川西昌台地区晚三叠世双壳生物群的分布与火山活动的相关性

川西昌台地区晚三叠世的海相火山活动频繁,每次火山活动的间歇期都沉积有一套深色岩系,主要为泥质板岩、粉砂质板岩和钙质板岩.这套沉积岩系产有丰富的双壳类化石,这套岩系底部与火山岩接触的层位,其所含的双壳类化石类别单一,个体较大,数量丰富,呈介壳形式产出,矿化明显.根据薄片鉴定结果、稀土元素分布模式以及微量元素的含量分析,认为川西昌台地区晚三叠世生物群的分布与火山活动密切相关,火山活动为海底热液的存在提供了通道,火山活动末期的热液环境参数包括还原性、高温、高金属离子浓度(金属硫化物)等.

The relativity between volcano activity and distribution of the bivalve-community in Late Triassic in Changtai, Western Sichuan, China

Volcano activity took place frequently in Late Triassic in the Changtai area of Western Sichuan. After every volcano activity, a suit of fuscous sediments also appeared, including black limy slate, argillite, silt shale. Many bivalve-fossils were buried in the suit of sediments. The most abundant fossils were buried in the bottom of the suit of sediments, imbedded in the rocks with shell form and mineralized evidently. Based on the characters of the rock slices and geochemistry-analysis, a conclusion is made, that is the volcano activity was related to the community closely. The volcano activity offered a channel way for the benthic hydrothermal activity in Irate Triassic in the Changtai area of Western Sichuan. In this term, the variation parameters of the environment including high temperature and high concentration etc. are favorable to the breeding of the bivalve-community.