冈底斯东段色日绒地区冈瓦纳相冰海杂砾岩特征及其意义

色日绒地区冰海杂砾岩产于砂泥质为主的陆缘碎屑岩段中,累计出露厚度约325 m。岩石学及沉积学特征指示其沉积于滨海—上部浅海环境;顶部的化石生物组合指示此段岩层沉积于晚石炭世—早二叠世的冷水型海洋环境。岩层中的坠石结构、压裂面以及与其同层位产出的冷水型生物群为冰海杂砾岩的成因提供了有力的证据,指示其形成于冰川作用下,是由冰筏搬运的海相沉积。通过资料综合收集、对比,确定了冰海杂砾岩形成的古构造及古地理、古气候控制条件。根据古构造位置及古地理特征,大致总结出了以该地区为代表的冈瓦纳相冰海杂砾岩的沉积及成因模式。

Characteristics and Its Significance of Glacial-marine Diamictite of Gondwana Facies in the Serirong Area,Eastern Gangdese Belt

Glacial marine diamictite of Serirong area comes from “arenopelitic suspended substance based” terrrigenous clastic rock and its exposing height is about 325 m. The petrology and sedimentary characteristics of these strata indicate the coastal-epactile environment; Fossil assemblage on the top indicate the cold water environment in Late Carboniferous-Early Permian. The dropstone, fracturing fracture and cold water biota from this strata providing forceful evidence on the cause of glacial-marine diamictite’s formation, and the characteristics above show that the glacial-marine diamictite deposited in the glaciers effects by the transportation of ice-raft. Through the information collection and comparison, explicating the controlling conditions of paleostructure, palaeogeography and paleoclimate were identified. Based on the characteristics of paleostructure, palaeogeography and paleoclimate, summarizing the genetic and deposition model of glacial-marine diamictite of gondwana facies in this area were identified. The sedimentary of glacial-marine diamictite and cold water biota in the Serirong area shows that gondwana facies deposited in the cold environment.