Petrological and Geochronological Preliminary Study of the Xiliu ～2.1Ga Meta-Gabbro from the Jiaobei Terrane, the Southern Segment of the Jiao-Liao-Ji Belt in the North China Craton
详细信息
- 责任者：Liu Pinghua (Institute of Geology ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Liu Fulai
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(7)
- 关键词：变辉长岩 ; metagabbro ; 岩石学 ; petrology ; 山东 ; Shandong Province
- 页码：p.2371-2390
- 图表：13 illus., 7 tables, 73 refs.
- 分类号：0802
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Xiliu meta-gabbros are composed predominantly of orthopyroxene-clinopyroxene granulites and clinopyroxene amphibolites,and are found as irregular lenses within the Neoachean granitic and tonalitic gneisses in the Jiaobei terrane.On the basis of petrography,mineral transformation,mineral composition,temperature-pressure estimation and in situ U-Pb dating of zircons,three distinct mineral assemblages of the meta-gabbros have been identified by the characteristics of mineral reactions and evolutions.The relict ophitic and gabbro textures represent the early index igneous textures.High-augite core in clinopyroxene is regarded as one of the early igneous assemblage (M 0).The magmaitic zircons record a weighted mean 207 Pb /206 Pb age of 2102 ± 3Ma,which represents the magmatic crystallization timing of the meta-gabbros.The granulite-facies metamorphism (M 1) is defined by the mineral assemblage of orthopyroxene + clinopyroxene + plagioclase + quartz,which formed at 800 ～ 850℃ and less than 0.65 ～ 0.75GPa.The mineral assemblage of amphibole + plagioclase + quartz formed at a cooling retrograde stage (M 2) with P-T conditions of 675 ～700℃ and 0.40 ～ 0.55GPa.The metamorphic zircon records a younger 207 Pb /206 Pb age of 1907 ± 16Ma,which represent the timing of the granuliteamphibolite facies metamorphism of the meta-gabbros.These data indicate that the meta-gabbros record a clockwise P-T path involving near-isobaric cooling (IBC) process.Combined with other investigations of the Jiaobei terrane,it was suggested that the Xiliu metagabbros were formed by crustal extension before the deposition of Paleoproterozoic strata,and were involved in the Late Paleoproterozoic (1.95 ～1.80Ga) collisional orogenic process in the Jiaobei terrane.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |