Collaborative Research: Sourcing A-type Granites in Ancient Rifts

Hogan：俄克拉荷马裂陷根南部的威奇托花岗岩是侵入大陆裂谷的a型花岗岩的经典例证，为花岗岩来源研究提供了新思路。关于威奇托花岗岩的有限的、新的化学和同位素数据表明，玄武岩是由晶体分选衍生而来的，与大多数先前提出的模型相反，玄武岩的地壳参与较小。从这一重要的A型花岗岩群中选取花岗岩进行化学和同位素联合研究，可以成功地确定地壳裂谷A型花岗岩的成因和成因过程。威奇托花岗岩已经被细分为三个化学组。对选定的花岗岩板材进行纹理、矿物学和化学研究，代表三个化学组，将澄清这些套件。将地球化学数据与同位素数据相结合，将使我们能够看穿分馏效应，从而确定烃源的特征。锆石和钛矿的年代学研究应该确定结晶年龄和潜在的来源年龄。如果要了解a型花岗岩的来源，就需要在构造约束良好的环境中进行这样的研究。

9316144 Hogan The Wichita granites of the Southern Oklahoma Aulacogen, a classic illustration of A-type granites intruded in a continental rift, represent an opportunity to develop new insights into granite sourcing. Limited, new chemical and isotopic data on the Wichita granites suggest derivation by crystal fractionation of basalt with minor crustal involvement contrary to most previously proposed models. A combined chemical and isotopic study of selected granites from this important group of A-type granites can successfully identify sources and processes involved in A- type granite petrogenesis in crustal rifts. The Wichita Granites have already been subdivided into three chemical groups. Textural, mineralogic, and chemical studies of selected granite sheets, representing the three chemical groups, will clarify these suites. Combining geochemical data with isotopic data will allow us to see through fractionation effects in order to characterize sources. Geochronological studies of zircon and titanite should define crystallization ages and potentially source ages. Such a study is required in a well constrained tectonic setting if the source of A-type granites is to be understood.