Environmental change and process of mass extinction of Paleozoic oranisms in Yangtze Block during Late Paleozoic to Early Mesozoic time

扬子地块古生代生物在古生代晚期至中生代早期的环境变化和生物大灭绝过程本项目的主要目的是研究扬子地块古生代或二叠纪末期生物大灭绝的环境变化和大灭绝过程。重点通过阳泽地块二叠纪至三叠纪的连续层序，阐明了珊瑚、放射虫、牙形刺、丝虫等巨型和微型化石的垂向分布。此外，我们的目标是重建跨越二叠系-三叠系界线的沉积环境。研究地区均位于阳泽地块的贵州西部和广西中西部。对贵州1-7个和广西8-12个断面进行了研究。2.毛沙津(紫云以南34公里)，D-G-I，400米；3.塞瓦(紫云以南18公里)，P3,1100米；4.太祖町(贵阳)，E-G-H-I，240米；5.都营(贵阳)，C…More-E-G-I-J，40M+；6.丹万沙(贵阳以南85公里)，D-G-I-K，220米；7.那水(罗甸西南40公里)，D3-T1；8.通天一恩(柳州以南20公里)，A-B，40M+；9.牛木坪(柳州东北10公里)，F-H，200米+；10.连浪(平果东北偏东20公里)，D3-T1,450米+；11.四平(平果西北20公里)，A-C-F-K，70米+；12.郭富隆丘(平果以西20公里)，P-T1，50m+(A)Chibsia组[P21]；(B)Kufebg FM。：(C)茅口调频。[P2，2]；(D)吴家坪FM。：(E)龙潭FM。：(F)鹤山调频。[p31]；(G)长兴FM。：(H)Talung FM。[p32]；(I)Tayeh FM。：(J)Yehlang FM。：(K)罗楼调频。[t11]在每个区段中，进行了岩石和生物地层学研究以及化石和沉积岩的系统采样。岩相上二叠统划分为碳酸盐、碎屑和改造碳酸盐、碎屑和硅质三种岩相，分别相当于台地沉积、斜坡沉积和盆地沉积。最上二叠统被下三叠统碎屑岩所覆盖。沉积相龙潭组显示三角洲成因的粗化-向上层序，以及偶尔出现潮坪沉积。钙质浊积岩相局部表现为旋回沉积，表现为堆积变薄向上的层序。将下三叠统碎屑相解释为常见的丘状交错层理所揭示的浅海沉积。生物面貌中二叠世常见的皱纹珊瑚，但在上二叠统(吴家坪组和长新组)稀少。珊瑚是相相关的，其分类组成因地区而异。最上层的二叠纪石灰岩偶尔含有丰富的海绵，并呈现鸟瞰结构。放射虫丰富，特别是在硅质岩的塔隆组中。较少

Environmental change and process of mass extinction of Paleozoic organisms in Yangtze Block during Late Paleozoec to Early Mesozoec timeThe main purpose of this project was to study the environmental changes and the processes of mass extinction of Paleozoic or, anisms at the end Permian. Emphasis was placed to clarify the vertical distributions of such mega- and microfossils as corals, radiolarians, conodonts and fusulinids through continuous straligraphc successions of the Permian to Triassic in the Yangize Block. In addition, we aimed to reconstruct the sedimentary environments across the Permian-Triassic boundary.The studied areas were west Guizhou and central to west Guangxi both on the Yangize Block. Following twelve sections (1-7 in Guizhou and 8-12 in Guangxi) were studied.1. Chouzushan (17km north of Anshun), G-H-I, 20m ; 2. Maoshachin (34km south of Ziyun), D-G-I, 400m ; 3. Saiwa (18km south of Ziyun), P3, 1100m ; 4. Taizucho (Guiyang), E-G-H-I, 240m ; 5. Duraying (Guiyang), C … More -E-G-I-J, 40m+ ; 6. Dwansha (85km south of Guiyang), D-G-I-K, 220m ; 7. Nashui (40km southwest of Luodian), D3-T1 ; 8. Tungtienyien (20km south of Liuzhou), A-B, 40m+ ; 9. Niumuping (10km northeast of Liuzhou), F-H, 200m+ ; 10. Linalang (20km east-northeast of Pingguo), D3-T1, 450m+ ; 11. Tsiping (20km northwest of Pingguo), A-C-F-K, 70m+ ; 12. Guofualungchiu (20km west of Pingguo), P-T1, 50m+(A) Chibsia Formation [P21] ; (B) Kufebg Fm. : (C) Maokou Fm. [P2, 2] ; (D) Wujiaping Fm. : (E) Lungtan Fm. : (F) Hoshan Fm. [P31] ; (G) Changxing Fm. : (H) Talung Fm. [P32] ; (I) Tayeh Fm. : (J) Yehlang Fm. : (K) Luolou Fm. [T11]In each section, litho- and biostratigraphic studies and systematic sampling of fossils and sedimentary rocks were carried out.1. LithofaciesThe Upper Permian is divided into three lithofacies ; carbonate, clastic and reworked-carbonate, and clastic and siliceous facies, which are equivalent to platform, slope and basin sediments, respectively. The uppermost Permian is conformably overlain by the Lower Triassic clastic rocks.2. Sedimentary faciesThe Lungtan Formation reveals coarsening-upward sequences of a deltaic origin as well as occasional occurrences of tidal flat deposits. The calcareous turbidite facies locally shows cyclic sedimentation demonstrated stacked thinning-upward sequences. Clastic facies of the Lower Triassic is interpreted as the shallow marine deposits as revealed by common presence of hummocky cross-stratification.3. BiofaciesRugose corals are common in the Middle Permian, but are sparse in the Upper Permian (Wujiaping and Changxin, Formations). Corals are facies-dependent and are variable in taxonomic composition from area to area. The uppermost Permian limestones occasionally contain abundant sponges and show bird's-eye structure. Radiolarians are abundant, especially in the Talung Formation of siliceous rocks. Less