Competition between 3D structural inheritance and kinematics during rifting: Insights from analogue models,Basin Research

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Competition between 3D structural inheritance and kinematics during rifting: Insights from analogue models
Basin Research ( IF 2.8 ) Pub Date : 2021-11-27 , DOI: 10.1111/bre.12642
Frank Zwaan ₁ , Pauline Chenin ₂ , Duncan Erratt ₂ , Gianreto Manatschal ₂ , Guido Scheurs ₁

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The competition between the impact of inherited weaknesses and plate kinematics determines the location and style of deformation during rifting, yet the relative impacts of these ‘internal’ and ‘external’ factors remain poorly understood, especially in 3D. In this study, we used brittle-viscous analogue models to assess how multiphase rifting, that is changes in plate divergence rate or direction, and the presence and orientation of weaknesses in the competent mantle and crust, influences rift evolution. We find that the combined reactivation of mantle and crustal weaknesses without any kinematic changes already creates complex rift structures. Divergence rates affect the strength of the weak lower crustal layer and hence the degree of mantle-crustal coupling; slow rifting decreases coupling, so that crustal weaknesses can dominate deformation localisation and surface structures, whereas fast rifting increases coupling and deformation related to mantle weaknesses can have a dominant surface expression. Through a change from slow to fast rifting mantle-related deformation can overprint structures that previously formed along (differently oriented) crustal weaknesses. Conversely, a change from fast to slow rifting may shift deformation from mantle-controlled towards crust-controlled. When changing divergence directions, structures from the first rifting phase may control where subsequent deformation occurs, but only when they are sufficiently well developed. We furthermore place our results in a larger framework of brittle-viscous rift modelling results from previous experimental studies, showing the importance of general lithospheric layering, divergence rate, the type of deformation in the mantle, and finally upper crustal structural inheritance. The interaction between these parameters can produce a variety of deformation styles that may, however, lead to comparable end products. Therefore, careful investigation of the distribution of strain localisation, and to an equal extent of basin depocenter locations over time is required to properly determine the evolution of complex rift systems, providing an incentive to revisit various natural examples.

中文翻译：

裂谷过程中 3D 结构继承与运动学之间的竞争：来自模拟模型的见解

遗传弱点的影响与板块运动学之间的竞争决定了裂谷过程中变形的位置和方式，但这些“内部”和“外部”因素的相对影响仍然知之甚少，尤其是在 3D 中。在这项研究中，我们使用脆粘性模拟模型来评估多期裂谷，即板块发散率或方向的变化，以及主管地幔和地壳中弱点的存在和方向，如何影响裂谷演化。我们发现，在没有任何运动学变化的情况下，地幔和地壳弱点的联合重新激活已经产生了复杂的裂谷结构。发散率影响弱下地壳层的强度，从而影响地幔-地壳耦合程度；缓慢的裂谷减少耦合，因此，地壳弱点可以主导变形定位和地表结构，而快速裂谷增加与地幔弱点相关的耦合和变形可以具有主要的地表表现。通过从慢速裂谷到快速裂谷的变化，与地幔相关的变形可以覆盖以前沿着（不同方向的）地壳弱点形成的结构。相反，从快速裂谷到慢速裂谷的变化可能会将变形从地幔控制转向地壳控制。当改变发散方向时，来自第一个裂谷阶段的结构可能会控制随后发生变形的位置，但前提是它们足够发达。我们进一步将我们的结果置于先前实验研究的脆性裂谷建模结果的更大框架中，显示了一般岩石圈分层、发散率、地幔变形类型以及最后上地壳构造继承的重要性。这些参数之间的相互作用可以产生各种变形样式，但是，这些变形样式可能会产生可比较的最终产品。因此，需要仔细研究应变局部化的分布，以及在同等程度上随着时间的推移盆地沉积中心位置，以正确确定复杂裂谷系统的演变，为重新审视各种自然例子提供动力。

更新日期：2021-11-27

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