Geohronology and Geochemistry Characteristics of the Granitic Mylonitic Gneiss in the Zhalantun Haduohe Area of the Northern the Great Hinggan Mountains Range
详细信息
- 责任者：Gao Feng (College of Earth Science ; Jilin University ; Changchun 130061 ; China) ; Zheng Changqing
- 刊名：Acta Geologica Sinica
- 出版年：2013
- 卷期：87(9)
- 关键词：糜棱岩 ; mylonite ; 片麻岩 ; gneisses ; 大兴安岭 ; Greater Hinggan Mountains
- 页码：p.1277-1292
- 图表：8 illus., 4 tables, 49 refs.
- 分类号：0802
- issnNo：ISSN0001-5717
- isbnNo：CN11-1951/P
摘要
The granitic mylonitic gneiss in Haduohe area is a set of metamorphic granitic rocks is mainly composed of fine grained biotite monzonitic granitic mylonitic gneiss,fine grained biotite granitic mylonitic gneiss and fine garnet mica granitic mylonitic gneiss.The results of geochemical study indicate that SiO2 values are in the range of 66.4%74.52%,K2O+Na2O between 7.36%8.84%,Al2 O3 values in the range of 13.43%15.74%,A/CNK=0.9741.092,suggesting that it belongs to high-K calc-alkaline and quasi-aluminous to weakly peraluminous rocks.The chondrite-normalized REE patterns demonstrate right-oblique linear REE patterns with weak negative Eu anomalies,higher total rare-earth content(ΣREE =94.15×10-6164.30×10-6),and LREE enrichment and HREE depletion.The trace element is characterized by a strong enrichment in large ion lithophile elements,such as Rb,Ba,U,K et al,depletion in Ta,Nb,P,Ti et al.The zircon U-Pb dating results indicate that the magma formation can be divided into two periods:the first period is around 320Ma,the representative rock is fine grained biotite granitic mylonitic gneiss and fine garnet mica granitic mylonitic gneiss;and the second period is around 304Ma,the representative rock is fine grained biotite monzonitic granitic mylonitic gneiss.Combined with petrography,chronology and rock geochemical characteristics,the protolith of the granitic mylonitic gneiss is high-K calc-alkaline I type granite which formed in the post-collision environment of Xing’an block and Songnen block during Late Carboniferous,and then suffered relatively strong ductile brittle metamorphism and deformation during Late Early Permian by the post-collision of Xing’an block and Songnen block.