Negative Haloes and Geochemical Field Systems of Hydrothermal Deposits

Primary haloes of hydrothermal deposits were previously considered as positive haloes. Although it has been recently suggested that primary haloes incude positive and negative ones, almost all the research work on primary haloes has still focused on positive haloes for various reasons. In order to understand the source of ore substances a number of large hydrothermal deposits related to magmatism including porphyry, skarn and vein type deposits have been studied. It has been found that negative haloes exist on the peripheries of positive haloes of a mineral deposit. On the basis of the study the authors propose the concept of the geochemical field system of ore-forming elements of hydrotherreal deposits, i. e., with the orebody as the centre outwards there occur the mineralized field, positive halo field, depleted field and background field successively.

热液矿床的负晕和地球化学场系

热液矿床原生晕以往都被视为正晕。近年来虽已提出原生晕包括正晕和负晕,但由于多种原因,到目前为止,原生晕的研究几乎仍局限于正晕。作者为研究矿质来源,对一批与岩浆活动有关的斑岩型、夕卡岩型和脉型等大型热液矿床进行了研究,发现在矿床的正晕外围都有成矿元素负晕。根据研究结果还提出了热液矿床成矿元素地球化学场系,即以矿体为中心,向外依次为矿化场、正晕场、降低场和背景场。

西南印度洋脊49.6°E热液区热液产物和玄武岩地球化学特征

利用X射线荧光法和ICP-MS等方法对取自超慢速扩张的西南印度洋脊(SWIR)49.6°E热液区的热液产物和玄武岩样品进行元素地球化学特征分析研究,结果表明:(1)与亏损型洋中脊玄武岩(N-MORB)相比,研究区玄武岩样品的主量元素组成显示其偏碱性,而微量元素对比表明该区玄武岩明显富集Pb元素;(2)对热液产物的综合分析表明这些样品多为Fe-Si-Mn氧羟化物且都为热液来源;(3)热液产物的∑REE含量介于玄武岩和海水之间,经球粒陨石标准化的稀土元素(REE)分布模式均表现出Eu正异常和轻稀土(LREE)富集的特征。另外,本研究还表明,利用玄武岩和热液产物地球化学指标不仅能够模拟出以热液喷口为中心的元素地球化学晕,而且能反映出热液活动的影响范围。

陕西大西沟重晶石菱铁矿—银硐子银铜铅多金属特大型矿床成矿成晕模

大西沟－ 银硐子银多金属矿床由同生断裂－ 热水流体－ 地球化学动力学的多重耦合作用形成。矿床在区域上处于柞山镇Ｐｂ、Ａｓ、Ｃｕ 地球化学省，ＮＷＷ 向富Ｃｕ 、Ｍｎ、Ｂａ、Ｐｂ、Ａｇ 和ＮＷ 向低Ｐｂ 高Ｃｕ、Ａｓ 及ＮＥ向富Ｐｂ、Ｚｎ 、Ｃｕ 的地球化学带３ 者交汇部位。矿床原生异常组合由西向东为Ｆｅ、Ｃｕ、Ｍｎ、Ｂａ（ 大西沟） →Ｃｕ、Ａｇ、Ｐｂ、Ｚｎ、Ｂａ、Ｍｎ（ 银铜矿） →Ｐｂ 、Ｚｎ、Ａｇ、Ｂａ（ 银铅矿） 。成矿成晕具有热水同生沉积－ 交代→热水混合同生沉积→热水同生沉积演化阶段性。成矿系统的动力学为成矿的主控因素，使地球化学失稳，触发矿质的骤沉。