Collaborative Research: Understanding the influence of tectonic setting on the depth of magmatic processes in the mid-ocean ridge system

合作研究：了解构造环境对大洋中脊系统岩浆过程深度的影响

基本信息

批准号：
2135828
负责人：
Gokce Ustunisik
金额：
$ 40.5万
依托单位：
South Dakota School of Mines and Technology
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2022
资助国家：
美国
起止时间：
2022-02-01 至 2025-01-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2135828&HistoricalAwards=false
关键词：
Collaborative Research Understanding influence tectonic

项目摘要

Collaborative Research: Understanding the influence of tectonic setting on the depth of magmatic processes in the mid-ocean ridge system The rocks that pave the seafloor cover ~70% of the Earth’s surface and are produced by volcanoes along the mid-ocean ridge (MOR) system. These volcanoes arguably represent the largest geologic system in the Earth’s crust. By analyzing the lavas erupted at the MOR, geologists understand how these magmas are produced and how they chemically change as they rise to the surface. However, less is understood about depths of formation and how that may change in different parts of the MOR system. New data on depth of formation of the crystals in MOR lavas, based on CO2 in trapped droplets of magma in crystals (melt inclusions), indicate that the crystals are produced over a wide depth range. Those crystals therefore provide a record of magma compositions encountered during transport from depth and of processes controlling ocean crust formation. This study will chemically analyze microscopic melt inclusions and crystals to understand how the depth of magma formation varies globally. This new data will provide information on the depth of crystallization in different MOR environments and the carbon budget of the mantle. A core aspect of this proposal involves outreach to students at the tribal colleges in South Dakota which will consist of three parts including current programs at South Dakota Mines, mentoring students from Oglala Lakota College (OLC), and providing advice on the development of the analytical facilities at OLC.Current understanding of the evolution of the ocean crust relies heavily on submarine volcanic glasses and, more recently, melt inclusion (MI) compositions. Such data is most informative about the complex array of mixing and differentiation processes active in the upper mantle and crust - in essence “what” is happening. What has been difficult to constrain is “where” specific processes are active in terms of depth, making it challenging to resolve the influences of processes occurring in the melting regime versus those that occur during transport to the surface. New data on depth of entrapment for melt inclusions (based on CO2 saturation/concentration) indicate that much of the crystal cargo in ocean floor basalts, particularly those from plagioclase ultraphyric basalts (PUB) are the products of crystallization at a wide range of pressure. They therefore provide an opportunity to investigate how the array of magma compositions evolves during transport and how the distribution of energy and mass of the processes controlling ocean crust formation differs between tectonic settings (different spreading rates, magma supply, extent of melting, etc.). This study will conduct combined analysis by electron microprobe (for major element composition), Laser ICP-MS (trace element compositions), secondary ion mass spectrometry (glass CO2, H2O, S), and Raman spectroscopy (MI bubble density/composition). The samples selected represent a number of PUB lavas from a range of settings, on axis, pull apart basins, ultra-slow to intermediate spreading rates and from ridges characterized by different crustal thicknesses. This new information will improve understanding of a number of fundamental questions in MORB petrology including: 1) the comparative depth of crystallization in different MOR environments for olivine and plagioclase (how crystal sorting influence what is being sampled), 2) the depth dependence of the processes responsible for MOR differentiation, 3) the extent to which CO2/trace element ratios can be used to estimate the mantle C budget. A core aspect of this proposal involves outreach to students at the tribal colleges in South Dakota which will consist of three parts including current programs at South Dakota Mines, mentoring students from Oglala Lakota College (OLC), and providing advice on the development of the analytical facilities at OLC.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

合作研究：了解构造环境对大洋中脊系统岩浆过程深度的影响铺平海底的岩石覆盖地球表面约 70%，由洋中脊沿线的火山产生 (MOR)这些火山可以说代表了地壳中最大的地质系统。通过分析 MOR 喷发的熔岩，地质学家了解这些岩浆是如何产生的以及它们在形成过程中如何发生化学变化。然而，关于 MOR 熔岩中晶体形成深度的新数据（基于晶体中被捕获的岩浆液滴中的二氧化碳），人们对形成深度以及其如何变化的了解较少。（熔体包裹体）表明晶体是在很宽的深度范围内产生的，因此这些晶体提供了从深度输送过程中遇到的岩浆成分以及控制洋壳形成过程的化学分析。了解全球岩浆形成的深度如何变化。这一新数据将提供有关不同 MOR 环境中的结晶深度和地幔碳预算的信息。该提案的一个核心方面涉及向南部部落学院的学生进行宣传。达科他州将由三部分组成，包括南达科他州矿业公司的当前项目、指导奥格拉拉拉科塔学院 (OLC) 的学生以及为 OLC 分析设施的开发提供建议。目前对洋壳演化的理解在很大程度上依赖于潜艇火山玻璃以及最近的熔体包裹体（MI）成分，这些数据对于上地幔和地壳中活跃的一系列复杂的混合和分化过程提供了最丰富的信息——本质上是“正在发生什么”。是特定过程在深度上活跃的“位置”，这使得解决熔化状态中发生的过程与传输到地表过程中发生的过程的影响具有挑战性。关于熔体夹杂物截留深度的新数据（基于二氧化碳）。饱和度/浓度）海底玄武岩中的大部分晶体物质，特别是斜长石超岩玄武岩（PUB）中的晶体物质，是在各种压力下结晶的产物，因此它们提供了研究岩浆成分在运输过程中如何演化的机会。控制洋壳形成过程的能量和质量分布因构造环境（不同的扩散速率、岩浆供应、熔化程度等）而异。本研究将通过电子显微探针（针对主要的）进行组合分析。元素成分）、激光 ICP-MS（痕量元素成分）、二次离子质谱（玻璃 CO2、H2O、S）和拉曼光谱（MI 气泡密度/成分）。所选样品代表了一系列 PUB 熔岩。这些新信息将提高对 MORB 岩石学中许多基本问题的理解，包括轴上、拉开盆地、超慢到中等扩散速率以及不同地壳厚度特征的山脊。 1) 橄榄石和斜长石在不同 MOR 环境中结晶的比较深度（晶体分选如何影响采样内容），2) 导致 MOR 分化的过程的深度依赖性，3) CO2/痕量元素比率的程度可用于估算地幔 C 预算。该提案的一个核心方面涉及对南达科他州部落学院的学生进行宣传，其中包括三部分，包括南达科他州矿业公司的当前项目、指导来自奥格拉拉的学生。拉科塔学院 (OLC)，并为 OLC 分析设施的开发提供建议。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

期刊论文数量（5）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Correlation of Depth of Formation with Petrogenetic Processes: Evidence from Plagioclase-Hosted Melt Inclusions

地层深度与成岩过程的相关性：斜长石熔融包裹体的证据

DOI：
10.7185/gold2023.17071
发表时间：
2023
期刊：
Proceedings of 2023 Goldschmidt Conference
影响因子：
0
作者：
Daynes, Olivia;Ustunisik, K. Gokce;Nielsen, Roger;Betts, Madison;Gaetani, Glenn
通讯作者：
Gaetani, Glenn

Correlation of Depth of Differentiation to Tectonic Setting: Evidence from Plagioclase Ultraphyric Basalts

分异深度与构造环境的相关性：来自斜长超晶玄武岩的证据