摘要
云英岩脉型锡矿是广西花山花岗岩的主要矿化类型之一。花山花岗岩是氧化型花岗岩,岩体中的锡主要以Sn4+的形式,赋存于黑云母、角闪石、榍石、金红石、钛铁矿和锡石等含锡矿物中。通过矿物学研究发现,云英岩化过程是:经充分分异和演化形成的残余岩浆流体与中细粒黑云母花岗岩相互作用。首先,黑云母等原生含锡矿物中的锡在岩浆流体的作用下被淋滤出,进入流体或次生矿物相,如金红石、白云母等,发生初步富集;其次,在蚀变后期,成矿流体使早先沉淀的含锡矿物发生重溶,锡溶解进入成矿流体再次富集。锡在流体中与丰富的F-,Cl-等络阴离子结合成稳定的配合物运移,随着云英岩化加深,流体的pH值升高、温度降低、络阴离子浓度降低,流体中配合物的稳定性降低发生沉淀形成锡矿化。
Greisen-vein type tin deposits are the most important mineralization type in Huashan granite, Guangxi, South China： The Huashan granite is an oxidized-type granite. In this granite body the element tin predominantly exists as Sn4＋ in primary tinbearing minerals, such as biotite, amphibole, titanite, rutile, ilmenite and cassiterite. Based on the comprehensive mineralogical study, we recognize that greisenization developed through interaction of the medium-fine-grained biotite granite with a residual magmatic fliud formed by adequate differentiation and evolution. At the early stage of alteration, the tin in the primary tin-bearing minerals was leached out by magmatic fliud, and entered into fluid or secondary mineral phases, such as rutile, muscovite etc. to accomplish the first concentration. Then, at the later stage of alteration, the mineralizing fluid was able to redissolve earlier precipitated tin-bearing minerals, and tin entered into mineralizing fluid to accomplish the second concentration. Tin dissolved in fluid combined with ligands, such as F-, Cletc. to form stable complexes and transported. During greisenization, there was an increase in pH, a decrease in temperature and a decrease in ligand concentration, the stabilities of tin complexes in fluid were dropped down, and then the tin mineral deposits were formed.
出处
《高校地质学报》
CAS
CSCD
北大核心
2010年第3期281-293,共13页
Geological Journal of China Universities
基金
国家自然科学基金(40730423),国家自然科学青年基金(40902017)
教育部博士点新教师基金(20090091120042)
中国地质调查局调查项目“南岭重要金属矿床成矿机理研究和找矿潜力预测”(1212010632100)和“深部探测技术与实验研究专项”(SinoProbe-03-01-4D)联合资助
关键词
花山
花岗岩
云英岩化
锡成矿
矿物学
Huashan
granite
greisenization
tin mineralization
mineralogy
