| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
|
| Initial Amendment Date: | January 17, 2012 |
| Latest Amendment Date: | January 17, 2012 |
| Award Number: | 1144945 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Sonia Esperanca
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | February 1, 2012 |
| End Date: | January 31, 2016 (Estimated) |
| Total Intended Award Amount: | $374,297.00 |
| Total Awarded Amount to Date: | $374,297.00 |
| Funds Obligated to Date: |
|
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
1850 RESEARCH PARK DR STE 300 DAVIS CA US 95618-6153 (530)754-7700 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
One Shields Ave Davis CA US 95616-8605 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): | Petrology and Geochemistry |
| Primary Program Source: |
|
| Program Reference Code(s): | |
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Insights into the development of silicic magma reservoirs over space and time from crystal- scale trace-element and isotopic data and U-Th dating
Intellectual merit. Caldera-forming eruptions are among the most dramatic and hazardous geologic events to occur on Earth. In addition, melting and assimilation at large silicic caldera systems represent over geologic time important mechanisms that influence chemical characteristics of the continental crust. Important outstanding questions about how silicic reservoir systems operate include how large bodies of silicic magmas are generated (i.e., the balance between re-melting of existing crustal material and differentiation of mantle-derived material), how silicic magma systems are organized in terms of their subsurface geometry and the distribution of distinct magma bodies within the reservoir, how and when large volumes of eruptible melt are accumulated prior to eruptions, and whether the processes of rhyolitic melt generation and storage differ with tectonic setting. Results of this project will contribute to the debate by providing insights into the heterogeneity or homogeneity of melt compositions in silicic reservoirs over space and time. Specific goals of this proposal are: 1) to determine the degree to which large silicic magma bodies are chemically heterogeneous in composition over space and time, which has implications for how silicic magmas are generated and amalgamated/stored prior to eruptions, and 2) to compare this information about subsurface geometry and heterogeneity between two large caldera systems in different tectonic settings. It is proposed to address these questions by analyzing samples from Yellowstone Caldera, Western US, and Okataina Caldera Complex, New Zealand. The project will utilize a novel combination of analytical techniques, including trace-element analyses and dating of zircon and major phases along with Hf isotopic compositions of zircon. A longer-term temporal record of chemical changes in magmatic systems will be obtained through two approaches: 1) analysis of surfaces on unpolished grains mounted with the crystal face parallel to the mounting medium, which will be combined with interior analyses of conventional polished mounts and with multiple interior regions of selected grains in a serial-sectioning approach, and 2) combining zircon analyses with U-Th dating and analyses of trace elements in mineral separates of major phases. The analysis of surfaces of grains will provide a the record of the most recent growth of zircon, which is difficult to obtain from spot analyses of polished interiors because thin zircon rims are smaller than the spot dimensions, leading to mixing of ages. Zircon grains in silicic magmas often record conditions in the subsurface tens to hundreds of thousands of years prior to the eruptions that brought them to the surface, whereas major phases are more likely to record information about the accumulation and storage of magma bodies within a few thousands of years prior to their eruption, thus the combined approach provides unique insights into the long-term subsurface history as well as the accumulation of silicic magmas in the lead-up to eruptions. Furthermore, the addition of in-situ Hf isotopic analyses of zircon that can be directly related to age and trace-element data is new and will provide an excellent method of fingerprinting different magma compositions/bodies and tracking their evolution and mixing history over time.
Broader impacts of this study include a better understanding of the growth of silicic systems, which has implications for volcanic hazards and for understanding the growth of the continental crust. This project will also support a female PI and possibly a female graduate student (MS student to be recruited). Two graduate students will gain valuable experience and training in a wide variety of cutting-edge analytical techniques. At least one undergraduate thesis will be supported by this work, and if possible we will recruit an additional undergraduate student each year to participate in this project. The PI has a track record of mentoring women and other underrepresented groups, and will continue to recruit underrepresented students for the graduate and undergraduate work in this proposal. This proposal will also support international collaborations and collaborations between the university and USGS.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
Note:
When clicking on a Digital Object Identifier (DOI) number, you will be taken to an external
site maintained by the publisher. Some full text articles may not yet be available without a
charge during the embargo (administrative interval).
Some links on this page may take you to non-federal websites. Their policies may differ from
this site.
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.
The main goals of this project were to better understand how large bodies of magma are generated and stored in settings like Yellowstone, WY, and the Taupo Volcanic Zone, New Zealand. This type of volcanic system produces some of the largest and most potentially hazardous eruptions on Earth, and understanding conditions within the magma storage zone beneath the surface is critical for interpreting monitoring data that can be used to forecast volcanic behavior.
Intellectual merit:
In this project, we have learned that magmas beneath Yellowstone are stored in two separate regions beneath the surface. Magmas are first stored in one region for long periods of time (tens to hundreds of thousands of years), and then move to a “staging area” where the final accumulation of the magma bodies that eventually erupt occurs over periods of time of less than a few thousand years (and likely much shorter). This is similar to information from recent studies of other, smaller, volcanic systems that suggests that the erupted magmas are stored for only decades to centuries prior to eruption. Our results for recent eruptions at New Zealand indicate a similar picture of magma storage, where the erupted magmas are present for relatively brief times before eruption. Furthermore, we identified differences in the chemical signatures of magmas before and after a recent large eruption at New Zealand (the Rotoiti eruption) which indicate that these large eruptions may lead to a major reorganization of the storage region beneath the surface.
Broader Impacts:
Our study contributes to a better understanding of the conditions and timing of magma storage prior to eruption and contributes to our understanding of how to interpret monitoring signals at volcanoes. The project has contributed to development of a scientific workforce by training three graduate students (two PhD theses and a third student) and six undergraduate students. The project provided training for graduate students in cutting-edge analytical techniques (electron microprobe analysis, mass spectrometry, chemical separation techniques) which have wide application outside of volcanology. It has also contributed to development of a diverse scientific workforce by training four women, one of whom is Latina.
Last Modified: 05/09/2016
Modified by: Kari M Cooper
Please report errors in award information by writing to: awardsearch@nsf.gov.
