摘要
本区先经历了区域动力热流变质作用，后经受动力变质作用的迭加，主要表现为韧性剪切变质带的广泛出现．杂岩体呈现着良好的递增变质带，从低变质级到高变质级依次为黑云母带→石榴石带→十字石带→兰晶石带→矽线石带，属于中压变质相系．根据矿物化学研究了单斜辉石、角门石、石榴石、黑云母、白云母、斜长石等变质矿物的特征。利用平衡变质矿物组合的温度压力计定量计算了星子群杂岩的变质温压条件，其范围是温度４２０℃～５７０℃，压力５．３～５．７ＰＰａ．研究表明星子变质核杂岩组成一个自外围向中心变质温度逐渐升高的热穹窿，成为江南地区少有的递增变质带．显示出江南古陆在广泛分布的前寒武纪浅变质岩系之下存在着由中深变质岩系组成的变质基底，属于早元古亩成熟陆壳．
In the early stage of formation,Xingzi group experienced regional dynamo-thermal metamorphism, and then superimposed by dynamo metamorphism so that ductile shear zone developed in its periphery. Because of progressive metamorphism,systematic zonation was found inthe complex,i. e.,from lower grade biotite zone and garnet zone 'to higher grade staurolite.kyanite and silliminate zone. All of them belong to middle pressure metamorphic factes series. Chemical compositions of clino-pyroxene. Based on geothermo-barameter calculation, equilibrium condition of the metamorphic mineral assemblages is in the range of 420 to 580℃and 5. 3 to 5. 7 GPa. Thermal gradient shows that the metamorphic core complex of XingziGroup occurs as a thermal arch with its metamorphic temperature increasing in ward. Theprogressive metamorphic zonation found in Xingzi is rather scarce in Jiangnan area. Thisdemonstrates that in Jiangnan Old Land kata-metamorphic basement exists under the widelydistributed precambrian epizonal metamorphic rocks. The basement used to be part of a mature continental crust.
基金
国家自然科学基金
关键词
星子群
变质核杂岩
变质作用
杂岩
north Jiangxi
xingzi group
metamorphic core comlex
metamorphism
