超高压变质岩中柯石英的产出和保存机制

了解柯石英的产出并制约其保存机制对于深入认识超高压变质岩的形成和演化具有重要的启示意义.早期的研究发现超高压变质岩中的柯石英主要以包裹体的形式产在刚性寄主矿物中，而粒间柯石英之前仅在苏鲁仰口的超高压双矿物榴辉岩中有过发现.目前提出的柯石英保存机制主要包括以下两种:涉及"构造超压"的"高压釜"模型和较干的变质演化环境.新近报道的大别山甘家岭超高压变沉积岩中的粒间柯石英和白云石中的大量柯石英包裹体肯定了较干的变质演化环境而削弱了传统的"高压釜"模型在保存柯石英方面所起的作用. 

Occurrences and Preservation Mechanisms of Coesite in Ultrahigh-Pressure Metamorphic Rocks

Insights into the occurrences and preservation mechanisms of coesite bear important implications for the formation and evolution of ultrahigh-pressure (UHP) metamorphic rocks. Early researches reveal that coesite usually appears as inclusions in strong host minerals in UHP rocks. Thus far,interstitial coesite has only been found in the UHP two-mineral eclogite from Yangkou,Sulu orogen. Two major mechanisms have been proposed for the preservation of coesite:the "pressure-vessel" model involving "tectonic overpressure" and dry metamorphic environment. Interstitial coesite and abundant coesite inclusions in dolomite recently discovered in a UHP metasedimentary rock from the Ganjialing area in Dabieshan highlight the role of dry metamorphic environment and undermine the importance of "pressure-vessel" model in preserving coesite.