中三叠世青岩生物群的群体古生态学初步研究

根据群体古生态学的初步研究，认为青岩生物群的富集是因为发育一个较为特殊的生态环境，即位于斜坡与台地交接处的一个小型盆地--护障性浅海中，生态类型分析结果表明，此处为低能稳定的水域，水深在正常浪基面之下、风暴浪基面之上，海水清彻、氧气充足、营养丰富，并可能富产海藻，因而十分有利于海相底栖生物繁衍。

PRELIMINARY PALAEOSYNECOLOGICAL ANALYSES ON THE UPPER ANISIAN (MIDDLE TRIASSIC)QINGYAN FAUNA

The Qingyan fauna (Upper Anisian, Middle Triassic) was found from a section located at about 30km south of Guiyang, the provincial capital of Guizhou Province, SW China. Here yields abundant well preserved and highly diversed fossils, involving 16-17 groups of organisms, among which gastropods, frachiopods and bivalves are dominant. Some macrofossils are a eommon sight here including corals, sponges, crinoids, scaphapods, ammonoids, nautilids, bryozoaus and echinoids. whereas others such as porifers, cnidarians and annelids are rare in occurrence but visible sometimes. Among microfossils abounded in this fauna, snch groups as ostracods, foraminiferans and calcareous algae were analysed. After a palaeosynecologic study combining with palaeogeographic analyses we believe that the Qingyan fauna might have developed in an environment of a protected shallow marine habitat, which was lacated at a position of the upper part of basin slope. The sea bottom was fine grained and stable. The rates of sedimentation were generally relatively low. The water was relatively deep and the organisms lived in the photic zone above the storm wave base and below the fair weather wave base. Epibenthic forms are the main groups in this primarily benthic fauna. Shallow burrowing in fauna and semiinfauna form smaller portions. In traphic habits, suspension feeders are the dominant group. In a ddition, there are herbivores (gastropods), detritus feeders, scavengers, and omnivores, a few deposit feeders and few micro and macro carnivores. The high percentage of suspension feeders in the fauna indicates that the water was clean and clear, gently moving, and rich in oxygen and nutrients. The highly diverse associations, especially bivalves and gastropods, most probablyre present selics of community which had lived in patches of macroalgae.