【摘要】 黔北务-正-道地区铝土矿形成于早二叠世大竹园期,属古风化壳沉积型。沉积环境是该类型铝土矿形成的重要因素,本文通过对反映沉积环境比较敏感的B、Ga、Sr、Ba、Th元素含量变化及B/Ga、Sr/Ba、Sr/Cu、Th/U、V/Ni、V/Cr、Ni/Co、Rb/K比值特征分析研究,认为含矿岩系大竹园组主要形成于陆相滨浅湖环境,其底部沉积时期曾遭受海侵影响,具海相→海陆过渡相→陆相沉积特点;深时气候主要为古赤道附近的热带-亚热带温湿气候;氧化还原条件以相对开放的氧化环境为主,局部区域存在相对封闭的贫氧-厌氧环境;铝土矿形成经历了风化早期的强氧化、碱性介质环境→风化中后期的氧化、酸性介质环境→风化物迁移、搬运阶段的弱氧化、弱酸-中性介质环境→沉积成岩成矿期的氧化-弱氧化,弱酸-弱碱性介质环境(局部为贫氧-厌氧环境)→次生淋滤改造富集阶段的氧化、酸性介质环境。铝土矿工业矿体的形成与次生淋滤改造作用密切相关。更多还原

【Abstract】 Bauxite deposit in the Wuchuan-Zheng’an-Daozhen region in northern Guizhou is one of the ancient weathering crust-type deposits formed in the Dazhuyuan period of Early Permian.Sedimentary environment is the important factor for the formation of bauxite deposits of this type.This study analyzed content change of Ga,Sr,Ba,B and Th elements(more sensitive to sedimentary environment)and B/Ga,Sr/Ba,Sr/Cu,Th/U,V/Ni,V/Cr,Ni/Co,Rb/K and their ratio characteristic.The results show that the Dazhuyuan Group(ore-bearing rock series)formed mainly in continental shore and shallow lake environment,with bottom sedimentation influenced by transgression and characteristics of marine→transition phase to the land and sea→continental sedimentary.The climate of deep time was mainly tropical and subtropical humid climate near the equator tropical.The redox conditions were dominated by relatively open oxidation environment, regionally with relatively closed lean oxygen-anaerobic environment.Bauxite mineralization experienced strong oxidation in an alkaline environment at early period of weathering,oxidation in an acid environment at middle and later periods of weathering,weak oxidation with migration of weathering material in a weak acid-neutral environment,oxidation-weak oxidation in a weak acid-weak alkali environment(locally lean oxygen-anaerobic environment)at the sedimentary period of diagenesis and mineralization,and finally secondary leaching transformation and enrichment stage in an oxidation-acid environment.The formation of bauxite industrial ore bodies is closely related to the secondary leaching effect.更多还原