine, the boundary pronounced stages of oceanic oxygen deficiency, in is precisely constrained between beds GUR310 and the latest Permian Hindeodus praeparvus-Clarkina GUR311 and corresponds to the replacement of meishanensis Zone and the earliest Triassic Neogondolella to Sweetospathodus and Isarcicella staeschei Zone. Updated marine Neospathodus . Brosse et al. (2017) also invertebrate fossil records show three sharp species observed a conspicuous δ13C positive excursion and richness declines at the Guryul Ravine. The first regarded it to a significant event at least at the scale decline occurred within the uppermost Permian storm of the Tethyan realm that could be used as a beds and is interpreted to represent a facies control secondary proxy for the Griesbachian-Dienerian in which a storm-agitated environment was Contributions to the Palaeozoic and Mesozoic of the Himalaya 223 inhospitable for benthos. The latter two biotic declines extinction at these boundaries. Carbon isotopic studies coincided with two marine anoxic events, as carried out on Mesozoic Spiti black shales show documented by pyrite framboid distributions. The same decrease in δ13C values or negative values (-22 to - two anoxic events are also recognized from PTB beds 27%), indicating an input of isotopically light carbon. in the adjacent, relatively shallower Barus Spur section Fluctuations of δ13C values recorded in the shales in Kashmir, in which newly obtained faunal data coincide with the Early Triassic period after which helped to constrain placement of the PTB. These the values return to relatively elevated values (from - authors reported a two-stage pattern of oceanic anoxia 27 to -24). These changes appear to be related with during the Permian-Triassic transition. They proposed glacial intervals at terminal Permian periods and Early that the two anoxic events at the Guryul Ravine Triassic period (may be related with the Permian- correlate precisely with anoxic events in the Meishan Triassic boundary). GSSP and some sections in South China suggesting that this event might have been characteristic of the Mesozoic Permian-Triassic transition in some specific geological The -Cretaceous marine sediments settings. The close relationship between oxygen represented by the Tagling (), Spiti, depletion and species richness decline suggests that Guimal (), and Chikkim (Late the former was an important contributor to the latter. Cretaceous) formations crop out in the Spiti Valley. Kumar et al. (2017) discussed geochemistry of The Spiti and Giumal formations are rich in ammonoids the Permian-Triassic sequences of the Guryul Ravine referable to Stage/Substage/Zone. Based on section, Jammu and Kashmir, India and its implications planktonic five planktonic foraminiferal for oceanic redox conditions. assemblages in the Chikkim Formation could be identified. The litho-biostratigraphic evaluation of the The studies on sandstones and black shales of Jurassic-Cretaceous succession in the Spiti Valley the Mesozoic successions from the Spiti region, Tethys reveals the presence of the T-OAE of late Early Himalaya, have yielded interesting results. The wide in the youngest few meters of the Tagling range of CIA values (i.e. 56-86) shown by these rock Formation, Late Weissert OAE, latest types indicate low to intense chemical weathering in Faraoni OAE and Early OAE1a the source area, which in turn implies variable climatic in the Giumal Formation, and probable an Early conditions that may have prevailed in the source OAE 1b, Late Albian OAE 1c and 1d, latest region. The Spiti sedimentary samples show dramatic OAE 2 and / OAE variation in the REE concentrations with prominent 3 in the Chikkim Formation (Pandey and Pathak, 2016). Ce positive and negative anomalies, which signifies the role of sea water dynamics (particularly changing Jurassic redox conditions) during the deposition of these Pandey and Pathak (2016) reported the presence sediments. The concentration and the ratios of redox- ofthe T-Oceanic Anoxic Event of late Early Toarcian sensitive elements (V/V+Ni, and V/Sc) of the in the youngest few meters of the Tagling Formation. Mesozoic Spiti black shales represent anoxic conditions for their deposition. This inference is in Krishna (2017) published an interesting book on conformity with the observed negative Ce anomalies the Indian Mesozoic geological evolution in perspective in the black shales. The average Corg content for of sequence stratigraphy. It is mainly based on black shales is 0. 745 (wt. %), with a range of 0.2 to ammonoid based high resolution scales in the Triassic 2.13 (wt. %), the lowest value recorded at Early and Jurassic period. In this book the Indian or at the P/T boundary and at Triassic/Jurassic – record is organized into five boundary. Thus, the Corg content noticeably fluctuates mega-sequences. from the Triassic to the Jurassic periods at different stratigraphic levels. This observation points that there Cretaceous was a decrease in C content perhaps due to a crash org The existing contribution to the understanding of the in productivity at theses boundaries, which in turn may Early Cretaceous ammonoid record in India was have become one of the prime reasons for mass carried out by Pandey et al. (2015) who suggested 224 O N Bhargava et al. that the ammonoid bearing Early Cretaceous the lower/upper Valanginian boundary. succession in the Spiti Himalaya, the Giumal Formation is ideal to carry out ammonoid based biostratigraphic Earlier, the Giumal Formation was assigned a studies. They opined that the record of the ammonoid vague Hauterivian – Albian age. Discovery of genera Odontodiscoceras and Berriasella from the Odontodiscoceras and Berriasella at the lowest basal sandstone bed and Colombiceras, Deshayesites, level and Colombiceras, Deshayesites and Cleoniceras and Australiceras from the upper most Australiceras in the topmost sandstone bed enabled sandstone beds, the age of the Giumal Formation precise dating of the Giumal Formation as – ranges from Berriasian to Early Aptian. Early Aptian (Pandey and Pathak, 2016, 2017; Pandey et al., 2018a, b). Discovery of this new faunal element Pandey and Pathak (2017) recorded new enables demarcation of Berriasian, Valanginian, species of the ammonoid genus Olcostephanus Hauterivian – Berremian and Aptian stages in the Neumayr from the Lower Cretaceous Giumal Giumal Formation. Formation exposed near Gete village in the Spiti Valley. Itis one of the most significant genera for intra- Pandey et al. (2018a) erected a new neocomitin basinal to intercontinental biochronostrati-graphic ammonite genus Geticeras from the Giumal correlation in view of its episodic global expansion Formation, named after Gete village. This discovery during the Valanginian. This first report included enabled the differentiation of Lower and Upper Olcostephanus (Olcostephanus) sakalavensis Valaginian substages within Valaginian. (Besairie), Olcostephanus (Olcostephanus) cf. The Chikkim Formation has been assigned a salinarius, Olcostephanus (Olcostephanus) cf. post-Aptian age (Pandey and Pathak, 2016, 2017; fascigerus and Olcostephanus (Olcostephanus) sp. Pandey et al. 2018b). 20 samples of black indet., from the Indian Cretaceous. Based on close carbonaceous shales in the Spiti and Chikkim resemblance with the well-known biostratigraphically formations of the Spiti valley of the Tethys Himalaya precised Mediterranean and South American (Pandey et al. 2018b) were subjected to maceral Olcostephanus species, the Indian taxa have been analysis, Rock-Eval Pyrolysis. Six samples were placed by these authors in the Neocomites analysed for Fourier Transform Infra-red platycostatus Subzone of the Karakaschicerasino Spectroscopy (FTIR) and nuclear magnetic resonance stranzewi Zone to the Saynoceras verrucosum (NMR) analyses. The study revealed the presence Subzone of the Saynoceras verrucosum Zone of mainly kerogen-III type of organic matter, some of interval of the Standard Tethyan Scheme. Pandey and the shale samples showed total organic carbon (TOC) Pathak (2017) also proposed a possible correlation to the tune of 3.19%. The results indicate the incidence with Olcostephanus bearing stratigraphic horizons of methane occurring as free and fixed hydrocarbon of South Africa, Madagascar and Pakistan. The in these samples. A few levels were found rich in findings confirmed a significant eustatic rise close to

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