晚震旦世陡山沱期后生生物群的古生态环境探讨

Palaeoecology and fossil preservation of the early metazoan biotas during the Doushantuoan(Late Sinian)

关键词:  后生生物群  古生态  庙河生物群  瓮安生物群

Key words:  metazoan biota  palaeoecology  Miaohe biota  Weng'an biota

摘要:

早期后生生物群是当前古生物学研究热点之一。我国上扬子区的庙河生物群和瓮安生物群是震旦纪的重要生物群,而生物群是怎样繁盛和埋藏保存是研究早期后生生物群的一个重要方面。作者研究认为瓮安生物群是由于洋流上升提供了大量的SiO₂和P₂O₅等养分,使生物在台地边缘大规模繁盛,其海水由于富SiO₂和P₂O₅所引起强烈的磷酸岩化及硅化作用,使大量的生物尸体被快速矿化,形成具有抗水动力强的骨架,避免水动力和氧化作用的破坏,因此,矿化作用是生物体保存为化石的另一个重要因素。最后,提出上扬子区陡山沱期为有利于生物群繁盛和保存区域。

Abstract:

This approach addresses the current research in palaeoecology which focuses on the early metazoan biotas in China during the Doushantuoan （Late Sinian）. Two important categories have been classified for the Sinian biotas: Miaohe and Weng’ an biotas on the Upper Yangtze platform. Of particular significance is why and how these biotas flourished and were preserved during geological time. The author contends that abundant SiO₂ and P₂O₅ supplied by the upwelling currents permitted the living organisms to get thriving on a larger scale on the margins of the platform. The steady increase in SiO₂ and P₂O₅ resulted in intense phosphatization and silicification; that is to say, the abundant organic remains were rapidly phosphatized and silicificated, and got out of oxidization and decomposition. It can be seen that mineralization （phosphatization, silicification and manganesation） may be interpreted as an important factor in the preservation of the organic remains as fossils, and that the Upper Yangtze area is a favourable region in China for the flourishing of organisms during the Doushantuoan （Late Sinian）.