阿尔泰3号伟晶岩脉绿柱石通道水氢同位素组成及其意义

The contents of H2O, hydrogen and oxygen isotopic compositions of water in channel of beryls, hydrogen isotopes of fluid inclusions and oxygen isotopes of beryls, alkali feldspars and quartzs from individual texrural zones of Altay No.3 pegmatite had been determined systematically in this project. The studies on the hydrogen isotopic compositions of muscovite, phosphorus contents in alkali feldspars, which are paragenesis with beryls, and microthermometry of fluid and melt inclusions also have been conducted. From the above studies, the main results and conclusions have been achieved as follows: 1) We put forward that the crystallization of Altay No.3 pegmatitic magma proceeds under relative closed system and the hydrogen isotopic composition of primary magmatic water was -61±4‰. 2) The relation between the content of H2O and dD of water in channel of beryls have been ascertained in this study. As the proceeding of evolution of pegmatite, both the content of H2O and dD of water in channel of beryls decreased. For fluid inclusion, the above relation was not found. 3) Here we also suggest that the magmatic degassing occurs after the muscovite-quartz textural zone was solidified. As D was strongly partitioned into steam gas phase, the contents of H2O and dD values of magmatic water in the residual magma decrease from 2.1~2.3 wt% H2O, -58‰~-65‰ dD to 0.7~1.7 wt% H2O and -63‰~-79‰ dD. 4) Based on the calculation of oxygen isotope equilibrium between beryl and H2O in channel of beryl, and between alkali feldspar and quartz, in combanation with microthermometric results of melt inclusions, the pegmatite-forming temperatures from 850°C to 450°C have been ascertained.

本项目主要研究阿尔泰3号脉各结构带绿柱石通道水、流体包裹和晶格氧以及共生陌自颇盖庋跬凰刈槌桑⒔岷衔熬а曳忠煅莼哪承┨卣髦甘致垩医臃⒎郑ㄋ┭莼⒀医纫汗山锥畏至蠹捌淇刂埔蛩亍Ｋ?号伟晶岩脉成因和岩浆－热液过渡阶段性质了解有重要的科学意义。