Towards Mass Balancing Arc Magmatic fluxes - Insights from the Central Mexican Volcanic Belt

走向质量平衡弧岩浆通量 - 来自墨西哥中部火山带的见解

• 批准号: 1220481
• 负责人: Susanne Straub
• 金额: $ 9.98万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-15 至 2015-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1220481&HistoricalAwards=false
• 关键词: Towards; Mass; Balancing; Arc; Magmatic

Towards mass balancing arc magmatic fluxes - insights from the central Mexican Volcanic Belt Intellectual Merit: A fundamental breakthrough in understanding the solid Earth geochemical cycle was the recognition of slab recycling in arcs. Quantifying the magnitude of the slab flux, however, is a complex task that requires understanding the petrogenesis of arc magmas, and in particular the causes of their high average SiO2 (50-65 wt%) by which they differ globally from magmas produced at mid-ocean ridges and intraplate settings. The purpose of this project is to investigate the provenance of high-Si andesites and dacites (=?silicic magmas?) in the central Mexican Volcanic Belt (MVB) from mantle vs. crustal sources. The presence of equilibrium olivines with high, mantle-type 3He/4He (=7-8 Ra) in coeval basaltic and andesitic MVB magmas suggests the possibility that the high-SiO2 melts may have a mantle origin. Studies of silicic volcanic rocks from Quaternary composite volcanoes Malinche,Popocateptl and Nevada de Toluca and from coeval silicic monogenetic volcanoes of The interjacent Sierra Chichinautzin Volcanic Field are proposed to test this idea. Comprehensive major and trace element and isotopic data (incl. Sr-Nd-Pb-Hf isotopes) will be measured in bulk rocks and phenocrysts to evaluate crust vs. mantle contributions to formation of these rocks, and specifically whether or not the silicic magmas are principally(i) crustal partial melts, vs. (ii) melts generated in a subarc mantle infiltrated by reactive silicic fluids and partial melts from the subducting slab. A crustal origin of the silicic magmas would emphasize the importance of intracrustal processing and recycling at the expense of the recycled crustal flux from slab. Confirming the existence of broader spectrum of basaltic to dacitic initial mantle melts in the central MVB, however, has transformative potential as to models of arc magma genesis, arc and continental crustal growth, arc-trench connectivity and hence the overall impact of arc fluxes on the broader geochemical cycles. Broader Impacts: The project furthers the careers of two female scientists (Straub, with a disability, and Bolge). Participation of undergraduate and graduate students will contribute to the training of the next generation. Scientific interaction between US scientists at Lamont and the Oregon State University and international colleagues in Mexico, Taiwan and Scotland will be furthered. The project proposed is of interest to the broader science community, as it addresses questions on the forefront of the GeoPRISMS Initiative and of the New Science Plan of the post-2013 International Ocean Discovery Program (IODP).

走向质量平衡弧岩浆通量 - 来自墨西哥中部火山带的见解 智力优点：理解固体地球化学循环的根本性突破是认识到弧中的板片回收。然而，量化板片通量的大小是一项复杂的任务，需要了解弧岩浆的岩石成因，特别是其高平均 SiO2 (50-65 wt%) 的原因，这使得它们在全球范围内与中期产生的岩浆不同。 -洋脊和板内设置。该项目的目的是从地幔和地壳来源中调查墨西哥火山带 (MVB) 中部高硅安山岩和英安岩（=？硅质岩浆？）的来源。在同时期玄武岩和安山岩 MVB 岩浆中存在具有高地幔型 3He/4He (=7-8 Ra) 的平衡橄榄石，这表明高 SiO2 熔体可能具有地幔起源。提出了对马林切、波波卡特普特尔和内华达托卢卡第四纪复合火山以及中间的奇奇纳钦山脉同期硅质单生火山的硅质火山岩的研究，以检验这一想法。将在大块岩石和斑晶中测量全面的主量元素和微量元素及同位素数据（包括 Sr-Nd-Pb-Hf 同位素），以评估地壳与地幔对这些岩石形成的贡献，特别是硅质岩浆是否是主要是（i）地壳部分熔融，与（ii）在弧下地幔中产生的熔融硅质流体和部分熔融俯冲板块。 硅质岩浆的地壳起源将强调地壳内处理和回收的重要性，而代价是从板片回收地壳通量。然而，确认 MVB 中央存在更广泛的玄武质到英安质初始地幔熔体，对于电弧岩浆成因、电弧和大陆地壳生长、电弧-海沟连通性以及电弧通量对电弧通量的总体影响模型具有变革潜力。更广泛的地球化学循环。 更广泛的影响：该项目促进了两位女科学家（身患残疾的斯特劳布和博尔格）的职业生涯的发展。本科生和研究生的参与将有助于培养下一代。拉蒙特和俄勒冈州立大学的美国科学家与墨西哥、台湾和苏格兰的国际同事之间的科学互动将得到进一步加强。拟议的项目引起了更广泛的科学界的兴趣，因为它解决了 GeoPRISMS 倡议和 2013 年后国际海洋发现计划 (IODP) 新科学计划的前沿问题。