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The Matzitzi Formation in southern Mexico: A record of Pangea final assembly or breakup initiation along inherited suture belts?
Basin Research ( IF 2.8 ) Pub Date : 2021-11-16 , DOI: 10.1111/bre.12638
Michelangelo Martini 1 , Jonathan A. Anaya Guarneros 2 , Luigi Solari 3 , Alejandra Bedoya 2 , Mildred Zepeda‐Martínez 2 , Uxue Villanueva‐Amadoz 4
Affiliation  

The breakup of Pangea fundamentally shaped modern continents and controlled the climatic distribution and biodiversity on Earth. Although our knowledge on the processes that control the assembly and breakup of supercontinents has significantly improved, the timing of supercontinent assembly and breakup initiation remains in some cases controversial. According to the available data, the assembly of Pangea was completed in middle Permian time, resulting in the formation of major orogenic belts and transform faults like the N–S-trending, dextral, Caltepec fault in Mexico. Pangea breakup initiation is bracketed to early Middle Triassic time. In this work, we present new sedimentological, structural and U-Pb geochronological data from a fluvial unit, the Matzitzi Formation of southern Mexico, the age and tectonic setting of which have remained an enigma for the past century. Our data document that the Matzitzi Formation is the stratigraphic record of a late Permian, anastomosing fluvial system that flowed in a—NNE-trending extensional trough developed on top of the Caltepense belt, a transpressive belt formed along the Caltepec fault. We propose and discuss three possible scenarios for the tectonic setting of the Matzitzi Formation. In the first scenario, the unit is the stratigraphic record of the Caltepec fault late activity, which caused local NW–SE extension along the western margin of Pangea during its final assembly. In the second scenario, the Matzitzi Formation was deposited in an extensional basin formed by slab rollback along the western equatorial Pangea margin. In the third scenario, the extensional basin of the Matzitzi Formation was formed in the framework of the Pangea breakup. In this case, our data would suggest that Pangea breakup initiation must be dated back to late Permian time, which is ca. 15 m.y. older than the Middle Triassic age documented by the previous work. Considering that evidence of Permian extension has also been reported along the Appalachian belt, we suggest that the Matzitzi Formation was deposited during regional-scale extension of western equatorial Pangea; therefore, we preliminarily support the third scenario. The distribution of Permian extension along suture belts developed during Pangea assembly highlights the fundamental role played by pre-existent zones of weakness in the breakup of a supercontinent.

中文翻译:

墨西哥南部的 Matzitzi 组:Pangea 沿继承缝合带最终组装或解体的记录?

盘古大陆的分裂从根本上塑造了现代大陆,并控制了地球上的气候分布和生物多样性。尽管我们对控制超大陆组装和分裂过程的认识有了显着提高,但在某些情况下,超大陆组装和分裂开始的时间仍然存在争议。根据现有资料,盘古大陆在二叠纪中期完成组装,形成了主要的造山带和墨西哥南北向、右旋、卡尔特佩克断层等转换断层。盘古大陆分裂开始被括在三叠纪中期早期。在这项工作中,我们提供了来自墨西哥南部 Matzitzi 组河流单元的新沉积学、结构和 U-Pb 年代学数据,在过去的一个世纪里,它的年龄和构造环境一直是个谜。我们的数据表明,Matzitzi 组是二叠纪晚期、吻合河流系统的地层记录,该河流系统流入在 Caltepense 带顶部发育的 NNE 走向的伸展槽中,该带是沿 Caltepec 断层形成的压断带。我们提出并讨论了 Matzitzi 组构造环境的三种可能情景。在第一种情况下,该单元是 Caltepec 断层晚期活动的地层记录,它在最终组装期间沿 Pangea 西部边缘造成了局部 NW-SE 延伸。在第二种情况下,Matzitzi 组沉积在一个伸展盆地中,该盆地是由沿西赤道盘古大陆边缘的板片回滚形成的。在第三种情况下,Matzitzi组伸展盆地形成于Pangea断裂的框架内。在这种情况下,我们的数据表明盘古大陆分裂的开始必须追溯到二叠纪晚期,即大约。15 我比以前的工作记录的中三叠纪年龄大。考虑到沿阿巴拉契亚带也报道了二叠纪伸展的证据,我们认为Matzitzi组沉积在赤道西部泛大陆的区域尺度伸展期间;因此,我们初步支持第三种情况。二叠纪延伸沿盘古大陆组装期间形成的缝合带的分布突出了先前存在的薄弱区在超大陆分裂中所起的基本作用。我们的数据表明,盘古大陆分裂的开始必须追溯到二叠纪晚期,即大约。15 我比以前的工作记录的中三叠纪年龄大。考虑到沿阿巴拉契亚带也报道了二叠纪伸展的证据,我们认为Matzitzi组沉积在赤道西部泛大陆的区域尺度伸展期间;因此,我们初步支持第三种情况。二叠纪延伸沿盘古大陆组装期间形成的缝合带的分布突出了先前存在的薄弱区在超大陆分裂中所起的基本作用。我们的数据表明,盘古大陆分裂的开始必须追溯到二叠纪晚期,即大约。15 我比以前的工作记录的中三叠纪年龄大。考虑到沿阿巴拉契亚带也报道了二叠纪伸展的证据,我们认为Matzitzi组沉积在赤道西部泛大陆的区域尺度伸展期间;因此,我们初步支持第三种情况。二叠纪延伸沿盘古大陆组装期间形成的缝合带的分布突出了先前存在的薄弱区在超大陆分裂中所起的基本作用。考虑到沿阿巴拉契亚带也报道了二叠纪伸展的证据,我们认为Matzitzi组沉积在赤道西部泛大陆的区域尺度伸展期间;因此,我们初步支持第三种情况。二叠纪延伸沿盘古大陆组装期间形成的缝合带的分布突出了先前存在的薄弱区在超大陆分裂中所起的基本作用。考虑到沿阿巴拉契亚带也报道了二叠纪伸展的证据,我们认为Matzitzi组沉积在赤道西部泛大陆的区域尺度伸展期间;因此,我们初步支持第三种情况。二叠纪延伸沿盘古大陆组装期间形成的缝合带的分布突出了先前存在的薄弱区在超大陆分裂中所起的基本作用。
更新日期:2021-11-16
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