Tectonic Setting and Magmatic Evolution of Eastern Laurentia in Late Paleozoic Time: Constraints from High Precision U-Pb Dating of Alleghanian Granites

;​你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是说你是4 @, -。/ 0 1 2 3 4 5 6 F Microsoft Word 6.0 Document MSWordDoc。6;​\WW60\CLIPART AUTOSAVE-PATH=R:\WWUSER PROGRAMDIR=N:\WW60 TOOLS-PATH=N:\WW60 STARTUP- path =R:\WWUSER\STARTUP - path =R:\WWUSER DOC-PATH=R:\WWUSER连字符1033,0=N:\WW60\HYPH.DLL,N:\WW60\HY_EN。LEX语法103,0 =N:\WW60\GRAM.DLL,N:\WW60\GR_AM。阿巴拉契亚山脉南部阿利哈尼亚造山运动中最不为人所知的一个方面是伴随造山运动的花岗岩岩浆的起源。确定花岗岩的构造背景直接关系到我们对劳伦西亚东部晚古生代构造演化的认识。关于阿勒卡尼期岩体的成因和构造背景，人们提出了多种模式，包括它们在西倾俯冲体系中形成、岩石圈拆沉作用下的形成、热覆盖作用下的形成以及地壳拱起作用下的挤压作用下的形成。这些模型的广泛差异反映了缺乏一个连贯的岩体地球化学数据库和缺乏高精度的花岗岩结晶年龄。最近的工作为阿勒卡尼亚花岗岩提供了大量的化学和同位素数据集，对可能的来源区域提出了重要的新限制。然而，目前缺乏花岗岩的精确年龄限制了我们在地球化学数据中检测时间趋势的能力，限制了花岗岩的构造背景，以及破译阿巴拉契亚地体未暴露部分的性质。本研究将利用高精度U-Pb锆石和独居石年代学技术，确定阿巴拉契亚南部所有主要岩石构造带的阿勒卡尼期岩体的结晶年龄。本研究的目的是：(1)确定阿勒卡尼期岩浆活动的开始和持续时间；(2)确定时间地球化学趋势是否存在(3)通过锆石异晶定年进一步确定未暴露的阿巴拉契亚地壳的性质；(4)通过对构造前、构造同期和构造后的岩体定年，限定了选定地体的变形事件时间。;Oh +' 0 $ H l D H R:\WWUSER\TEMPLATE\NORMAL。费莉西娅：你是我的朋友，我是你的朋友，我是你的朋友，我是你的朋友史密斯费利西亚史密斯@ @ @ @微软Word 6.0 1;e = e j j j j j j j j j Q 1 3 t5 Q j Q j j j j j j j阿巴拉契亚山脉南部阿利哈尼亚造山运动的一个鲜为人知的方面是伴随造山运动的花岗质岩浆的起源。确定花岗岩的构造背景直接关系到我们对劳伦西亚东部晚古生代构造演化的认识。关于阿勒卡尼期岩体的成因和构造背景，人们提出了多种模式，包括它们在西倾俯冲体系中形成、岩石圈拆沉作用下的形成、热覆盖作用下的形成以及地壳拱起作用下的挤压作用下的形成。这些模型的广泛差异反映了缺乏一个连贯的岩体地球化学数据库和缺乏高精度的花岗岩结晶年龄。最近的工作为阿勒卡尼亚花岗岩提供了大量的化学和同位素数据集，对可能的来源区域提出了重要的新限制。然而，目前缺乏花岗岩的精确年龄限制了我们探测时间趋势的能力

; R o o t E n t r y F u C o m p O b j b W o r d D o c u m e n t O b j e c t P o o l u u 4 @ , - . / 0 1 2 3 4 5 6 F Microsoft Word 6.0 Document MSWordDoc Word.Document.6 ; \WW60\CLIPART AUTOSAVE-PATH=R:\WWUSER PROGRAMDIR=N:\WW60 TOOLS-PATH=N:\WW60 STARTUP-PATH=R:\WWUSER\STARTUP INI-PATH=R:\WWUSER DOC-PATH=R:\WWUSER Hyphenate 1033,0=N:\WW60\HYPH.DLL,N:\WW60\HY_EN.LEX Grammar 1033,0=N:\WW60\GRAM.DLL,N:\WW60\GR_AM.LEX 9526823 Samson One of the least understood aspects of the Alleghanian orogeny in the southern Appalachians is the origin of the granitic magmas that accompanied orogensis. Determining the tectonic setting of the granites is directly linked to our understanding of the tectonic evolution of eastern Laurentia during late Paleozoic time. Various models have been proposed to explain the origin and tectonic setting of the Alleghanian plutons, including their formation in a west dipping subduction system, generation by lithospheric delamination, generation by thermal blanketing, and formation in a transpressional regime by crustal arching. The wide variation in these models reflects the lack of a coherent geochemical data base for the plutons and a paucity a high precision crystallization ages for the granites. Recent work has produced a large chemical and isotopic data set for the Alleghanian granites that places significant new constraints on likely source regions. However, the current lack of precise ages of the granites limits our ability to detect temporal trends in the geochemical data, constra in the tectonic setting of the granites, and to decipher the nature of the unexposed portions of Appalachian terranes. This study will determine crystallization ages of Alleghanian plutons from all of the major southern Appalachian lithotectonic belts by using high-precision U-Pb zircon and monazite geochronologic technique. The goals of the study are to (1) determine the initiation and duration of Alleghanian magmagenesis; (2) determine whether temporal geochemical trends exist (3) determine further the nature of unexposed Appalachian crust by dating zircon xenocrysts; and (4) constrain the timing of deformation events in selected terranes by dating pre-, syn- and post-tectonic plutons. ; Oh +' 0 $ H l D h R:\WWUSER\TEMPLATE\NORMAL.DOT 9526823 Felicia S u m m a r y I n f o r m a t i o n ( + Smith Felicia Smith @ @ @ @ Microsoft Word 6.0 1 ; e = e j j j j j j j Q 1 3 T 5 Q j Q j j j j ~ j j j j 9526823 Samson One of the least understood aspects of the Alleghanian orogeny in the southern Appalachians is the origin of the granitic magmas that accompanied orogensis. Determining the tectonic setting of the granites is directly linked to our understanding of the tectonic evolution of eastern Laurentia during late Paleozoic time. Various models have been proposed to explain the origin and tectonic setting of the Alleghanian plutons, including their formation in a west dipping subduction system, generation by lithospheric delamination, generation by thermal blanketing, and formation in a transpressional regime by crustal arching. The wide variation in these models reflects the lack of a coherent geochemical data base for the plutons and a paucity a high precision crystallization ages for the granites. Recent work has produced a large chemical and isotopic data set for the Alleghanian granites that places significant new constraints on likely source regions. However, the current lack of precise ages of the granites limits our ability to detect temporal trends i