美国俄亥俄州立大学W. Ashley Griffith课题组通过锆石年代学记录了美国犹他州西南部塞维尔重力滑坡侵位过程中的摩擦弱化和再强化。这一研究成果发表在2025年2月25日出版的《地质学》杂志上。

长径流滑坡的特殊运输距离需要一种降低滑动摩擦阻力的机制。

研究组使用塞维尔重力滑坡（美国犹他州西南部）侵位过程中产生的摩擦磨损产物中的锆石来确定材料来源如何随运输距离而演变，并讨论摩擦强度的变化如何反映在该数据集中。在滑坡约38公里的偏转距离内，基底磨损产物具有独特的锆石年龄分布或构造年代相，这反映了物质来源的变化，并表明整个结构的混合不良。在这段距离的大部分时间里，基底材料是通过滑块的分解形成的，而来自下层基材的输入很少。这表明基底滑动面具有低摩擦强度，缓冲了基材的变形。

研究组还观察到，随着运输距离的增加，基底层内锆石的平均年龄会降低，因为在滑动过程中，磨料磨损集中在上覆块体的底部。朝向滑块的远端部分，基底层中基底锆石的量增加，这与减速过程中更大的摩擦耦合相一致。将塞维尔重力滑坡基底层内锆石记录的独特构造物源与较大的变形样式联系起来，研究组认为观察到的摩擦强度的空间演化与广泛的流体加压是一致的。

附：英文原文

Title: Zircon geochronology records frictional weakening and restrengthening during emplacement of the Sevier gravity slide, southwest Utah (USA)

Author: Michael Braunagel, David Malone, David Hacker, Robert Biek, Tiffany Rivera, Zachary Loffer, McKenna Holliday, W. Ashley Griffith

Issue&Volume: 2025-02-25

Abstract: The exceptional transport distance of long-runout landslides requires a mechanism for reduced frictional resistance to sliding. Here, we use zircons in the frictional wear products generated during emplacement of the Sevier gravity slide (southwest Utah, USA) to identify how the source of material evolves with transport distance and discuss how changes in frictional strength are reflected in this data set. Across the ～38 km runout distance of the slide, basal wear products have unique zircon age distributions, or tectonic chronofacies, which capture changes in material sources and indicate poor mixing across the structure. Over much of this distance, basal material forms by breakdown of slide blocks, with little input from the underlying substrate. This suggests the basal slide plane has low frictional strength, buffering the substrate from deformation. We also observe a decrease in the mean age of zircons within the basal layer with increasing transport distance as abrasive wear is localized at the base of the overlying block during slip. Toward the distal portion of the slide, the amount of substrate zircons in the basal layer increases, consistent with greater frictional coupling during deceleration. Tying the unique tectonic provenance recorded by zircons within the basal layer of the Sevier gravity slide to larger deformation styles, we argue that the observed spatial evolution in frictional strength is consistent with widespread fluid pressurization.

DOI: 10.1130/G52838.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G52838.1/652369/Zircon-geochronology-records-frictional-weakening