Medina-Sánchez Javier, McLaren Sue J, Ortega-Ramírez José, Valiente-Banuet Alfonso
Department of Geography, University of Leicester, University Road, LE1 7RH, Leicester, UK.
Laboratorio de Geofísica, Instituto Nacional de Antropología e Historia, Moneda 16 Centro Histórico, C.P. 06060, México City, México.
Heliyon. 2020 Mar 19;6(3):e03584. doi: 10.1016/j.heliyon.2020.e03584. eCollection 2020 Mar.
The morphological evolution of the basins in the Sierra Madre del Sur (SMS), southern México is poorly understood. This work explains for the first time the geomorphological development of the tectonic, fluvially-interconnected SMS basins named San Juan Raya (SJRb) and Zapotitlán (ZAPb). The evolution of the SJRb and ZAPb are analysed within the context of the transformations of the well-studied Tehuacán basin (TEHb). A new interpretation of a series of tectonic features of the TEHb valley area is also presented. Published geological data and extensive field work provided the basis for our geomorphological and evolutionary interpretation of basin evolution of this part of Mesoamerica during the late Cenozoic. Stratigraphic and sedimentary records suggest that after the late Cretaceous-early Cenozoic orogeny the TEHb and ZAPb were closed basins, and that the TEHb graben system was activated during the Paleogene as a response to the dominant regional NW-SE trending faults. We propose that the ZAPb and SJRb formed sequentially during the Neogene as a result of new E-W, N-S and NE-SW faults. The continuation of the TEHb extension during the Oligocene widened its lowland area and allowed the formation of an extensive lake. No alluvial or fluvial records of this interval are found in the ZAPb and SJRb. No sedimentation rather than formation and subsequent erosion of such sediments is supported by the basin morphology and by the absence of re-worked alluvial deposits at the outlet area where both connect to the TEHb. By middle to late Miocene the TEHb lost its endorheic configuration, ending the lake-type deposition while new faults initiated the opening of the ZAPb. Intensive tectonics, alluvial deposition and the confinement of the Tehuacán lake to the north sector of this basin characterised the Pliocene. During the late Pliocene to the early Pleistocene the formation of the SJRb was initiated. Quaternary faulting related to basin extension along the north watershed of the SJRb and ZAPb is supported by independent data on the biogeography of the cactus . We introduce the idea that the departure from the regional NW-SE fault alignment that formed the major Miocene basins to a more local E-W trend that formed Neogene-Quaternary basins was probably a response to the latest post-orogenic relaxation of the crust in the Mixteca terrane.
墨西哥南部南马德雷山脉（SMS）盆地的形态演化尚不清楚。这项工作首次解释了构造上相互连通的SMS盆地圣胡安·拉亚（SJRb）和萨波蒂特兰（ZAPb）的地貌发育情况。在经过充分研究的特瓦坎盆地（TEHb）的转变背景下，分析了SJRb和ZAPb的演化。还提出了对TEHb山谷地区一系列构造特征的新解释。已发表的地质数据和广泛的野外工作为我们对中美洲这一地区晚新生代盆地演化的地貌和演化解释提供了依据。地层和沉积记录表明，在晚白垩世 - 早新生代造山运动之后，TEHb和ZAPb是封闭盆地，并且TEHb地堑系统在古近纪期间因主要的区域NW - SE走向断层而被激活。我们认为，ZAPb和SJRb在新近纪期间由于新的E - W、N - S和NE - SW断层而相继形成。渐新世期间TEHb的持续伸展拓宽了其低地地区，并形成了一个广阔的湖泊。在ZAPb和SJRb中未发现该时期的冲积或河流记录。盆地形态以及与TEHb相连的出口区域缺乏再加工冲积沉积物，这支持了没有沉积而是沉积物形成并随后被侵蚀的观点。到中新世中期至晚期，TEHb失去了其内陆水系格局，湖泊型沉积结束，而新的断层引发了ZAPb的开启。上新世的特征是强烈的构造活动、冲积沉积以及特瓦坎湖局限于该盆地的北部区域。在晚上新世至早更新世期间，SJRb开始形成。与SJRb和ZAPb北分水岭沿线盆地伸展相关的第四纪断层活动得到了仙人掌生物地理学独立数据的支持。我们提出这样的观点，即从形成主要中新世盆地的区域NW - SE断层走向转变为形成新近纪 - 第四纪盆地的更局部的E - W走向，可能是对米斯特卡地体地壳最新的造山后松弛的一种响应。
