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是一组构造地层地体，它们在前寒武纪晚期合并在一起，在古生代中早期以复合地体的形式增生到北美洲，并在随后分散到不同的距离。复合地体内部组成地体元素的识别一直存在争议，其构造热演化不确定，合并、增生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省西南部阿瓦隆复合地体的代表性部分进行全面的结构和40Ar/39Ar地质年代学研究来解决这些问题，最近的研究表明，该地区可能存在一个重要的前寒武纪晚期地体边界。40Ar//39Ar同位素测量结果表明，研究区具有重要的同位素贡献。该项目将详细的构造填图、运动学分析和岩石学研究与40Ar/39Ar矿物定年相结合，旨在解决该地区的构造热演化问题。该研究将大大提高人们对阿瓦隆复合地体记录的构造热事件的性质、时间和运动学的认识，从而极大地促进了晚前寒武纪地体组成的识别和对比。

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.