Southern Mexico is a key area for unraveling the tectonic evolution of North America because it contains the stratigraphic and structural record of the major tectonic events that shaped this continental mass, such as the breakup of Pangea and the growth of the North America Cordilleran Orogeny. However, multiple reactivations of faults and erosion of the stratigraphic record do not permit to adequately assess the timing of these tectonic events. Although most authors suggested that lithospheric extension and exhumation of continental blocks during Pangea breakup started in Mexico by Early Jurassic time, works published in the last decade provide an increasing number of thermo-tectonic evidence of an earlier phase of continental thinning. In this work, we present detrital apatite thermochronological and geochemical data (trace elements including rare earth elements) from fluvial deposits of the Tianguistengo formation, which is the oldest stratigraphic unit of the Otlaltepec Basin, a major basin in southern Mexico that has been linked to Pangea breakup. Our data show that at least a part of the Tianguistengo formation was derived from the adjacent Pennsylvanian–Cisuralian Totoltepec pluton. Apatite fission-track-based time–temperature modelling for unreset apatite populations suggests that the main exhumation of the Totoltepec pluton, which prompted the deposition of a part of the Tianguistengo formation, took place during Late Triassic time. Thus, our results suggest that Pangea breakup in southern Mexico started at least by Middle–Late Triassic time (240–230 Ma), as it is recorded in the Otlaltepec Basin.

墨西哥南部是解开北美构造演化的关键区域，因为它包含形成该大陆块的主要构造事件的地层和结构记录，例如盘古大陆的破裂和北美科迪勒拉造山带的增长。然而，断层的多次重新激活和地层记录的侵蚀不允许充分评估这些构造事件的时间。尽管大多数作者认为，在早侏罗世时期的墨西哥，盘古大陆分裂期间岩石圈的伸展和剥露开始于墨西哥，但过去十年发表的著作提供了越来越多的大陆变薄早期阶段的热构造证据。在这项工作中，我们提供了来自 Tianguistengo 地层的河流沉积物的碎屑磷灰石热年代学和地球化学数据（包括稀土元素在内的微量元素），该地层是墨西哥南部主要盆地 Otlaltepec 盆地最古老的地层单元，与 Pangea 断裂有关。我们的数据显示，至少一部分 Tianguistengo 地层来自相邻的宾夕法尼亚-西苏拉尔托托尔特佩克岩体。未复位磷灰石种群的基于磷灰石裂变轨迹的时间-温度模型表明，托托尔特佩克岩体的主要挖掘发生在晚三叠世时期，这促使了一部分 Tianguistengo 地层的沉积。因此，我们的结果表明，墨西哥南部的盘古分裂至少在中-晚三叠世时期（240-230 Ma）开始，