Fluid-present melting of the deep crust: implications for the tectonics of large convergent orogens

陆壳深部流体与岩石的相互作用对山带的造山带和崩塌过程中的质量和能量的重新分配以及矿床的成因起着至关重要的作用。在建造大型山脉带的过程中，地壳增厚会导致地壳深层的温度和压力升高。广泛的流体流入山脉下的深热地壳促进了部分熔融，这极大地削弱了大陆地壳的大片区域。这些熔融减弱的地区可能起到促进造山的大规模剪切带的作用，也可能向造山前缘横向流动，从而形成高海拔高原。例如，地球物理成像表明，喜马拉雅山脉下存在大片部分熔融的地壳，这种熔融减弱的物质的横向运动被认为在青藏高原的发展中起到了一级作用。虽然广泛的流体熔融部分熔融可能具有重要的构造后果，但这些流体的来源、成分和输送路径受到的约束很差。这在一定程度上是由于缺乏进入现代山脉带下的深层地壳的途径。

The interaction of fluids with rocks in the deep continental crust plays a critical role in the redistribution of mass and energy during the buildup and collapse of mountain belts and the genesis of ore deposits. During the construction of large mountain belts, crustal thickening generates elevated temperatures and pressures in the deep crust. Widespread fluid influx into the deep hot crust beneath mountain belts promotes partial melting, which drastically weakens large regions of continental crust. These melt-weakened regions may act as large-scale shear zones that facilitate mountain buildup or may flow laterally towards orogenic fronts resulting in the formation of high-elevation plateaux. For example, geophysical imaging suggests that large regions of partially molten crust are present beneath the Himalayan mountain belt and the lateral movement of this melt-weakened material is proposed to play a first-order role in the development of the Tibetan Plateau. While widespread fluid-fluxed partial melting may have important tectonic consequences, the sources, compositions and transport pathways of these fluids are poorly constrained. This is due, in part, to the lack of access to the deep crust beneath modern mountain belts.