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

这项提议是伦斯勒理工学院的F.S.斯皮尔和纽约州立大学奥尔巴尼分校的T.M.哈里森共同努力的结果。这项研究的目的是确定来自新英格兰中部的变质岩在阿卡迪亚造山期间的压力-温度-时间路径。选择进行研究的地区包括马萨诸塞州中部、新罕布夏州南部和佛蒙特州以及新罕布夏州北部的四个横断面。将综合运用地热压力法、分区变质斑岩、岩石成因格网和结构分析等岩石学技术，为不同构造层次的岩石确定变质压力-温度路径。通过分析矿物生长与组构发育的关系，将P-T路径与构造演化联系起来。角闪石、白云母、黑云母和钾长石的40Ar/39Ar释放谱的分析将得到岩石冷却历史的年龄限制。ANU SHRIMP离子微探针上的锆石年代学将用于获得岩体侵位的绝对年龄，并限制构造发展的时间。这项研究的最终目的是获得对阿卡迪亚造山过程中地壳热构造行为的四维(x-y-z-time)控制。预计这些结果将有助于更好地了解大陆岩石圈在碰撞造山过程中的演化。

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.