合肥工业大学Xinyue Xu等的最新研究揭示了灰岩同化、钙硅酸盐熔体和“岩浆矽卡岩”的熔融包裹体证据。相关论文于2023年3月17日发表于国际顶尖学术期刊《地质学》杂志上。

课题组人员描述了在灰岩同化作用下的浅斑岩环境中，硅酸盐熔体和碳酸盐岩之间普遍存在化学交换的证据。中国东部茶亭铜金矿床内矽卡岩中的熔体包裹体揭示，矽卡岩形成时钙硅酸盐组合(透辉石+钙铁榴石±硅灰石±绿帘石)处于熔融状态，并与CO₂蒸汽以及硫酸盐和氯化物盐熔体共存。因此，研究人员认为，茶廷的内矽卡岩是由碳酸盐岩同化产生的不混溶钙硅酸盐熔体结晶形成的，在硫酸盐和其他助熔体的作用下，促进了侵入岩浆的脱硅，并促进了CO₂的强烈释放。

研究人员表示，硅酸盐岩浆与碳酸盐岩之间的化学交换对火成岩分馏、大气CO₂通量和矿床的形成具有重要意义。然而，这一过程只被部分理解，碳酸盐岩是否、在哪里以及如何被硅酸盐熔体消化的长期问题仍然存在争议。

附：英文原文

Title: Melt inclusion evidence for limestone assimilation, calc-silicate melts, and “magmatic skarn”

Author: Xinyue Xu, Xiaochun Xu, Marko Szmihelsky, Jun Yan, Qiaoqin Xie, Matthew Steele-MacInnis

Issue&Volume: 2023-03-17

Abstract: Chemical exchange between silicate magmas and carbonate rocks has major implications for igneous fractionation, atmospheric CO₂ flux, and formation of mineral deposits. However, this process is only partly understood, and long-standing questions of whether, where, and how carbonate rocks can be digested by silicate melts remain controversial. We describe evidence for pervasive chemical exchange between silicate melt and carbonate rock in a shallow porphyry setting driven by limestone assimilation. Melt inclusions in endoskarn from the Chating Cu-Au deposit in eastern China reveal that the calc-silicate assemblage (diopside + andradite ± wollastonite ± epidote) was molten at the time of skarn formation and coexisted with CO₂ vapor as well as sulfate- and chloride-salt melts. Hence, we argue that endoskarn at Chating formed by crystallization of an immiscible calc-silicate melt produced by assimilation of carbonate rock, aided by the presence of sulfate and other fluxes, which in turn promoted desilication of the intruding magma and drove vigorous CO₂ release.

DOI: 10.1130/G50893.1

Source: https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G50893.1/621091/Melt-inclusion-evidence-for-limestone-assimilation