湖南新邵巨口铺中泥盆世生物礁生长动力学研究

GROWTH DYNAMICS OF THE MIDDLE DEVONIAN JUKOUPU BIOHERM, XINSHAO, HUNAN

本文详细研究了湖南巨口铺生物礁的生长过程、古生态学特征及其生物造礁作用。该生物礁岩共有10种微相类型。礁体内生物十分丰富,共鉴定出7个门类的32个属,主要是珊瑚、层孔虫和藻类。它们组成5个造礁群落,并形成独特的群落结构。对全部造礁群落的分析表明,该生物礁的生物造礁功能十分复杂,当生物礁发展到高级阶段时,同种生物可同时具有多种造礁功能。该生物礁的生长过程可分为5个阶段:(1)层状礁阶段;(2)生物定殖阶段;(3)格架式造礁阶段;(4)粘结——覆盖式造礁阶段;(5)障积式造礁阶段.

This paper discusses in detail the growth process, palaeoecological features and the function of organisms in reef building of the Juko(?)pu bioberm in Hunan.The bioherm has been divided into 10 microfacies. Organisms are very abundant in the reef. 32 genera belonging to 7 phyla have been recognized. They consis^+ mainly of stromatoporoids, corals, algae and form 5 communities, each of which has its own salient ecological features. The 5 communities are as follows:1. Stromatopora-Hexagonaria Community: This is a reef building community with its framework resisting the stormy waves. The diversity of the community is the highest among the 5 communities. Tht main framework organisms are stromatopora and Hexagonaria. This community built up a stratified reet.2. Crinoidea-Clathrodic yon Community: This is a benthonic community fixed by stems. A great number of crinoids built up a subaqueous shoal of skeleton fragments.3. Hexagonia-Alveolites Community: This is a community which is able to resist stormy waves by its framework. Hexagonaria built up the typical reef.4. Stromatopora-Alveolites Community: The skeleton of reef-building organisms of the community cover and bound loose sediments to form reef frameworks. in the early stage, chick board skeleton of Alveolites and stromatopora covered the limemud and fragments of organisms. In the late stage, Stromatopora and Sphaerocodium were dominant fenera. Their thin skeleton bound up the lime-mud.5. Szachyodes-Parachaetetes Community: This is a final reef-building communny with monctonous organisms. Stachyodes and Parachaetetes baffled lime-mud to form bafflestone. Because the sea basin was restricted, Amphtpora is the principal organism instead of reef-building organisms and the reef ends growing.An analysis of all communities shews that the organic functions are very complex. The same kind of organisms may possess diverse functions simultaneously as the reef body grows.The growth process of the reef may involve five stages: (1) biostrome stage; (2) stabilizetion stage; (3) framework reef stage; (4) bind-cover reef stage; (5) baffle reef stage.