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Melting Behavior of Mafic Lower Crust in Continental Arcs

大陆弧中镁铁质下地壳的熔化行为

基本信息

批准号：
9805079
负责人：
Allen Glazner
金额：
$ 3万
依托单位：
University of North Carolina at Chapel Hill
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：
1998-08-01 至 2000-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=9805079&HistoricalAwards=false
关键词：
Melting Behavior Mafic Lower Crust

项目摘要

9805079GlaznerWe request one year of funding to complete a study of the relationships between granites and the mafic rocks (diorites and gabbros) commonly accompany them in continental arcs. In many arcs granites bear a strong isotopic resemblance to coeval mafic rocks, suggesting that the two suites are linked by a differentiation process such as fractional crystallization or partial melting. Remelting of mafic lower crust is one way (but not the only way) to generate granitoid magmas with mantle-like isotopic characteristics. We have undertaken a study of the dehydration melting of hornblende gabbros and diorites with variable K2O contents to investigate the origin of granitoid magmas of the Sierra Nevada batholith and elsewhere. Melting experiments at 8 kilobar pressure on Sierran mafic rocks have successfully produced silicic to intermediate liquids similar in composition (including K2O and Na2O) to common I-type granite and granodiorite. We request funding to complete this study. Work to be performed will include further electron microprobe analyses of synthesized mineral phases and glasses, ion microprobe analysis of experimental glasses, and geochemical modeling to test the hypothesis that the granites could be derived by melting of mafic lower crust.

[805079]格拉兹纳我们申请一年的经费，以完成花岗岩与大陆弧中常见的基性岩（闪长岩和辉长岩）之间关系的研究。在许多弧中，花岗岩与同时期的基性岩石具有很强的同位素相似性，这表明这两套花岗岩是通过分异过程（如分异结晶或部分熔融）联系在一起的。基性下地壳的重熔是产生具有地幔样同位素特征的花岗岩岩浆的一种方法（但不是唯一的方法）。我们对可变K2O含量角闪辉长岩和闪长岩的脱水熔融进行了研究，以探讨内华达山脉岩基和其他地区花岗岩岩浆的成因。在8千巴压力下对锡兰基性岩石进行了熔融实验，成功地产生了与普通i型花岗岩和花岗闪长岩组成相似的硅-中间液体（包括K2O和Na2O）。我们请求资金来完成这项研究。将要进行的工作将包括对合成矿物相和玻璃进行进一步的电子探针分析，对实验玻璃进行离子探针分析，并建立地球化学模型，以验证花岗岩可能是由基性下地壳熔融产生的假设。