Collaborative Research: Argon Retentivity and Closure Temperature in Micas and Amphiboles

该项目涉及对天然角闪石和云母中控制Ar保留、Ar闭合温度和40Ar/39Ar冷却年龄的成分和其他因素的合作、多方面和多学科的研究。基本研究目标是：(1)确定二八面体云母、三八面体云母和常见角闪石中氩保持力的组分依赖性；(2)研究晶界和亚晶域对Ar保留率的影响；(3)研究这些矿物中Ar的扩散几何形状或各向异性；(4)严格检验Ar保留的离子孔隙模型，其次检验Sr和Ca的离子孔隙模型；(5)完善了我们对影响Ar输运和闭合温度的晶体学因素的基本认识；(6)增加了对选定造山带冷却历史的现有知识。拟议工作的实地方面将集中在纽约州的阿迪朗达克山脉和SD的黑山。

9614822 Dahl This project involves a collaborative, multi-faceted, and multi-disciplinary investigation of compositional and other factors governing Ar retention, Ar closure temperature, and 40Ar/39Ar cooling ages in natural amphiboles and micas. The fundamental research objectives are to: (1) determine the compositional dependence of Ar retentivity within dioctahedral and trioctahedral micas and common amphiboles; (2) examine the role of grain boundaries and sub-grain domains on Ar retentivity; (3) examine the diffusion geometry or anisotropy of Ar in these minerals; (4) test rigorously the ionic-porosity model for Ar retention, and secondarily for Sr and Ca; (5) refine our basic understanding of the crystallographic factors influencing Ar transport and closure temperatures, and (6) add to existing knowledge of cooling history in selected orogenic terranes. The field aspect of the proposed work will be focussed in the Adirondack Mountains, NY, and the Black Hills, SD.