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凯莱门该项目是对塔尔凯特纳岛弧（阿拉斯加）裸露地壳剖面进行的一项多年期跨学科研究，目的是探讨会聚边缘大陆生长的速度和机制。 塔尔凯特纳弧段，特别是在内尔希纳-通西纳地区，是一个地壳剖面，穿过一个增生的、与侏罗纪俯冲有关的岩浆弧，从顶部的火山岩、火山碎屑岩和沉积岩到底部的残留地幔橄榄岩。 对暴露的岛弧剖面进行详细研究可以在地球物理观测和地球化学蛇绿岩研究之间提供一个关键的联系，为海洋地球物理学和洋中脊玄武岩分析提供了一个理想的对照点，有助于全面了解大洋扩张脊的地壳增生情况，研究未来十年的弧岩浆作用和地壳成因。会聚边缘的大陆生长速度和机制是什么？ 塔尔凯特纳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，这些地壳一般不暴露在活动弧中。 PI将应用各种分析技术来解决地壳成因的各个方面：1）改进的地质测绘; 2）确定下地壳岩石的变形历史，寻找断层和缺失部分; 3）对该部分典型岩石进行物理性质测量; 4）对残余地幔方辉橄榄岩和地壳底部的火成超镁铁质岩进行详细调查; 5）在弧形地壳剖面中描绘出液体下降线; 6）岩石学和微量元素模拟; 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.***