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

晚古生代—中新生代早期扬子地块古生代生物大灭绝的环境变化与过程本项目的主要目的是研究二叠纪末古生代生物大灭绝的环境变化与过程。通过对扬子地块二叠系至三叠系连续地层序列的研究，重点阐明了珊瑚、放射虫、牙形刺、毛藻等大型和微型化石的垂向分布。此外，我们还试图重建二叠纪-三叠纪边界的沉积环境。研究区域为贵州西部和广西中部至西部，均位于扬子地块上。以下12个区（贵州1 ~ 7区、广西8 ~ 12区）为研究对象。丑祖山（安顺以北17公里），G-H-I， 20米；2. 毛沙钦（紫云以南34公里），D-G-I， 400米；3. 赛瓦（紫云以南18公里）P3, 1100米；4. 太祖町（贵阳），E-G-H-I, 240m；5. Duraying（贵阳），C…More -E-G-I-J, 40m+；6. 宽沙（贵阳以南85公里），D-G-I-K， 220米；7. 那水（罗店西南40公里）D3-T1；8. 东条县（柳州以南20km）， A-B, 40m+；9. 牛坪（柳州东北10km）， F-H, 200m+；10. 临纳郎（平果东北偏东20公里），D3-T1, 450米以上；11. 齐平（平果西北20公里），A-C-F-K， 70米+；12. 郭富龙丘（平果以西20km）， P-T1, 50m+(A)赤壁组[P21]；(B)库菲格Fm。：(C)茅口楼。[p2, 2]；(D)吴家坪：(E)龙潭站。：(F) Hoshan Fm。(奔跑);（七）长兴楼。：(H)塔隆Fm。(第9);（一）塔耶Fm。：(J) Yehlang Fm。：(K)楼楼楼。[T11]在每个剖面中，进行了岩性和生物地层学研究，并对化石和沉积岩进行了系统取样。岩相上二叠统划分为3个岩相；碳酸盐岩相、碎屑岩相和改造碳酸盐岩相、碎屑岩相和硅质相，分别相当于台地沉积、斜坡沉积和盆地沉积。上二叠统被下三叠统碎屑岩整合覆盖。沉积相龙潭组为三角洲起源的粗化-向上层序，偶见潮滩沉积。钙质浊积相局部表现为旋回沉积，呈叠薄向上层序。下三叠统的碎屑相被解释为浅海沉积，普遍存在丘状交叉层序。生物相中二叠统常见，上二叠统（吴家坪组和长新组）较少。珊瑚是相依赖的，在不同地区的分类组成是可变的。上二叠统灰岩偶有丰富的海绵，呈鸟眼状结构。放射虫丰富，特别是在硅质岩的塔隆组。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