摘要
通过苏鲁超高压变质地体南部不同类型超高压变质岩石的原岩重塑,揭示超高压变质岩的原岩形成于由大陆玄武质岩石、辉长岩、表壳岩和花岗岩组成的被动陆缘拉伸构造环境。中国大陆科学钻探主孔中不同类型超高压变质岩石的锆石SHRIMP U-Pb定年表明,花岗质片麻岩原岩年龄为780-680Ma;榴辉岩、石榴角闪岩的原岩年龄为765—730Ma,副片麻岩中包含了730Ma、680Ma、621Ma和较年轻的继承性碎屑锆石和结晶锆石年龄。结合前人的研究成果表明,苏鲁超高压变质地体南部正片麻岩类和榴辉岩的原岩所代表的花岗岩浆和基性岩浆活动为罗迪尼亚超大陆形成后的新元古代裂解事件的产物,而副片麻岩的原岩为新元古代-古生代时期形成的扬子被动陆缘的沉积-火山表壳盖层,它们与结晶基底一起在240- 220Ma期间经历了超高压变质作用。
The protoliths for different types of UHP metamorphic rocks- eclogite, garnet amphibolite, paragneiss and orthogneiss in the south Sulu UHP metamorphic terrane formed under the extensional environment at the passive continental margin composed of continental basaltic rocks, supercruct rocks and granites. Zircon SHRIMP U-Pb dating for the south Sulu UHP metamorphic rocks in the CCSD-MH shows 780 - 680Ma ages for the protoliths of granitic gneiss, 765 - 730Ma ages for protoliths of eclogite and garnet amphibolite; as well as 730Ma, 680Ma, 621Ma, and even yonger ages for inherited detrital zircons and magmatic zircons of paragneiss. Aboved-mentioned dating combined with previous data shows that the protoliths of the south Sulu UHP metamorphic rocks had been inferenced by Neoprotorozoic Rodinia supercontinent breakup event represented by granitic and basic magmatisms. The supercruct protolith of paragneiss as volcano-sedimental covers of the Yangtze passive continental margin formed during Neoprotorozoic-Paleozoic. Both of them had experienced UHP metamorphism during 240 - 220Ma.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2006年第7期1745-1760,共16页
Acta Petrologica Sinica
基金
本研究得到国家自然科学基金重大项目(编号40399143)
中国大陆科学钻探工程
国家重点基础研究发展规划项目(编号2003CB716502)
国土资源部科技项目(编号2002207)的资助.
