RUI: Collaborative Research: The Roles of Incremental Input, Magma Chamber Processes and Eruption on the Construction of the Bimodal Vinalhaven Plutonic-Volcanic Complex, Maine

RUI：合作研究：增量输入、岩浆室过程和喷发对缅因州维纳尔黑文双峰深成火山杂岩构造的作用

• 批准号: 0943339
• 负责人: David Hawkins
• 金额: $ 6.43万
• 依托单位: Wellesley College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0943339&HistoricalAwards=false
• 关键词: RUI; Collaborative; Research; Roles; Incremental

This proposed research on the Vinalhaven intrusion and related volcanic rocks, exposed on the coast of Maine, attempts to understand (1) how this bimodal, plutonic-volcanic complex was constructed, and (2) how input, magma chamber processes and loss by eruption affected the compositions and textures of the Vinalhaven granite. This complex, which contains both plutonic rocks with evidence for a wide range of magma chamber processes and coeval volcanic rocks, is an ideal magmatic system in which to test the model of incremental pluton growth. High-precision U-Pb zircon geochronology provides a time frame for pluton construction and the eruption of coeval volcanic rocks. Prior studies established highly contrasted Sr and Nd isotopic compositions of mafic (87Sr/86Sri = 0.70234; epsilon Nd = +6) and felsic (87Sr/86 Sri = 0.70713; epsilon Nd = -2) input. The research will document the magmatic evolution of the Vinalhaven complex, including the history of mafic and silicic replenishment, rejuvenation, crystallization, and the evolution of coeval volcanic rocks. Intensive fieldwork will be combined with petrography, whole-rock and mineral chemistry. Mapping and study of depositional features in the granite will establish the spatial and temporal consolidation history of the granite. The crystallization history of granite, silicic feeders and rhyolite will be constrained by high-resolution imaging of compositional zoning in zircon, feldspar and quartz. Finally, whole rock Sr, Nd and Hf isotopic compositions and the Hf isotopic composition of previously dated zircon crystals/fragments, combined with petrochemical data, should provide insights into the relative influences of the source region, magma chamber processes, silicic and mafic input, and the eruption of evolved rhyolite on the chemical and isotopic composition of the granite. The results of this study will help identify firm petrologic links between plutonic and volcanic processes and products. It will also provide a plutonic perspective on a number of magma chamber processes inferred by volcanologists, including replenishment, magma mingling and mixing, rejuvenation of granitic crystal mush, convective stirring, and fractionation. Geochronologic data will provide fundamental constraints on the rates at which these processes operate and permit direct comparison to the timescales of analogous volcanic centers. Finally, this research will assess the relative contributions of the source region and magma chamber processes to the geochemical and isotopic composition of granite and should provide fresh insights into the interpretation of whole-rock isotopic data from both plutonic and volcanic systems.

本研究拟对缅因州海岸出露的维纳黑文侵入体和相关火山岩进行研究，试图了解（1）这种双峰式深成火山杂岩是如何构造的，以及（2）输入、岩浆房过程和喷发损失如何影响维纳黑文花岗岩的成分和结构。这个复杂的，其中包含的证据，广泛的岩浆房过程和同时代的火山岩的深成岩，是一个理想的岩浆系统，在其中测试的增量岩体生长的模型。高精度的锆石U-Pb年代学为岩体的建造和同时代火山岩的喷发提供了时间框架。先前的研究建立了镁铁质（87 Sr/86 Sri = 0.70234; Nd = +6）和长英质（87 Sr/86 Sri = 0.70713; Nd = -2）输入的高对比Sr和Nd同位素组成。该研究将记录Vinalhaven复杂的岩浆演化，包括镁铁质和镁铁质补充，再生，结晶和同时代火山岩的演化历史。密集的实地考察将与岩相学，全岩和矿物化学相结合。对花岗岩沉积特征的测绘和研究将建立花岗岩的时空固结历史。锆石、长石和石英的成分分带的高分辨率成像将制约花岗岩、石英和流纹岩的结晶历史。最后，全岩Sr，Nd和Hf同位素组成和Hf同位素组成的锆石晶体/碎片，结合石化数据，应提供洞察源区的相对影响，岩浆房的过程中，岩浆和镁铁质输入，和喷发的演化流纹岩的化学和同位素组成的花岗岩。这项研究的结果将有助于确定深成和火山过程和产品之间的岩石学联系。它还将提供火山学家推断的许多岩浆房过程的深圳湾观点，包括补给、岩浆混合和搅拌、花岗岩晶体浆的复兴、对流搅拌和分馏。地质年代学数据将对这些过程的速率提供基本的限制，并允许与类似火山中心的时间尺度进行直接比较。最后，这项研究将评估源区和岩浆房过程的相对贡献的地球化学和同位素组成的花岗岩，并应提供新的见解解释全岩同位素数据从深成和火山系统。