苏鲁高压-超高压变质带南部花岗片麻岩-花岗岩的多时代演化  

Multi Age-Time Evolution of Granite Gneisses-Granite in the Southern Sulu HP-UHP Metamorphic Belt

作　　者：徐惠芬[1] 杨天南[1] 刘福来[1] J.G.Liou 

机构地区：[1]中国地质科学院地质研究所 [2]Department of Geological and Enviromrntal Sciences,Stanford University,Stanford,CA,USA 94305

出　　处：《地质学报》2001年第3期371-378,T003,T004,共10页Acta Geologica Sinica

基　　金：国土资源部"九五"重点科技项目"大别造山带形成与演化及有关成矿作用"部分成果;部分资料来自中国大陆科学钻探选址预研究项目

摘　　要：苏鲁高压-超高压变质带中,广泛分布有花岗片麻岩-花岗岩系列,有关其形成的时代和成因机制长期存在争议。岩石露头表现为强烈的片麻理,并且多数和榴辉岩及榴辉岩相岩石密切伴生。其岩石类型有变化,从斜长片麻岩-花岗闪长质片麻岩-二长花岗片麻岩演化到花岗岩。矿物和地球化学变化也较大。从残留的高压和超高压矿物及其退变质反应等,说明它们中有部分曾经历了高压-超高压变质作用。该变质带南部连云港地区4个二长花岗片麻岩-花岗岩岩体中精选的单颗粒锆石,运用Pb-Pb法(质谱计双带源逐层蒸发-沉积法)和U-Pb法(离子探针SHRIMP分析),获得的年龄值跨度大,从859Ma到150Ma,分别属于4个年龄段(时段),但是主要数据集中在600～859Ma和220～250Ma两个时段。锆石的形貌特征研究显示,这些花岗片麻岩-花岗岩是苏鲁高压变质带中长期演化的产物,其物质来源与古元古代,乃至太古宙变质表壳岩密切相关。新元古代大量岩浆结晶型锆石指示了当时存在强烈的花岗岩浆活动,导致大量花岗岩类岩石的形成。古生代(加里东期)和中生代早期(印支期)分别经历了变质作用,尤其是印支期,至少一部分和榴辉岩原岩一起经历了高压-超高压变质作用,并且伴随有地壳部分熔融,引起又一次花岗岩浆活动,再生花岗岩,该区南部东海地区尤为明显。中生代晚?A large number granite gneiss and granite have been distrubuted in the southern Sulu HP-UHP metamor-phic belt. Most of these rocks associate with lenses or like-layers of eclogite and have a strongly tectonic deformation showing zoning and gneissose structure.These rocks, which contain variable mineral and chemical composition, are classified from plagioclase gneiss through granodioritic gneiss to monzonitic gneiss. According to their rest HP-UHP mineral and retro-graphic reaction, suggest that granite gneisses of the Sulu area have been subjected to the HP-UHP metamor-phism. The chronological age of Pb-Pb ( Evaporation method for 207Pb/206Pb Ratio ) and U-Pb ( SHRIMP, Tera wasserburg concordia with common Pb correction ) grain zircon which select from four monzonitic gneiss and granite terrans of the Lianyungang location in the southern Sulu area, are ranged from 859Ma to 150Ma with four age- time stages. However, mainly focus to two age-time stages; 600-800Ma (the late Proterozoic ) and 220Ma (the Triassic ). these age data with morphological feature of the zircon suggested that these gneiss granites, which have a original magmatic source from the Medium Proterozoic or the New Archean, the crystallization was occurred at the New Proterozoic and HP-UHP metamorphism at the Triassic.In the southern Sulu area, towards to southern, the Triassic metamorphism and magmatism show more and more strongly. The granite gneiss and granite in the Sulu area has a long-term evolution and multistage change.

关 键 词：晋宁期 印支期 花岗片麻岩 榴辉岩 超高压变质带 单颗粒锆石 形成时代 成因机制 

分 类 号：P588.3[天文地球—岩石学]