期刊
CANADIAN MINERALOGIST
卷 47, 期 6, 页码 1301-1327出版社
MINERALOGICAL ASSOC CANADA
DOI: 10.3749/canmin.47.6.1301
关键词
albite-rich subsolvus granite; peralkaline; tin; niobium; cryolite; immiscibility; Madeira granite; Pitinga mine; Brazil
类别
资金
- CNPq [HTC: 141927/96-8, RD: 400038/99, 463196/2000-7, 307469/2003-4]
- Academy of Finland [SA 30600]
The 1.818 Ga magmatic, subsolvus, Madeira albite-rich granite of the Pitinga province, exploited at the Pitinga mine, in northern Brazil, crystallized from a F-rich melt, also enriched in Sn, Rb, and HFSE. It is composed of a peralkaline, cryolite-bearing core facies and a peraluminous to metaluminous, oxidized, fluorite-bearing border facies, generated by autometasomatic processes after the crystallization of the core facies. A metaluminous to peralkaline hypersolvus granite is comagmatic with the albite-rich granite. Petrographic studies indicate that quartz was the first phase to crystallize, at similar to 700 degrees C; the quartz-K-feldspar cotectic was attained at around 650 degrees C, and the ternary feldspar solvus and onset of albite crystallization, down to the solidus, estimated at around 500 degrees C. Massive cryolite and pegmatitic rocks found in the center of the stock were derived from the residual melt. The albite-rich granite probably originated by crystallization of a dense, F-rich, peralkaline phase derived from a peralkaline to metaluminous parental melt by immiscibility.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据