The Triassic-Jurassic boundary is one of the most important geological boundaries in the Earth's evolutionary history. Previous paleoclimate studies focused primarily on Tethys realm at low and middle latitudes, while the northern hemisphere has yet to be studied. Here, we report Mg-Zn-Cu isotopic data for a continuous terrestrial sedimentary section in the southern margin of the Junggar Basin to constrain chemical weathering intensity and climatic change during this critical interval at high latitude. This section is enriched in heavy Mg isotopes with δ²⁶Mg ranging from 0.08‰ to 0.43‰. It displays a decreasing Zn isotopic composition with δ⁶⁶Zn ranging from −0.05‰ to 0.24‰, as well as limited Cu isotope fractionation (δ⁶⁵Cu = −0.06‰ to 0.09‰). These isotopic results, combined with major and trace elemental variations, suggest a reduced sedimentary environment and increasingly intensive chemical weathering across the boundary, responding to a warmer and more humid paleoclimate. Compared with other places located around Tethys, this regional climatic change in high latitude areas can be linked to known global climate change during this period. Our study provides new insights from high-latitude Asia to reconstruct the global pattern of climate change at the Triassic-Jurassic boundary.

三叠纪-侏罗纪边界是地球演化史上最重要的地质边界之一。以前的古气候研究主要集中在低纬度和中纬度的特提斯领域，而北半球还有待研究。在这里，我们报告了准噶尔盆地南缘连续陆地沉积剖面的 Mg-Zn-Cu 同位素数据，以约束高纬度这一关键区间的化学风化强度和气候变化。该剖面富含重镁同位素，δ ²⁶ Mg 范围为0.08‰～0.43‰。它的 Zn 同位素组成呈递减趋势，δ ⁶⁶ Zn 范围从 -0.05‰ 到 0.24‰ ，以及有限的 Cu 同位素分馏 (δ ⁶⁵Cu = -0.06‰ 至 0.09‰)。这些同位素结果与主要和微量元素变化相结合，表明沉积环境减少，跨边界化学风化作用越来越强烈，对更温暖和更潮湿的古气候作出反应。与位于特提斯周围的其他地方相比，高纬度地区的这种区域性气候变化可以与这一时期已知的全球气候变化联系起来。我们的研究提供了来自高纬度亚洲的新见解，以重建三叠纪-侏罗纪边界的全球气候变化格局。