Nd-Sr Isotopes and the Tectonic Significance of the Paleo- zoic Acatlan Complex, Southern Mexico

本研究旨在了解北美洲南部克拉通和加勒比海地区的构造史，特别是古生代（?）阿卡特兰变质杂岩（与古生代海洋闭合有关）和格伦维尔时代（1Ga）瓦哈坎结晶杂岩（高品位麻粒岩地体）。这些复合体类似于北美东部的阿巴拉契亚-加里多尼亚造山带和格伦维尔造山带，只是它们具有“反向极性”（即阿卡特兰在瓦哈卡西部，而阿巴拉契亚-加里多尼亚造山带在格伦维尔东部）。一个目标是确定这些带是否确实相关（在这种情况下，墨西哥暗示了构造重组），或者阿卡特兰是否是一个与阿巴拉契亚无关的太平洋大陆。重点将放在acatlan详细的Rb-Sr和Sm-Nd地质年代学上，以及相对于墨西哥中北部以下地壳的同位素演化。

The proposed research is aimed at understanding tectonic history of the southern N. American craton and the Caribbean region - especially the relations between the Paleozoic (?) Acatlan metamorphic complex (related to closure of a Paleozoic ocean) and the Grenville age (1Ga) Oaxacan crystalline complex (high-grade granulite terrane). These complexes are analogous to the Appalachian-Caledonian and Grenville orogenic belts of eastern N. America except that they have 'reversed polarity' (i.e. Acatlan is west of Oaxacan, whereas appalachian-Caledonian is east of Grenville). One goal is to determine if these belts actually correlate (in which case tectonic reorganization is implied in Mexico) or if Acatlan is an accreted Pacific terrane unrelated to Appalachia. Emphasis will be on detailed Rb-Sr and Sm-Nd geochronology of acatlan, and on its isotopic evolution relative to the crust below north-central Mexico.