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“Brittle structural facies” analysis: A diagnostic method to unravel and date multiple slip events of long-lived faults
Earth and Planetary Science Letters ( IF 5.3 ) Pub Date : 2020-09-01 , DOI: 10.1016/j.epsl.2020.116420
Giulia Tartaglia , Giulio Viola , Roelant van der Lelij , Thomas Scheiber , Alberto Ceccato , Jasmin Schönenberger

Abstract Regional-scale faults typically experience complex, long-lasting histories, commonly recording evidence of multiple reactivation events. Therefore, they contain multiscalar structural domains characterised by varying microstructures, mineralogical compositions and kinematics. These domains result from differential strain partitioning during the recorded faulting stages, and, as a result, can preserve the isotopic and kinematic signature of the different slip periods. Their detailed structural analysis integrated with K-Ar dating of the fault rock assemblage can help to identify these commonly tightly juxtaposed, although not coeval, domains, which we refer herein to as “Brittle Structural Facies” (BSF). BSF analysis is pivotal (i) to understand the structural heterogeneity of fault zones, (ii) the diachronic formation of geometrically and kinematically complex fault cores and (iii) to reconstruct faults' evolution in time and through space. Following this approach, this study relies on meso- and microstructural analysis, chemical characterisation and K-Ar dating to unravel the evolution of the Laerdal-Gjende Fault (LGF, southwestern Norway). The LGF is a multiply reactivated top-to-the-NW extensional fault with a 1 m thick poorly consolidated core. We recognised, sampled and characterised five BSF: I) Indurated dark reddish gouge, (II) Poorly consolidated cataclasite, (III) Weakly foliated greenish gouge, (IV) Clay-rich gouge and (V) A few mm-thick clay smear decorating the principal slip surface. Samples were separated into five grain size fractions (from

中文翻译:

“脆性构造相”分析:揭示和确定长寿命断层多次滑动事件的诊断方法

摘要 区域尺度的断层通常经历复杂、持久的历史,通常记录多次再激活事件的证据。因此,它们包含以不同的微观结构、矿物组成和运动学为特征的多标量结构域。这些域由记录的断层阶段期间的差异应变划分产生,因此可以保留不同滑动周期的同位素和运动学特征。他们的详细结构分析与断层岩组合的 K-Ar 测年相结合,可以帮助识别这些通常紧密并列但并非同时代的区域,我们在本文中将其称为“脆性结构相”(BSF)。BSF 分析是关键 (i) 了解断层带的结构异质性,(ii) 几何和运动学复杂断层核的历时形成和 (iii) 重建断层在时间和空间上的演化。按照这种方法,本研究依靠细观和微观结构分析、化学表征和 K-Ar 测年来揭示 Laerdal-Gjende 断层(LGF,挪威西南部)的演化。LGF 是一个多次重新激活的从顶部到 NW 的伸展断层,具有 1 m 厚的固结不良的核心。我们识别、采样和表征了五种 BSF:I) 坚硬的暗红色凿岩,(II) 固结差的碎裂岩,(III) 弱叶绿凿,(IV) 富含粘土的凿岩和 (V) 几毫米厚的粘土涂抹装饰主滑移面。样品被分成五个粒度级分(从 时间和空间的进化。按照这种方法,本研究依靠细观和微观结构分析、化学表征和 K-Ar 测年来揭示 Laerdal-Gjende 断层(LGF,挪威西南部)的演化。LGF 是一个多次重新激活的从顶部到 NW 的伸展断层,具有 1 m 厚的固结不良的核心。我们识别、采样和表征了五种 BSF:I) 坚硬的暗红色凿岩,(II) 固结差的碎裂岩,(III) 弱叶绿凿,(IV) 富含粘土的凿岩和 (V) 几毫米厚的粘土涂抹装饰主滑移面。样品被分成五个粒度级分(从 时间和空间的进化。按照这种方法,本研究依靠细观和微观结构分析、化学表征和 K-Ar 测年来揭示 Laerdal-Gjende 断层(LGF,挪威西南部)的演化。LGF 是一个多次重新激活的从顶部到 NW 的伸展断层,具有 1 m 厚的固结不良的核心。我们识别、采样和表征了五种 BSF:I) 坚硬的暗红色凿岩,(II) 固结差的碎裂岩,(III) 弱叶绿凿,(IV) 富含粘土的凿岩和 (V) 几毫米厚的粘土涂抹装饰主滑移面。样品被分成五个粒度级分(从 化学表征和 K-Ar 测年以解开 Laerdal-Gjende 断层(LGF,挪威西南部)的演变。LGF 是一个多次重新激活的从顶部到 NW 的伸展断层,具有 1 m 厚的固结不良的核心。我们识别、采样和表征了五种 BSF:I) 坚硬的暗红色凿岩,(II) 固结差的碎裂岩,(III) 弱叶绿凿,(IV) 富含粘土的凿岩和 (V) 几毫米厚的粘土涂抹装饰主滑移面。样品被分成五个粒度级分(从 化学表征和 K-Ar 测年以解开 Laerdal-Gjende 断层(LGF,挪威西南部)的演变。LGF 是一个多次重新激活的从顶部到 NW 的伸展断层,具有 1 m 厚的固结不良的核心。我们识别、采样和表征了五种 BSF:I) 坚硬的暗红色凿岩,(II) 固结差的碎裂岩,(III) 弱叶绿凿,(IV) 富含粘土的凿岩和 (V) 几毫米厚的粘土涂抹装饰主滑移面。样品被分成五个粒度级分(从 (IV) 富含粘土的凿子和 (V) 几毫米厚的粘土涂片装饰主滑动面。样品被分成五个粒度级分(从 (IV) 富含粘土的凿子和 (V) 几毫米厚的粘土涂片装饰主滑动面。样品被分成五个粒度级分(从
更新日期:2020-09-01
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