Provenance and Sedimentologic Constraints on a Microconti- nent-Continent Collision, Gravina Belt, Southeast Alaska

通过微大陆的加积作用的大陆生长 造山运动是一个重要的造山过程，但人们对其了解甚少。 弗兰吉利亚-亚历山大超级杯是最好的之一 在科迪勒拉山脉西部有记录的微大陆， 立即了解其构造和沉积历史 早在白垩纪的时候 该项目是一个详细的 西摩运河物源和沉积学研究 重力带的形成及侏罗-白垩纪层序 复理石和火山岩沉积在内侧斜坡的 最终关闭前的弗兰吉利亚-亚历山大微大陆， 以限制这种碰撞的性质。 项目 将集中在格拉梅西带的少量变质部分， 进行砂岩和砾岩的岩相学研究 碎屑，再加上斜长石的矿物化学研究， 砂岩和火成岩中的单斜辉石， 物源和构造环境 它将整合浊积岩 岩相分析、遗迹相和古水流研究 为了重建盆地历史， 结合新微体化石的沉积格架 火山岩和碎屑岩放射性测年生物地层学 使用氩气40/39方法测定黑云母和角闪石颗粒。 这些 研究将有助于记录沉积学和构造过程 在这次微大陆碰撞中起作用， 对其他更神秘的侏罗纪-白垩纪复理石的初步研究 科迪亚克山脉的盆地。

Continental growth by the accretion of microcontinental terranes is an important but poorly understood orogenic process. The Wrangellia-Alexander superterrane is one of the best documented microcontinents in the western Cordillera, yet little is known of its tectonic and depositional history immediately prior to its Cretaceous accretion. This project is a detailed study of the provenance and sedimentology of the Seymour Canal Formation of the Gravina belt, and Jura-Cretaceous sequence of flysch and volcanic rocks deposited on the inboard slope of the Wrangellia-Alexander microcontinent prior to final closure, in order to constrain the nature of this collision. The project will focus on little-metamorphosed portions of the Gravina belt, and carry out petrographic studies of sandstones and conglomerate clasts, coupled with mineral chemistry studies of plagioclase and clinopyroxene in sandstones and igneous rocks to establish provenance and tectonic setting. It will integrate turbidite lithofacies analysis and ichnofacies and paleo- current studies in order to reconstruct basin history, and refine the temporal framework of deposition by combining new microfossil biostratigraphy with radiometric dating of volcanic and detrital biotite and hornblende grains using Argon 40/39 methods. These studies will help document sedimentologic and tectonic processes operative in this microcontinent collision, and may serve as a pilot study for other, more enigmatic Jura-Cretaceous flysch basins of the Cordilleran.