Determination of the Magnitude of Metasediment-Derived Melt Assimilation in the Southern Sierra Nevada Batholith

内华达山脉南部基岩中变沉积物衍生的熔体同化程度的测定

基本信息

批准号：
9815024
负责人：
Jason Saleeby
金额：
$ 10.3万
依托单位：
California Institute of Technology
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
1998
资助国家：
美国
起止时间：
1998-12-01 至 2001-11-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=9815024&HistoricalAwards=false
关键词：
Determination Magnitude Metasediment Derived Melt

项目摘要

9815024SaleebyThis study is a petrologic investigation of the high temperature metamorphism and migmatization of mid- crustal pelitic pendants from the southern Sierra Nevada batholith, California. The primary goals are: (1) determine the extent of partial melting of batholith metasedimentary pendants during the large scale plutonism, and (2) quantify the efficiency of two-component mixing between batholith- and pendant-derived melts and the incorporation of pendant melts into large granitoid plutons. This study is designed to test the importance of assimilation of pre-existing shallow crust in the mass budget of the composite batholith. The pelites of the study area underwent extensive high-grade metamorphism and local migmatization in response to the intrusion of large granitoid plutons during the late Cretaceous. The isotopic ratios of Sr, Nd, and O of the batholithic rocks and the compositionally uniform pelite are distinct in the area. Hence, these isotopic ratios will be used as the principal tool in order to: (1) distinguish between batholith-derived and pelite-derived melts, and (2) constrain the mixing between the two in both migmatitic leucosomes and within the batholith. Petrographic studies of mineral and melting reactions within the migmatitic pelite as well as major and trace element chemistry will complement the isotopic data. The significance of crustal hybridization of Cordilleran batholiths with partial melts from metasedimentary host rocks is a controversial topic with important applications to quantifying crustal recycling in Phanerozoic magmatic arcs. This study should put important constraints on the extent and limits of such assimilation and hybridization.

9815024 SaleebyThis研究是对来自加利福尼亚州塞拉山脉南部内华达州南部山利岩的高温变质和中壳毛状吊坠的岩石学研究。主要目标是：（1）确定在大规模plutonism期间沐浴岩底层吊坠的部分熔化程度，（2）（2）量化巴达斯（Batholith）和吊坠衍生的熔体之间的两种组分混合的效率，以及将吊坠融合到大型粒状plutons中。这项研究旨在测试复合浴石质量预算中既有浅层地壳的同化的重要性。研究区域的小脑材经历了广泛的高级变质和局部夹层，以响应晚白垩纪晚期的大花岗岩岩体的侵入。 SR，ND和O的同位素比在该区域与茎岩石的O和O构图均匀的螺旋岩是不同的。因此，这些同位素比将用作主要工具，以：（1）区分浴力石衍生和黑质衍生的熔体，（2）（2）约束两者中两者之间在Migmatitic白细胞体中的混合之间的混合。岩岩纤维中的矿物质和熔化反应以及主要和痕量元素化学的岩石学研究将补充同位素数据。羊皮兰沐浴石的地壳杂交具有与沉积物宿主岩石的部分熔体的重要性是一个有争议的话题，具有量化质量岩层岩浆弧中的地壳回收利用的重要应用。这项研究应在这种同化和杂交的程度和限制上施加重要限制。