摘要
云龙锡矿是产于高度混合岩化的崇山群变质岩中的一个中型锡矿床。对矿体中石英流体包裹体的研究表明,该矿床成矿流体具有中—高温(300～400℃),高盐度(31.0～38.0 eq.wt.%NaCl),并且盐度变化大的特点。对矿体中电气石和石英H、O同位素测试结果显示,电气石的δ^(18)O值(SMOW标准,下同)为9.0‰～11.4‰,δD值为-83‰～-68‰;计算的与电气石达到同位素平衡的成矿流体的δ^(18)O和δD值变化范围分别为5.8～10.1‰和-58～-31‰(t=300～400℃);石英的δ^(18)O值为10.1‰～13.0‰,计算的流体δ^(18)O值稍低,为3.7‰～8.9‰(t=300～400℃);石英流体包裹体水的δD值(-112‰～-92‰)明显低于与电气石平衡的流体的δD值。结合云龙锡矿区域地质和矿床特征及前人研究结果,笔者推测该矿床中电气石可能形成于由区域变质和混合岩化作用产生的混合岩浆水,而石英则形成于混合岩浆水与大气降水的混合流体,它们记录了成矿作用过程中成矿流体的演化。
The Yunlong tin deposit, western Yunnan, is a medium-sized tin deposit, which occurred in highly migmatized metamorphic rocks of the Chongshan Group. Fluid inclusions in quartz from the Yunlong tin deposit suggest that the tin ore formed at medium to high temperatures (300～400℃) with high (31. 0～ 38. 0 eq. wt. % NaCl) but variable salinities. Tourmalines in ore bodies have δ^(18)O_(SMOW) and δD_(SMOW) values of 9. 0‰～ 11. 4‰ and — 83‰～-68‰, respectively, and the calculated ore-forming fluids equilibrated with them have δ^(18)O_(SMOW) and δD_(SMOW) values of 5. 8‰～10. 1‰ and —58‰～-31‰ (t=300～400℃) , respectively. Quartz from the ore bodies have δ^(18)O_(SMOW) values of 10. l‰～13.0‰. The calculated mineralization fluids equilibrated with quartz at t= 300～400℃ show slightly lower δ^(18)O_(SMOW) values (3. 7‰～8. 9‰) than those fluids equilibrated with tourmaline, and the fluid inclusions in quartz have much lower δD_(SMOW) values ( — 112‰～-92‰). Combined evidence from regional geology, ore deposit geology, and previous geochemical research with our results, the authors proposed that the tourmalines were probably formed from magmatic hydrothermal fluids derived from regional metamorphism and migmatization, while quartz was deposited from a mixed fluid of magmatic hydrothermal fluid with meteoric waters. Therefore, the fluid inclusions and H, O isotopic compositions in tourmaline and quartz record the evolutionary history of ore-forming fluids of the Yunlong tin deposit.
出处
《地质论评》
CAS
CSCD
北大核心
2002年第S1期250-255,共6页
Geological Review
基金
国家重点基础研究项目(编号G1999043208)
国家杰出青年科学基金(编号49925306)资助的成果
