Constraints of the Genesis of Continental Crust via Arc Magamatism: Geology, Geochemistry, Structure and Physical Properties of the Talkeetna Arc Section South Central Alaska

[9910899] kelemen这个项目是对Talkeetna岛弧（阿拉斯加）裸露的地壳部分进行多年的跨学科研究，以解决大陆在辐合边缘生长的速度和机制。Talkeetna弧段，特别是Nelchina-Tonsina地区的Talkeetna弧段，是一个通过增生的侏罗纪俯冲岩浆弧的地壳剖面，从顶部的火山、火山碎屑岩和沉积岩到底部的残余地幔橄榄岩。对暴露的岛弧剖面的详细研究可以提供地球物理观测和地球化学之间的关键联系，蛇绿岩研究为海洋地球物理学和海洋中脊玄武岩分析提供了理想的对照，有助于在未来十年中全面了解海洋扩张脊的地壳增生、弧岩浆作用和地壳成因的研究。该项目解决了一个关于弧过程的关键问题：大陆在辐合边缘的增长速度和机制是什么？Talkeetna剖面的工作可以对中下弧地壳的组成和增生时间提供关键的限制，这些地壳通常不会在活动弧中暴露出来。P.I.s将处理地壳成因的各个方面，应用各种分析技术：1)改进地质制图；2)确定下地壳岩石变形史，寻找断层和缺失剖面；3)剖面典型岩石物性测量；4)详细研究了地壳底部残余地幔黑子岩和火成岩；5)圈定弧形地壳剖面的液体下降线；6)岩石学和微量元素建模；7)确定下地壳的P-T-t历史

9910899KelemenThis project is for a multi-year, interdisciplinary study of the exposed crustal section of the Talkeetna island arc (Alaska) to address the rate and mechanism of continental growth at convergent margins. The Talkeetna arc section, particularly in the Nelchina-Tonsina region, is a crustal section through an accreted, Jurassic subduction-related magmatic arc, from volcanic, volcaniclastic and sedimentary rocks at the top to residual mantle peridotites at the base. Detailed studies of exposed, island arc sections can provide a crucial link between geophysical observations and geochemical ophiolite studies have provided an ideal counterpoint to both marine geophysics and analysis of mid-ocean ridge basalts in developing a complete picture of crustal accretion at oceanic spreading ridges, studies of arc magmatism and crustal genesis over the coming decade.The project addresses a key question regarding arc processes: What is the rate and mechanism of continental growth at convergent margins? Work on the Talkeetna section can provide crucial constraints on the composition and timing of accretion of the middle and lower arc crust, which are generally not exposed in active arcs. The P.I.s will address various aspects of crustal genesis, applying a variety of analytical techniques: 1) improved geological mapping; 2) determine deformation history of lower crustal rocks, look for faults and missing sections; 3) physical properties measurements on typical rocks in the section; 4) detailed investigations of residual mantle harzburgites and igneous utlramafic rocks at base of crust; 5) delineate liquid lines of descent in the arc crustal section; 6) petrological and trace element modeling; and 7) determine the P-T-t history of the lower crust.***