Lithofacies palaeogeography of the Cambrian in central and southern Hunan Province
Liang Wei1,2, Mou Chuanlong1,2, Zhou Kenken1,2, Ge Xiangying1,2
1 Chengdu Institute of Geology and Mineral Resources,China Geological Survey,Chengdu 610081,Sichuan 2 Key Laboratory of Sedimentary Basins ＆ Oil and Gas Resources of Ministry of Land and Resources,Chengdu 610081,Sichuan
Abstract：Based on the sedimentary characteristics of the Cambrian,the carbonate shelf subfacies,clastic shelf subfacies,mixed shelf subfacies,and deep-water basin facies onto the shelf had been distinguished in the central and southern Hunan Province,which located in the intermediate zone between Yangtze Block and Cathaysia Block.During the Terreneuvian to Early Epoch 2(Meishucun Age-Canglangpu Age),the deep-water basin facies was nearly dominated in the study area,and the clastic shelf subfacies just distributed in the southeastern Hunan Province.In the Late Epoch 2(Longwangmiao Age),due to the relative sea level declining and the scope of the deep-water basin decreasing,the carbonate sediments had gradually been the main deposition of the northwestern study area;meanwhile the scope of the clastic shelf subfacies had kept unchanged.In the Epoch 3(Maozhuang Age-Gushan Age),the carbonate shelf subfacies and clastic shelf subfacies gradually occupied the central Hunan Province from both sides of deep-water basin facies,whose range decreased sharply,and the mixed shelf subfacies with the mixed sediment of carbonates and clasolites developed in the northwestern study area.Till the Furongian(Changshan Age-Fengshan Age),the carbonate shelf subfacies increased tempestuously as the carbonate aggradation,while the deep-water basin facies still kept decreasing.The clastic shelf subfacies developed adjacently to carbonate shelf subfacies,and the mixed shelf subfacies appeared in the southern Hunan Province.In a word,the mixed sediments existed between Yangtze Block and Cathaysia Block,and the sedimentary facies were continuous and integrates.It indicated that Yangtze Block and Cathaysia Block maybe had been in the same neritic area,and its depositional pattern was characterized by water depth that became deeper gradually from the northwest and southeast to the middle in the Cambrian.
Liang Wei,Mou Chuanlong,Zhou Kenken et al. Lithofacies palaeogeography of the Cambrian in central and southern Hunan Province[J]. JOPC, 2014, 16(1): 41-54.
