INVESTIGATING THE UTILITY OF FORAMINIFERAL ISOTOPE PROXIES FOR SEA-LEVEL VARIABILITY IN THE BUENOS AIRES PROVINCE, ARGENTINA

HAWKES, A.; PETH, J.; LANE, C.; DONNELLY, J.; PRATOLONGO, P.; GOMEZ, E.

Baltimore

Congreso; 2015 GSA Annual Meeting; 2015

The Geological Society of America

The utility of sediment and foraminiferal isotopic proxies are tested for developing relative sea-level (RSL) records in coastal central Argentina. Single and multi- proxy reconstructions were investigated based on foraminiferal δ13C and δ18O signatures and bulk sedimentary δ13C compositions with respect to modern marsh elevations. An absence of agglutinated foraminifera commonly used for RSL reconstructions necessitated alternative proxy development. Ammonia parkinsoniana δ13C and δ18O values produced the strongest linear correlations with modern marsh elevation compared to other species or sediment isotopic composition. There was positive covariance between the δ13C and δ18O signatures defining the parameters of four marsh zones with elevation (tidal flat, low marsh, mid-marsh, and high marsh). However, initial tests show that the isotopic range of each of the four zones varies by site making the proxy site specific. This site specificity is likely due to changes in vital effects (respiration), microhabitat effects related to pore water composition (pH, OM degradation), or a combination of both.When applied to sediment cores, the proxy reconstruction approaches (δ13C, δ18O, and multi) record a sea-level regression