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 Mesozoic 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 (Cambrian, Ordovician and Permian) and hydrocarbon reservoirs. The thick argillaceous Mesozoic (late Cretaceous) 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 Series Diplichnites, Dimorphichnus, Monomorphichnus, 2, Stage 4 to Wulian Stage, Miaolingian 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 Silurian 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 Oryctocephalus 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 Cambrian Series 2-Wuliaun Stage, Miaolingian Series boundary. Singh et al. (2017b) described the Cambrian The FAD and LAD of O. indicus are preserved at Wuliuan Stage, Miaolingian Series, trilobite fauna 7.74 and 14.61 m respectively, indicating 6.87 m comprising Peronopsis 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 Pagetia and Kunmingaspis, together at 7.34 m known Oryctocephalus indicus biozone 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 Kaili Formation, 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 Furongian (Paibian) part, hence most part of the Wuliuan Stage, Miaolingian Series. not useful for demarcating the Ediacaran-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