Abstract Disagreements over how to define shear zones within packages of pervasively recrystallized rock impede our ability to map and correlate these structures. Here, we explore a new approach for delineating the spatial extents of shear zones using quartz petrofabric, temperature, and kinematic data collected from two transects across the Main Central thrust (MCT) in western Bhutan. We calculated cylindricity, a fabric intensity parameter that has been previously interpreted as a proxy for finite strain magnitude, for each sample. Cylindricity values (measured on a scale from 0 to 1) increase upward from 0.11 to 0.47 between 2.3 and 1.3 km below the MCT, vary between 0.55 and 0.93 between 700 m below and 200 m above the MCT, and decrease upward from 0.68 to 0.37 between 2.4 and 11.7 km above the MCT. Fabric intensity increases with proximity to the MCT and defines a ~900 m-thick zone of elevated intensity that overlaps spatially with an interval of inverted metamorphism. Our results add to a growing number of recent studies that suggest that spatial patterns of fabric intensity, when integrated with temperature data and kinematic observations, can be used to delineate relative strain patterns across shear zones in the Himalaya and elsewhere.

中文翻译：

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使用石英结构强度参数来描绘跨越喜马拉雅主冲断层的应变模式

摘要 关于如何在广泛再结晶的岩石包内定义剪切带的分歧阻碍了我们绘制和关联这些结构的能力。在这里，我们探索了一种使用从不丹西部主中央冲断层 (MCT) 的两个横断面收集的石英岩织物、温度和运动学数据来描绘剪切带空间范围的新方法。我们计算了圆柱度，这是一个织物强度参数，以前被解释为每个样品的有限应变大小的代表。圆柱度值（在 0 到 1 的范围内测量）在 MCT 以下 2.3 和 1.3 km 之间从 0.11 上升到 0.47，在 MCT 以下 700 m 和 200 m 之间在 0.55 到 0.93 之间变化，并从 0.68 上升到 0.37在 MCT 上方 2.4 至 11.7 公里之间。织物强度随着接近 MCT 而增加，并定义了一个约 900 米厚的强度升高区域，该区域与倒变质作用的间隔在空间上重叠。我们的结果增加了最近越来越多的研究，这些研究表明，当与温度数据和运动学观察相结合时，织物强度的空间模式可用于描绘喜马拉雅山和其他地方剪切带的相对应变模式。