四川龙门山区早泥盆世Emsian期群落古环境分析

PALAEOENVIRONMENTS OF EIGHT BENTHIC COMMUNITIES IN EMSIAN STAGE OF LOWER DEVONIAN FROM MT. LONGMEN, SICHUAN PROVINCE

通过对群落特征生物构造、生态习性、成活曲线、赋存围岩沉积及群落构成内容等特征分析,本文认为四川龙门山区Emsian期地层已经识别的以腕足动物为主的八个底栖群落生态位集中于B.A.3,少数可归入B.A.2,其相当的沉积环境主要为浅海内陆棚相、台地生物礁相。

The analysis from structures, habits, living curves of dominative species with community components and host rocks,shows that six communities were in B. A. 3 and two in B. A. 2,inclding Otospirifer xie jiawanensis community and Neoathyrisina community. These benthic communities has been lived in a shallow sea in which physical environment factors such as temperature, salinity etc. were moderate. Two kinds of substrate are concluded from the study: mud/silt soft substrate in Ganxi Formation, harder line/reef substrate in Yanmenba Formation. The living curve of most communities were steady and there was no determinated fluctuation in environment factors.