Mineral compositions provide key information on the petrogenesis and tectonic settings of granitoid rocks. These relationships are addressed in the present paper, which is focused on the Eocene Gapdan pluton, near Zahedan in eastern Iran. The pluton is part of a granitoid suite intruded into Late Cretaceous to Middle Eocene flysch of the Sistan suture zone. It is zoned, consisting of granodiorite in the center and biotite granite at the margin, and is cross-cut by late diorite dykes. The country rocks are low to medium grade biotite schists with subordinate amphibolite. Biotite is the only ferromagnesian mineral in the Gapdan granitoids, consistent with calc-alkaline and I-type affinities, and with formation in an arc-related tectonic setting. Thermo-barometry and geochronology, combined with lithological observations, establish the following sequence of events: (i) melting of mantle related to subduction of the Sistan oceanic slab and closure of the oceanic basin, generation of basaltic magma, and finally crustal melting and hybridization with crustal melts during ascent. (ii) At 44.31 ± 0.21 Ma the resulting granitic magma crystallized at 4–5.4 ± 1 km depth; biotite and feldspar thermometers indicate crystallization temperatures of ~ 850˚C and ~ 730˚C, respectively. (iii) This stage was tectonically controlled and the pluton was exhumed to shallower crustal levels of ~ 2.5 km, imparting a mylonitic fabric on the granite. (iv) At 42.15 ± 0.55 Ma granodiorite was emplaced in the center of the pluton at a depth of ~ 2.5 km. Crystallization depths are supported by the pressure estimates from Al-in-hornblende in rocks of the contact aureole. (v) Cross-cutting diorite dykes were emplaced at ~ 2.5 km, but they contain phenocrysts of magnesio-hastingsite that had crystallized at 894 ± 55 °C and ~ 23 km depth during ascent of the magma, followed by kaersutite crystallization at temperature decreasing to 744 ± 15 °C at ~ 12 km depth.

矿物成分提供了有关花岗岩的成因和构造环境的关键信息。这些关系在本论文中得到解决，该论文的重点是伊朗东部 Zahedan 附近的始新世 Gapdan 岩体。岩体是侵入到锡斯坦缝合带晚白垩世至中始新世复理石的花岗岩组的一部分。它被划分为中心的花岗闪长岩和边缘的黑云母花岗岩，并被晚闪长岩脉横切。围岩为中低品位黑云母片岩，含有次生角闪岩。黑云母是加普丹花岗岩中唯一的铁锰矿矿物，与钙碱性和I型亲和力一致，并在与弧有关的构造环境中形成。热气压和地质年代学，结合岩性观测，建立以下事件序列：(i) 与锡斯坦大洋板块俯冲和大洋盆地关闭相关的地幔熔化，玄武质岩浆的产生，最后在上升过程中地壳熔化和与地壳熔体的杂交。(ii) 在 44.31 ± 0.21 Ma，由此产生的花岗岩岩浆在 4–5.4 ± 1 km 深度结晶；黑云母和长石温度计显示的结晶温度分别为 ~850˚C 和 ~730˚C。(iii) 这一阶段受到构造控制，岩体被挖掘到约 2.5 公里的较浅地壳水平，在花岗岩上形成糜棱岩结构。(iv) 在 42.15 ± 0.55 Ma 花岗闪长岩被安置在岩体中心约 2.5 公里的深度。接触光环岩石中角闪石中铝的压力估计值支持结晶深度。