Empirical record, geochronology and theoretical determinates of Mesozoic climate in the Junggar Basin, NW China, in relation to other basins in NE China

Abstract

Mesozoic continental basins of northern China, including the Junggar Basin, provide some of the most spectacular and important fossil assemblages in the world, but their climatic and environmental contexts have been shrouded in uncertainty. Here we examine the main factors that determine those contexts: palaeolatitude; the effects of changing atmospheric gases on the radiative balance; and orbitally paced variations in insolation. Empirical evidence on these factors is accumulating rapidly and promises to upend many long standing paradigms. We focus primarily on the Junggar Basin in Xinjiang northwest China with the renowned Shishugou Biota and the basins in Liaoning, Hebei, and Inner Mongolia with their famous Jehol and Yanliao Biotas. Accurate geochronology is necessary for disentangling these various factors and we review the Late Triassic to Early Cretaceous U-Pb ages for these areas and supply one new LA-ICP-MS age for the otherwise un-dated Sangonghe Formation of Early Jurassic age. We review climatic-sensitive facies patterns in North China and show that the climatic context changed synchronously in northwestern and northeastern China consistent with a previously proposed huge Late Jurassic-earliest Cretaceous True Polar Wander (TPW) event with all the major plates of East Asia docked with Siberia and moving together since at least the Triassic, when the north China Basins were at Arctic latitudes. We conclude that this TPW shift is was responsible for the coals and ice rafted debris being produced at high latitudes and the red beds and eolian strata being deposited at low latitudes, within the same basin. The climatic and taphonomic context in which the famous Shishugou, Yanlaio and Jehol biotas preserved was thus a function of TPW as opposed to local tectonics or climate change. Supplementary material at https://doi.org/10.6084/m9.figshare.c.6738045

A fluvial‐aeolian system in response to aridification during the Late Mesozoic, Junggar Basin, Central Asia

“…Although the Junggar Basin is nowadays a foreland basin (Hendrix et al., 1994; Li et al., 2011), it was an intracontinental half‐graben basin during the Early to early Middle Jurassic (Fang et al., 2004; Guan et al., 2016; Ma et al., 2021; Wang et al., 2018), and a transpressional basin during the late Middle to Late Jurassic (He et al., 2008, 2018; Yu, Liu, et al., 2016). Its palaeogeographic position changed from ~71° N in the Early Jurassic to ~32° N in the Late Jurassic (Chen et al., 1991; Olsen et al., 2022, 2024; Sha et al., 2015; Yi et al., 2019).…”