CAREER: Resolving the detrital thermal signatures and natural biases of sediment recycling and weathering in orogenic systems

大陆的风化和侵蚀是岩石循环和地球表面变化的核心组成部分。然而，地球科学中的一个基本问题是，在识别来自原生结晶岩侵蚀的沉积物与可能代表多个风化、侵蚀和运输事件的沉积物方面存在固有的困难。解决这些差异对于理解大陆地壳的生长，大陆尺度的河流流域逆转和冰川-间冰期景观变化至关重要。该项目将侧重于南美洲Sierras Pampeanas省演化过程中碎屑矿物地球化学的再循环信号。Sierras Pampeanas是岩石圈对平板俯冲反应的现代原型，也是开发更好地了解大陆岩石圈演化所需的再循环地球化学特征的改进指标的理想环境。教育活动的重点是通过将高中与研究生院的实验室和实地经验联系起来，增加在STEM（科学、技术、工程和数学）方面代表性不足的群体的参与和保留。与康涅狄格大学的大学入学方案合作，将为高中生提供暑期实习机会，使他们尽早接触地球科学。在哈特福德裂谷盆地地质实地考察，动手和虚拟实验室热年代学实验，并由本科生和研究生的指导将扩大学生实习生的经验和成功的高等教育干的机会。对研究生进行热年代学培训将有助于加强技术队伍，以支持地球科学的主要仪器和技术举措。项目合作将加强美国和阿根廷合作机构之间的研究基础设施和教育技术转让。该项目的中心是推进大陆岩石圈演化过程中沉积物再循环的控制因素和诊断地球化学特征的科学知识。通过使用新兴的碎屑独居石热年代学，锆石地质年代学，热年代学和沉积成分档案，综合沉积物源分析将捕捉离散的多环历史的大陆生长和盆地演化的Sierras Pampeanas。该计划的研究内容包括：（1）野外工作和样品收集，（2）碎屑锆石地质年代学和热年代学，（3）碎屑独居石双定年钍-铅-氦（Th-Pb-He）热年代学的发展，（4）成分物源分析，以及（5）数据集的合成和热历史建模，以探索不同的沉积物再循环方案如何影响碎屑数据集。这项研究将产生碎屑指纹和Sierras Pampeanas的源特性，以跟踪在平板变形过程中预先存在的结构和盆地反转对沉积物转移的影响;简化碎屑独居石地质年代学，地球化学和热年代学的分析工作流程;并开发一种新的多代指标，用于多环环境中的沉积物再循环。这些基础性的进展在地球科学中具有广泛的适用性，可以正确地量化大陆风化和侵蚀速率、地壳生长、源-汇沉积物预算以及与构造和地震周期相关的岩石变形历史。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知识价值和更广泛的影响审查标准进行评估来支持。

The weathering and erosion of the continents is a central component of the rock cycle and modification of the Earth’s surface. Yet, a fundamental problem in Earth sciences is the intrinsic difficulty in recognizing sediment derived from the erosion of primary crystalline rocks versus sediment that may represent multiple episodes of weathering, erosion, and transport. Resolving these differences is essential to understanding the growth of the continental crust, continental-scale river drainage reversals, and glacial-interglacial landscape change. This project will focus on the signals of recycling on the geochemistry of detrital minerals during the evolution of the Sierras Pampeanas province of South America. The Sierras Pampeanas are the modern archetype for the lithospheric response to flat slab subduction and an ideal setting to develop improved metrics for geochemical signatures of recycling needed to better understand the evolution of the continental lithosphere. Educational activities focus on increasing participation and retention of under-represented groups in STEM (science, technology, engineering and mathematics) by bridging high school through graduate school laboratory and field experiences. Partnership with the University College Access Program at the University of Connecticut will develop summer internships designed for high school students to gain early exposure to Earth sciences. Geologic field trips in the Hartford Rift Basin, hands-on and virtual laboratory experiments in thermochronology, and mentoring by undergraduate and graduate students will broaden student interns’ experiences and success in higher education STEM opportunities. Graduate student training in thermochronology will contribute towards a stronger technical workforce in support of major instrumentation and technological initiatives in the Earth sciences. Project collaborations will enhance research infrastructure and education technology transfer among collaborating U.S. and Argentine institutions.This project centers on advancing scientific knowledge of the controlling factors and diagnostic geochemical signatures of sediment recycling during the evolution of the continental lithosphere. By using the emerging detrital monazite thermochronometer alongside established zircon geochronology, thermochronology, and sedimentary compositional archives, an integrated sedimentary provenance analysis will capture the discrete polycyclic histories of continental growth and basin evolution in the Sierras Pampeanas. Research components of the program include: (1) fieldwork and sample collection, (2) detrital zircon geochronology and thermochronometry, (3) development of detrital monazite double-dating thorium-lead-helium (Th-Pb-He) thermochronometry, (4) compositional provenance analysis, and (5) synthesis and thermal history modeling of datasets to explore how different sediment recycling scenarios impact detrital datasets. This research will generate detrital fingerprinting and source characterization of the Sierras Pampeanas to track the influence of pre-existing structures and basin inversion on sediment transfer during flat-slab deformation; streamlined analytical workflows for detrital monazite geochronology, geochemistry, and thermochronometry; and development of a new multiproxy metric for sediment recycling in polycyclic settings. These fundamental advances have wide-ranging applicability in the Earth sciences for correctly quantifying continental weathering and erosion rates, crustal growth, source-to-sink sediment budgets, and constraining rock deformational histories tied to tectonic and earthquake cycles.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.