【摘要】 贵州省兴义市周边中三叠统埋藏有丰富的兴义动物群化石,但由于详细的地层学工作不足,导致长期以来难以从实证的角度对这一动物群的古环境、古地理背景进行探讨。本研究对贵州省兴义市乌沙镇泥麦古剖面和义龙试验区顶效镇浪幕山剖面含兴义动物群下部化石组合的层段按自然层进行连续发掘,并通过详细的地层测量和岩石微相分析对两个剖面相关层段进行高精度地层对比,进而比较该动物群在区域内的古环境特征。通过岩石微相分析,本研究将两个剖面划分出9种微相类型。根据沉积相序列划分的旋回和相对海平面变化,以及化石组合特征的对比,推断这两个剖面可以对应,具有等时性。浪幕山剖面的第192和183自然层分别对应泥麦古剖面的第22和35自然层。通过对上述微相建立相组合,在两个剖面中划分出局限海浅潮下带、深潮下带和台内盆地环境。同时期内顶效地区水体相对较深,乌沙地区水体环境相对更浅。综合而言,以兴义动物群下部化石组合为代表的海生动物类群曾广泛分布于碳酸盐岩台地内部和边缘。更多还原

【Abstract】 A large amount of fossils of Middle Triassic Xingyi Fauna were deposited around Xingyi City, Guizhou Province. Due to the absence of detailed field investigation, the palaeoenvironmental and palaeogeographic background of the fauna has not been discussed with solid evidence. Two sections, Nimaigu section(in Wusha Town) and Langmushan section(in Dingxiao Town) from which the lower fossil assemblage of Xingyi Fauna was found have been studied layers by layers. On the basis of stratigraphic measurement and microfacial analysis, the palaeoenvironmental background of the lower fossil assemblage of Xingyi Fauna in both sections were revealed. Nine types of microfacies have been recognized. The evidences of microfacial sequences, relative sea level change and the fossil records suggested that the Layer 22 and Layer 35 in Nimaigu section can be correlated to Layer 192 and Layer 183 in Langmushan section respectively. By establishing microfacial assemblages, it can be identified that the palaeoenvironment in these two areas were shallow subtidal, deep subtidal and intraplatform basin. Comparing the corelated layers in both sections, it showed that Langmushan section had a deeper water depth, while it was shallower in Nimaigu section. According to these results, the marine reptiles from the lower assemblage of Xingyi Fauna were widely distributed not only in the interior part but also on the margin of the carbonate platform.更多还原