Abstract

Middle Devonian rocks in Southern China exhibit a variety of lithofacies and biotas. Three facies areas can be recognized, including four facies zones or belts. The distribution of various facies zones was not only controlled by a basement fracture system but also by syndepositional faults.

The reefs range in age from late Emsian to Eifelian and from Givetian to the end of Frasnian time. They are mainly distributed along the northwest-trending Nandan-Yadu fault zone and along the northeast- trending Yongfu-Taojiang fault zone.

Some of the Givetian reefs in Southern China are laterally differentiated into fore-reef, reef-core and back-reef subfacies. In vertical section they exhibit in ascening order repeated cycles of reef basement, reef, dolomitized reef and biodetrital limestones.

Hematite ore deposition occurs preferentially in the transition zone between clastic rocks and argillaceous limestone in the central part of the littoral facies area. Siderite and its sister deposits typically occur in the transitional terrane between the reef platform and depressional facies so they, too, are related to the reef facies.

The Devonian of South China was deposited in an epicontinental sea which onlapped paleo-landmasses. On the east the epicontinental sea was bounded by the Cathaysian landmass, on the north and northwest by the Jiangnan landmass and the Qianbei landmass respectively, and on the west by the Kongdian landmass. These paleo-landmasses were source areas for terrigenous material that was transported, respectively, from east to west, from north and northwest to south and from west to east during the Devonian marine transgression which advanced mainly from the southwest toward the northeast.

The Middle Devonian of South China exhibits diverse lithofacies and biotas culminating in the development of reef complexes. Studying these rocks gives us a general understanding of the Devonian facies pattern and reef development in South China.