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在丫江桥过铝花岗岩中,锆石可以分作两期,分别形成于岩浆定位前的深部岩浆房内和岩浆定位后的侵入部位,这两期锆石的原位Hf同位素分析揭示,该花岗岩浆主要来自地壳物质的深部熔融.然而,部分较高的176Hf/177Hf数据表明,这些花岗质锆石中可能包裹了形成于幔源岩浆的细小锆石(其粒径小于激光束斑),事实上,背散射电子图像和电子探针分析显示,在部分第1期锆石内部存在着另一种形态和成分不同的锆石晶体,它们可能是在花岗质岩浆形成初期混入的幔源岩浆中的结晶产物.因此,推测丫江桥过铝花岗岩的产生与地幔岩浆的底侵怍用有联系.
In the Yajiangqiao peraluminous granite, the zircons can be divided into two phases, which are formed in the deep magma chamber before the magma locating and the intruded parts after the magma locating. The in situ Hf isotopic analysis of these two stages of zircons reveals that the However, some of the higher 176Hf / 177Hf data suggest that these granitic zircons may enclose small zircons formed in mantle magma (smaller than the laser beam spot size) In fact, backscattered electron image and electron probe analysis showed that there was another zircon crystal with different morphology and composition in the part of the first period zircons, which may be the mantle mixed in the early stage of granitic magma formation Therefore, it is speculated that the formation of Yijiangqiao peraluminous granite is related to the intrusion of mantle magma.