| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | July 2, 2019 |
| Latest Amendment Date: | July 2, 2019 |
| Award Number: | 1921182 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Jennifer Wade
jwade@nsf.gov (703)292-4739 EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | July 15, 2019 |
| End Date: | June 30, 2023 (Estimated) |
| Total Intended Award Amount: | $190,661.00 |
| Total Awarded Amount to Date: | $190,661.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
4910 N CHESTNUT AVE FRESNO CA US 93726-1852 (559)278-0840 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
California State University, Fre Fresno CA US 93740-0001 |
| 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): |
Tectonics, Petrology and Geochemistry |
| 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
Recent studies of active volcanoes show that volcanic eruptions are often triggered by earthquakes, which occur in response to plate tectonic forces. But the active faults on such volcanoes cannot be directly examined as they are deeply buried by sediments and earlier erupted volcanic materials. The PIs of this study have discovered three Miocene-age volcanic centers in eastern California, in a region called the Walker Lane that, through uplift and erosion, have exposed the rarely-seen roots of Cascade volcanoes. Their work has both scientific and societal broader impacts. First, because the active Lassen Volcanic Center in northern California is also in the Walker Lane region, their proposed work will be directly applicable to understanding eruption triggering mechanisms there, and at other active Cascade volcanoes. Their recent work has also uncovered the largest volcanic eruption rates known in either the modern or ancient Cascades, and their new work will delimit the tectonic conditions that allow for very large volcanic eruptions to occur. In addition, the PIs will be training a new generation of scientists. Fresno State undergraduate students will be involved in all aspects of the work. They are mostly first generation college students, and are often from under-represented groups and low income families. This NSF support is crucial to bringing research experiences to an underserved community. Through the Fresno State-University of California Davis collaboration, Fresno State students will have the opportunity to collaborate with a PhD student as well as undergraduate field and lab assistants at UC Davis. Students will take the lead not only on research projects, but on presentations at professional meetings, and will be co-authors or lead authors on papers. Most Fresno State students will also serve California's Central Valley as Geologists after graduation, working on projects that range from earthquake hazards to groundwater quality. This early support for their research experiences thus pays dividends to the Central Valley many years after the grant is over. The project is supported by both the Petrology & Geochemsitry and Tectonics programs.
The ancestral Cascade volcanoes of central California that the PIs and their students will study are the ancient analogs of active volcanoes, such as Lassen Peak and Mt Shasta in northern California, or Mt. St. Helens in Washington. The ancestral Cascades formed from about 16 to 5 million years ago and have been uplifted at the eastern edge of the Sierra Nevada Mountain range. Uplift and erosion have exposed 5 km of structural relief on three volcanic centers. The PIs will take advantage of these deep exposures to map the geologic faults that allowed these ancestral Cascade volcanoes to develop. Their earlier work showed that volcanoes develop in what are called transtensional basins; the faults that form these basins allow pathways for magmas to reach the surface. Their new geologic maps and age dates will constrain the timing of both fault activity and volcanic eruptions, and will allow a test whether the volume and style (explosive vs. effusive) of volcanic eruptions is directly related to the magnitude of fault activity. One of their hypotheses is that episodes of active transtensional faulting will allow deeper, hotter magmas to be erupted. The PIs will analyze the compositions of the lava flows, and use thermodynamic models, to determine whether the magmas were stored in deep or shallow reservoirs prior to eruption. The PIs have also discovered a suite of lavas that represent the single largest eruption rates ever recorded in either the modern or ancient Cascades. Their new data will determine whether such large eruptions tapped sources that are unusually deep or hot, and whether such episodes are controlled by fault activity. With these results, it may be possible to examine earthquakes at modern volcanoes to predict eruption volume and style.
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.
Our preliminary data show a surpisring result in that volcanic rocks erupted from the Sonora Pass derive from staging areas that are deeply rooted in the lower crust and upper mantle. But in contrast all of the volcanic rocks erupted from the slightly smaller and younger Ebbetts Pass volcanic center (which is still quite large - about the size of the Lassen volcanic center) are only rooted in the upper crust. Some of the volcanic rocks from Ebbetts show a high-T history, and the range of compositions erupted at these two volcanic systems are nearly identical. But the sturcture of their plumbing systems is entirely different. The only obvious difference between these two related systems is that the Ebbetts system experienced higher peak rates of extension. We surmise that if the Ebbetts crust was being pulled apart at greater rates that this action set up stresses within the crust that made it easier for magmas to bypass deep crustal storage sites en route to the surface (or en route to the shallow crust, where the magmas were stored prior to eruption).
Our findings are improtant for the assessment of voclanci hazards as it implies that high rates of extension may mean the absence of deep-seated pre-eruptive seismic signals prior to eruption. Our work also shows that not all volcanic systems are "transcrustal" - some, like Ebbetts, can erupt a very wide range of volcanic rock types from a very narrow range of magma chamber depths that can be restricted to the upper crust.
Last Modified: 08/29/2023
Modified by: Keith D Putirka
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