The Sangonghe biota in the Junggar Basin, NW China: age constraints and climate implications

ABSTRACT

A distinct coal break occurs widely in the late Early Jurassic in Central Asia, the cause of which, however, is still debated largely due to the uncertainty of its age constraint. In the Junggar Basin of northwestern China, this coal break coincides with the Sangonghe Formation, which is well exposed along the basin margins, and is mainly composed of lacustrine deposits rich in a variety of fossils, including plants, pollens and spores, bivalves, clam shrimps, insects and some vertebrates. Here we name them as the Sangonghe biota and review their biostratigraphic framework. The Sangonghe biota constrains the Sangonghe Formation to the late Pliensbachian to the early Aalenian. Abundant thermophilous plants and Classopollis, together with frequent occurrences of red beds and carbonate nodules in the middle part of the Sangonghe Formation, are indicative of an arid climate in Central Asia at that time. This arid interlude should be responsible for the coal break, which may be related to the global warming in the early Toarcian. However, more precise dating evidence is needed to substantiate this.

KEYWORDS:

• Sangonghe Formation
• late Early Jurassic
• Central Asia
• climate
• arid
• coal break

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was supported by the National Natural Science Foundation of China [41730317, 42288201, 42293280], Strategic Priority Research Program of the Chinese Academy of Sciences [XDB26000000] and Shenyang Normal University (BS202209) plus the CAS President’s International Fellowship Initiative (PIFI).