古地理学报2011，Vol.13Issue(1)：1-10,10.
上扬子地区早三叠世异常碳酸盐岩的分类与特征
Classification and characters of the Early Triassic anomalous carbonate rocks in Upper Yangtze Area
摘要
Abstract
The anomalous carbonates of the late period of Late Permian and Early Triassic in the Upper Yangtze Area can be divided into three main types by genesis: A—biogenic anomalous carbonate rocks, B—abiogenetic (chemical and hydrodynamic ) anomalous carbonate rocks, C—multi-genetic anomalous carbonate rocks. Eight specific sorts of the anomalous carbonate rocks can be further distinguished, including microbiolite, brecciform limestone, flat-pebble limestone, ribbon limestone, thinbedded or laminated argillaceous limestone, oolitic limestone and 2 kinds of vermiculate limestone ( Type a and Type b). The extreme palaeoceanic environment and paleoclimatic conditions are the basis of the development of the anomalous carbonate rocks (mainly anachronistic facies) around P/T boundary. After the P/T mass extinction, the destruction of benthonic animals living on the surface of marine sediments was nearly stopped and the ocean currents were almost stagnated, meanwhile the surface layer of the sea water suffered the disturbing of megamonsoon and cyclonic storms, the algo-fungus ecosystem of euphoriczone grew and formed the wave-resistance microbiolites on the biohermal facies or on the shallow water carbonate platform. Seafloor was often affected by frequent storms which tear up the unconsolidated syngenetic carbonate ooze and thus the syngenetic pebble formed. At the same time, the particular gradient of the paleotopography intensified the development of carbonate gravity flows which might also be triggered by the storms; moreover the calcium carbonate-supersaturated sea water allowed the carbonate directly precipitating in the forms of chemical precipitation on the seafloor and the clays brought by the megamonsoon deposited together with the carbonate chemical precipitation. All the mentioned process happened at the earliest Early Triassic specific palaeoenvironment, which resulted in the appearance of the diverse anomalous carbonate deposition in the Upper Yangzte Area.关键词
异常碳酸盐岩/错时相/P/T界线/风暴沉积/蠕虫状灰岩/巨型季风/上扬子地区Key words
anomalous carbonate rock/ anachronistic facies/ Permian - Triassic boundary/ storm deposit/ vermiculate limestone/ megamonsoon/ Upper Yangtze Area分类
天文与地球科学引用本文复制引用
时志强,安红艳,伊海生,张华,曾德勇..上扬子地区早三叠世异常碳酸盐岩的分类与特征[J].古地理学报,2011,13(1):1-10,10.基金项目
国家自然科学基金(编号:40872082、40972084)资助 （编号:40872082、40972084）
