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.
