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

9614822 DAHL这个项目涉及对天然角闪石和云母中Ar保留量、Ar封闭温度和40Ar/39Ar冷却年龄的成分和其他因素进行合作、多方面和多学科的调查。基本的研究目标是：(1)确定双八面体和三八面体云母和普通角闪石中Ar保留率的成分依赖关系；(2)研究晶界和亚晶域对Ar保留率的作用；(3)研究Ar在这些矿物中的扩散几何形状或各向异性；(4)严格测试Ar保留量的离子孔洞模型，其次是锶和钙；(5)完善我们对影响Ar输运和闭合温度的结晶学因素的基本认识，以及(6)增加对选定造山带地体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南达科他州的黑山。

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.