Collaborative Research: Resolving Conflicting Models for the Laramide Orogeny and the Flat-Slab Paradigm in the Southern California Batholith

合作研究：解决拉拉米德造山运动模型与南加州基岩平板范式之间的冲突

• 批准号: 2138733
• 负责人: Joshua Schwartz
• 金额: $ 39.39万
• 依托单位: The University Corporation, Northridge
• 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: 2022-06-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2138733&HistoricalAwards=false
• 关键词: Collaborative; Research; Resolving; Conflicting; Models

Understanding how the Rocky Mountains developed in the western United States is a problem of vital importance because they host precious mineral resources such as gold, lead, copper, and silver, which are important for our national economy. Many of these economic resources were brought to the surface along large faults which formed in the Late Cretaceous during a mountain building event, termed the Laramide orogeny. A key problem is that the timing and origin of the driving force behind this event and the formation of the Rocky Mountains are highly controversial and there is no consensus on the tectonic setting in which these mountains formed. The investigators hypothesize that the answer to understanding the origin of the Rocky Mountains and the Laramide orogeny lies in the San Gabriel Mountains of southern California. This region contains two important features which make it the focus of this study: (1) they preserve a complete temporal history of the Laramide orogeny from the earliest phase until its termination, which is important in reconstructing the driving force behind the event, and (2) they contain a unique section of the deep crust including a major ductile fault system that was active during the beginning of the Laramide orogeny. Analysis of these features will offer critical insights on the beginning of the Laramide orogeny, which will be essential in resolving conflicting hypotheses. The research plan for this project will involve 3 seasons of field work and data collection in the San Gabriel and nearby mountains. Laboratory analyses of rocks collected from the San Gabriel Mountains will consist of geochronology, geochemistry and microstructural work at the California State University Northridge Laser Ablation and LatinXellence in STEM Laboratories. The project will advance societal outcomes through innovative summer workshops, and an academic-year mentoring program termed, LA-ROCS, both of which are aimed at providing research experiences to underrepresented students at minority-serving institutions in southern California. These mentorship and research opportunities for undergraduate students will expose them to cutting-edge analytical research facilities and will aid in developing a diverse, globally competitive STEM workforce. This proposal aims to resolve the controversial beginnings of the Laramide orogeny by testing conflicting hypotheses about the origin and tectonic effects of Laramide orogenesis on the evolution of the Southern California batholith at ca. 85-70 million years ago. This critical period in the development of the U.S. Cordillera is commonly associated with shallow-slab subduction beneath Southern California, which is thought to have driven the transition from thin-skin (Sevier-style) to thick-skin (Laramide-style) deformation. A key problem with the flat-slab model is that the team's preliminary geochronology data show that the initiation of the Laramide orogeny in Southern California is spatially and temporally linked to a magmatic flare-up event in the same region where flat-slab subduction is postulated to have occurred. This contradiction makes the Laramide orogeny distinct from other areas of flat-slab subduction, including the modern-day Sierras Pampeanas in Argentina, which is characterized by a magmatic gap. To resolve this problem, the investigators propose a multiscale approach that focuses on the roots of the Southern California batholith and combines field work with a variety of state-of-the art analytical techniques (Uranium-Lead geochronology, Hafnium- and Osmium-isotope geochemistry, electron backscatter diffraction (EBSD) and microstructural analysis, structural analyses along continuous transects). These data will allow the investigators to link magmatism in the Southern California batholith with deformation and plate-kinematic information at mid-lower crustal depths to resolve conflicting models associated with the flat-slab paradigm and the initiation of the Laramide orogeny.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.

了解落基山脉在美国西部是如何发展的是一个至关重要的问题，因为这里蕴藏着金、铅、铜和银等宝贵的矿产资源，这些资源对我们的国民经济非常重要，其中许多经济资源都被带到了这里。沿白垩纪晚期造山活动（称为拉拉米德造山运动）形成的大断层的地表 一个关键问题是，这一事件和落基山脉形成背后的驱动力的时间和起源存在很大争议。尚无共识研究人员认为，了解落基山脉和拉拉米德造山运动起源的答案在于南加州的圣盖博山脉，该地区具有两个重要特征，这使其成为本研究的重点： （1）它们保存了拉拉米造山运动从最早阶段到结束的完整时间历史，这对于重建事件背后的驱动力非常重要，（2）它们包含深部地壳的独特部分，包括主要的延性部分故障系统对这些特征的分析将为拉拉米德造山运动的开始提供重要的见解，这对于解决相互矛盾的假设至关重要。该项目的研究计划将涉及 3 个季节的实地工作和研究。对从圣盖博山脉收集的岩石进行的实验室分析将包括加州州立大学北岭分校激光烧蚀和 STEM 中的 LatinXellence 的地质年代学、地球化学和微观结构工作。该项目将通过创新的夏季研讨会和名为 LA-ROCS 的学年指导计划来推动社会成果，这两个项目都旨在为南加州少数族裔服务机构中代表性不足的学生提供研究经验。本科生的研究机会将使他们接触到尖端的分析研究设施，并有助于培养一支多元化的、具有全球竞争力的 STEM 劳动力队伍。该提案旨在通过测试有关起源和构造的相互矛盾的假设来解决拉拉酰胺造山运动的有争议的起源。大约 85-7000 万年前拉拉米德造山作用对南加州岩基演化的影响通常与南加州下方的浅板俯冲有关。从薄皮（Sevier 型）到厚皮（Laramide 型）变形的转变 平板模型的一个关键问题是该团队的初步地质年代学数据表明：南加州拉拉米德造山运动的启动在空间和时间上与假定发生平板俯冲的同一地区的岩浆爆发事件有关，这一矛盾使得拉拉米德造山运动与其他平板俯冲区域不同。为了解决这个问题，研究人员提出了一种多尺度方法，重点关注南加州岩基的根部，并将实地工作与现场工作相结合。各种最先进的分析技术（铀铅地质年代学、铪和锇同位素地球化学、电子背散射衍射（EBSD）和微观结构分析、沿连续横断面的结构分析）这些数据将使研究人员能够进行分析。将南加州岩基的岩浆活动与中下地壳深度的变形和板块运动学信息联系起来，以解决与平板范式相关的相互冲突的模型和拉拉米德造山运动的启动。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

Mesozoic Fabric Influence on the formation and geometry of the Quaternary Cucamonga Fault

中生代构造对第四纪库卡蒙加断层的形成和几何形状的影响

• 发表时间: 2022-09
• 期刊: Southern California Earthquake Center abstracts
• 作者: Francine Robles; Joshua Schwartz
• 通讯作者: Joshua Schwartz

LATE CRETACEOUS ARC FLARE UP AND SINISTRAL INTRA-ARC DUCTILE DEFORMATION IN THE SOUTHERN CALIFORNIA BATHOLITH

南加州岩基中白垩纪晚期的弧爆发和左旋弧内延性变形

• DOI: 10.1130/abs/2022am-381618
• 发表时间: 2022-01
• 期刊: Abstracts Geological Society of America
• 作者: Schwartz, Joshua;Lackey, Jade Star;Miranda, Elena;Klepeis, Keith;Mora;Robles, Francine;Bixler, Jonathan
• 通讯作者: Bixler, Jonathan

TECTONIC AND MAGMATIC CONSTRUCTION OF LOWER CRUST IN THE SOUTHERN CALIFORNIA BATHOLITH

南加州岩基下地壳的构造和岩浆构造

• 发表时间: 2024-05
• 期刊: Geological Society of America abstracts
• 作者: Schwartz; J.J.
• 通讯作者: J.J.

CONSTRAINING THE TIMING AND CONDITIONS OF MAGMATISM AND GRANULITE- TO UPPER AMPHIBOLITE-FACIES METAMORPHISM IN THE LOWER CRUST OF THE SOUTHERN CALIFORNIA BATHOLITH USING U-PB ZIRCON GEOCHRONOLOGY AND TI-IN-ZIRCON THERMOMETRY

利用U-PB锆石地质年代学和锆石中钛测温法约束南加州岩基下地壳岩浆作用和麻粒岩到上角闪岩相变质作用的时间和条件

• DOI: 10.1130/abs/2022am-381996
• 发表时间: 2022-01
• 期刊: Geological Society of America abstracts
• 作者: Robles, Francine;Schwartz, Joshua;Miranda, Elena;Klepeis, Keith;Mora
• 通讯作者: Mora

MAGMA-DEFORMATION INTERACTIONS IN THE SOUTHERN CALIFORNIA BATHOLITH DURING LATE CRETACEOUS ONSET OF THE LARAMIDE OROGENY, SAN GABRIEL MOUNTAINS, CALIFORNIA

加利福尼亚州圣盖博山拉拉米德造山运动白垩纪末期开始时南加利福尼亚岩基的岩浆-变形相互作用

• DOI: 10.1130/abs/2023am-394141
• 发表时间: 2023-10
• 期刊: Geological Society of America Abstracts with Programs
• 作者: Klepeis, Keith;Schwartz, Joshua;Miranda, Elena;Robles, Francine;Baskin, Jillyan;Mora
• 通讯作者: Mora