| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | July 9, 2019 |
| Latest Amendment Date: | July 9, 2019 |
| Award Number: | 1925489 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Candace Major
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | August 1, 2019 |
| End Date: | July 31, 2023 (Estimated) |
| Total Intended Award Amount: | $279,152.00 |
| Total Awarded Amount to Date: | $279,152.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
3100 MARINE ST Boulder CO US 80309-0001 (303)492-6221 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
3100 Marine St Rm 481 572 UCB Boulder CO US 80303-1058 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): |
FRES-Frontier Rsrch Earth Sci, XC-Crosscutting Activities Pro |
| Primary Program Source: |
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| Program Reference Code(s): | |
| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Over its history, Earth has experienced warm ice-free and cold glacial climates, but it is unknown if transitions between these background climate states were the result of changes in CO2 sources or sinks. On these multi-million year geological timescales, CO2 enters the ocean and atmosphere primarily by volcanic outgassing and is removed primarily though the chemical erosion of rocks, which delivers calcium and magnesium via rivers to the ocean where they react with CO2 to form carbonate. It is hypothesized that the tectonic closure of ocean basins and formation of mountains at equatorial latitudes could drive cooling by creating topography and eroding highly soluble oceanic rocks in the warm, wet tropics. This process increases global weatherability, thereby increasing Earth's potential to sequester CO2 in carbonates through chemical erosion. The investigators aim to test the hypothesis that changes in global weatherability have controlled the Earth's background climate state with coupled geological, geochemical, and modelling studies. This broader impact of this work will benefit society by generating and disseminating knowledge about geological climate change at both the K-12 and college level.
The researchers have developed a global database of arc-continent collisions through the Phanerozoic, which mark the closure of former ocean basins, and reconstructed their position with state-of-the-art paleogeographic models. The results from this analysis revealed a temporal coincidence between the maximum global extent of arc-continent collision in the tropics and the occurrence of every major glacial period in the Phanerozoic. The investigators will refine geological constraints and tectonic reconstructions in five critical belts. Through these case studies, the researchers will generate thermochronological data and refine the exhumation history of New Guinea and construct a new paleogeographic model for suturing in the Alpine-Himalaya belt. The investigators will also acquire new stratigraphic, geochronological, geological, petrographic, geochemical, and paleomagnetic data along Permo-Carboniferous sutures from Mexico to South America, Ordovician sutures in the northern Appalachian, and Neoproterozoic sutures in the Arabian-Nubian Shield. These field and laboratory data will be integrated with paleogeographic, weathering, and climate models to develop estimates for the change in pCO2 resulting from arc-continent collisions in the tropics utilizing the GEOCLIM model framework. This framework integrates climate models run at varying pCO2 with global weathering models such that the variable climatology can be used to estimate the effect of changes in global weatherability model on long-term steady-state pCO2 levels. In this framework, the investigators will perform sensitivity tests to isolate the effects of specific parameters such as lithology or topography. The researchers will further calibrate these models with source-to-sink cation studies in modern and paleo ophiolite watersheds. Finally, they will develop statistical methods to evaluate the strength of correlation and test hypothesized causal mechanisms for environmental change. Through this research the investigators will directly train a postdoctoral researcher, 5 PhD students and numerous undergraduate research assistants. To disseminate this basic research, the team will hold public seminars and workshops with K-12 teachers, and construct classes on Tectonics and Climate with online course materials, both at the high-school and undergraduate level.
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.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Overview.
Low-latitude arc-continent collisions are hypothesized to drive cooling by exhuming and eroding mafic and ultramafic rocks in the warm, wet tropics, thereby increasing Earth?s potential to sequester carbon through chemical weathering. The major goals of this project were to test this hypothesis with integrated field, laboratory, climate modelling, and statistical studies.
Intellectual Merit.
The primary contribution of the CU-Boulder team to the larger project was to spearhead constraining the exhumation history and erosional fluxes of the Central Range of New Guinea over the past 10 million years. The thermochronologic work was lead by CU-Boulder postdoc Peter Martin together with PI Flowers and UCSB PI Macdonald. Martin acquired 112 new zircon and apatite (U-Th)/He analyses for a suite of samples along three transects across the Central Range Orogen, combined these results with a palinspastic reconstruction of the orogen generated by collaborator Nadine McQuarrie from surface geological constraints and seismic data, and employed thermokinematic modeling to constrain the topographic and erosional history of the New Guinea arc-continent collision. The outcomes of this work document rapid topographic uplift and regional erosion between 10 and 6 million years ago. Martin then collaborated with UC-Berkeley postdoc Pierre Maffre to use the erosional fluxes from the palinspastic reconstruction and thermokinematic model as input to a coupled global climate and weathering model in GEOCLIM. This model estimates 0.6-1.2 ?C of cooling associated with the Late Miocene rise of New Guinea due to increased silicate weathering alone, with this CO2 sink continuing to the present. These data and modeling experiments support the hypothesis that tropical arc-continent collision and the rise of New Guinea contributed to Neogene cooling due to increased silicate weathering. This collaborative work is in press at PNAS (Proceedings of the National Academy of Sciences) and was a major contribution toward the larger project goals to integrate geology, thermochronology, and silicate weathering modules to evaluate hypotheses about the effect of the emergence of the Southeast Asian Island, and particularly New Guinea, on Neogene climate.
We also acquired apatite and zircon (U-Th)/He data from the Coast Range ophiolite to better constrain the timing of Mesozoic ophiolite exhumation in the Cordillera. The preliminary data imply a substantial heating signal between the 147 Ma age of the volcanic ash and the ca. 130 Ma ZHe dates, with later Oligo-Miocene cooling/exhumation recorded by the AHe dates. These outcomes have potential for understanding ophiolite exhumation mechanisms and possible contributions to climate cooling during ophiolite erosion and weathering.
Broader Impacts.
This project supported, and provided scientific training and professional development, for postdoc Peter Martin. Martin engaged with a large group of primary- and home-schooled children through the Skype a Scientist program, in which he was interviewed about his experience as a geologist and in particular about the science of geochronology. Martin also mentored a student in the CIRES Research Experience for Community College Students (RECCS) program; the RECCS student then presented his work in AGU?s specialized student presentation forum. Martin has started a job as an Earth and Data Scientist at Kobold Metals focused on using machine learning and other scientific computing techniques to increase the ethical supply of battery critical materials.
Throughout the first two project years we participated in bi-weekly zoom meetings with the larger project team in which the groups presented their research and discussed relevant papers on a rotating basis. In May 2022, PI Flowers with UCSB PI Macdonald hosted a two-day in person workshop for the project at CU-Boulder that encompassed presentations from all groups in the larger project team, included outside speakers with differing perspectives and expertise, and facilitated broad discussions about the project science and next steps toward understanding links and feedbacks among tectonics, erosion, weathering, and climate.
Last Modified: 08/25/2023
Modified by: Rebecca M Flowers
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