History of Groundwater Flow in the Southern Great Basin Inferred From Paleo-deposits
Poster Number
21A
Format
Poster Presentation
Faculty Mentor Name
Laura K. Rademacher
Faculty Mentor Department
Geological and Environmental Science
Additional Faculty Mentor Name
Yadira Ibarra
Additional Faculty Mentor Department
Department of Earth & Climate Sciences, San Francisco State University
Additional Faculty Mentor Name
Marty D. Frisbee
Additional Faculty Mentor Department
Department of Earth, Atmospheric, and Planetary Sciences, Purdue University
Graduate Student Mentor Name
Zachary P. Meyers
Graduate Student Mentor Department
Department of Earth, Atmospheric, and Planetary Sciences, Purdue University
Abstract/Artist Statement
Paleohydrologic deposits (“spring mounds”) from the Great Basin were analyzed for petrographic indicators of past changes in groundwater flow throughout the groundwater system. This pilot study focuses on carbonate samples collected from spring mounds in Death Valley National Park (DVNP), CA and Ash Meadows National Wildlife Refuge (AMNWR), NV. The sampled springs that host these carbonate deposits are part of a larger project investigating the relationship between groundwater flow and ecological diversity in the modern environment. This study seeks to understand how and why portions of the flow system have dried over time, while others remain active. Results from our investigation provides insight into how the Basin and Range spring systems have evolved through changing climate regimes.
Hand samples were collected from two sites: one site in eastern DVNP and one site in north-east AMNWR. Sampling locations were located in the distal, non-flowing regions of large modern springs. In the lab, samples were photographed at high resolution and then cut and polished into standard thin sections for petrographic analysis. Petrographic analyses on all samples revealed that they are largely calcium carbonate. However, the analyzed samples vary in crystal size from micrite layers to bands of bladed spar crystals that may represent seasonal changes in temperature during deposition. Several samples appear to have undergone diagenetic changes while others exhibit only minimal post-depositional changes.
Future work will include carbon and oxygen isotope analysis that may suggest paleoenvironmental changes, that coupled with the petrographic analysis, will provide insight into particular paleo-climate conditions that may have correlated with a change in crystal structure or periods of growth or non-growth in the carbonates, thus providing insight into flow histories. In addition, future luminescence dating of the cores to provide a timeline for these observed changes.
Location
DeRosa University Center Ballroom
Start Date
27-4-2018 12:30 PM
End Date
27-4-2018 2:30 PM
History of Groundwater Flow in the Southern Great Basin Inferred From Paleo-deposits
DeRosa University Center Ballroom
Paleohydrologic deposits (“spring mounds”) from the Great Basin were analyzed for petrographic indicators of past changes in groundwater flow throughout the groundwater system. This pilot study focuses on carbonate samples collected from spring mounds in Death Valley National Park (DVNP), CA and Ash Meadows National Wildlife Refuge (AMNWR), NV. The sampled springs that host these carbonate deposits are part of a larger project investigating the relationship between groundwater flow and ecological diversity in the modern environment. This study seeks to understand how and why portions of the flow system have dried over time, while others remain active. Results from our investigation provides insight into how the Basin and Range spring systems have evolved through changing climate regimes.
Hand samples were collected from two sites: one site in eastern DVNP and one site in north-east AMNWR. Sampling locations were located in the distal, non-flowing regions of large modern springs. In the lab, samples were photographed at high resolution and then cut and polished into standard thin sections for petrographic analysis. Petrographic analyses on all samples revealed that they are largely calcium carbonate. However, the analyzed samples vary in crystal size from micrite layers to bands of bladed spar crystals that may represent seasonal changes in temperature during deposition. Several samples appear to have undergone diagenetic changes while others exhibit only minimal post-depositional changes.
Future work will include carbon and oxygen isotope analysis that may suggest paleoenvironmental changes, that coupled with the petrographic analysis, will provide insight into particular paleo-climate conditions that may have correlated with a change in crystal structure or periods of growth or non-growth in the carbonates, thus providing insight into flow histories. In addition, future luminescence dating of the cores to provide a timeline for these observed changes.