ALEUTIAN ARC MAGMATISM IN SPACE AND TIME: A GEOCHEMICAL AND PETROLOGIC STUDY

阿留申岛弧岩浆作用的空间和时间：地球化学和岩石学研究

• 批准号: 8707577
• 负责人: Robert Kay
• 金额: --
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-07-01 至 1989-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8707577&HistoricalAwards=false
• 关键词: ALEUTIAN; ARC; MAGMATISM; SPACE; TIME

Magmatic processes occurring over an entire island are crustal section are reflected in rock units found in the Aleutian arc, Alaska. These processes assume more than local importance in that they have shaped a large proportion of terrane collagesw, and perhaps the continental crust in general. In the Aleutian arc, most on-going magmatic studies emphasize recent volcanic rocks. To complete the crustal cross-section, this project will focus on the more voluminous subvolcanic levels as represented by plutons and xenolithic fragments. Specific studies are proposed for plutonic xenoliths from Tertiary volcanic rocks on Kanaga Island and the Hidden Bay pluton on Adak Island in the central Aleutians. These rock units indicate a buried oceanic crustal component in the Aleutian lithosphere and record details of the processes of magmatic segregation in the crust. In the western Aleutians on Attu Island and in the Komandorski Islands (USSR), a striking pattern of Tertiary magmatic evolution reflects changes in plate convergence. On Attu, specific studies are planned to study these changing magmatic conditions as reflected by Oligocene rhyolites, lower-Miocene alkaline rocks, and upper- Miocene calc-alkaline lavas. The evolution of subcrustal magma sources (including alkaline sources) and the crustal assimilation and fractional crystallization of calc-alkaline magmas intruding back-arc crust will be studied. Analytical studies include mineralogical analyses of major and trace elements as well as isotopes (O, Sr, and Nd). These are to be used uespectively as tracers of physical conditions (P, T, volatile fugacities) and isotopically distinct tectonic units.

在整个岛上发生的岩浆过程是地壳部分，反映在阿拉斯加的阿留格特人弧中发现的岩石单元中。 这些过程比当地的重要性更重要，因为它们塑造了大部分的地形collagesw，也许是大陆地壳。 在阿留申弧中，大多数正在进行的岩浆研究都强调了最近的火山岩。 为了完成地壳横截面，该项目将集中在岩石和异种石器时代片段所示的更大量的亚volcolcanic水平上。 提出了针对卡纳加岛第三纪火山岩和中央阿留申岛Adak岛的隐藏湾冥王星的冥王星异种石的具体研究。 这些岩石单元表明阿留申岩石圈中的一个被埋入的海洋地壳成分，并记录了地壳中岩浆隔离过程的细节。 在阿图岛（Attu Island）和科曼多斯基群岛（Komandorski Islands）（苏联）的西部阿留申岛（Aletarians）中，大三级岩浆进化的一种引人注目的模式反映了板块收敛的变化。 在ATTU上，计划研究这些不断变化的岩浆条件，如渐新线流纹岩，下新世碱性岩石和上新世钙碱性熔岩所反映的那样。 将研究侵入后弧形地壳的钙含量同化和分数结晶的地壳岩浆源（包括碱性源）的演变。 分析研究包括对主要元素和同位素的矿物学分析（O，SR和ND）。 这些将被视为物理条件的示踪剂（P，T，挥发性逃犯）和同位素不同的构造单位。