(1. 中南大學(xué) 有色金屬成礦預(yù)測與地質(zhì)環(huán)境監(jiān)測教育部重點(diǎn)實(shí)驗(yàn)室，長沙 410083； 2. 中南大學(xué) 地球科學(xué)與信息物理學(xué)院，長沙 410083； 3. 湖南省地質(zhì)博物館，長沙 410004)
摘 要: 湘西花垣鉛鋅礦田隨著楊家寨、大腦坡及清水塘等一系列大型–超大型鉛鋅礦床的發(fā)現(xiàn)，已經(jīng)成為世界千萬噸級(jí)鉛鋅礦田。通過礦脈切穿關(guān)系和不同的礦物共生組合，將花垣礦田成礦過程分為3個(gè)階段。對礦田內(nèi)主成礦期方解石的REE及Sr同位素進(jìn)行了研究，并與含礦圍巖及不同時(shí)代地層的REE和Sr同位素進(jìn)行了對比。結(jié)果表明：方解石稀土元素特征與地層具有相似性，其中I階段方解石REE含量較低，ΣREE為1.73×10-6~10.94×10-6，平均為4.77×10-6；LREE/HREE為6.21~10.19，平均為7.96；87Sr/86Sr比值0.70935~0.71001，平均為0.709643。II階段方解石REE含量比I階段高，ΣREE為24.53×10-6~67.88×10-6，平均為46.71×10-6；LREE/HREE為6.21~10.19，平均為7.96；87Sr/86Sr比值為0.70923~0.70944，平均為0.709301，比I階段的低，說明I、II階段成礦流體存在差異。結(jié)合圍巖及不同時(shí)代地層地球化學(xué)特征認(rèn)為，I階段成礦流體主要為含礦層建造水，混有深循環(huán)熱鹵水；II階段成礦流體主要為深循環(huán)熱鹵水，混有大氣降水，從I階段至II階段成礦流體還原性增強(qiáng)。
關(guān)鍵字: 方解石；稀土元素；鍶同位素；成礦流體；花垣鉛鋅礦田
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, Changsha 410083, China; 2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China; 3. The Geological Museum of Hunan, Changsha 410004, China）
Abstract:With the discovery of the large to super large Yangjiazhai, Danaopo and Qingshuitang Pb-Zn deposits, the Huayuan orefield becomes a world-class super large Pb-Zn orefield. According to the crosscutting relationship of ore veins and coexisting mineral assemblage, the mineralization process was subdivided into three stages. REE and strontium isotope of calcites were analyzed and compared with those of ore-hosting limestone and strata of different geological times. The results show that the REE patterns of calcites are similar to those of strata. Stage I calcites display low total contents of REE (ΣREE=1.73×10-6-10.94×10-6，average 4.77×10-6), 87Sr/86Sr ratios ranging from 0.70935 to 0.71001 (average 0.709643) and LREE/HREE ratios range from 6.21 to 10.19 (average 7.96). Stage II calcites display higher contents of REE (ΣREE=24.53×10-6-67.88×10-6，average 46.71×10-6) and lower 87Sr/86Sr ratios ranging from 0.70923 to 0.70944 (average 0.709301) than those of stage I calcite, and similar LREE/HREE ratios range from 6.21 to 10.19 (average 7.96). These indicate that the ore-forming fluids of stages I and II are derived from different origins. According to geochemical characteristics of wall rock and strata of different geological times, it is concluded that the ore-forming fluids of stage I are mainly connate water in ore-hosting strata, mixed by deep-source circular brine; the ore-forming fluids of stage II are mainly deep-source circular brine, mixed by meteoric water, and the reducibility increases from stage I to II.
Key words: calcite; REE; Sr isotope; ore-forming fluids; Huayuan Pb-Zn orefield
