The Central Aar Granite: Highly differentiated calc-alkaline magmatism in the Aar Massif (Central Alps, Switzerland)
The Central Aar Granite: Highly differentiated calc-alkaline magmatism in the Aar Massif (Central Alps, Switzerland)
复制标题
中央阿尔花岗岩：阿尔地块（瑞士中部阿尔卑斯山）高度分化的钙碱性岩浆作用
DOI：
10.1127/ejm/2/2/0245
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发表时间：
1990
影响因子：
2.1
通讯作者：
U. Schaltegger
中科院分区：
文献类型：
--
作者：
U. Schaltegger
中央阿尔花岗岩是一个钙碱性岩基的晚威斯特伐利亚年龄形成核心的阿尔地块（中央阿尔卑斯山）。这些高度分异的岩石，从花岗闪长岩到浅色花岗岩，已经在三个剖面中进行了研究，分别是Grimsel，Göscheneralp和Reuss山谷横截面。花岗岩受阿尔卑斯低级变质作用的叠加，但仍具有原生地球化学成分。花岗岩套在分异过程中富集不相容微量元素Rb、U、Th、Y和Nb，亏损Sr、Ba、La、Zr、P和过渡元素。微量元素模式表明斜长石，钾长石，黑云母，磷灰石和褐帘石的分离结晶，但显示出一些特征，不能解释任何组合的分馏矿物。因此，其他过程（混合、同化、同化-分离结晶）可能对所观察到的微量元素趋势有贡献。花岗岩主要表现为地幔特征，地壳混染程度较低。它们被认为是在变质和挤压变形高峰期后侵入海西造山带的深部地壳熔体。关键词：阿尔地块，中央阿尔卑斯山，I型花岗岩，海西造山带，分离结晶。
The Central Aar Granite is a calc-alkaline batholith of late Westphalian age forming the core of the Aar Massif (Central Alps). These highly differentiated rocks, ranging from granodiorites to leucogranites, have been investigated in three profiles through the massif: the Grimsel, Göscheneralp and Reuss valley cross sections, respectively. The granites are overprinted by Alpine low-grade metamorphism, but still exhibit primary geochemical compositions. The granite suite is characterized by enrichment of the incompatible trace elements Rb, U, Th, Y and Nb and by considerable depletion of Sr, Ba, La, Zr, P and the transition elements during differentiation. The trace element patterns suggest fractional crystallization of plagioclase, K-feldspar, biotite, apatite and allanite, but show some characteristics that cannot be explained by any combination of fractionating minerals. Other processes (mixing, assimilation, assimilation-fractional crystallization) may there fore contribute to the observed trace element trends. The granites display predominantly mantle characteristics with a minor degree of crustal contamination. They are believed to represent deep-seated crustal melts, which were intruded into the Hercynian orogen after the peak of metamorphism and compressional deformation. Key-words : Aar Massif, Central Alps, I-type granites, Hercynian orogeny, fractional crystallization.