权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Three dimensional distributions of chemical and isotopic compositions of granitic pluton and its formation process

花岗岩岩体化学和同位素组成的三维分布及其形成过程

基本信息

批准号：
06640609
负责人：
ARAKAWA Yoji
金额：
$ 1.22万
依托单位：
Saitama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

In this research, three dimensional distributions of element compositions and Sr isotope ratios of single granitic pluton were analyzed for the purpose of investigating the structure of shallow magma body and its differentiation process during the cooling and solidification. The Sori pluton was selected for this study.For the vertical distributions of element concentrations for bulk rocks, which are measured for boling core samples with 1500m depth in the middle of the pluton, SiO_2 wt%, Fe_2O_3, MgO,MnO,K_2O/Na_2O,Ba, Rb, Y,Zn, U,Th increase, while Al_2O_3, CaO,Na_2O,Sr decrease with increasing depth. This vertical distributions of compositions correlate well with the petrography of the rocks, but not agree with the vertical distributions of other plutons such as Ariake and Okueyama. In horizontal distributions, the same tendency of element concentrations with increasing depth was recognized from the margin toward the core of the pluton. The Sr isotope ratios of the rocks are concentrated in a very narrow range, indicating that the magma was derived from isotopically homogeneous source without marked contamination of wall rocks.These distributions of element contents and petrographical characteristics for the Sori pluton are explained by in situ fractionation during the cooling and solidification from margin to inner part.The other plutons in different tectonic settings, Mesozoic plutons in the Hida belt and Paleozoic and Precambrian plutons, are also studied for comparison of the structure and formation process of the plutons.

本研究对单个花岗质岩体的元素成分三维分布和Sr同位素比值进行了分析，旨在研究浅部岩浆体的结构及其冷却凝固过程中的分异过程。本研究选取索里岩体为研究对象,对岩体中部1500m深度的岩心样品测定的大块岩石元素浓度垂直分布显示,SiO_2 wt%、Fe_2O_3、MgO、MnO、K_2O/Na_2O、Ba、Rb、Y、Zn、U、Th增加,而Al_2O_3、 CaO、Na_2O、Sr随深度增加而减少。这种成分的垂直分布与岩石的岩相学密切相关，但与有明和奥江山等其他岩体的垂直分布不一致。在水平分布中，从岩体边缘到岩体核心，元素浓度随深度增加具有相同的趋势。岩石的Sr同位素比集中在一个很窄的范围内，表明岩浆来自同位素均质源，没有明显的围岩污染。Sori岩体的这些元素含量分布和岩相特征是通过从边缘到内部的冷却和凝固过程中的原位分异来解释的。其他不同构造背景的岩体，中生代岩体还对飞騨带和古生代、前寒武纪岩体进行了研究，以比较岩体的结构和形成过程。