中源地震脱水脆变机制的岩石学研究进展

The Advance of Petrologic Mechanism of Dehydration Embrittlement in Intermediate-depth Earthquakes

中源地震的成因机制问题一直是固体地球科学研究的热点问题,其中被广泛接受的是脱水脆变机制。中源地震带在俯冲板块中多呈双层带状分布,分别对应着含水变玄武岩层与岩石圈地幔蛇纹岩层的脱水过程。在过去的研究中,对中源地震脱水脆变机制的主要验证研究方法包括:①理论研究与活动俯冲带地震数据解释;②高温高压实验室模拟研究。而最近10年,陆续在阿尔卑斯等古俯冲带中发现了出露于地表的榴辉岩相假玄武玻璃或脆性破裂岩,被认为是古中源地震的直接野外岩石学证据,从而成为研究中源地震的一种新的途径。重点介绍了中源地震脱水脆变机制的岩石学研究进展。

The mechanisms of intermediate-depth earthquakes were always attracting extensive researches of interest. Among various hypotheses about the mechanisms, the close relationship between the dehydration embrittle- ment and earthquakes is generally accepted. The intermediate-depth earthquakes in subducting slabs occur mainly in two distinct layers, corresponding with the dehydration respectively in the hydrous meta-basahs and the serpen- tinite layers. In the past decades, theory researches, interpretations of seismic data and laboratory experiments have been widely adopted as the major approaches to attest the hypothesis of dehydration embrittlement. However, in the latest ten years, pseudotachylytes and some brittle structures have been discovered in paleo-subduction zones like Alps, shedding a light for a new way to study intermediate-depth earthquakes.