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Tectonic controls on late Cambrian-Early Ordovician deposition in Cordillera oriental (Northwest Argentina)
International Journal of Earth Sciences ( IF 2.3 ) Pub Date : 2020-05-29 , DOI: 10.1007/s00531-020-01879-9
Romain Vaucher , N. Emilio Vaccari , Diego Balseiro , Diego F. Muñoz , Antoine Dillinger , Beatriz G. Waisfeld , Luis A. Buatois

The western Gondwana margin underwent a complex geodynamic history during the early Paleozoic, and major uncertainties remain as to the role of tectonism in sedimentary dynamics. This study focuses on the lower part Santa Rosita Formation and the coeval Guayoc Chico Group (Cordillera Oriental; Northwest Argentina), ranging from the late Cambrian (Furongian; Age 10) to Early Ordovician (early Tremadocian; Tr1). This stratigraphic interval has been previously interpreted as deposited in an extensional basin to a retro-arc basin without major regional tectonic-induced deformation during its deposition, only recording long-term relative sea-level fluctuations. Four areas (Sierra de Cajas, Angosto del Moreno, Quebrada de Trancas, and Quebrada de Moya) were chosen because they host the most complete and temporally well-constrained stratigraphic sections of the Cordillera Oriental. Throughout the stratigraphic sections, four main facies zones are described and attributed to deposition in estuarine, foreshore-shoreface, delta-front, and offshore environments. Trilobite biozones are used as the biostratigraphic framework. By integrating sedimentary facies analysis, biostratigraphy, and sequence stratigraphy from the four selected sections, a new scenario showcasing the evolution of the basin is proposed. This scenario interprets a tectonically induced deformation during the deposition of the Santa Rosita Formation and the coeval Guayoc Chico Group. The newly acquired sedimentological data show that physiographical changes took place during the Cambrian-Ordovician transition and are expressed in various localities. This major change is recorded in the stratigraphic architecture, where extensive wave-ravinement surfaces and sedimentary hiatus are the result of local, syn-depositional basement uplifts. The initiation of the Puna-Famatinian volcanic arc during the Early Ordovician on the western margin was likely responsible for deformation in the retro-arc basin and the proposed scenario is consistent with the stratigraphic evolution in other areas of the Cordillera Oriental (e.g., Sierra de Mojotoro) and the Sierra de Famatina. Therefore, this study helps to constrain the evolution of the western Gondwana margin during the early Paleozoic, showing changes in the stratigraphic architecture and basin evolution from an extensional to a retro-arc style.



中文翻译:

东方山脉(阿根廷西北部)寒武纪-早奥陶纪晚期沉积的构造控制

冈瓦纳西部边缘在古生代早期经历了复杂的地球动力学历史,关于构造运动在沉积动力学中的作用仍存在主要不确定性。这项研究的重点是下部的圣罗西塔组和中世纪的瓜约克奇科集团(东方的科迪勒拉山脉;阿根廷西北部),范围从寒武纪晚期(富隆纪; 10岁)到奥陶纪早期(特里玛多纪早期; Tr1)。该地层间隔先前被解释为沉积在伸展盆地中,形成后弧盆地,沉积期间没有大的区域构造引起的变形,仅记录了长期的相对海平面波动。四个地区(塞拉利昂德卡哈斯,安格斯托德尔莫雷诺,克夫拉达德特兰卡斯,之所以选择Quebrada de Moya和Quebrada de Moya,是因为它们拥有东方山脉最完整,时间最受限制的地层。在整个地层剖面中,描述了四个主要相带,并归因于河口,滨海前缘,三角洲前缘和近海环境中的沉积。三叶虫生物区被用作生物地层学框架。通过对四个选定剖面的沉积相分析,生物地层学和层序地层学进行整合,提出了一个新的场景,说明该盆地的演化。该场景解释了圣罗西塔组和古圭尤奇奇科集团沉积过程中的构造诱发变形。新获得的沉积学数据表明,在寒武纪-奥陶纪过渡期发生了地貌变化,并在各个地方得到了表达。这一重大变化记录在地层构造中,在该构造中,广泛的波浪起伏表面和沉积裂隙是局部同沉积沉积基底隆升的结果。在西奥陶纪早奥陶世期间,Puna-Famatinian火山弧的爆发可能是造成后弧盆地变形的原因,并且所提出的方案与东方山脉其他地区(例如,塞拉利昂山脉)的地层演化相一致。 Mojotoro)和Sierra de Famatina。因此,这项研究有助于限制古生代早期的冈瓦纳西部边缘的演化,

更新日期:2020-05-29
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