地质科技情报2013，Vol.32Issue(1)：62-70,9.
黔北务正道地区铝土矿鲕状矿石中鲕粒的微区元素地球化学特征及其成矿意义
Microscopic Geochemical Characteristics of Oolite in Oolitic Bauxite Ores from Wuchuan-Zheng'an-Daozhen Area in the Northern Guizhou Province and Their Metallogenic Significance
摘要
Abstract
Varied proportions of pisolitic-oolitic ore are recognized in most bauxite deposits, but the genesis of this texture and its relationship with Al-mineralization remain controversial. This paper reports a comprehensive geochemical study of typical oolitic ores of the bauxite deposits from the Wuchuan-Zheng' an-Daozhen area, northern Guizhou Province and uses methods of in situ major element analysis by EPMA and major- and trace element analyses by laser ablation plasma mass spectrometry. It shows that the ooids were epigenetic relative to their matrix, and it is highly unlikely that the bauxitization was solely resulted from surface chemical weathering of laterized sedimentary profiles. By contrast, geochemistry of oolitic textures infers that the ooids are formed in strongly oxidizing and highly acidic environment. Coupled with documented whole rock data and field observation, a genetic model is then suggested. A large amount of pyrite was formed during seawater transgression upon laterized profiles and distributed at a broad coastal plain. The pyrites were constrained to have formed at a middle depth range of the profiles due to variation of oxygen fugacity. Oxidation and decomposition of pyrite during regression resulted in strong sulfuric acid aqueous solution, which carried out a large quantity of matrix elements (e. g. Si and Fe) and advanced bauxitization. This process is featured by multiple recycling. In fact, the bauxitization is a coupling result of periodically transgression-regression recycling of seawater and laterized profiles locating at broad coastal plain of long-term uplifted continental margin under tropical humid condition.关键词
黔北/铝土矿/鲕粒/微区原位分析/地球化学特征/成矿意义Key words
northern Guizhou Province/ bauxite deposit/ oolite/ in situ microscopic analysis/ geochemical characteristics/ metallogenic significance分类
天文与地球科学引用本文复制引用
张亚男,张莹华,吴慧,丁晓英,凌文黎,雷志远,翁申富,马倩,杜远生..黔北务正道地区铝土矿鲕状矿石中鲕粒的微区元素地球化学特征及其成矿意义[J].地质科技情报,2013,32(1):62-70,9.基金项目
贵州省地勘基金项目"贵州务正道地区铝土矿基础地质与成矿规律研究" （）
