Paleoenvironmental and paleoclimatic evolution and cyclo- and chronostratigraphy of upper permian-Lower triassic fluvial-lacustrine deposits in Bogda Mountains, NW China – Implications for diachronous plant evolution across the permian-triassic boundary
Paleoenvironmental and paleoclimatic evolution and cyclo- and chronostratigraphy of upper permian-Lower triassic fluvial-lacustrine deposits in Bogda Mountains, NW China – Implications for diachronous plant evolution across the permian-triassic boundary
复制标题
中国西北博格达山上二叠世-下三叠世河流-湖泊沉积物的古环境和古气候演化以及旋回和年代地层学——对跨越二叠纪-三叠纪边界的历时植物演化的启示
DOI：
10.1016/j.earscirev.2021.103741
复制
发表时间：
2021
影响因子：
12.1
通讯作者：
Christian A. Sidor
中科院分区：
文献类型：
--
作者：
Wan Yang;Mingli Wan;James L. Crowley;Jun Wang;Xiaorong Luo;Neil Tabor;Kenneth D. Angielczyk;Robert Gastaldo;John Geissman;Feng Liu;Peter Roopnarine;Christian A. Sidor
博格达山脉的地层剖面详细记录了东北盘古大陆古中纬度地区晚二叠世-早三叠世的古环境和古气候演化。这些剖面位于塔尔龙-陶东沟、大龙口和照壁山地区，相距约100 km，总厚度约5000 m。利用塔龙-陶东沟剖面7个高分辨率U-Pb锆石CA-TIMS年龄建立了一个年龄模型，并投影到另外两个地区的剖面上，将岩石地层和旋回地层转换为年代地层。沉积环境主要为辫状河、曲流河、湖泊三角洲和湖盆-滨海环境。根据高次旋回的重复环境变化、高次旋回的叠加样式和低次旋回的长期气候和构造趋势，建立了旋回地层学。吴家坪阶上部-梧桐沟阶中期的沉积证据表明，该时期的气候总体上是湿润-半湿润的，并在梧桐阶早期逐渐向季节性干旱的方向变化。繁茂的植被一直延续到二叠纪和三叠纪的分界线，直到印度早期。印度中期-下奥列尼克阶韭菜园和下奥列尼克阶烧房沟LC沉积时期为半湿润-半干旱环境。这三个LC基本上是连续的，并通过整合和间隙分开。地堑内和地堑间的地层变异性反映在厚度、沉积体系和平均沉积速率的变化上，并导致空间和时间地层分辨率的变化。这种地层变异主要受源区和汇水盆地的古地理位置、沉积中心移位以及幕式升降控制。植物群落的转变发生在印度早期，晚于二叠世末海洋大灭绝。然而，河岸植被和高地森林仍然存在，从中期印度到早期Olenekian，并担任陆地生态系统，包括脊椎动物的主要食物来源。将博格达山长兴纪末至印度纪早期维管植物的演化历史与澳大利亚和中国南方报道的维管植物进行对比，表明盘古大陆上存在着一种历时性的植物区系转换。博格达地区晚二叠世-早三叠世的岩石地层、旋回地层和年代地层，在时代模式的制约下，为今后研究博格达地区大陆沉积、气候、生物和生态系统的演化提供了基础。它还提供了一种手段，使中古纬度地区的陆地事件与世界其他地区的海洋和非海洋记录相关联。
Stratigraphic sections in the Bogda Mountains, NW China, provide detailed records of late Permian–Early Triassic terrestrial paleoenvironmental and paleoclimatic evolution at the paleo-mid-latitude of NE Pangea. The sections are located in the Tarlong-Taodonggou, Dalongkou, and Zhaobishan areas, ~100 km apart, and ~5000 m in total thickness. An age model was constructed using seven high-resolution U-Pb zircon CA-TIMS dates in the Tarlong-Taodonggou sections and projected to sections in two other areas to convert the litho- and cyclo-stratigraphy into a chronostratigraphy. Sediments were deposited in braided and meandering streams, and lacustrine deltaic and lakeplain-littoral environments. A cyclostratigraphy was established on the basis of repetitive environmental changes for high-order cycles, stacking patterns of high-order cycles, and long-term climatic and tectonic trends for low-order cycles (LC). Sedimentary evidence from the upper Wuchiapingian–mid Induan Wutonggou LC indicates that the climate was generally humid-subhumid and gradually became variable toward a seasonally dry condition in the early Induan. Lush vegetation had persisted across the Permo–Triassic boundary into the early Induan. A subhumid-semiarid condition prevailed during the deposition of mid Induan–lower Olenekian Jiucaiyuan and lower Olenekian Shaofanggou LCs. These three LCs are largely continuous and separated by conformities and diastems. Intra- and inter-graben stratigraphic variability is reflected by variations in thickness, depositional system, and average sedimentation rate, and results in variable spatial and temporal stratigraphic resolution. Such stratigraphic variability is mainly controlled by paleogeographic location, depocenter shift, and episodic uplift and subsidence in the source areas and catchment basin.A changeover of plant communities occurred during the early Induan, postdating the end-Permian marine mass extinction. However, riparian vegetation and upland forests were still present from the mid Induan to early Olenekian, and served as primary food source for terrestrial ecosystems, including vertebrates. Correlation of the vascular plant evolutionary history from the latest Changhsingian to early Induan in the Bogda Mountains with those reported from Australia and south China indicates a diachronous floral changeover on Pangea. The late Permian–Early Triassic litho-, cyclo- and chrono-stratigraphies, constrained by the age model, provides a foundation for future studies on the evolution of continental sedimentary, climatic, biologic, and ecological systems in the Bogda region. It also provides a means to correlate terrestrial events in the mid-paleolatitudes with marine and nonmarine records in the other parts of the world.