阿尔金山巴什考供地区斜长角闪岩的岩石地球化学和Sm—Nd，Ar同位素特征

阿尔金山巴什考供地区斜长角闪岩的岩石地球化学和Sm—Nd，Ar同位素特征

张志诚, 郭召杰

北京大学造山带与地壳演化教育部重点实验室，地球与空间科学学院，北京 100871

收稿日期:2004-12-20 修回日期:2004-12-20 出版日期:2004-12-20 发布日期:2004-12-20

Sm-Nd, Ar Isotopic and Geochemical Characteristics of Plagioclase Amphibolites in the Bashikaogong Area, Altun Tagh Mountains

ZHANG Zhi-cheng, GUO Zhao-jie

Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Peking University, Beijing 100871, China

Received:2004-12-20 Revised:2004-12-20 Online:2004-12-20 Published:2004-12-20

摘要/Abstract

摘要： 阿尔金山地区巴什考供以北、阿尔金山北缘断裂以南为一套变质程度达角闪岩相的片岩、大理岩夹少量斜长角闪岩。地球化学研究表明，这些斜长角闪岩原岩为玄武质成分，具有拉班玄武岩的特点。斜长角闪岩全岩Sm—Nd同位素等时线年龄为1185±130(2σ)Ma，其INd=0．51140，εNd(f)=+5．8±0．6，表明原岩形成于中元古代晚期，源自亏损地幔。斜长角闪岩中角闪石柏^40Ar—^39Ar同位素分析显示变质作用发生在612±5．8Ma之前，进一步表明其原岩应该形成于前寒武纪。这些年龄的确定，为探讨阿尔金山地区中晚元古代的古构造格局提供了重要的证据。

Abstract: A set of schist and marble rocks with a few layers of plagioclase amphibolites are distributed to the north of Bashikaogong，Ahun Tash mountains，and experienced amphibolite facies metamorphism．These plagioclase amphibolites exhibit the features of tholeiite in their major element compositions and REE patterns，indicating their basaltic parent rocks．Four samples of these plagioclase amphibolites were analyzed for Sm-Nd isotopes．An isochron with 1 185±130 Ma was obtained whth INd=0．511 40 and ENd(t)=+5．8±0．6，suggesting that these plagioclase amphibolites were formed at the later Mesopmtemzoic and derived from the depleted mantle．Integrated with 40Ar-39Ar data of metamorphic homblendes with the greatest metamorphic age of612±5．8 Ma．it is further proved that these plagioclase amphibolites were formed during the Precambrian．These geochronological and isotopic new data give us some important information about the Late-Precambrian tectonic framework in the Ahun Tagh Mountains．

张志诚, 郭召杰. 阿尔金山巴什考供地区斜长角闪岩的岩石地球化学和Sm—Nd，Ar同位素特征[J]. J4.

ZHANG Zhi-cheng, GUO Zhao-jie. Sm-Nd, Ar Isotopic and Geochemical Characteristics of Plagioclase Amphibolites in the Bashikaogong Area, Altun Tagh Mountains[J]. J4.