發(fā)布時間：2018-06-23 12:11

  本文選題：密西西比河谷型 + 鉛鋅礦��； 參考：《地質學報》2017年01期

【摘要】：華南泥盆系密西西比河谷型(MVT)鉛鋅礦床,受控于泥盆系海進序列的臺地碳酸鹽巖,大體可分為以凡口為代表的中低溫熱液型和以泗頂、北山為代表的低溫熱液型。在礦床學研究基礎上,對研究區(qū)內不同類型的鉛鋅礦、硫鐵礦開展系統(tǒng)的硫、鉛同位素分析,收集和測定493件S和64件Pb同位素數(shù)據(jù),總結硫、鉛的來源和硫同位素分餾機制,并初步探討了成礦機制。硫同位素研究顯示,礦石硫有多種來源,主要來自于還原性鹵水,部分來自氧化性鹵水中ΣSO_4~(2-)的還原,少量硫來自于礦區(qū)含礦地層。不同礦床在成礦作用過程中硫同位素的分餾機制不同。在以凡口為代表的中低溫熱液礦床中,礦石δ~(34)S值高且相對集中,以熱力學分餾為主,生物分餾作用較微弱;在以泗頂、北山為代表的低溫熱液礦床中,礦石δ~(34)S值低且分散,以生物分餾作用為主,僅部分中粗粒鉛鋅礦石以熱力學分餾為主。成礦作用過程中硫同位素分餾遠未達到平衡狀態(tài)。不同礦床的礦石鉛同位素組成呈線性分布,反映出不同來源鉛的混合。古老鉛來自遭剝蝕的古陸,年輕鉛代表泥盆系沉積物的普通鉛。二者的比例與巖石中陸源物質(Pb)的含量相對應。成礦時的鉛直接來自于氧化性鹵水,間接來自于鹵水對流經的泥盆系含礦層(尤其是底部碎屑巖)的淋濾,更間接地來自古陸剝蝕區(qū)以及海相沉積物。金屬物質的迅速沉淀成礦作用與兩類流體的混合有關,氧化性鹵水來自蒸發(fā)鹽紅層盆地,沿泥盆系底部紫色砂巖經區(qū)域性遷移,其中富含大量金屬成礦元素,并含有少量呈ΣSO_4~(2-)的硫;而還原性流體中富含ΣH2S的硫。流體的混合作用局限于礦區(qū)范圍內,并不存在區(qū)域性的簡單大規(guī)模流體混合過程。
[Abstract]:The Devonian Mississippi River Valley type (MVT) lead-zinc deposit in South China, controlled by the platform carbonate rocks of the Devonian transgressive sequence, can be divided into moderate and low temperature hydrothermal type represented by Fankou and low temperature hydrothermal type represented by Siding and Beishan. On the basis of ore deposit study, the sulfur and lead isotopic data of 493 S and 64 Pb isotopes were collected and determined for different types of lead-zinc ore and pyrite in the study area. The sources of sulfur and lead and the mechanism of sulfur isotope fractionation were summarized. The metallogenic mechanism was also preliminarily discussed. Sulfur isotope studies show that there are many sources of sulfur in ore, mainly from reductive brine, partly from the reduction of 危 so _ 4- ~ (2-) in oxidized brine, and a little from ore-bearing strata. The fractionation mechanism of sulfur isotopes in different ore deposits is different. The 未 ~ (34) S value of ore is high and relatively concentrated, the thermodynamic fractionation is dominant, the biological fractionation is weak, and the 未 ~ (34) S value of ore is low and dispersed in the low-temperature hydrothermal deposit represented by Siding and Beishan. Biological fractionation is the main activity, and thermodynamics fractionation is the main component of the coarse lead zinc ore. Sulfur isotope fractionation is far from equilibrium during mineralization. The isotopic composition of ore lead in different ore deposits is linearly distributed, reflecting the mixing of lead from different sources. Ancient lead comes from the eroded ancient land, and young lead represents the common lead of Devonian sediments. The ratio of them corresponds to the content of terrestrial matter (Pb) in rocks. The lead during mineralization comes directly from oxidizing brines, indirectly from the leaching of the Devonian ore-bearing beds (especially from the bottom clastic rocks) flowing through the brines, and more indirectly from the paleocontinental denudation areas and marine sediments. The rapid precipitation and mineralization of metal matter is related to the mixing of two kinds of fluids. The oxidized brine comes from the evaporative salt red bed basin, and the purple sandstone moves along the bottom of the Devonian system through regional migration, which is rich in a large number of metal metallogenic elements. It also contains a small amount of 危 SO4-, while the reductive fluid is rich in 危 H2S. Fluid mixing is confined to the mining area, and there is no regional simple large-scale fluid mixing process.
【作者單位】： 北京礦產地質研究院;中國地質調查局發(fā)展研究中心;廣東凡口鉛鋅礦;有色金屬礦產地質調查中心;
【基金】：中國地質調查局Ⅱ級項目“內蒙古赤峰有色金屬基地綜合質調查”(DD20160072) 國家科技支撐課題“湖南錫田地區(qū)深部成礦巖體空間結構與成礦預測”(2011BAB04B08) 全國危機礦山接替資源找礦項目“湘南-粵北地區(qū)錫鎢多金屬礦床成礦規(guī)律總結研究”(20089927)聯(lián)合資助
【分類號】：P618.4;P597

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