摘要
通过对山东沂水地区紫苏花岗岩野外地质特征、岩相学及地球化学特征等的研究，认为山东沂水地区紫苏花岗岩为变质表壳岩经深熔作用形成．其主要证据为：（１）紫苏花岗岩与变质表壳岩在空间上密切伴生，二者多为渐变过渡接触关系，且他们的片麻理协调一致；（２）在变质表壳岩中发育大量长英质或花岗质脉体，这些脉体的矿物成分、地球化学特征与紫苏花岗岩一致；（３）紫苏花岗岩与变质表壳岩具有相似的稀土配分型式；（４）紫苏花岗岩亏损大离子亲石元素及生热元素，其原岩应为经历了深变质作用的岩石；（５）紫苏花岗岩中锆石多为圆粒状和椭球状，并发育磨蚀坑，说明其原岩主要为变沉积岩；（６）麻粒岩相变质作用时间与紫苏花岗岩形成时间基本一致．
Through the study of petrology, mineralogy and geochemistry of charnockites from Yishui area, Shandong Province, we conclude that the charnockites are formed by anatexis of Archaean metamorphic supracrustal rocks. Some pieces of evidence are shown as follows. (1) Charnockites always exist with metamorphic supracrustal rocks in space, and the relationship of charnockites and metamorphic supracrustal rocks is gradual transition. (2) Many veins of charnockites occur in the metamorphic supracrustal rocks, and the mineral and chemical compositions of characteristics in veins are the same as those in mass. (3) Charnockites are similar in REE patterns to metamorphic supracrustal rocks.(4) Big ion lithophile elements and heat generation elements are depleted in charnockites. In this sense, the parent rocks of charnockites may be the Neoarchaean rocks undergoing high_grade metamorphism. (5) The crystalline shapes of zircon in charnockites are mainly round and ellipsoidal with corrosion pit. (6) The forming ages of charnockites are 2537 ～2582Ma, and the ages of granulite facies metamorphism are 2572～2585Ma. It implies that charnockites and granulite facies metamorphism have connection of origin.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
1999年第1期57-62,共6页
Earth Science-Journal of China University of Geosciences
基金
高等学校博士学科点专项科研基金
