(1. 中南大學(xué) 有色金屬成礦預(yù)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. 中國科學(xué)院 地球化學(xué)研究所 礦床地球化學(xué)國家重點(diǎn)實(shí)驗(yàn)室，貴陽 550002；
4. 廣西堂漢鋅銦股份有限公司，南丹 547200)
摘 要: 位于大廠礦田東帶的大福樓錫礦床是一個(gè)以產(chǎn)錫和鋅為主、研究程度相對(duì)較低且規(guī)模較大的錫石硫化物型礦床。針對(duì)該礦床特征典型、研究薄弱、成礦條件優(yōu)越及找礦前景可觀等因素，對(duì)流體包裹體和硫同位素特征進(jìn)行了研究。結(jié)果表明：大福樓礦床主要發(fā)育6種類型的流體包裹體(單相氣相包裹體、單相鹽水溶液包裹體、兩相富蒸汽包裹體、兩相富液體包裹體、含CO2相包裹體和含NaCl子礦物包裹體)，包裹體大小一般為5~25 μm，少數(shù)為30 μm，主要呈多邊形、米粒狀、橢圓形、長方形以及不規(guī)則狀，少數(shù)呈三角形以及半自形的負(fù)晶形。包裹體主要含Ca2+、Mg2+、K+、Na+、SO42−、Cl−和NO3−等液相成分以及CO2、CO、CH4和N2等氣相成分。成礦流體屬于Na(K)-Ca(Mg)-Cl型鹵水溶液，呈弱酸性，包裹體中不含O2，表明成礦過程中沒有游離氧的存在，而CO2、CH4和H2的含量相對(duì)較高，表明成礦流體具有較強(qiáng)的還原性。礦物中含NaCl子礦物包裹體的大量存在，顯示成礦流體具有巖漿熱液特征。包裹體中的氟對(duì)錫的遷移和沉淀起著非常重要的作用，而硫鹽礦物的存在可能對(duì)錫的富集沉淀造成不利影響。硫同位素研究結(jié)果顯示，礦石的δ(34S)值為−1.54×10−3~2.18×10−3，極差為 3.72×10−3，均值為1.141×10−3，以正值為主，礦石δ(34S)值稍微偏離基性巖類硫的范圍，而與隕石硫的同位素組成非常接近，具有重硫富集和典型巖漿來源的特征。錫礦硫元素可能部分來源于龍箱蓋隱伏復(fù)式花崗巖體，顯示巖漿活動(dòng)在成礦過程中具有重要意義，錫礦與I型花崗巖聯(lián)系緊密。
關(guān)鍵字: 大廠礦田；大福樓；錫多金屬礦床；流體包裹體；硫同位素；地質(zhì)；地球化學(xué)
（1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education,
Central South University, Changsha 410083, China;
2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China, ;
3. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry,
Chinese Academy of Sciences, Guiyang 550002, China;
4. Guangxi Tanghan Zinc & Indium Co., Ltd., Nandan 547200, China）
Abstract:The Dafulou tin deposit, located in the eastern of the Dachang ore field, is a large-scale cassiterite-sulfide deposit, of which the main mineral types include tin and zinc. Because of the typical deposit characteristics, weak research degree, excellent mineralization conditions and good prospecting potential, the fluid inclusions and sulfur isotopes were studied. The results show that there are six types of fluid inclusions (e.g. single-phase gas inclusions, single-phase brine inclusions, two-phase vapor-rich inclusions, two-phase liquid-rich inclusions, carbon dioxide-bearing, containing NaCl daughter minerals). The size of the fluid inclusion is 5−25 μm, yet 30 μm in the minority, whose shapes consist of polygon, rice-shape, oval, rectangular and irregular shape, but little in the shape of triangle and negative crystal. The liquid and gas components are composed of Ca2+, Mg2+, K+, Na+, SO42−, Cl−, NO3− and CO2, CO, CH4, N2, respectively. The fluid is characterized by the type of Na(K)-Ca(Mg)-Cl brine solution and weak acid, without oxygen existing, which suggests that the free oxygen does not exist. The high contents of CO2, CH4 and H2 indicate the strong reduction of the ore-forming fluid. A plenty of daughter minerals containing NaCl show the magmatic hydrothermal features of the fluid. The content of fluorine plays an important role to tin in the migration and precipitation, but the sulfur has an adverse effect on tin mineralization. The sulfur isotopes studies indicate that the δ(34S) values change from −1.54×10−3 to 2.18×10−3, with the maximum difference value of 3.72×10−3 and an average value of 1.141×10−3, dominated by the positive value. In the whole, the δ(34S) values deviate from the value scope of the magma and accord with that of the meteorite sulfur, characterized by the heavy sulfur-rich and typical magma source. In the Dafulou ore deposit the sulfur may be supplied by the Longxianggai concealed granite, which plays an important role in the mineralization. The tin ore is related closely to I-type granite.
Key words: Dachang ore field; Dafulou; tin-polymetallic ore deposit; fluid inclusion; sulfur isotope; geology; geochemistry
