【摘要】：紅山大型銅多金屬礦床位于云南中甸地區(qū),包括紅山、紅牛和恩卡3個(gè)礦段,礦體主要呈層狀-似層狀產(chǎn)于石榴石夕卡巖、角巖、大理巖和硅質(zhì)巖之中,或者呈細(xì)脈浸染-網(wǎng)脈狀賦存于深部隱伏花崗斑巖體之中。目前學(xué)術(shù)界關(guān)于該礦床的成因類型仍然存在不同認(rèn)識(shí),本文使用激光剝蝕電感耦合等離子體質(zhì)譜儀(LAICPMS)對(duì)礦區(qū)硅質(zhì)巖、夕卡巖礦石中的黃鐵礦和磁黃鐵礦進(jìn)行了微區(qū)原位成分的測(cè)試,進(jìn)而根據(jù)微量元素特征來(lái)約束礦床的成因。分析結(jié)果表明,不同產(chǎn)狀的黃鐵礦具有明顯不同的微量元素組成,硅質(zhì)巖中的黃鐵礦相對(duì)富集Ti、Mn、Ni、As、Pb、Bi、Te、Ag和Sb等微量元素,Co/Ni比值小于1,表現(xiàn)為典型同生沉積黃鐵礦的微量元素特征;而夕卡巖礦石中的黃鐵礦則相對(duì)富集Co和Cu,虧損As、Se和Sb等低溫元素,且Co/Ni比值多數(shù)大于1,顯示高溫巖漿熱液黃鐵礦的微量元素特征。此外,硅質(zhì)巖中磁黃鐵礦的Co、Ni和Se等微量元素組成與黃鐵礦的組成十分類似,表明它們的化學(xué)組成主要受到沉積環(huán)境的控制。夕卡巖中的磁黃鐵礦與黃鐵礦相比強(qiáng)烈虧損Co,這可能歸因于早期黃鐵礦沉淀時(shí)帶走了大量的Co,從而導(dǎo)致殘余熱液中Co濃度的大幅降低。通過(guò)研究,我們還查明紅山礦區(qū)黃鐵礦中的Co、Ni、As和Se等元素主要以固溶體的形成存在,而Pb、Bi、Ag、Cu和Mn等元素則主要以顯微包裹體的形式存在。黃鐵礦和磁黃鐵礦中Pb和Bi均表現(xiàn)為正相關(guān)關(guān)系,暗示它們可能以顯微包裹體或納米微粒的形式分布于這兩種硫化物中。結(jié)合野外地質(zhì)產(chǎn)狀與前人已有研究,我們認(rèn)為紅山礦區(qū)至少存在兩期成礦作用,其中晚三疊世沉積成巖作用形成的黃鐵礦富集了一定的Ag、Bi和Pb等成礦元素,而晚白堊世的巖漿-熱液活動(dòng)則帶來(lái)了大量的Cu和Mo等金屬元素,從而在紅山礦區(qū)形成了復(fù)合型的Cu-Mo-Pb-Zn-Ag多金屬礦化體系。
[Abstract]:The Hongshan large copper polymetallic deposit is located in Zhongdian area, Yunnan Province, including Hongshan, Hongbiu and Enka ore sections. The orebodies are mainly bedded and bedded in garnet skarn, hornstone, marble and siliceous rock. Or in the deep concealed granitic porphyry as vein-dipping-reticular veins. At present, there is still different understanding about the genetic type of the deposit in academic circles. In this paper, the siliceous rocks in the ore area are treated by laser denudation inductively coupled plasma mass spectrometer (LAICPMS). Pyrite and pyrrhotite in skarn ore were measured in situ and the origin of the deposit was restricted according to the characteristics of trace elements. The results show that the pyrite with different occurrence has different trace element composition, and the pyrite in siliceous rock is relatively enriched in TiMnPbBPbBiTE-Ag and SB, and the ratio of Co / Ni is less than 1, which shows the trace element characteristic of typical synsedimentary pyrite. The pyrite in skarn ore is relatively rich in Co and Cu, depleted in low temperature elements such as As-se and SB, and the Co/Ni ratio is more than 1, which shows the trace element characteristics of high-temperature magmatic hydrothermal pyrite. In addition, the trace element composition of pyrrhotite in siliceous rock is very similar to that of pyrite, indicating that their chemical composition is mainly controlled by sedimentary environment. Compared with pyrite, pyrrhotite in skarn has a strong loss of Co, which may be attributed to the large amount of Coin taken away during the early pyrite precipitation, which leads to a significant decrease in the concentration of Co in residual hydrothermal solution. Through the study, we also find that the elements such as Co-NiAs and se in pyrite of Hongshan mining area mainly exist in the form of solid solution, while the elements such as PbPbBBiAg-Ag-Cu and mn exist mainly in the form of microinclusions. The positive correlation between Pb and Bi in pyrite and pyrrhotite suggests that they may be distributed in the form of microinclusions or nanoparticles. In combination with the field geological occurrence and previous studies, we believe that there are at least two stages of mineralization in Hongshan ore area, in which pyrite formed by late Triassic sedimentary diagenesis has enriched some metallogenic elements, such as Agnb Bi and Pb, etc. During the late Cretaceous magma hydrothermal activity resulted in a large amount of Cu and Mo metal elements thus forming a complex Cu-Mo-Pb-Zn-Ag polymetallic mineralization system in Hongshan mining area.
【作者單位】： 中國(guó)地質(zhì)科學(xué)院地質(zhì)研究所;中國(guó)科學(xué)院地球化學(xué)研究所礦床地球化學(xué)國(guó)家重點(diǎn)實(shí)驗(yàn)室;
【基金】：澳大利亞塔斯馬尼亞大學(xué)國(guó)家優(yōu)秀礦床研究中心科研基金項(xiàng)目(CODES-P2A3) 國(guó)家自然科學(xué)基金項(xiàng)目(41373051,41003023) 中國(guó)科學(xué)院“西部之光”項(xiàng)目
【分類號(hào)】：P618.2
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本文編號(hào)：2195134