Award Abstract # 2219564
EAR-Climate: Estimating Seawater Boron Isotope Ratios from Halite Evaporites

NSF Org: EAR
Division Of Earth Sciences
Recipient: UNIVERSITY OF CHICAGO
Initial Amendment Date: August 1, 2022
Latest Amendment Date: August 1, 2022
Award Number: 2219564
Award Instrument: Standard Grant
Program Manager: Jonathan G Wynn
jwynn@nsf.gov
 (703)292-4725
EAR
 Division Of Earth Sciences
GEO
 Directorate for Geosciences
Start Date: September 1, 2022
End Date: August 31, 2025 (Estimated)
Total Intended Award Amount: $408,968.00
Total Awarded Amount to Date: $408,968.00
Funds Obligated to Date: FY 2022 = $408,968.00
History of Investigator:
  • Clara Blattler (Principal Investigator)
    cblattler@uchicago.edu
Recipient Sponsored Research Office: University of Chicago
5801 S ELLIS AVE
CHICAGO
IL  US  60637-5418
(773)702-8669
Sponsor Congressional District: 01
Primary Place of Performance: The University of Chicago
6054 South Drexel Avenue
Chicago
IL  US  60637-2612
Primary Place of Performance
Congressional District:
01
Unique Entity Identifier (UEI): ZUE9HKT2CLC9
Parent UEI: ZUE9HKT2CLC9
NSF Program(s): Geobiology & Low-Temp Geochem
Primary Program Source: 01002223DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s):
Program Element Code(s): 729500
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.050

ABSTRACT

This research will improve estimates of ocean pH and atmospheric carbon dioxide concentrations ~36 million years ago by resolving how the composition of boron in seawater has changed over time. The composition of boron in seawater needs to be known in order use the small amounts of boron in fossil shells to determine the pH of the water they grew in and the carbon dioxide that would be in equilibrium with that water. This project will analyze rock salt deposits where boron is present in small amounts of evaporated seawater that are captured within the salt crystals, as well as within minerals. By analyzing the boron in these salt deposits and determining the composition of boron in ancient seawater, this research will allow the boron in fossil shells to be translated into more accurate estimates for atmospheric carbon dioxide, which will improve understanding about the connection between climate and carbon dioxide. The project will support two early-career women scientists and one under-represented minority scientist, and the researchers will share their scientific expertise on these topics with a high-school educational outreach program on the South Side of Chicago.

The project will investigate the behavior of boron in halite evaporite formations to determine the phases that host boron (e.g. fluid inclusions or trace minerals disseminated in the halite) and constrain the stable isotopic composition of boron in ancient seawater. By measuring major element compositions across several halite subsamples bearing fluid inclusions, mixing relationships between the various mineral and fluid components that contribute boron to bulk dissolved halite samples will be established, which will allow for calculation of the endmember composition of the fluid inclusions and the boron isotopic composition of ancient seawater. Experimentally precipitated halites, natural salt cores, and ultimately a ~36 million year old marine halite sample from Spain will be studied in this project. Stable isotope analysis of boron by inductively coupled plasma mass spectrometry will be established in the geochemical facilities at the University of Chicago. In addition to providing an independent constraint on ocean pH and the carbonate system, this research will also determine the distribution coefficient of boron in gypsum and resolve the long-term evolution of the boron geochemical cycle.

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.

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