| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
|
| Initial Amendment Date: | June 27, 2014 |
| Latest Amendment Date: | August 13, 2020 |
| Award Number: | 1348028 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Jennifer Wade
jwade@nsf.gov (703)292-4739 EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | July 1, 2014 |
| End Date: | June 30, 2021 (Estimated) |
| Total Intended Award Amount: | $188,960.00 |
| Total Awarded Amount to Date: | $188,960.00 |
| Funds Obligated to Date: |
FY 2016 = $54,718.00 |
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
800 ALGOMA BLVD OSHKOSH WI US 54901-3551 (920)424-3215 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
800 Algoma Blvd Oshkosh WI US 54901-8649 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): | Petrology and Geochemistry |
| Primary Program Source: |
01001617DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
|
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Subduction zones are important sites of volcanism, continental crustal growth, and mass transfer from the mantle, through the crust, to the surface. The Cascade Arc in western North America is located above a subduction zone and encompasses some of the most active volcanic sites in the contiguous US. Previous investigations of the evolution of magmas in the Cascades focused on large-scale complexities in geochemistry, using individual primitive (or mantle-derived) basalts that erupt there to characterize the mantle. However, the geochemical array of primitive basalts erupted in close proximity to one another suggests that heterogeneous mantle domains may exist on a much smaller scale than previously recognized. Furthermore, many basalts that fit the definition of 'primitive' also have geochemical characteristics typical of some crustal or magmatic processing. The project will be conducted at two PUIs (University of Wisconsin Oshkosh and California State University, Chico) and will train 3-5 undergraduate students per year. The wide range of compositions and small area of the PLC will provide numerous small-scale research questions that can be answered with geochemical techniques, thus preparing undergraduate students for graduate study and careers in STEM. This work is transformative for its important implications for future work in the Cascades and other complex arcs where large-scale variations of a single volcanic center, across arc segments, and along entire arc systems are investigated.
The goal of this project is to identify and characterize small-scale heterogeneities in the sub-Cascadian mantle using compositional variations in a suite of basalts in the Poison Lake chain (PLC) near the Lassen Volcanic Center (LVC) in California. Detailed study of the geochemical variations in the PLC will shed light on the nature of mantle diversity beneath the LVC, the Cascades and other complex subduction zone systems. Given the restricted time and space represented by PLC primitive basalts (~110-100 ka and 50km2), this work is unique because it concentrates solely on the variable of composition. Proposed work focuses on two working hypotheses: 1) Small-scale heterogeneities exist in the mantle and are represented by those PLC basalts that have not been processed; and 2) a variety of post mantle processes can be recognized in other PLC basalts, which do not represent direct mantle melt compositions. Geochemical and petrologic compositions of the most primitive PLC basalts will be used to characterize heterogeneous mantle domains and the scale of chemical variation there (Hypothesis 1). Compositions of modified (less primitive) samples from the PLC will provide insight into crustal processes that may modify mantle melts on their traverse from mantle to surface (Hypothesis 2). In this way, the project will result in models that reflect the scale and composition of mantle heterogeneity and subsequent intracrustal modification processes based on a very isolated section of the LVC.
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 intellectual merit of this work includes a multi-faceted, collaborative approach to geochemical characterization of lavas erupted in the volcanic region of the southernmost Cascades – specifically the Poison Lake chain near Lassen Peak. This work explored compositional variation of basalts in a small area with lavas that are the same age but varied in chemical composition to better understand the processes that affect lavas on their traverse from their source in the mantle, through the crust, to their eruption on the surface. Through this study, we used lavas with mantle-like compositions to characterize some small-scale, but significant differences, in source using isotopic and chemical analyses that “fingerprint” the origin of the lavas. Other lavas, with more modified compositions contained minerals with chemistry that records the complex development of these magmas on their journey through the crust. The changes in chemistry of these minerals allowed characterization of the variety of chemical processes that these lavas experienced. This work establishes a much smaller scale of mantle (source) heterogeneities beneath the southernmost Cascades and describes the complex journey lavas may take in volcanic regions such as the Lassen area. These insights provide a basis for study of other areas in in the Cascade arc as well as in other arcs.
The most significant broader impacts of this project involve the education and training of the next generation of geoscientists. As of June 2021, 24 University of Wisconsin Oshkosh undergraduate researchers have participated in the Poison Lake chain project. Student collaborators gain experience is all aspects of research, from project development through completion and presentation of their work. Students work closely with the PI to carve out aspects of the larger project that are doable in a short period of time. Students who have participated in this research project have engaged in proposal writing (on-campus and external funding), fieldwork, geochemical and mineral analyses, interpretation of results, and presentation at conferences. Research training includes weekly meetings with the PI where we discuss journal articles, progress on student projects and interpretation of the results of their projects. The work among students and PI are shared collaboratively and incorporated into publications with student authorship as appropriate.
Last Modified: 09/27/2021
Modified by: Joseph Peterson
Please report errors in award information by writing to: awardsearch@nsf.gov.
