地质学报2012，Vol.86Issue(1)：198-208,11.DOI:11-1951/P.20120104.1640.002
危地马拉硬玉岩与硬玉化绿辉石岩的岩石学特征及其地质意义
Petrology of the Jadeitite and Jadeitized Omphacitite from Guatemala and Its Geological Implications
摘要
Abstract
In the Guatemala jadeitite area, there are several rock types such as jadeitites, eclogites and albitites etc, among which omphacitite has not been reported in detail before. Jadeitite and omphacitite studied in this paper are from Guatemala jadeitite area, which is located in the Fault Zone between North America and Caribbean plates. Jadeitite mainly consists of jadeites with high content of Jd end-member, and has granular or coarser - grained mosaic texture. Most jadeites show rhythmic zoning; in cores and other light areas (BSE images), Jd contents are slightly lower (from 94. 81% to 95. 48%) relative to dark areas, where Jd contents are more than 97. 92%. Omphacitite has metasomatic texture, mainly consists of omphacites and jadeites; omphacites have high CaO (9.01% ~ 10.80%) and MgO (6.09% ~ 7.94%), but low FeO (2.84% ~ 4.89%), jadeites have CaO (0.59% ~ 4.30%), MgO (0.26% ~ 3.05%) and FeO (0. 76% ~ 2. 87%). Presence of fluid inclusions in jadeites and textures of omphacite replaced by jadeite indicate the jadeitite was formed by crystallization from a jadeitic fluid, which subsequently leads to the replacement of adjacent pyroxenes, showing similarity to those from the Myanmar jadeitite. The zonal texture in jadeites reflects that the system of P-T-C varied rhythmically, and their straight and continuous boundaries indicate a HP/LT condition stable for jadeite crystallization. These petrographic features indicate that at least three stages of replacements existed, and the omphacitite wase possibly a production of replacement between jadeitic material and pyroxenite during formation of the jadeitite, and further indicate extensive infiltration of jadeitic fluid and diverse features of replacement within the subduction zone.关键词
硬玉/硬玉岩/绿辉石岩/流体/交代/危地马拉Key words
Jadeite/ Jadeitite/ Omphacitite/ Fluid/ Replacement/ Guatemala引用本文复制引用
张智宇,施光海,欧阳秋眉,柳维,龚庆贺..危地马拉硬玉岩与硬玉化绿辉石岩的岩石学特征及其地质意义[J].地质学报,2012,86(1):198-208,11.基金项目
本文为国家自然科学基金项目(编号40672046)和教育部新世纪优秀人才支持计划(编号NCET-07-0771)资助的成果. （编号40672046）
