The Middle Triassic is thought to have had a greenhouse paleoclimate with a few short humid phases. However, the timing of these humid events, and the extent to which orbital forcing influenced the evolution of climate, are unclear. Here, a cyclostratigraphic analysis has been carried out based on the integrated study of magnetic susceptibility, elemental chemistry and lithofacies from two shallow-marine carbonate platform sections in Guizhou, South China. Combined, these sections (Pohong and Yongyue) span the late Anisian to early Carnian. Spectral analyses of magnetic susceptibility, Fe/Al and P through the studied sections show significant cycles of ~85-m, ~7-m and ~ 4-m. Based on independent age constraints and sedimentation rate modelling, these cycles are interpreted as orbital cycles that reflect 405-kyr long-eccentricity, ~33-kyr obliquity, and ~ 20-kyr precession forcing, respectively. Tuning of the records to the stable 405-kyr long-eccentricity parameter in each section yields a tuned astronomical time scale spanning ~7.4 ± 0.2 Myr, which covers from ca. 244.4 to 237.0 Ma and includes the entire Ladinian Stage. Magnetic susceptibility and Fe/Al data from the studied sections show intervals with relatively high values in the middle-late Anisian (ca. 244.0 to 242.6 Ma), and the latest Anisian to early Ladinian (ca. 241.8 to 240.9 Ma). These geochemical changes, combined with lithological changes, indicate enhanced terrigenous flux caused by the acceleration of hydrological circulation under a warmer and more humid climate. In addition, P data records two sharp falls that appear broadly coeval with the previously postulated late Ladinian ecological crisis. Our new astrochronology also reveals that ~1.2-Myr obliquity amplitude modulation cycles are expressed in the Middle Triassic. The regional sea level changes inferred from sequence stratigraphy and sedimentary noise modelling can be correlated with Tethyan and global sea level change. This work demonstrates the utility and power of sedimentary noise modelling in shallow marine environments for inferring past sea level dynamics. It also furthers constrains the timing of putative Middle Triassic climatic and ecological events.

据认为，中三叠纪的温室古气候为几个短的湿润期。但是，尚不清楚这些潮湿事件的发生时间以及轨道强迫影响气候演变的程度。在此基础上，结合贵州华南两个浅海碳酸盐岩台地段的磁化率，元素化学和岩相的综合研究，进行了地层分析。这些部分（宝宏和永岳）结合起来，跨越了阿尼西晚期至卡尼早期。通过研究部分的磁化率，Fe / Al和P的光谱分析显示，〜85-m，〜7-m和〜4-m的周期明显。根据独立的年龄限制和沉积速率模型，这些周期被解释为反映了405-kyr长偏心率，〜33-kyr倾角，和〜20 kyr进动强迫。将记录调整为每节中稳定的405 kyr长偏心率参数，可产生约7.4±0.2 Myr的调谐天文时标，其覆盖范围约为。244.4至237.0 Ma，包括整个拉丁期。来自研究区域的磁化率和Fe / Al数据显示，中晚期Anisian（约244.0至242.6 Ma）以及最新的Anisian至早期Ladinian（约241.8至240.9 Ma）具有相对较高的值区间。这些地球化学变化与岩性变化相结合，表明在温暖和潮湿的气候下，由于水文循环加速而引起的陆源通量增加。此外，P数据记录了两次急剧下降，这与先前假定的晚期拉丁尼亚生态危机大致相同。我们的新天文年代学还揭示了在中三叠纪表达了约1.2毫秒的倾角振幅调制周期。由层序地层学和沉积物噪声模型推断出的区域海平面变化可以与特提斯和全球海平面变化相关。这项工作证明了在浅海环境中进行过去海平面动力学推断时，沉积噪声建模的效用和作用。它还进一步限制了假定的中三叠纪气候和生态事件的发生时间。这项工作演示了在浅海环境中模拟过去的海平面动力学的沉积噪声建模的实用性和强大功能。它还进一步限制了假定的中三叠纪气候和生态事件的发生时间。这项工作演示了在浅海环境中模拟过去的海平面动力学的沉积噪声建模的实用性和强大功能。它还进一步限制了假定的中三叠纪气候和生态事件的发生时间。