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: 0536969
• 负责人: David Hawkins
• 金额: $ 10.97万
• 依托单位: Denison University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2010-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0536969&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.

本文拟对暴露于缅因州海岸的维纳尔黑文侵入岩和相关火山岩进行研究，试图了解(1)这种双峰型、深部-火山复合体是如何形成的；(2)岩浆室的输入过程和喷发损失如何影响维纳尔黑文花岗岩的成分和结构。该杂岩既包含具有广泛岩浆房作用证据的深部岩体，也包含同时期的火山岩，是检验渐进式岩体生长模型的理想岩浆系统。高精度U-Pb锆石年代学为岩体构造和同时期火山岩喷发提供了时间框架。先前的研究建立了镁铁（87Sr/86Sri = 0.70234; epsilon Nd = +6）和长硅（87Sr/86Sri = 0.70713; epsilon Nd = -2）输入的Sr和Nd同位素组成对比强烈。该研究将记录维纳尔黑文杂岩的岩浆演化，包括镁质和硅质补充、再生、结晶和同时期火山岩演化的历史。密集的野外工作将结合岩石学，全岩和矿物化学。对花岗岩的沉积特征进行制图和研究，可以建立花岗岩的时空固结史。花岗岩、硅石和流纹岩的结晶历史将受到锆石、长石和石英成分分带的高分辨率成像的约束。最后，通过对整个岩石Sr、Nd、Hf同位素组成和锆石晶体/碎屑Hf同位素组成的测年分析，结合岩石化学资料，揭示源区、岩浆房作用、硅基和基性输入、演化流纹岩喷发等因素对花岗岩化学和同位素组成的相对影响。这项研究的结果将有助于确定深成岩作用和火山作用及其产物之间牢固的岩石学联系。它还将为火山学家推断的一些岩浆房过程提供一个深成岩的视角，包括补充、岩浆混合和混合、花岗岩晶体糊状的恢复、对流搅拌和分馏。地质年代学数据将对这些过程的运行速度提供基本的限制，并允许与类似火山中心的时间尺度进行直接比较。最后，本研究将评估源区和岩浆房过程对花岗岩地球化学和同位素组成的相对贡献，并为深部和火山系统的全岩同位素数据的解释提供新的见解。