THE SILURIAN SYSTEM OF CHINA
Lin Baoyu (Chinese Academy of Geological Sciences)
The present article deals with the following contents:1. According to the difference in bio-physicochemical conditions under which the sediments were deposited, the Silurian of China is divisible into 10 sedimentary provinces (See Table 1 and Fig. 1). (1) the Hingan Province; (2) the Tianshan—Neimongol Province; (3) the Tarim Province; (4) the Qilianshan Province; (5)the Kunlun—Qinling Province; (6) The Xizang—Western Yunnan Province; (7) The Yangzi Province; (8) the Himalaya Province; (9) the Jiangnan Province and (10) the South China Province.2. The lower limit of the Silurian. The Wufeng shale with its Dicellograptus szechuanensis—D, anceps fauna can be correlated with the Ashgillain of Britain. Locally there is a Dalmanitina-bearing formation of limestone, marl or mudstone, separating the overlying Lower Silurian black shale from the underlying Wufeng black shale. The Wufeng shale belongs to the Upper Ordovician.The age of the Dalnanitina bed has been a topic of long debate. In China most of he palaeontologists are inclined to consider it as a part of the Upper Ordovician, on the grounds that: (1) the associated corals, brachiopods and the trilobite are more closely akin to those of the underlying Ordovician; (2) it is stratigraphically below the lower most Silurian horizon of Glyptograptus persculptus; (3) the Dalmanitina bed represents a different facies and is an equivalent of the shale with Diplograptus bohemicus or Dicellograptus anceps.3. The upper limit of the Silurian. In China the Silurian—Devonian boundary is drawn at the base of the Monograptus uniformis Zone, Icriodus worschmidti Zone or Warburgella rugolosa sinensis Zone.4. The Silurian System of China is divisible into three series and six stages: Longmaxian ; Shiniulanian; Baisha'an; Xiushanian; Guandian; Miaogao'an (See Table 1).5. Correlation of Chinese and World Silurian System (See Table 2).6. For the Silurian faunas three distinct zoogeographical provinces in China——The Junggar-Hingan Province, the Yangzi province and Xizan—Western Yunnan province are recognized.7. During the Silurian Period eight marine realms, more or less interconnected, may be distinguished (Figs. 3, 4): (1) the Hingan—Junggar sea; (2) the TianshanNeimongol sea; (3) the Qilianshan sea; (4) the Kunlun-Qinling sea; (5) the Xizang—West Yunnan sea; (6) the Himalaya sea; (7) the Yangzi sea and (8) the South China sea.8. The Silurian Oldlands of China include: (1) The Northeastern China; (2) the North China; (3) Junggar; (4) Tarim and Qaidam; (5) Jiangnan; (6) Kang—dian; (7) Huaxia.