COLLABORATIVE RESEARCH: 40 Ar/39 Ar and Structural Investi-gation and Constraints on the Tectonothermal Evolution of the Avalon Composite Terrane in SW New Brunswick

阿巴拉契亚造山带北部的阿瓦隆复合地体代表了一组构造地层地体，它们在晚前寒武纪合并，在早、中古生代作为复合地体增加到北美，随后彼此分散成不同距离的地体。复合地体中组成地体元素的识别一直存在争议，它们的构造热演化尚不确定，合并、沉积和扩散的性质和时间限制较差。该项目将通过对新不伦瑞克西南部具有代表性的阿瓦隆复合地体的一部分进行全面的结构和40Ar/39Ar年代学研究来解决这些问题，最近的研究表明，那里可能存在一个重要的晚期前脑地体边界。~(40)Ar//~(39)Ar同位素普查结果表明，在拟议的研究区可以做出重大贡献。该项目将详细的构造制图、运动学分析和岩石学研究与40Ar/39Ar矿物测年程序结合起来，旨在解决该地区的构造热演化问题。这项研究将大大提高对阿瓦隆复合地体中记录的构造热事件的性质、时间和运动学的认识，从而极大地促进晚前寒武纪地体成分的识别和对比。

The Avalon composite terrane of the northern Appalachian orogen represent a college of tectonostratigraphic terranes that were amalgamated in the late Precambrian, accreted as a composite terrane to North America during the early-middle Paleozoic, and were subsequently dispersed variable distances relative to each other. Identification of the constituent terrane elements within the composite terrane has been controversial, their tectonothermal evolution is uncertain, and the nature and timing of amalgamation, accretion and dispersal are poorly constrained. This project will address these issue through a comprehensive structural and 40Ar/39Ar geochronological study of a representative portion of the Avalon composite terrane in southwestern New Brunswick where recent studies have shown an important late Precambrain terrane boundary may exist. Results of a reconnaissance 40Ar//39Ar isotopic survey indicate that a significant contribution can be made in the proposed study area. The project couples detailed structural mapping kinematic analysis and petrological studies with a program of 40Ar/39Ar mineral dating designed to resolve the region's tectonothermal evolution. The study will substantially improve knowledge of the nature, timing and kinematics of tectonothermal events recorded in the Avalon composite terrane and, thereby, will greatly facilitate the identification and correlation of constituent late Precambrian terranes.