P-T-D-t paths for Mesoproterozoic supracrustal rocks: a new window into the elevated geotherm and intraplate deformation of the ca. 1.4 Ga Picuris Orogeny

中元古代表壳岩石的 P-T-D-t 路径：了解约 20 世纪地温升高和板内变形的新窗口。

• 批准号: 2241801
• 负责人: Chloe Bonamici
• 金额: $ 40.82万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2241801&HistoricalAwards=false
• 关键词: paths; Mesoproterozoic; supracrustal; rocks; new

Most of Earth’s mountain belts have formed at the boundaries of tectonic plates, where the stresses from plate motions are powerful enough to fold, break, and pile up rocks. However, a few mountain belts have formed far away from high-stress plate boundaries, and they suggest that tectonic plates are not always entirely strong and rigid. This project will investigate one of these unusual plate-interior mountain belts to better understand how strong tectonic plates can be weakened and deformed from the inside out. The Picuris Mountains of northern New Mexico contain sedimentary and volcanic rocks that were deposited around 1.5 billion years ago and then rapidly deformed and metamorphosed, capturing a record of a rare plate-interior mountain building event. By studying the structures, minerals, chemistry, and radiogenic isotopes of the Picuris rocks, investigators will determine how heat, stress, and time worked together to warp the North American plate interior. This research will use state-of-the-art analytical approaches and instrumentation to address long-standing tectonic mysteries, as well as train up to five graduate and undergraduate students in conducting high-level earth science field and lab research. The investigator and student researchers will also create a field trip for members of the public with mobility challenges highlighting the geology, mineral resources, and landscapes of a plate-interior mountain belt.Intraplate orogenesis challenges the paradigm of rigid tectonic plates and provides clues to the long-term, nonlinear evolution of continents, cratons, and plate strength. This project will focus on the Picuris Mountains of New Mexico, where mountain-building occurred far inboard of the presumed active Laurentian continental margin 1.4 billion years ago. Investigators will extract the Pressure-Temperature-Deformation-time (P-T-D-t) record of the Picuris Orogeny preserved in rare rocks with Mesoproterozoic protoliths as a means to elucidate the mechanism(s) of the ca. 1.4 Ga intraplate orogenesis. The Principal Investigator, two graduate students, and one or more undergraduates will perform field work; construct detailed P-T-D-t paths for Mesoproterozoic supracrustal rocks using modern petrologic and structural approaches; perform U-Pb titanite and zircon dating to establish the absolute timing of Picuris metamorphism and deformation; and use whole-rock and zircon trace-element geochemistry to determine the tectonomagmatic setting of Mesoproterozoic volcanic rocks. Additionally, the Principal Investigator and a graduate student will build a digital field guide to Precambrian outcrops for Wisconsin geoscience-curious community members, especially including those with mobility challenges. Lessons learned from developing this accessible field experience will be shared with UW-Madison faculty to inform efforts toward making field-based geoscience education more inclusive.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.

地球上大多数的山脉带都是在构造板块的边界上形成的，在那里，板块运动产生的应力足以折叠、破碎和堆积岩石。然而，一些山脉带已经在远离高应力板块边界的地方形成，它们表明构造板块并不总是完全坚固和刚性的。该项目将调查这些不寻常的板块内部山脉带之一，以更好地了解强大的构造板块如何从内到外被削弱和变形。新墨西哥州北方的皮库里斯山脉包含大约15亿年前沉积的沉积岩和火山岩，然后迅速变形和变质，记录了罕见的板块内部造山事件。通过研究Picuris岩石的结构，矿物，化学和放射性同位素，研究人员将确定热量，应力和时间如何共同作用以扭曲北美板块内部。这项研究将使用最先进的分析方法和仪器来解决长期存在的构造之谜，并培养多达五名研究生和本科生进行高水平的地球科学领域和实验室研究。调查员和学生研究人员还将为公众创造一次实地考察，突出地质，矿产资源和板块内部山脉带的景观。板内造山挑战刚性构造板块的范式，并为大陆，板块和板块强度的长期非线性演化提供线索。该项目将侧重于新墨西哥州的Picuris山脉，那里的造山运动发生在14亿年前假定的活跃劳伦大陆边缘的内侧。研究人员将提取保存在含有中元古代原岩的稀有岩石中的Picuris造山运动的压力-温度-变形-时间（P-T-D-t）记录，作为阐明这种机制的一种手段。1.4 Ga板内造山作用首席研究员、两名研究生和一名或多名本科生将进行实地工作;使用现代岩石学和结构方法构建中元古代表壳岩的详细P-T-D-t路径;进行U-Pb钛铁矿和锆石定年，以确定Picuris变质和变形的绝对时间;利用全岩和锆石微量元素地球化学确定了中元古代火山岩的构造岩浆环境。此外，首席研究员和一名研究生将为威斯康星州对地球科学感兴趣的社区成员，特别是那些有流动性挑战的人，建立一个前寒武纪露头的数字实地指南。从开发这一可访问的实地经验中吸取的经验教训将与威斯康星大学麦迪逊分校的教师分享，为使实地地球科学教育更具包容性的努力提供信息。该奖项反映了NSF的法定使命，并被认为值得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来支持。