Exploring the Significance of Na-Alkaline Magmatism in Subduction Systems, a Case Study From the Ross Orogen, Antarctica

探索俯冲系统中钠碱性岩浆作用的意义——以南极洲罗斯造山带为例

• 批准号: 1043152
• 负责人: John Cottle
• 金额: $ 31.14万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1043152&HistoricalAwards=false
• 关键词: Exploring; Significance; Na; Alkaline; Magmatism

Intellectual Merit: Magmas generated during subduction of oceanic lithosphere beneath active continental margins typically have a calc-alkaline chemistry. However, igneous rocks with signatures usually associated with anorogenic magmatism are increasingly being found with calc-alkaline rocks in subduction zones. These enigmatic rocks provide insight into a variety of magmatic and structural processes that are fundamental to subduction zone dynamics but processes that lead to their petrogenesis remain a matter of debate. This project will investigate the Koettlitz Glacier Alkaline Province (KGAP) in the Transantarctic Mountains, which is a section through a Na-alkaline province bounded to the north and south by calc-alkaline magmatism. This province potentially contains key information on the thermo-mechanical processes leading to generation of Na-alkaline rocks in subduction systems. The PI will examine structures that bound the KGAP as well as intrusives and metasedimentary rocks contained within it to determine the tectonomagmatic history in the framework of two end-member hypotheses: the KGAP represents a crustal-scale extensional or transtensional domain in a subduction setting; or the KGAP formed in response to ridge subduction. Broader impacts: This study will train three graduate and three undergraduate students incorporating hands-on experience with state of the art instrumentation. Each summer, four high school students will be incorporated into various aspects of the laboratory-based research through the UCSB research mentorship program. This project will stimulate refinement of in-situ LA-ICPMS methods and development of collaborative linkages with Antarctic geologists at GNS Science in New Zealand. Results will be disseminated via papers and presentations at international conferences.

智力优势：在活动大陆边缘之下的大洋岩石圈俯冲过程中产生的岩浆具有典型的钙碱性化学性质。然而，通常与非造山岩浆活动有关的火成岩特征越来越多地与俯冲带中的钙碱性岩石一起被发现。这些神秘的岩石提供了深入了解各种岩浆和结构过程，是俯冲带动力学的基础，但导致其岩石成因的过程仍然是一个有争议的问题。该项目将调查跨南极山脉的Koettlitz冰川碱性区（KGAP），该冰川碱性区是一个钠碱性区的一部分，南北以钙碱性岩浆活动为界。这个省可能包含的关键信息的热机械过程中，导致在俯冲系统中的钠碱性岩石的产生。PI将检查约束KGAP的结构以及其中包含的侵入岩和变质沉积岩，以确定两个端元假设框架内的构造岩浆史：KGAP代表俯冲环境中的地壳规模的伸展或扭张域;或KGAP形成于对洋脊俯冲的响应。更广泛的影响：本研究将培训三名研究生和三名本科生，结合最先进的仪器的实践经验。每年夏天，四名高中生将通过UCSB研究导师计划被纳入实验室研究的各个方面。该项目将促进改进现场LA-ICPMS方法，并与新西兰GNS科学公司的南极地质学家建立合作联系。研究结果将通过论文和在国际会议上的发言加以传播。