缺氧环境类型及生物相特征

THE MAIN TYPES AND BIOFACIAL CHARACTERISTICS OF ANOXIC ENVIRONMENT

本文简要介绍了缺氧环境的类型和生物相特征。根据缺氧环境的主导因素和地理背景条件概括为四种缺氧环境类型:1.大型缺氧湖泊,一般处于温暖多雨地区的早期沉陷山间盆地,如现代东非的坦噶尼喀湖;2.缺氧的隔离盆地,往往为温湿的内克拉通海和陆棚的“袋形”洼地,如现代黑海;3.上升洋流引起的缺氧层,多发育在低纬度大陆酉侧的大洋陆棚区,常合磷酸盐和硅藻,现代的秘鲁陆棚带为典型代表;4、缺氧的开放大洋,多位于温暖气候区的大陆两侧,如现代印度洋。根据不同的生物组合特征可划分为三种生物相:1.喜氧生物相——具多种底栖生物和生物扰动构造;2.贫氧生物相——软体动物占统治地位,个体一般较小,常保存为黄铁矿铸模;3、厌氧生物相——只有放射虫和浮游生物,不见底栖类。

The main types and biofacial characteristics of anoxic enviroment are briefly introduced in this paper. According to geographic setting and other factors anoxic enviroment is classified into four main types: ( 1 ) large anoxic lakes, which usually occur in the rainy, warm climatic conditions; ( 2 ) anoxic silled basins with positive water balance; ( 3 ) anoxic layers caused by upwelling rich in phosphate and diatom. ( 4 ) anoxic layers of open-ocean usually located at the west side of the continent. In terms of biological association,the biofacies are divided as follows: ( 1 ) aerobic biofacies with variety of benthon; ;%#;;( 2 ) dysaerobic biofacies dominated by vagile molluscas,which usually occur in small body and pyritic steinkerns; ( 3 ) anaerobic biofacies, which only consists of radiolarian and pelagic organisms.