Browsing by Author "Tiwari, R.P."

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    The 22 June 2020 Mizoram, India earthquake (Mw5.5): an unusual intra-wedge shallow earthquake in the Indo-Burmese Wedge
    (Indian Academy of Sciences, 2022-03-08T00:00:00) Malsawma, J.; Lalnuntluanga, Paul; Sailo, Saitluanga; Vanthangliana, V.; Tiwari, R.P.; Gahalaut, V.K.
    Earthquakes in the Indo-Burmese arc occur due to interaction of India and Sunda plates along the Indo- Burmese Wedge and Sagaing Fault. Majority of the moderate to major magnitude earthquakes in the Indo-Burmese Wedge occur within the Indian slab and very few of them occur on the plate interface. Earthquakes within the wedge are rare and the 22 June 2020 earthquake of magnitude 5.5 (Mw) on the India�Myanmar border in Mizoram, India, at shallow depth is probably one such earthquake. The earthquake caused moderate damage (maximum intensity VIII on MSK scale) in remote border villages (Vaphai and Chawngtui) with sparse population without any fatality. The earthquake did not seem to be related with the Mat Fault, which was transverse to the north�south trending wedge, as various estimates of mainshock and the region of maximum damage was ~20 km northeast of the surface trace of the Mat Fault. It appeared to be associated with almost north� south oriented Churachandpur Mao Fault (CMF) with dextral slip which mapped extensively and monitored geodetically in the neighbouring regions of Manipur and Nagaland to the north. Occurrence of this shallow depth earthquake may imply that some segment of the CMF might be seismically active, unlike in the north, where it appears to be predominantly aseismic. This implies that the seismic hazard along the CMF may vary along its length. � 2021. All Rights Reserved.
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    Chondrichthyan and osteichthyan fauna from the middle Miocene deposits of Palasava, Kutch, India: implication for paleoenvironment and paleobiogeography; [Faune de chondrichtyens et d�ost�ichtyens provenant des d�p�ts du Mioc�ne moyen de Palasava, Kutch, Inde: implication pour le pal�oenvironnement et la pal�obiog�ographie]
    (Academie des sciences, 2022-12-13T00:00:00) Singh, Nongmaithem Amardas; Choudhary, Deepak; Singh, Y. Priyananda; Singh, Ningthoujam Premjit; Patnaik, Rajeev; Tiwari, R.P.; Sharma, K. Milankumar
    The Neogene of Kutch, India is well known for its rich marine and terrestrial vertebrate assemblages. However, the data of piscean fauna from the middle Miocene of India is very scarce. We report here additional chondrichthyan and osteichthyan remains from the middle Miocene deposit of Chhasra Formation, Palasava site, Kutch, Gujarat, India. The elasmobranchs include Carcharhinus Blainville, 1816 (C. brevipinna (M�ller & Henle, 1839), C. falciformis (M�ller & Henle, 1839), C. cf. leucas, C. aff. perezi, Carcharhinus sp.), Negaprion Whitley, 1940 (Negaprion sp.), Aetobatus Blainville, 1816 (Aetobatus sp.), Myliobatis Cuvier, 1816 (Myliobatis sp.), Dasyatis Rafinesque, 1810 (D. probsti Cappetta, 1970, D. rugosa Probst, 1877), Himantura M�ller & Henle, 1837 (H. menoni Sahni & Mehrotra, 1981), Pastinachus R�ppell, 1829 (Pastinachus sp.), and Taeniurops Garman, 1913 (Taeniurops sp.). The teleosts of Palasava are represented by four families including Bagridae Bleeker, 1858, Channidae Fowler, 1934, Characidae Latreille, 1925 and Cyprinidae Cuvier, 1817. S�rensen-Dice coefficient data of Palasava elasmobranchs show a good similarity index with their counterparts in the Mediterranean Sea suggesting the existence of short-lived reopening of the marine pathway. However, a much higher faunal affinity with those of Eastern Pacific indicates a gradual shift in migration path through the Pacific Ocean to Indo-Pacific region after the permanent landbridge was formed. The vertebrate fauna from the Palasava suggests a coastal, marginal marine, near-shore littoral to neritic environment of deposition with the influence of freshwater riverine system. The integration of the floras and faunas from Palasava locality indicates the presence of warm, humid/ wet, tropical to sub-tropical environmental conditions during the middle Miocene. � 2022 Elsevier Masson SAS. All rights reserved.
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    First report on late Miocene (Tortonian: ~ 11�10�Ma) charophyte gyrogonites from Tapar, Kachchh District, Gujarat State, western India
    (Springer Nature, 2022-09-05T00:00:00) Singh, Nongmaithem Amardas; Singh, Ningthoujam Premjit; Sharma, K. Milankumar; Patnaik, Rajeev; Tiwari, R.P.; Sehgal, Ramesh Kumar; Kumar, Vinay; Wazir, Wasim Abass; Singh, Y. Priyananda; Choudhary, Deepak
    This paper describes the first record of charophyte gyrogonites from the late Miocene (Tortonian; ~ 11�10�Ma) Tapar locality of Kachchh, Gujarat State, western India. The recovered charophyte assemblage is constituted by Chara globularis var. aspera, C. globularis var. globularis, Lychnothamnus cf. sahnii, Lychnothamnus sp. and Nitellopsis sp. In addition, the present article discusses the palaeoenvironment based on the recorded charophyte gyrogonites (this study) and previously known faunal data (mainly vertebrates) from the Tapar locality, Kutch Basin, western India. Further, considering the significant extension of the biostratigraphic range [especially the First Appearance Datum (FAD)] of fauna from the Kutch Basin (in particular from the Tapar locality), we herein make an attempt to compare biostratigraphically the faunal assemblages from Kutch with those from the Siwalik Group, north India. � 2022, Indian National Science Academy.
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    Sharks and rays (chondrichthyes, elasmobranchii) from the miocene sediments of Kutch, Gujarat, India: paleoenvironmental and paleobiogeographic implications
    (Taylor and Francis Ltd., 2021-03-05T00:00:00) Sharma, K Milankumar; Singh, N Amardas; Patnaik, Rajeev; Tiwari, R.P.; Singh, Ningthoujam Premjit; Singh, Y Priyananda; Choudhary, Deepak; Lalotra, Sushil Kumar
    We report here a diverse assemblage of sharks and batoids representing the genera Carcharhinus, Rhizoprionodon, Galeocerdo, Sphyrna, Myliobatis, Aetobatus, Dasyatis, Pastinachus, Himantura and Pristis from Tapar and Jangadia the two late and early Miocene sites, respectively, of Kutch (Gujarat, India). The shark Rhizoprionodon and batoids, Dasyatis rugosa, D. cf. probsti, Dasyatis sp., Pastinachus and Himantura are being reported for the first time from the Miocene of western coast of India. The presence of Carcharhinus sp., Rhizoprionodon sp., Lamna sp., Negaprion sp., Sphyrna lewini, Myliobatis sp., Aetobatus sp. in the early Miocene Khari Nadi Formation exposed at Jangadia suggest existence of lagoonal, near shore to outer shelf environment. The rich batoid assemblage at the Late Miocene hominoid (Sivapithecus) bearing site of Tapar indicates the presence of a fresh to brackish water environmental condition. The faunal similarity of Miocene chondrichthyan of Indian Ocean and the Mediterranean Sea regions has been assessed using the beta diversity (S�rensen�Dice coefficient) data. The early Miocene elasmobranchs from Kutch shows close affinities with those from Mediterranean Sea. Similarly, in the Indian Ocean region Miocene fauna of Kutch shows close similarity with those of Baripada Beds, Orissa, Bhuban Formation of Mizoram, Gogha Coast, Piram Island and Madagascar. � 2021 Informa UK Limited, trading as Taylor & Francis Group.