Crustal Formation and Assembly in the NW Pacific: Aleutians and Kamchatka

西北太平洋的地壳形成和组装：阿留申群岛和堪察加半岛

• 批准号: 9406195
• 负责人: Robert Kay
• 金额: $ 5.38万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-08-15 至 1996-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9406195&HistoricalAwards=false
• 关键词: Crustal; Formation; Assembly; NW; Pacific

9406195 Kay Throughout Tertiary time, Kamchatka has collected fragments of continental crust (terranes) that formed as oceanic island arcs and plateaus in the Bering Sea and the Pacific Ocean. Accretion of the fragments has resulted in a subcontinental mass. The process is thought by many to be the main mechanism of present day continental growth. Kamchatka is a particularly good site to study this type of continental growth due to its youth, due to the availability of information on similar but as yet unaccreted oceanic fragments (especially, the Aleutian islands) and due to widespread post-accretion magmatism that records conditions at depth. This investigation focuses on alkaline basaltic magmas that originate in mantle that lies under the Kamchatka terranes. Existing trace element data on these magmas lack typical signatures (e.g. high Ba/La, La/Ta ratios), and support delamination models that call fro wholesale replacement of mantle lithosphere by underlying Oceanic Island Basalt (OIB)-like asthenosphere. Isotope analyses (Pb, Sr, Nd) as well as additional trace element analyses will permit identification of mas reservoirs and quantification of mas fluxes related to fundamental processes of crustal growth and consolidation.

9406195 Kay在整个第三纪时期，堪察加半岛收集了白令海和太平洋中形成为海洋岛弧和高原的大陆地壳碎片。 碎片的增生形成了次大陆块体。 这个过程被许多人认为是当今大陆生长的主要机制。 堪察加半岛是一个特别好的网站，研究这种类型的大陆增长，由于它的年轻，由于类似的，但尚未增生的海洋碎片（特别是阿留申群岛）的信息的可用性，并由于广泛的后吸积岩浆作用，记录在深度的条件。 本次调查的重点是碱性玄武岩浆，起源于地幔，位于堪察加半岛。 这些岩浆的现有微量元素数据缺乏典型的签名（如高Ba/La，La/Ta比值），并支持分层模型，呼吁从地幔岩石圈的底层大洋岛玄武岩（OIB）的软流圈大规模更换。 同位素分析（铅，锶，钕）以及额外的微量元素分析将允许识别的质量水库和量化的质量通量有关的地壳生长和巩固的基本过程。