北京科技大学 Chang Yu 研究团队提出了科马提岩是高级变质岩中造山型金矿来源的新见解，为变质脱挥发分模型的扩展做了贡献。相关论文于2023年11月15日发表在《地质学》杂志上。

研究表明，在角闪岩相条件下，水合科马提岩（前寒武纪绿岩带体积上重要的岩性单位）的脱挥发作用是一种可能导致金矿化的可行模式。热力学模拟表明，科马提岩在约 700℃ (上部角闪岩相)的固相线下，变质脱挥发性组分可以通过滑石和绿泥石脱水释放大量的金。这一成因模式得到了浅成金矿的地球化学特征、估计的压力—温度(P-T)形成条件以及绿岩带中的次带状沉积物与科马提岩之间密切的时空联系的支持。本研究拓宽了变质脱挥发分模型的 P-T 范围，提高了其在解释变质地体中金矿化的准确性。

据了解，造山型金矿占了世界金矿储量的最大比例，其成矿成分的来源被认为是绿片岩—角闪岩相转变过程中，变泥质岩或变基性岩的变质脱挥发作用。然而，在这一背景下，浅成造山型金矿成为了一个谜。当温度超过含石英长石岩的湿固相线时，其中一些造山型金矿显然形成于高级变质岩中；因此，这些流体是如何在源头产生、在没有造成部分熔融的情况下在地壳中迁移是令众多研究人员费解的原因。

附：英文原文

Title: Expanding the metamorphic devolatilization model: Komatiites as a source for orogenic gold deposits in high-grade metamorphic rocks

Author: Chang Yu, Richen Zhong, Andrew G. Tomkins, Hao Cui, Yanjing Chen

Issue&Volume: 2023-11-15

Abstract: Orogenic gold deposits contribute the largest proportion of the world’s gold reserves, and the source of their ore-forming components has been recognized as the metamorphic devolatilization of metapelites or metabasites across the greenschist- to amphibolite-facies transition. However, hypozonal orogenic gold deposits represent an enigma in this context. Some of these apparently formed in higher-grade metamorphic rocks when temperatures were beyond the wet solidus of quartz-feldsparbearing rocks; it is therefore puzzling how these fluids were generated in the source and migrated through the crust without causing partial melting. Here, we show that devolatilization of hydrated komatiites, a volumetrically significant lithological unit in Precambrian greenstone belts, is a viable model that can plausibly lead to gold mineralization at amphibolite-facies conditions. Our thermodynamic simulations indicate that subsolidus metamorphic devolatilization of komatiites at ～700 °C (upper amphibolite facies) can unlock significant amounts of gold via dehydration of talc and chlorite. This genetic model is supported by the geochemical characteristics of, and estimated pressure-temperature (P-T) formation conditions of, hypozonal gold deposits and the intimate spatiotemporal association between hypozonal deposits and komatiites in greenstone belts. This work expands the P-T range of the metamorphic devolatilization model and enhances its robustness in explaining gold mineralization in metamorphic terranes.

DOI: 10.1130/G51446.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G51446.1/629493/Expanding-the-metamorphic-devolatilization-model