关岭生物群产出地层的岩石微相和环境意义

Petrographic Microfacies and Environmental Implications on the Bearing Horizons of Guanling Biota

关岭生物群产于中国贵州关岭县新铺乡,在贵州省会贵阳以西约188km的晚三叠世早期地层小凹组底部。化石群主要门类有海生爬行类(鱼龙、海龙、鳍龙、盾齿龙等)、海百合、菊石、双壳、腕足、牙形刺、鱼类和植物。以保存完整精美、数量巨大的海生爬行类和棘皮动物海百合为标志。化石产出地层岩石为(微含泥质)含生物屑泥晶灰岩,其上下地层的岩石还有(含泥质)含粉砂质不等晶灰岩和含生物屑泥晶灰岩。根据岩石组成、结构、构造、微相特征提出关岭生物群生活环境离岸较近、沉积作用以悬浮方式为主,少牵引流影响、水体总体比较安静。

Guanling biota was generated from the base of the Xiaowa Formation of the Upper Triassic strata at Xinpu Village of Guanling County, Guizhou, China, approximately 188 km west of Guiyang, the capital of Guizhou Province. Primary genera of fossils group consist of marine reptiles (ichthyosaurus, thalattosaurus, sauropterygia, placodus), crinoid, ammonite, bivalve, brachiopoda, conodont, fish and plants. Marine reptiles and echinoderm crinoid that feature intact and delicate preservation and large quantity serve as the mark. The rocks of fossils-generated horizons are bioclast-bearing micrite with lightly pelitic and the rocks of upper and lower layers also possess of silt-bearing unequal crystal limestone with argillaceous and bioclast-bearing micrite as well. According to lithologic composition, texture, structure and microscopic properties, it is represented that the habitat of Guangling biota stands in the vicinity of the shore and sedimentation process give priority to the floating mode, which is insufficiently subject to tractive flow and water body generally stay peaceful.