Bristen granite: a highly differentiated, fluorite-bearing A-type granite from the Aar massif, Central Alps, Switzerland
Bristen granite: a highly differentiated, fluorite-bearing A-type granite from the Aar massif, Central Alps, Switzerland
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Bristen 花岗岩：一种高度差异化的含萤石 A 型花岗岩，产自瑞士中部阿尔卑斯山的 Aar 地块
DOI：
10.1007/s00015-017-0294-z
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发表时间：
2018
影响因子：
3.1
通讯作者：
Ulrike Seelig
中科院分区：
文献类型：
--
作者：
K. Bucher;Ulrike Seelig
布里森花岗岩是一种细粒浅色花岗岩体，产于阿尔卑斯山脉中部的圣哥达铁路隧道。在隧道施工过程中，沿着沿着600米长的隧道段钻取了布里森花岗岩（Brgr）。细晶花岗岩属于阿尔布费拉地区华力西期花岗岩类侵入体，含有多种高度分异花岗岩的典型副矿物。成岩萤石，部分富集钇（Y）和稀土元素（REE），与晚期含Y和稀土的碳酸盐矿物同晶岩共生。花岗岩中含有多种Ti-和Y-REE-辉长岩、钍石和锆石。与钙碱性中央Aar花岗岩（cAgr）相比，Bristen花岗岩强烈亏损Ti、P、Mg、Sr、Ba，显著富集Rb、Th、U、Nb、Y、HREE、F等不相容元素。Bristen花岗岩是阿尔赫西拉斯最成熟的花岗岩类岩石。Brgr的成分是典型的碰撞后还原（亚铁）A型花岗岩。Brgr熔体形成于下地壳，在接近100 MPa和700 °C的石英-长石系统中的CO_2点从高度分异的熔体结晶。Brgr侵入作为一个小的孤立的股票前华力西片麻岩与急剧不协调的接触。Nb、Ta、Y、U、Th和REE的主要岩浆寄主是黑云母，此外还有少量的褐帘石和锆石。Y-REE-萤石、正长岩、斜长岩、钇、钛磷灰石等稀土矿物的存在可能与岩浆黑云母和原生萤石与热液的反应有关。该反应与阿尔卑斯变质作用有关，因为在阿尔卑斯裂隙中发现了含钇萤石和正长岩。原生黑云母转化为黑云母和白云母在较低绿片岩相条件下释放出重金属氧化物，在约300 °C下形成阿尔卑斯山诊断矿物硬黑锰矿。
Bristen granite is a body of fine-grained leucogranite occurring in the Gotthard rail base tunnel in the Central Alps. During construction of the tunnel, Bristen granite (Brgr) has been drilled along a 600 m long section. The aplite-granite belongs to the suite of Variscan granitoid intrusions of the Aar massif and contains a variety of accessory minerals typical of highly differentiated granites. Rock forming fluorite, partly enriched in yttrium (Y) and rare earth elements (REE), is intergrown with the late Y- and REE-bearing carbonate mineral synchysite. The granite contains a variety of Ti- and Y-REE-niobates, thorite, and zircon. Compared with the calc-alkaline central Aar granite (cAgr), Bristen granite is strongly depleted in Ti, P, Mg, Sr, and Ba and shows a remarkable enrichment in incompatible elements such as Rb, Th, U, Nb, Y, HREE and F. Bristen granite is the most evolved granitoid rock of the Aar massif. The composition of Brgr is typical of post-collisional reduced (ferroan) A-type granites. The Brgr melt formed in the lower crust and crystallized from a highly differentiated melt at the cotectic point in the quartz-feldspar system close to 100 MPa and 700 °C. The Brgr intruded as a small isolated stock pre-Variscan gneisses with sharply discordant contacts. The primary igneous host of Nb, Ta, Y, U, Th and REE is biotite in addition to minor amounts of allanite, and zircon. The presence of Y-REE-fluorite, synchysite, parisite and Y- and Ti-niobates and other REE-minerals can be related to reaction of igneous biotite and primary fluorite with hydrothermal fluids. The reaction is associated with alpine metamorphism, because Y-bearing fluorite and synchysite have been reported from Alpine fissures. The transformation of primary biotite to chlorite and muscovite released the heavy metal oxides under lower greenschist facies conditions that formed the Alpine diagnostic mineral stilpnomelane at about 300 °C.
影响因子：
3.1
作者：
Whitney, Donna L.;Evans, Bernard W.
通讯作者：
Evans, Bernard W.