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Normal Fault Kinematics and the Role of Lateral Tip Retreat: An Example From Offshore NW Australia
Tectonics ( IF 3.3 ) Pub Date : 2021-04-02 , DOI: 10.1029/2020tc006631
Bailey A. Lathrop 1 , Christopher A.‐L Jackson 1 , Rebecca E. Bell 1 , Atle Rotevatn 2
Affiliation  

Understanding how normal faults grow is key to determining the tectono‐stratigraphic evolution of rifts. According to recent studies, normal faults tend to grow in two temporally distinct stages: a lengthening stage, followed by a throw/displacement accumulation stage. However, this model is still debated and not widely supported by many additional studies. Relatively few studies have investigated what happens to a fault as it becomes inactive, that is, does it abruptly die, or does the at‐surface trace‐length progressively shorten by so‐called tip retreat? We, here, use a 3D seismic reflection data set from the Exmouth Plateau, offshore Australia, to develop a three‐stage fault growth model for seven normal faults of various sizes and to show how the throw‐length scaling relationship changes as a fault dies. We show that during the lengthening stage, which lasted <30% of the faults’ lives, faults reached their near‐maximum lengths, yet accumulated only 10%–20% of their total throw. During the throw/displacement accumulation stage, which accounts for c. 30%–75% of the faults’ lives, throw continued to accumulate along the entire length of the faults. All of the studied faults also underwent a stage of lateral tip‐retreat (last c. 25% of the faults’ lives), where the active at‐surface trace‐length decreased by up to 25%. The results of our study may have broader implications for fault growth models, slip rate variability during fault growth, and the way in which faults die, in particular the role of lateral tip‐retreat.

中文翻译:

正常断层运动学和侧向后退的作用:澳大利亚近海西北部的一个例子

了解正常断层的生长方式是确定裂谷构造地层演化的关键。根据最近的研究,正常断层倾向于在两个时间上不同的阶段生长:延长阶段,然后是投掷/位移累积阶段。但是,该模型仍在争论中,许多其他研究并未广泛支持。相对较少的研究调查了故障变为非活动状态后会发生什么,即故障突然消失,还是通过所谓的尖端退回来逐渐缩短了表面迹线长度?在这里,我们使用来自澳大利亚近海埃克斯茅斯高原的3D地震反射数据集,为七种不同大小的正断层开发了一个三阶段断层增长模型,并展示了随着断层的消失,投掷长度比例关系如何变化。 。我们表明,在延长阶段中(持续了断层寿命的30%),断层达到了其最大长度,但仅累积了其总投掷量的10%至20%。在投掷/位移累积阶段,占c。在断层的整个长度上,断层寿命的30%–75%不断累积。所有研究过的断层也经历了侧向后退的阶段(最后约占断层寿命的25%),其中活跃的地表迹线长度最多降低了25%。我们的研究结果可能对断层生长模型,断层生长过程中的滑移率变异性以及断层的死亡方式(尤其是侧向尖端退缩的作用)具有更广泛的意义。但累计仅占总投掷的10%至20%。在投掷/位移累积阶段,占c。在断层的整个长度上,断层寿命的30%–75%不断累积。所有研究过的断层也经历了侧向后退的阶段(最后约占断层寿命的25%),其中活跃的地表迹线长度最多降低了25%。我们的研究结果可能对断层生长模型,断层生长过程中的滑移率变异性以及断层的死亡方式(尤其是侧向尖端退缩的作用)具有更广泛的意义。但累计仅占总投掷的10%至20%。在投掷/位移累积阶段,占c。在断层的整个长度上,断层寿命的30%–75%不断累积。所有研究过的断层也经历了侧向后退的阶段(最后约占断层寿命的25%),其中活跃的地表迹线长度最多降低了25%。我们的研究结果可能对断层生长模型,断层生长过程中的滑移率变异性以及断层的死亡方式(尤其是侧向尖端退缩的作用)具有更广泛的意义。断层寿命的25%),活动的地面走线长度最多减少了25%。我们的研究结果可能对断层生长模型,断层生长过程中的滑移率变异性以及断层的死亡方式,尤其是侧向尖端退缩的作用具有更广泛的意义。断层寿命的25%),活动的地面走线长度最多减少了25%。我们的研究结果可能对断层生长模型,断层生长过程中的滑移率变异性以及断层的死亡方式(尤其是侧向尖端退缩的作用)具有更广泛的意义。
更新日期:2021-05-07
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