Pressure-Temperature-Time Evolution of the Acadian Orogen, Central New England: Constraints from Detailed Petrologic and Geochronologic Studies: Collaborative Research

这项提案是伦斯勒理工学院的F.S. Spear和纽约州立大学奥尔巴尼分校的T.M. Harrison共同努力的结果。提出的研究目的是确定阿卡迪亚造山运动期间新英格兰中部变质岩的压力-温度-时间路径。选定的研究区域包括四个横断面，横跨马萨诸塞州中部、新罕布什尔州南部和佛蒙特州以及新罕布什尔州北部。利用岩石学技术，包括地温测压法、分带变质母细胞法、成岩格网法和结构分析，确定不同构造层次岩石的变质作用压力-温度路径。通过分析与织物发育有关的矿物生长，P-T路径将与结构演化相关联。通过对角闪石、白云母、黑云母和钾长石中40ar / 39ar释放光谱的分析，获得了岩石冷却历史的年龄约束。澳大利亚国立大学SHRIMP离子探针的锆石年代学将用于获得岩体侵位的绝对年龄，并限制构造发育的时间。本研究的最终目的是获得阿卡迪亚造山运动期间地壳热构造行为的四维（x-y-z-时间）控制。预计这些结果将使人们对碰撞造山过程中大陆岩石圈的演化有一个更好的认识。

This proposal represents a collaborative effort between F.S. Spear of Rensselaer Polytechnic Institute and T.M. Harrison of SUNY-Albany. The objective of the proposed research is the determination of pressure-temperature-time paths for metamorphic rocks from central New England during the Acadian orogeny. The areas chosen for study comprise four transects across central Massachusetts, southern New Hampshire and Vermont, and northern new Hampshire. Pressure-temperature paths of metamor- phism will be determined for rocks of different structural levels utilizing a combination of petrologic techniques including geothermobarometry, zoned metamorphic prophyroblasts, petrogenetic grids, and textural analysis. P-T paths will be correlated with structural evolution through analysis of mineral growth in relation to fabric development. Age constraints on the cooling histories of the rocks will be obtained from analysis of 40 Ar/39 Ar release spectra in hornblende, muscovite, biotite and K-feldspar. Zircon chronology on the ANU SHRIMP ion microprobe will be used to obtain absolute ages on pluton emplacement and to constrain the timing of structural development. The ultimate goal of this research is to obtain 4- dimensional (x-y-z-time) control on the thermo-tectonic behavior of the crust during the Acadian orogeny. It is anticipated that these results will lead to an improved understanding of the evolution of the continental lithosphere during collisional orogenesis in general.