| 沉积叠加改造型矿床的物源及富集机制的地球化学研究 |
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| 引用本文：.1999.Geochemical Study on Sources and Enrichment Mechanism of the Reformed and Super-inposed Sedimentary Deposit[J].Mineral Deposits,18(2):110~120 |
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| 基金项目:国家自然科学基金 (49 7173187)和国家“八五”科技攻关计划 (85-901-03-08D) |
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| 中文摘要:通过对长江中下游及其邻区震旦系—早古生界内一些沉积叠加改造型锑-金矿床、银多金属矿床的物源及富集机制的地球化学研究认识到，在研究该类矿床的成矿作用时，不能仅仅局限在传统的认识和思维模式上，而是应该从更大的时、空域，用地球化学的思维去观察、去分析它们的“源、运、储”；该类矿床成矿的有利因素，除了矿源层的物源基础（成矿元素丰度，赋存形式）外，其决定因素还在于后期叠加改造作用对成矿元素浓集能力的高低和效率强弱的控制。 |
| 中文关键词:沉积叠加改造型矿床 物源 富集机制 震旦系-下古生界 长江中下游及邻区 |
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| Geochemical Study on Sources and Enrichment Mechanism of the Reformed and Super-inposed Sedimentary Deposit |
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| Abstract:Based on geochemical studies on sources and enrichment mechanism of several Sinian-Lower Paleozoic reformed and superimposed sedimentary deposits such as antimony-gold deposits and silver-polymetallic deposits in the lower and middle reaches of the Yangtze River and neighboring areas, the authors have acquired the following understanding; First, when we study the ore-forming process of this kind of deposits, we should observe and analyse their source, transportation and reservior geochemically from a broader time-space domain instead of being confined to the traditional knowledge and mode of thinking. Second, the key factors of ore-forming process for this type of deposits include the advantageous material basis of the source bed (abundances of ore-forming elements mode of occurrence) and, more decisively, the concentration capacity and the efficiency of the orr-forming elements derived from late reformation and superimposition. In this study, some conclusions have been reached: (l) as different rocks of Sinian-Lower Paleozoic strata in the study area have different source materials, deposition environments and element properties, element contents vary considerably, with the differences ranging from several times to hundreds of times ; (2) thc ore-forming elements in various rocks exist in such readily-releasing phase forms as sulfides, ferromanganese oxides and adsorption phase, which provides advantageous prerequistie for element mobilization and extraction in later reformation and superimposition; (3) the leading factor of the ore-forming process in the study area is the local special mechanism in later reformation and superimposition, as exemplified by the Zengjialong antimony polymetallic orefield in Jiangxi, whose leading ore-forming mechanism is the underplating of Mesozoic melted crustal granite. The ore-forming material of the tin-arsenic orebody came from ore-bearing hydrothermal fluid in late remelting magmatic stage. The ore-forming elements in the Zhangshiba silver-zine:-lead orebody mainly came from the basement and ore-bearing surrounding rocks, and the geological agent for their mobilization and transportation is apparently the thermal field of underplating magma. The widespread fluoritization in the ore field resulted from the decomposition of the complex compound: when the magmatic fluid rich in voiatiles ( F- etc. ) was the form of complexion [SnF6]2- in the process of transportation, the complex compound was decomposed, cassiterite (SnO2) was precipitated, and the complex anion F- was combined with Ca2+ in surrounding rocks, consistent with the change or the physicochemical conditions. Another possible mechanism for widespread fluoritization (especially the single fluorine ore formed in the periphery) might be the activation and recombination of high fluorine ( 1458×10-6～2620×10-6 ) matter in Sinian-Cambrian argillite under the action of magmatic thermal field. |
| keywords:Reformed and superimposed sedimentary deposit, source, enrichment mechanism, Sinian-Lower Paleozoic, the Lower and middle reaches of the Yangtze River and neighboring areas |
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