Here, we study slate microfabrics from the exhumed accretionary wedge of the central European Alps and focus on the development of foliation. High-resolution micrographs from novel BIB-SEM imaging and Synchrotron X-ray Fluorescence Microscopy are analysed with 2D auto-correlation functions to quantify the geometry and spacing of slate microfabrics along a metamorphic gradient covering the outer and inner wedge (200–330 °C). The sedimentary layering primarily controls the morphology of the slate microfabrics. However, from outer to inner wedge, a fabric evolution is observed where diagenetic foliations gradually transform to secondary continuous and spaced foliations. With increasing metamorphic grade, the amount of recrystallized phyllosilicate grains and their interconnectivity increase, as does clast/microlithon elongation (aspect ratios up to 11), while foliation spacing decreases to <20 μm. This foliation evolution under non-coaxial deformation involves a combination of mechanical rotation of phyllosilicates, fracturing, and fluid-assisted pressure-dissolution-precipitation creep. The latter is the dominant deformation mechanism at T > 230 °C and accommodates background strain in the inner wedge. The evolving microstructural anisotropy is interpreted to lead to strain weakening by structural softening and may provide preferential fluid pathways parallel to the foliation, enabling the dehydration of large rock volumes in accretionary sediment wedges undergoing prograde metamorphism.

在这里，我们研究了欧洲中部阿尔卑斯山挖出的增生楔的板岩微织物，并专注于叶理的发展。使用 2D 自相关函数分析来自新型 BIB-SEM 成像和同步加速器 X 射线荧光显微镜的高分辨率显微照片，以量化沿覆盖外楔和内楔（200–330 °C）的变质梯度的板岩微织物的几何形状和间距）。沉积层理主要控制板岩微织物的形态。然而，从外楔到内楔，观察到织物演化，其中成岩叶理逐渐转变为次生连续和间隔叶理。随着变质品位的增加，重结晶的页硅酸盐颗粒数量及其相互联系增加，碎屑/微石的伸长率（纵横比高达 11）也是如此，而叶理间距减小到 <20 μm。这种非同轴变形下的叶理演化涉及页硅酸盐的机械旋转、压裂和流体辅助压力-溶解-沉淀蠕变的组合。后者是 T > 230 °C 时的主要变形机制，并适应内楔中的背景应变。不断演变的微观结构各向异性被解释为通过结构软化导致应变减弱，并可能提供与叶理平行的优先流体通道，从而使经历前变质作用的增生沉积楔中的大量岩石脱水。这种非同轴变形下的叶理演化涉及页硅酸盐的机械旋转、压裂和流体辅助压力-溶解-沉淀蠕变的组合。后者是 T > 230 °C 时的主要变形机制，并适应内楔中的背景应变。不断演变的微观结构各向异性被解释为通过结构软化导致应变减弱，并可能提供与叶理平行的优先流体通道，从而使经历前变质作用的增生沉积楔中的大量岩石脱水。这种非同轴变形下的叶理演化涉及页硅酸盐的机械旋转、压裂和流体辅助压力-溶解-沉淀蠕变的组合。后者是 T > 230 °C 时的主要变形机制，并适应内楔中的背景应变。不断演变的微观结构各向异性被解释为通过结构软化导致应变减弱，并可能提供与叶理平行的优先流体通道，从而使经历前变质作用的增生沉积楔中的大量岩石脱水。