Middle to Late Ordovician (Darriwilian-Sandbian) conodonts from the Dawangou section, Kalpin area of the Tarim Basin, northwestern China

Abstract

Forty-four conodont species are documented from the Dawangou section in the Tarim Basin, which spans the Darriwilian to Sandbian interval and is the global auxiliary stratotype for the base of the Upper Ordovician. Five conodont zones are recognized in this section, including the Yangtzeplacognathus crassus, Histiodella holodentata and H. kristinae zones in the upper part of the Dawangou Formation, the Pygodus anserinus Zone from the upper part of the Saergan Formation to the lower part of the Kanling Formation, and the Baltoniodus alobatus Zone in the upper part of the Kanling Formation. Presence of the P. serra Zone is based on occurrences of this species on shale bedding planes in the lower and middle Saergan Formation, but could not be confirmed in acid-leached samples studied from this interval. The Middle/Upper Ordovician boundary occurs within graptolitic black shale of the upper Saergan Formation. Although the boundary interval was intensively sampled, conodonts were very rare, probably due to stagnant or stratified basinal environments. This documentation of the conodont faunas and biostratigraphy of the Dawangou section is considered preliminary and more detailed conodont studies are required, but the remoteness of the site hinders the further extensive sample collection needed for this purpose.

On the integration of Ordovician conodont and graptolite biostratigraphy: new examples from Gansu and Inner Mongolia in China

“…5B), a genus first described from Australia (Burrett 1979, Zhen et al 2010 but which subsequently has been recorded from many localities on the North China Platform (e.g., An et al 1983, An & Ding 1985, Pei & Cai 1987, An & Zheng 1990, Lin & Qiu 1990. As a whole, the Pingliang fauna is similar to pandemic deep/cold water conodont faunas of late Darriwilian-early Sandbian age, such as those from Dawangou, Kalpin (Zhen et al 2011), the Pratt Ferry Member of the Athens Shale of Alabama (Sweet & Bergström 1962), the Lenoir Limestone and associated strata in eastern Tennessee (Bergström & Carnes 1976), the Womble Shale of Arkansas (Repetski & Ethington 1977), the Cobbs Arm Limestone of Newfoundland (Bergström et al 1974, Fåhraeus & Hunter 1981 and the Furudal and Dalby formations in Sweden (Bergström 2007a, Bergström et al 2011). This type of conodont fauna is also known from the Sandbian GSSP at Fågelsång in southernmost Sweden (Bergström 2007b).…”

“…The purpose of the present report is to describe the conodont biostratigraphy of these sections and assess its relations to the graptolite biostratigraphy. Because most of the conodont species encountered are well known and have been dealt with taxonomically in recent papers describing other conodont faunas (see e.g., Zhen et al 2011), we feel there is no need to include species descriptions. However, we illustrate the most important taxa.…”

A regional tectonic event of Katian (Late Ordovician) age across three major blocks of China

“…the Yingan Formation of early Katian age, or the Tierekeawati Formation of possibly late Katian age) in the well-known Dawangou succession yields no conodonts. At Dawangou, the youngest recovered Ordovician conodonts are from the Kanling Formation (latest Sandbian) and they represent the Baltoniodus alobatus Subbiozone of the Amorphognathus tvaerensis Biozone [24]. However, at Yakrik, Wushi County, ca.…”

Conodont biostratigraphy and global correlation of the middle Darriwilian-lower Sandbian (Ordovician) Las Aguaditas Formation, Precordillera of San Juan, Argentina

“…This zone correlates with equivalent strata in Newfoundland , the Marathon basin, Texas (Bergström, 1978), strata in the Great Basin and Rocky Mountains (Harris et al, 1979), Poland (Dzik, 1994), Sweden (Bergström, 1971(Bergström, , 2007, northwestern China (Zhen et al, 2011a), Thailand (Agematsu et al, 2007), Kazakhstan , and New South Wales in Australia (Zhen et al, 2003).…”

“…The Periodon and Histiodella lineages have great potential for global correlation (Stouge, 1984(Stouge, , 2012Stouge et al, 2011;Chen et al, 2006;Stouge and Zhao, 2006) and support a correlation with equivalent strata in Canada (Uyeno and Barnes, 1970;Barnes and Poplawski, 1973;Pyle et al, 2003;Stouge, 2012), USA (Bauer, 2010;Graves and Ellison, 1941;Bradshaw, 1969), Norway (Rasmussen and Stouge, 1995;Rasmussen, 2001), Sweden (Stouge and Bagnoli, 1999;Löfgren, 2004;Mellgren and Eriksson, 2009), Estonia (Löfgren, 2004), China (e.g., Zhang, 1998a;Chen et al, 2006;Zhang and Gao, 1991;Zhao et al, 2000;Stouge and Zhao, 2006;Stouge et al, 2011;Zhen et al, 2011a), Australia (Zhen and Percival, 2004), New Zealand (Zhen et al, 2009;Zhen et al, 2011b), and Kazakhstan (Zhylkaidarov, 1998;Tolmacheva et al, 2004).…”