The Jurassic system in the Qinshui Basin, Shanxi Province, with notes on the bivalve province of North China

Abstract

There are two kinds of Jurassic strata in Shanxi Province of China: fluvial-lacustrine coal-bearing beds distributed in the Luliang-Taihang fault-block depression, and volcanic-sedimentary clastic rocks scattered in the Yanshan fault-block depression. The Jurassic in the Qinshui Basin belongs to the former, which yields a Ferganoconcha-Yananoconcha-Margaritifera (FYM) bivalve fauna. The fauna is very close to the Yan'an Formation bivalve fauna in the Shaanxi-Gansu-Ningxia Basin and intimately associated with bivalve fauna of the Eadat Formation of Siberia, in Chulim-Yenisei Basin, all of them belonging to the Paleo-Asian Province. The characteristics of the Middle Jurassic bivalves of Siberia and some typical elements of the Yorkshire flora of Britain suggest that the coal-bearing Jurassic of Shaanxi Province and the Qinshui Basin of Shanxi Province should belong to the Middle Jurassic; while the coal-bearing strata containing some elements of the FYM fauna in the Yanliao area are Early Jurassic in age, as evidenced by the fact that many Upper Triassic and Liassic elements, Thaumatopteris-Cladophlebis assemblage, exist in the strata. Thus the Jurassic coal-bearing beds in North China show a diachronous phenomenon from east to west. The FYM fauna was composed of ecologic communities in shallow lakes and meandering rivers of hilly areas under a warm-humid climate.