Late Paleozoic and Triassic bryozoans from the Tethys Himalaya (N India, Nepal and S Tibet)

Abstract

New findings of Late Paleozoic and Triassic bryozoans from the Tethys Himalaya are reported. Fifteen species, including three undetermined, were described, while determinations at order, family or genus level were obtained on fragmentary material. The studied bryozoans were framed in a solid lithostratigraphic scheme spanning across the Tethys Himalaya for over 1500 km, from NW India (Zanskar and Spiti) through Nepal (Dolpo and Manang) to South Tibet; they are concentrated in correlatable stratigraphic intervals corresponding to the Upper Devonian-Tournaisian, Bashkirian, Sakmarian, Midian and Lower Norian. This study allowed us to integrate bryozoan occurrences reported from the literature, mostly referring to the Tournaisian, Bashkirian and Early Norian, and to refine the available biostratigraphic dates. Bryozoan-rich intervals are interpreted as associated to long-term transgressions, in turn driven by major climatic and/or tectonic events. Cosmopolitan genera which prevail in the Paleozoic, are replaced by provincial forms after the Triassic crisis.

Dimension of Greater India in the early Mesozoic: Paleomagnetic constraints from Triassic sediments in the Tethyan Himalaya

“…Previous mapping has determined the ages of the stratigraphy of the study area (Wan et al, 2000;Sakagami et al, 2006;Hu et al, 2008;Brühwiler et al, 2010;Forel et al, 2011). Table 1 lists the most recent stratigraphic scheme: (1) the Middle-Upper Permian Selong Group, with basalts alternating with shales and sandstones; (2) the Lower to Upper Triassic Tulong group, with gray laminated limestone alternating with shales and sandstones;…”

A new Early Triassic brachiopod fauna from southern Tibet, China: Implications on brachiopod recovery and the late Smithian extinction in southern Tethys

“…There may be an unconformity between the Selong Group below the Permian-Triassic boundary and the Kangshare Formation above the boundary (Yuan et al, 2018). The lower part of the Selong Group consists of 24 m thick bioclastic limestone and dark silty shales, and the upper part consists of massive crinoid grainstone beds that contain abundant brachiopods, crinoids, bryozoans, and corals (Shen et al, 2000, 2001, 2006b; Sakagami et al, 2006; Yuan et al, 2018). The lowermost part of the Kangshare Formation is characterized by brown dolomitized crinoidal packstone and thick-bedded packstone beds (i.e., Waagenites Bed and Otoceras Bed), yielding brachiopods, corals, bryozoans, ammonoids, ostracodes, foraminifers, and calcareous sponges.…”

Carboniferous floras in siliciclastic rocks of Kashmir Himalaya, India and the evolutionary history of the Tethyan Basin

“…The underlying Syringothyris Limestone Formation is generally accepted as Tournaisian to early Viséan in age based mainly on evidence of brachiopods (Waterhouse & Gupta, 1979; Sakagami et al . 2006). Overlying the stratigraphically lower plant bed interval of the Fenestella Shale is Member B sensu Singh, Maithy & Bose (1982) which has also yielded a diverse marine fauna.…”