Unveiling Subduction Dynamics: A Study of Metamorphosed Deep-Sea Sediment at Jenner Beach, California
Location
PANEL: Exploring Ecological Frontiers: Freshwater Snails, Plants, and Deep-Sea Sediments
Science Center A254
Document Type
Presentation
Start Date
4-26-2024 2:00 PM
End Date
4-26-2024 3:00 PM
Research Program
National Science Foundation
Abstract
Subduction zones play a crucial role in seismic activity and volcanism, making them of paramount importance in Earth Sciences. The Franciscan Formation, exposed at the surface, serves as a valuable laboratory for subduction studies. This study examines a previously undescribed sample of metamorphosed deep-sea sediment that was subducted and then returned to the surface at Jenner Beach, California. Our primary objective is to analyze and reconstruct its metamorphic history, explain complex interactions at subduction interfaces, and clarify the role of fluids in shaping Earth's lithosphere and mantle.
Our approach involves conducting Scanning Electron Microscope - Energy Dispersive X-ray Spectrometer mapping to outline mineral distributions and compositions, complemented by thermodynamic modeling to create Equilibrium Assemblage Diagrams. We then use these to reconstruct pressures and temperatures of metamorphism. The presence of garnet, glaucophane, muscovite, epidote, and sphene most closely matches the predicted assemblage at ~500˚ and ~14 kbar, similar to metamorphosed basalts from the same locality. This data indicates that our sample reached depths as far down as 45 km, just above where the melting that forms arc magma occurs. We can utilize this data to examine the geochemical processes crucial in arc formation.
The discovery of the first metaquartzite at Jenner Beach can add to the geological understanding of the region, indicating unique metamorphic conditions. By adding Fe3+ to the model, we hope to refine the conditions of metamorphism. We are seeing this rock form under similar conditions and future studies can use this as a geochemical probe into geochemical processes.
Keywords:
Geosciences, Subduction, Metamorphism, Thermodynamics
Recommended Citation
Vann, Adell and Page, F. Zeb, "Unveiling Subduction Dynamics: A Study of Metamorphosed Deep-Sea Sediment at Jenner Beach, California" (2024). Research Symposium. 18.
https://digitalcommons.oberlin.edu/researchsymp/2024/presentations/18
Major
Earth Materials; Biomedical Technology
Project Mentor(s)
F. Zeb Page, Geosciences
2024
Unveiling Subduction Dynamics: A Study of Metamorphosed Deep-Sea Sediment at Jenner Beach, California
PANEL: Exploring Ecological Frontiers: Freshwater Snails, Plants, and Deep-Sea Sediments
Science Center A254
Subduction zones play a crucial role in seismic activity and volcanism, making them of paramount importance in Earth Sciences. The Franciscan Formation, exposed at the surface, serves as a valuable laboratory for subduction studies. This study examines a previously undescribed sample of metamorphosed deep-sea sediment that was subducted and then returned to the surface at Jenner Beach, California. Our primary objective is to analyze and reconstruct its metamorphic history, explain complex interactions at subduction interfaces, and clarify the role of fluids in shaping Earth's lithosphere and mantle.
Our approach involves conducting Scanning Electron Microscope - Energy Dispersive X-ray Spectrometer mapping to outline mineral distributions and compositions, complemented by thermodynamic modeling to create Equilibrium Assemblage Diagrams. We then use these to reconstruct pressures and temperatures of metamorphism. The presence of garnet, glaucophane, muscovite, epidote, and sphene most closely matches the predicted assemblage at ~500˚ and ~14 kbar, similar to metamorphosed basalts from the same locality. This data indicates that our sample reached depths as far down as 45 km, just above where the melting that forms arc magma occurs. We can utilize this data to examine the geochemical processes crucial in arc formation.
The discovery of the first metaquartzite at Jenner Beach can add to the geological understanding of the region, indicating unique metamorphic conditions. By adding Fe3+ to the model, we hope to refine the conditions of metamorphism. We are seeing this rock form under similar conditions and future studies can use this as a geochemical probe into geochemical processes.
