中上扬子地区栖霞期缺氧沉积特征

Anoxic Deposition Characteristics of Upper Middle Yangtze Region in Qixia Stage

中上扬子地区栖霞期缺氧沉积在研究区东部贵阳-建始-瑞昌一带较为发育。缺氧沉积的岩石类型主要有暗色泥页岩-薄层硅岩-泥晶石灰岩组合和含泥石灰岩即眼球状石灰岩的"眼皮"部分。分别对这两种组合的地球化学特征、岩石特征、古生物特征进行了研究,并分析了各自的缺氧环境的成因。研究区栖霞组缺氧沉积的成因主要是上升流,主要形成Ⅱ类缺氧沉积;其次是大规模海侵作用,主要和Ⅰ类缺氧沉积有关。

Anoxic deposition of upper middle Yangtze region in Qixia stage has a early development in the east of study area Guiyang-Jian Shi-Ruichang. Anoxic deposition rock types mainly include dark mud shale rock-thin layer of silicon-mud SPAR limestone combination and mud-contained namely the ‘eyelid＇ part of eye-shaped limestone. It respectively analyzes the geochemical characteristics, rock features and paleontological characteristics of the two kinds of combinations, besides, it analyzes the causes of the anaerobic environment. The reason of anoxic deposition of Qixia group in study area is mainly the upwelling and it mainly forms theanoxic deposition. Followed is the large-scale of transgression function, which mainly has relation with class-I anoxic deposition.