Asian aridification during the Cenozoic was strongly related to moisture flux modulated by sea incursion and the retreat fluctuations of the proto-Paratethys Sea via the Westerlies. However, the extents of the sea incursions are poorly constrained, and there is a lack of sedimentary records beyond the Central Asian basins. The Middle to Late Cretaceous Simao Basin and the Khorat Plateau in Southeast Asia contain thick continental sequences of red beds, evaporites, and aeolian deposits, but whether the depositional environment of the evaporites was marine or continental has been hotly debated. In this study, we compiled multiple sedimentology proxies, biomarkers, element geochemistry, and isotopic geochemistry of the fine-grained sediments of the Mohan section in the Simao Basin. Sedimentological analyses show that this section is composed of subtidal flat fine-grained siliciclastic and carbonate rocks and supratidal flat conglomerates and evaporites. The paleosalinity proxies show that the B concentration and B/Ga and Sr_corrected/Ba ratios range from 30.3 to 81.7 ppm, 2.4 to 5.0, and 0.05 to 0.60, respectively, which indicate brackish conditions. The two typical increases in these proxies are consistent with the stratigraphic horizons of the diagnostic marine biomarkers 24-n-propyl- and 24-iso-propylcholestanes, which suggests seawater recharge. The carbonate δ¹³C and δ¹⁸O values (−4.84‰ to −1.75‰ and −8.25‰ to −3.69‰, respectively) and the bulk δ¹³C_org values (−26.5‰ to −23.22‰) also indicate the influence of seawater. We propose that the seawater likely originated from the proto-Paratethys Sea during a marine incursion. We propose for the first time that the proto-Paratethys seawater incursions extended into the Simao Basin and the Khorat Plateau. These results provide a novel paleogeographic configuration for East Asia during the Middle to Late Cretaceous. The retreat of the proto-Paratethys Sea, the northeast Trade Winds, and the tectonic uplift dramatically decreased the moisture and intensified the extreme aridification in the Simao Basin and the Khorat Plateau.

新生代的亚洲干旱化与海侵调节的水汽通量和原始西洋的经由西风的后退波动密切相关。但是，海上入侵的程度受到限制，而且在中亚盆地之外缺乏沉积记录。东南亚的中白垩统思茅盆地和霍拉特高原有厚厚的大陆层层红床，蒸发岩和风积沉积物，但是，蒸发岩的沉积环境是海洋的还是大陆的，一直引起了激烈的争论。在这项研究中，我们汇总了思茅盆地莫汉剖面的细颗粒沉积物的多种沉积学代理，生物标志物，元素地球化学和同位素地球化学。沉积学分析表明，该断层由潮下带细粒硅质碎屑岩和碳酸盐岩以及上滩带砾岩和蒸发岩组成。古盐度表明B浓度，B / Ga和Sr_校正后的/ Ba比值分别在30.3至81.7 ppm，2.4至5.0和0.05至0.60的范围内，表明存在咸味。这些替代物的两个典型增加与诊断性海洋生物标记物24-正丙基和24-异丙基胆甾烷的地层范围一致，表明海水补给。δ碳酸盐¹³ C和δ ^18个O值（-4.84‰至-1.75‰和-8.25‰至-3.69‰，分别地）和体δ ¹³ C ^_有机值（−26.5‰至−23.22‰）也表明了海水的影响。我们建议海水在海洋入侵期间可能起源于原始百姓海。我们首次建议原对虾的海水入侵扩展到思茅盆地和霍拉特高原。这些结果为白垩纪中晚期的东亚地区提供了一种新颖的古地理构造。原始Paraatethys海的退缩，东北信风和构造隆升极大地降低了思茅盆地和哈拉特高原的水分，并加剧了极端干旱化。