Collaborative Research: Locating the Mantle Component in Granite

合作研究：定位花岗岩中的地幔成分

• 批准号: 0003660
• 负责人: Daniel Lux
• 金额: $ 9.2万
• 依托单位: University of Maine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-02-01 至 2004-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0003660&HistoricalAwards=false
• 关键词: Collaborative; Research; Locating; Mantle; Component

Hogan, Lux, and GibsonEAR-0003417/0003660/0003694Granitic plutons of the Coastal Maine Magmatic Province (CMMP) commonly display dramatic field relations that record interaction between magmas of markedly different composition (chemical and isotopic) and physical properties. Silicic magma chambers, derived from the crust, received influxes of denser mafic magma that spread out along the floor of these chambers to produce a compositional stratification know as Mafic and Silicic Layered Intrusions (MASLI). The spectacular field relations and large compositional variation in the vicinity of the interface between contrasting magma types are well document by recent studies. In contrast, the extent of physical and chemical coupling between the base of the chamber, that receives mafic influx, and the overlying silicic magma remains poorly understood. Three known or presumed MASLI plutons in the CMMP, the Vinalhaven, Deer Isle, and Mt. Waldo granites, have been selected for study to address this important issue. Specifically, what processes and other factors determine the extent to which heat and material are exchanged between contrasting magma types? Is heat and mass subsequently distributed to the upper reaches of the chamber? By combining textural, compositional and isotopic studies of zoned plagioclase and accessory minerals (using electron and ion-microprobe techniques), along with data for magmatic enclaves from each of the granites, the relative timing and extent of variation in composition of the magma from with individual minerals crystallized can be assessed. Comparison of internal variations among adjacent mineral grains will be used to constrain the relative extent to which material is redistributed within the chamber. Furthermore, studies such as this will enhance our understanding of magma chamber dynamics and growth, enable recognition of the contribution of mantle and crustal components in granite petrogenesis, and evaluate models for the growth and evolution of continental lithosphere.

霍根、勒克斯和吉布森-0003417/0003660/0003694沿海缅因州岩浆区（CMMP）的花岗岩岩体通常显示出戏剧性的场关系，记录了成分（化学和同位素）和物理性质明显不同的岩浆之间的相互作用。来自地壳的硅质岩浆房接受了密度更大的镁铁质岩浆，这些岩浆沿着这些岩浆房的底部沿着，产生了一种被称为镁铁质和硅质层状侵入体（MASLI）的成分分层。最近的研究很好地证明了在对比岩浆类型之间的界面附近的壮观的场关系和大的成分变化。相比之下，物理和化学耦合的程度之间的基地室，接受镁铁质流入，和上覆的岩浆仍然知之甚少。三个已知的或假定的MASLI岩体在CMMP，Vinalhaven，鹿岛，山。沃尔多花岗岩，已被选定为研究，以解决这一重要问题。具体来说，是什么过程和其他因素决定了不同岩浆类型之间热量和物质交换的程度？热量和质量是否随后分布到腔室的上游？通过结合结构，成分和同位素研究分区斜长石和辅助矿物（使用电子和离子微探针技术），沿着从每个花岗岩的岩浆包体的数据，相对的时间和程度的变化，从个别矿物结晶的岩浆的成分可以进行评估。相邻矿物颗粒之间的内部变化的比较将用于限制材料在腔室内重新分布的相对程度。此外，这样的研究将提高我们对岩浆房动力学和生长的理解，使认识的花岗岩成岩中的地幔和地壳成分的贡献，并评估大陆岩石圈的生长和演化的模型。