Preserved extensional structures in an inverted Cretaceous rift basin, northwestern Argentina: Outcrop examples and implications for fault reactivation
Preserved extensional structures in an inverted Cretaceous rift basin, northwestern Argentina: Outcrop examples and implications for fault reactivation
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DOI：
10.1029/2006tc001993
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发表时间：
2008-02
期刊：
影响因子：
4.2
通讯作者：
C. R. Monaldi;J. Salfity;J. Kley
中科院分区：
文献类型：
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作者：
C. R. Monaldi;J. Salfity;J. Kley
在白垩纪—始新世期间，阿根廷西北部形成了一套陆内裂谷盆地，即萨尔塔群裂谷。后来，在新生代缩短期间，裂谷的个别段经历了不同程度的反转。东科迪勒拉西侧的特拉斯克鲁塞斯次盆地发生了强烈的变形，现在是一个以北向南构造为主的厚皮冲断带的一部分。在其东部边界，由于褶皱和逆冲而产生的倾斜以及随后的侵蚀产生了保存完好的东向伸展构造的特殊露头，包括半地堑、翻转背斜和伸展断层扩展褶皱。再往西，虽然北向和东向构造的干扰，以及带有刺状伸展的奇特的圆顶状背斜，表明北向和东向的白垩纪断层被重新激活，特别是在它们的交叉点附近，但辐合带演替只是间歇性地暴露出来。对已发表数据的整理和对萨尔塔裂谷新数据的分析表明，有利于正断层收缩再激活的三个主要因素是：倾角低于约60°，特别是对于大致为正向收缩的断层；与收缩方向的距离不小于约30°；低下倾断层曲率。偶尔的东向断层的倾滑重新激活与安第斯山脉目前和长期的应力状态不匹配，这是一个尚未解决的问题。
During the Cretaceous‐Eocene interval a system of intracontinental rift basins, the Salta group rift, evolved in northwestern Argentina. Individual segments of the rift later suffered different degrees of inversion during Cenozoic shortening. The Tres Cruces subbasin, on the west side of the Eastern Cordillera, was strongly deformed, being now part of a thick‐skinned thrust belt with a predominantly N‐S structural trend. On its eastern border, tilting due to folding and thrusting and subsequent erosion have produced exceptional outcrops of preserved east‐trending extensional structures including half grabens, rollover anticlines, and extensional fault‐propagation folds. Farther west, the synrift succession is only intermittently exposed, although the interference of north‐ and east‐trending structures as well as peculiar, dome‐shaped anticlines with spur‐like extensions suggest that north‐ and east‐trending Cretaceous faults were reactivated, particularly near their intersections. Compilation of published data and analysis of our new data focused on the Salta rift indicates three main factors favoring the contractional reactivation of normal faults: dip angles lower than approximately 60°, especially for faults striking roughly normal to contraction; strikes no closer to the contraction direction than approximately 30°; and low downdip fault curvatures. Occasional dip‐slip reactivation of east‐trending faults does not match the present and long‐term Andean stress regimes and presents an unresolved problem.