论大别地块中榴辉岩与围岩的变质关系及区域“递增”变质带的形成  

METAMORPHIC CORRELATION BETWEEN ECLOGITES AND THEIR COUNTRY ROCKS AND FORMATION OF REGIONAL "PROGRESSIVE" METAMORPHIC ZONES IN DABIE MASSIF

作　　者：刘晓春[1] 刘先文[1] 胡克[1] 

机构地区：[1]长春地质学院地质系

出　　处：《长春地质学院学报》1992年第4期366-372,共7页

基　　金：国家自然科学基金

摘　　要：研究表明,大别地块中榴辉岩形成时的变质压力从东南向西北呈递减趋势,由2.8～3.5GPa降至约1.0GPa,而温度变化则不明显,由647～755℃略增至684～829℃.榴辉岩的围岩中某些残留高压矿物或其假象的发现证明它们与榴辉岩一起经历了原地高压变质作用过程.不同地区榴辉岩的退变组合及P—T条件与围岩同步变化,从绿帘角闪岩相、角闪岩相到麻粒岩相,从而表明现今围岩所展示出的“递增”变质带是由榴辉岩相退变质作用造成的,其形成时代可能不早于晚元古代.Dabie massif, bounded by faults, is located in central China, between the North China plate and Yangtze plate. The pressure of eclogite facies metamorphism is decreasing gradually from southeast to northwest, ranging from 2. 8-3. 5 GPa to 1. 0 GPa, while the temperature increasing unobviously from 647-755℃ to 684-829℃. Some relics of high-pressure minerals and/or their pseudomorphs, including jadeite, omphacite and phengite as well as quartz pseudomorph after coesite and calcite pseudomorph after aragonite, were found in country rocks (such as quartzites, gneisses and marbles). It suggests that eclogites underwent in situ high-pressure metamorphism with their country rocks. The changing of retrogressive metamorphic mimeral assemblages and the P-T conditions both in eclogites and in country rocks are synchronous, which range from epidote amphibolite facies (470-575℃ , 0. 5-0. 8GPa) through amphibolite facies (520-660℃ , 0. 35-0. 7 GPa) to granulite facies (670-850℃ , 0. 4-0. 9GPa). It indicates that the 'progressive' metamorphism of country rocks was resulted from the retrogressive metamorphic event of eclogite facies. The metamorphic ages are no earlier than Late Protero-zoic.

关 键 词：地块 榴辉岩 围岩 变质 

分 类 号：P588.3[天文地球—岩石学]