First record of ostracods from the Upper Ordovician red-coloured marine sandstones of the Tierekeawati Formation in Tarim Basin, NW China: implications on palaeoenvironment and palaeobiogeography

Jun-Jun Song,Peng Tang,Qi-Jian Li,Xiao-Le Zhang,Yi-Xin Shen,Zheng-Jiang Luo

doi:10.1186/s42501-020-00064-y

Abstract

Ostracods are described for the first time from the red-coloured marine sandstones of Arisu section (Arisu red beds) of the Upper Ordovician Tierekeawati Formation in Kalpin area of northwestern Tarim Basin, Xinjiang Uygur Autonomous Region (Xinjiang), Northwest China. Twenty-two species belonging to thirteen genera are described and figured. The ostracod fauna suggests a probable Sandbian–Katian age for these beds. The palaeoecological assemblage of ostracod fauna implies the deposition in a nearshore-offshore environment during a regression when the Arisu red beds of the Tierekeawati Formation were laid down in the Tarim Basin. Many cosmopolitan and provincial genera were present in diversified ostracod fauna of the Arisu red beds, suggesting the possible biogeographic relationships among the Tarim, Tibet, and South China plates, as well as Europe and North America continents during the Late Ordovician. Ostracods experienced faunal exchanges between Laurentia and the Tarim Plate during the Late Ordovician Period.

Highlights

Ostracods are one of the most widespread and diverse group of crustaceans since the Early Ordovician and are still thriving today (Horne et al 2002; Siveter 2008)
The goal of this paper is to report the ostracods occurring in these Arisu red beds of the Upper Ordovician Tierekeawati Formation in northwestern Tarim Basin, Xinjiang, Northwest China, and to discuss their biostratigraphical, palaeoecological and palaeogeographical implications
4 Results The ostracod faunas obtained from the Arisu red beds of the Tierekeawati Formation are composed by Palaeocopida (e.g., Aparchitoidea, Drepanelloidea, Hollinoidea), Metacopida (e.g., Healdioidea, Longisculoidea, Thlipsuroidea), and Podocopida (e.g., Bairdioidea)

Summary

Introduction

Ostracods are one of the most widespread and diverse group of crustaceans since the Early Ordovician and are still thriving today (Horne et al 2002; Siveter 2008). Ordovician strata are widely distributed and exposed in northwestern Tarim Basin, Northwest China, especially in the Arisu section in Kalpin area (Fig. 1), and its lithostratigraphy and biostratigraphy have been studied in detail (e.g., Zhou 2001; Wu 2003; Chen et al 2012, 2013; Zhang and Munnecke 2016; Han et al 2017). We discovered ostracods in red-coloured marine siliciclastic sediments (referred to as Arisu red beds) from the lower part of the Upper Ordovician Tierekeawati Formation in Kalpin area (Fig. 2). The goal of this paper is to report the ostracods occurring in these Arisu red beds of the Upper Ordovician Tierekeawati Formation in northwestern Tarim Basin, Xinjiang, Northwest China, and to discuss their biostratigraphical, palaeoecological and palaeogeographical implications.

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Discussion

Conclusion