三叠纪牙形石的古环境与古地理意义

PALAEOENVIRONMENTAL AND PALAEOGEOGRAPHIC SIGNIFICANCE OF THE TRIASSIC CONODONTS

牙形石广泛分布于寒武纪至三叠纪的古海洋里。三叠纪牙形石的种类、形态、大小和产出频率受海水盐度、深度、温度和水动力条件等因素控制 ,不同的牙形石生态特征即牙形石相反映不同的沉积环境 ,所以根据三叠纪牙形石相和牙形石特征属种的丰度 ,不但可区分三叠纪不同的沉积相区 (台地相区、台地边缘相区和盆地相区 )和恢复三叠纪古地理面貌 ,而且可划分出牙形石生物地理区。中国早三叠世牙形石归属特提斯生物大区亚洲生物省 ,并可进一步划分出两个生物亚省和若干生态区。

Conodonts were distributed widely in the palaeoocean from the Cambrian through the Triassic. The species variety, morphotype and output rate of the Triassic conodonts were controlled by the factors of the sea water, such as salinity, depth, temperature and hydrodynamic condition. Different ecological characteristics of conodonts, i.e. conodont facies, can reflect different sedimentary environments. Therefore, the conodont facies and abundance of the characteristic conodont species can be used to differantiate the sedimentary facies regions (platform facies region, platform margin facies region and basinal facies region) of the Triassic, and to reconstruct the Triassic palaeogeography, as well as to study biogeographical zonation of the conodonts. The Early Triassic conodonts in China are attributed to the Asia biogeographical province of the Tethys biogeographical realm, and the latter can be further subdivided into two biogeographical sub provinces and several communities.