Early Thrust Nappes and Late Metamorphic Shear Zones in Acadian Tectonic Development and Metamorphism, Central Massachusetts and Adjacent New Hampshire and Connecticut

泥盆纪阿卡迪亚造山运动是北美和东部大陆物质碰撞构造的结果。阿卡迪亚的构造发育包括早期褶皱和逆冲推覆，随后是复杂的后褶皱，并伴有构造和变质构造。变质等梯度模式和重建的P-T轨迹与变形阶段有着复杂的关系。这一结合构造和岩石学的研究旨在建立一个更清晰、年代更精确的构造和热史。马萨诸塞州中部的高变质等级暴露可以与北部的含化石单元相关联，因此，允许地层层序成为理解大规模构造特征和变质矿物生长模式的有用工具，将用于确定变形和热事件的相对年龄，并评估不同岩石所承受的压力和温度条件的顺序。研究结果将有助于更全面地了解这一主要山带发育过程中的地壳中过程。

The Devonian Acadian orogeny was the result of collisional tectonics involving North America and continental material to the east. Acadian tectonic development involved early fold and thrusts nappes followed by complex back folding with structural and metamorphic fabrics accompanying stages. The pattern of meta- morphic isograds and reconstructed P-T trajectories bear a complex relationship to the deformation stages. This combined structural and petrologic study is aimed at developing a clearer and chronologically more precise tectonic and thermal history of the belt. Exposures of high metamorphic grade in central Massachusetts can be correlated with fossil-bearing units to the north, thus allowing stratigraphic sequence to be a useful tool in understanding the pattern of large-scale structural features and the growth of metamorphic minerals will be used to establish the relative ages of deformation and thermal events and to evaluate the sequence of pressure and temperature conditions to which different rocks were subjected. Results will help develop a fuller understanding of mid-crustal processes during the develop- ment of this major mountain belt.