新铺地区晚三叠世早期腕足类及其古生态环境——兼论海百合类和双壳类假浮游古生态

Succession and Palaeoecologic environments of brachiopod faunas through the early Upper Triassic from Xinpu area,Guanling,Guizhou,China-with comments on palaeoecology of pseudopelagic crinoids and bivalves

本文论述贵州关岭新铺地区上三叠统下部竹杆坡组中部至小凹组下段所产的腕足动物群及其古生态环境。该区目前共获得腕足类6个目,6个科,7个属,8个种(含4新种)和1个属种未定。根据这些腕足类的固着方式、生活习性、贝体形态和大小,以及组合特征,可以从下到上将它们分为Pseudokoninckina,Laballa,L ingu loid等3个群落。该3个群落的生态底域分别位于BA4至BA3外侧、BA2和BA1,表明本区从竹杆坡组中部至小凹组下段的沉积环境是由较为深水逐步向较为浅水过渡,应为海退过程的沉积产物。同时,本文还论证了当时不可能存在为海百合类和双壳类提供假浮游的载体,它们应是底栖生物,并且指出那些被认为是假浮游的化石证据的分析与推断存在片面性。

This paper deals with the middle part of the Zhuganpo Formation to the Lower Member of the Xiaowa Formation of the early Upper Triassic （Camian） brachiopod faunas from Xinpu area, Guanling, Guizhou, Southwest China. Those brachiopods contain 6 orders, 6 families, 7 genera, 8 species （ including 4 new species）, and 1 gen. et sp. indet. , which are divided into ascending order of Pseudokoninckina, Laballa , and Linguloid etc. 3 communities, indicating a change from deeper - seawater to shallow - seawater, and a gradual regression in Xinpu area, Guanling at Carnian （ early Upper Triassic）. The previous views that crinoids and bivalves in a pseudopelagic lifestyle is against by the evidence that the carrier for those creatures at that time was not exist, which indicate that they are benthic organism and the fossil evidence for previous views are unilateral and needing reconsideration.