Physical modelling of the interplay between salt-detached gravity gliding and spreading across complex rift topography, Santos Basin, offshore Brazil,Basin Research

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Physical modelling of the interplay between salt-detached gravity gliding and spreading across complex rift topography, Santos Basin, offshore Brazil
Basin Research ( IF 2.8 ) Pub Date : 2022-07-16 , DOI: 10.1111/bre.12695
Leonardo M. Pichel _{1,

2} , Oriol Ferrer _{3,

4} , Christopher A.‐L. Jackson _{1,

5} , Eduard Roca _{3,

4}

Affiliation

The Santos Basin, offshore Brazil contains a complex set of salt-tectonic structures, the origins of which are debated, that is, the Albian Gap and the São Paulo Plateau (SPP). The Albian Gap is a ca. 450 km long, 60 km wide feature characterized by a post-Albian, counter-regional rollover overlying depleted Aptian salt, and in which the Albian is largely absent. The SPP, located immediately downdip, is defined by a pre-salt structural high overlain by ca. 2.5 km thick salt. Another prominent feature is the Merluza Graben, a rift-related depocentre that underlies the southern portion of the Albian Gap and displays significant (3–4 km) base-salt relief along its main faults. Two competing hypotheses have been proposed to explain the kinematics of these provinces. One invokes post-Albian extension in the Albian Gap and kinematically-linked contraction in the SPP. The other invokes post-Albian salt expulsion in the Albian Gap and salt inflation in the SPP. Recent studies, however, suggest these processes likely alternate in time and space, contributing nearly equally to the evolution of these domains. We apply 3D physical modelling to (i) test this hypothesis; and (ii) to more generally understand how gravity gliding and spreading over three-dimensionally variable base-salt relief control regional salt tectonics. The results show a similar salt-related evolution and structural styles to those proposed in the most recent studies. They also (i) explain the origin of the ca. 25 km wide diapir precursor of the Albian Gap by early salt inflation against base-salt steps; (ii) show that normal faults with different polarities and rollover types form due to the interplay between gliding and spreading over different base-salt domains and (iii) provide a mechanism for the origin of strata encased within salt structures. This improves our understanding of the distribution and origin of salt-related structural styles in worldwide salt basins.

中文翻译：

巴西近海桑托斯盆地盐分离重力滑动与复杂裂谷地形扩散之间相互作用的物理模型

巴西近海的桑托斯盆地包含一组复杂的盐构造结构，其起源存在争议，即阿尔比安峡谷和圣保罗高原 (SPP)。阿尔比安峡谷是一个 ca。长 450 公里，宽 60 公里的地物，其特征是后阿尔布期、反区域翻转覆盖在枯竭的阿普第期盐之上，阿尔布期基本不存在。SPP 位于紧靠下倾的位置，由覆盖约 2.5公里厚的盐。另一个显着特征是 Merluza Graben，这是一个与裂谷相关的沉积中心，位于阿尔比安峡谷南部的下方，并显示出沿其主要断层的显着（3-4 公里）基盐地貌。已经提出了两个相互竞争的假设来解释这些省份的运动学。一个调用 Albian Gap 中的后 Albian 扩展和 SPP 中的运动学相关收缩。另一个援引阿尔比安缺口的后阿尔比安盐排放和 SPP 的盐膨胀。然而，最近的研究表明，这些过程可能在时间和空间上交替出现，对这些领域的演化贡献几乎相同。我们应用 3D 物理建模来 (i) 检验这个假设；(ii) 更普遍地了解重力在三维可变基盐地貌上的滑动和扩散如何控制区域盐构造。结果显示与最近研究中提出的盐相关的进化和结构样式相似。他们还 (i) 解释了 ca 的起源。阿尔比安峡谷 25 公里宽的底辟前驱物，由早期的盐膨胀作用于基盐阶梯；(ii) 表明由于在不同基盐域上滑动和扩散之间的相互作用，形成了具有不同极性和翻转类型的正断层，并且 (iii) 提供了一种机制来解释包裹在盐结构中的地层的起源。这提高了我们对全球盐盆地与盐相关的结构样式的分布和起源的理解。

更新日期：2022-07-16

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