Yarkant Gr
Type Locality and Naming
Tarim Basin. It was named by De Terra, H. as the Yarkant System in 1932. The naming locality is situated on the left bank of the Yarkant River (in the Tarim area; also translated as Yarkand or Ye'erqiang), Xinjiang Uygur Autonomous Region. Comprised of the upward succession of the Shalitashi Fm (conglomerate), Kangsu Fm (sandstone) and Yangye Fm and Ta'erga Fm (claystone).
Synonym: （叶尔羌群）, Ye'erqiang Gr, Yeerqiang Gr, Yarkand Gr
Lithology and Thickness
The particular group represents a set of grey-green coal-bearing clastics deposits, composed of grey-green mudstones, siltstones, sandstones and conglomerates, intercalated with violet banded mudstones, locally with poor-quality coal beds. The thickness of the particular formation is changeable from region to region. It is 5000 m thick in the Tuoyun Basin, 4300 m thick in the Kashi region, yet with a great decrease in its thickness in the southwestern part of the Shache region, being of only 500-200 m.
Relationships and Distribution
Lower contact
Its basal part overlies unconformably the Proterozoic Arkesu Gr or the Devonian System (in the Tuoyun Basin and Kashi region), or overlies disconformably the Permian System (in the Yingjisha region). Regionally, the next older unit is the late Triassic Huoxiaer Fm (column TJ16) or the early Triassic Wuzunsayi Fm (column TJ17).
Upper contact
Its top part being overlain conformably by the Kuzgongsu Fm.
Regional extent
The group is distributed in the Tuoyun Basin, the Tarim Basin and its southwestern margin, the frontland of the Kunlun Mts and foothill of the Aljin Mts with a good development of the particular group having been found in the Tuoyun-Kansu region and the surrounding area of Kashi City, where it can be subdivided into the above-mentioned four formations. Till the area southwest of the Shache County town (Hantiereke, Kezyletao, Kusilapu) it gradates into grey-violet and purple fine clastic rocks, intercalated with coarse clastic rocks. And there are scattered exposures of the particular group having been found to occur only in the Hetian and Yecheng counties on the southwestern margin of the Tarim Basin and in the foothill of the Kunlun Mts, with a great decrease in its thickness, and with no possibility of it being subdivided.
GeoJSON
Fossils
In the Wuyitak area, the group yields plant fossils as represented by Coniopteris hymenophyloides, Ctenis cf. chinensis, Neocalamites sp. and Phoenicopsis sp., but tields Coniopteris sp. and Phoenicopsis sp.; as well as bivalve fossils as represented by Pseudocardinia sp.; Ostracoda fossils as represented by Darwinula sp. and “conchostracan” fossils in the Dagangou area of the Targa region of Wucha County and Wucha Coal Mine west of the Kuzgongsu River.
Age
Depositional setting
Additional Information