Assessing the relationship between strain localization and magmatism during rift evolution

评估裂谷演化过程中应变局部化与岩浆作用之间的关系

基本信息

批准号：
1850606
负责人：
Tyrone Rooney
金额：
$ 35.05万
依托单位：
Michigan State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-05-15 至 2024-04-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1850606&HistoricalAwards=false
关键词：
Assessing relationship between strain localization

项目摘要

The majority of Earth's surface is covered in oceans, below which lie rocks that constitute the oceanic crust. Unlike Earth's continents, which may persist for billions of years, the oceanic crust is continually destroyed and created. These dynamic processes lead to the opening and closure of ocean basins, and even the breaking apart of continents. Continental rifts, which manifest as a series of interconnected linear to arcuate valleys on continents, are the manifestation of the process by which continents may split and new oceans form. Insights into the creation of new oceans thus depends on the processes active within continental rifts. This project focuses on the generation of large volumes of lavas within continental rifts. These lavas form the basis of later oceanic crust, but the mechanism of magma generation is currently unclear. The project focuses on the East African rift - the premier example of a modern continental rift, and examines how magmas are generated in the mantle, evolve in the crust, and eventually erupt in this rift. One of the eventual aims of this project is to develop an understanding as to why large-volumes of lavas flood onto the surface of the rift during certain periods, while during other periods the lavas are restricted to linear belts. This work can feed into evolving models that seek to constrain the architecture of the crust within rifts and nascent ocean basins. Insights gained from East Africa have broad implications in understanding rifted margins globally, and how the crust and offshore basins along these margins develop. By examining rocks that are exposed in East Africa, we may generate better conceptual models of regions where these rocks may be buried by kilometers of sediments (e.g., Eastern U.S. seaboard). Broader Impacts include undergraduate research experience.In this proposal new geochemical and petrographic constraints on lavas from the East African rift will be obtained. The focus will be on lava fields that represent end members in eruption style - large lava flows, isolated shields, and smaller lava cones. The proposed study regions in East Africa are the following: (i) Afar, a region where researchers vigorously debate if ocean crust is already being formed, and (ii) Turkana, a region where an earlier rifting event has made the crust thinner than would be anticipated. The work being undertaken in this proposal will be arranged around four interlinked questions: (A) What is the mechanism of magma generation for the different lavas fields? (B) What mantle sources contribute to magma creation within these lavas fields? (C) How does magma generation/ source contribution change over time? (D) Is there a difference in the conditions of magma evolution within the crust between the different lava fields? The region this project focuses on spans two of the targets elucidated by the GeoPRISMS Implementation Plan. Turkana lies within the "Primary area for focused investigations", while Afar lies within the "collaborative target" region. Thus, the results of this study can be collated with other NSF-sponsored science being undertaken in the same region to address GeoPRISMS science goals. When combined, these data will be used to address the science question: "How is strain accommodated and partitioned throughout the lithosphere, and what are the controls on strain localization and migration?" The results of this work will have further impact upon other science questions related to the distribution of deep mantle material in the East African upper mantle. These questions are currently being addressed through other interdisciplinary studies and the proposed work would add a critical component to the the constraints on the rifting process that is recorded in the recent lavas. When considered in aggregate, these studies aim to push the boundaries of current knowledge as to how rifting initiates, evolves, and transitions to oceanic spreading.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.

地球的大部分表面都覆盖着海洋，下面是构成海洋壳的岩石。与可能持续数十亿年的地球大陆不同，海洋壳被不断摧毁和创造。这些动态的过程导致了海盆的开放和关闭，甚至是大陆的破裂。大陆裂纹表现为一系列互连的线性与大陆上的山谷，是该过程的表现，大陆可能会分裂并形成新的海洋。因此，对新海洋创造的见解取决于在大陆裂痕中活跃的过程。该项目着重于大陆裂谷中大量熔岩的产生。这些熔岩构成了后来的海壳的基础，但岩浆产生的机制目前尚不清楚。该项目的重点是东非裂谷 - 现代大陆裂谷的主要例子，并研究了地幔中岩浆的产生，在地壳中进化，并最终在此裂谷中爆发。该项目的最终目的之一是对为什么在某些时期内大量熔岩泛滥到裂谷的表面，而在其他时期，熔岩仅限于线性带。这项工作可以进化为不断发展的模型，这些模型试图限制裂谷和新生海盆中的地壳的结构。从东非获得的见解对了解全球的裂痕以及这些边缘沿这些边缘的地壳和海上盆地的发展具有广泛的影响。通过检查东非暴露的岩石，我们可能会产生更好的区域概念模型，在这些区域中，这些岩石可能被埋葬的沉积物（例如，美国东部沿海地区）埋葬。更广泛的影响包括本科研究经验。在这项提案中，将获得新的地球化学和岩石学限制对来自东非裂谷的熔岩的限制。重点将放在代表喷发风格的最终成员的熔岩场上 - 大型熔岩流，孤立的盾牌和较小的熔岩锥。拟议的东非研究区域如下：（i）远处，在该地区，研究人员强烈争论是否已经形成了海皮，以及（ii）Turkana，Turkana，该地区较早的裂痕事件使地壳变得比预期的要薄。该提案中正在进行的工作将围绕四个相互联系的问题进行安排：（a）不同熔岩领域的岩浆产生机制是什么？（b）哪些地幔资源在这些熔岩领域内有助于岩浆创造？（c）随着时间的推移，岩浆的生成/源贡献如何变化？（d）不同熔岩场之间的地壳内的岩浆演化条件有差异吗？该项目的重点是跨越被寻格主义实施计划阐明的两个目标。图尔卡纳（Turkana）位于“重点调查的主要领域”之内，而远处则位于“协作目标”地区。因此，这项研究的结果可以与在同一地区进行的其他NSF赞助的科学进行整理，以解决Geoprisms科学目标。合并后，这些数据将用于解决科学问题：“在整个岩石圈中如何容纳和分割应变，以及对应变定位和迁移的控制权是什么？” 这项工作的结果将进一步影响与东非上层地幔中深幔材料分布有关的其他科学问题。这些问题目前正在通过其他跨学科研究解决，拟议的工作将为最近熔岩记录的裂纹过程的约束增加关键组成部分。当总计考虑时，这些研究旨在突破当前知识的界限，以了解裂谷如何发展，发展和过渡到海洋传播。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子优点和更广泛影响的审查标准来评估的值得通过评估的。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

The Cenozoic magmatism of East Africa: Part II – Rifting of the mobile belt

东非新生代岩浆作用：第二部分 — 移动带的裂谷

DOI：
10.1016/j.lithos.2019.105291
发表时间：
2020
期刊：
Lithos
影响因子：
3.5
作者：
Rooney, Tyrone O.
通讯作者：
Rooney, Tyrone O.

The Cenozoic magmatism of East Africa: Part III – Rifting of the craton

东非新生代岩浆作用：第三部分 — 克拉通裂谷

DOI：
10.1016/j.lithos.2020.105390
发表时间：
2020
期刊：
Lithos
影响因子：
3.5
作者：
Rooney, Tyrone O.
通讯作者：
Rooney, Tyrone O.

Transition to magma-driven rifting in the South Turkana Basin, Kenya: Part 2

肯尼亚南图尔卡纳盆地向岩浆驱动裂谷的转变：第 2 部分

DOI：
10.1144/jgs2021-160
发表时间：
2022
期刊：
Journal of the Geological Society
影响因子：
2.7
作者：
Rooney, Tyrone O.;Wallace, Paul J.;Muirhead, James D.;Chiasera, Brandon;Steiner, R. Alex;Girard, Guillaume;Karson, Jeffery A.
通讯作者：
Karson, Jeffery A.

Magmatism During the Continent – Ocean Transition

大陆—海洋转变期间的岩浆作用