Joint 72nd Annual Southeastern/ 58th Annual Northeastern Section Meeting - 2023

Paper No. 28-20
Presentation Time: 8:00 AM-12:00 PM

PALEOENVIRONMENTAL RECONSTRUCTION OF MENDON PONDS PARK, NY THROUGH HIGH RESOLUTION X-RAY FLUORESCENCE AND LOSS-ON-IGNITION ANALYSES


PERLMAN, Eliana, Geology and Geography, Mount Holyoke College, South Hadley, MA 01075, CURTIN, Tara M., Department of Geoscience, Hobart & William Smith Colleges, Geneva, NY 14456, FINKELSTEIN, David B., Geoscience, Hobart and William Smith Colleges, 300 Pulteney St, Geneva, NY 14456 and NEYDON, Kali, Geology and Environmental Science, James Madison University, 801 Carrier Dr, Harrisonburg, VA 22807

High-resolution geochemical records from a small, shallow, pond in western New York were used to investigate its post-glacial and Holocene environmental history. We collected a ~7-m long core from the wetland fringe of Deep Pond that spans the last ~13 ka. We identified five lithofacies on the basis of visual core description, magnetic susceptibility (MS), m-XRF core scanning, loss-on-ignition, and smear slides. Unit 1, a basal silty clay, reflects deposition of primarily clastic sediment in a deep proglacial lake. High MS, high % lithogenous, high Ti and K, and low concentrations of Zr/Rb confirms clay-sized phyllosilicates and silt-sized quartz dominates. A rapid transition to unit 2, a silty carbonate unit with scattered mollusks, is coincident with a dramatic drop in MS, % lithogenous, Ti and Zr and rise in % carbonate, Ca/Ti, % organic matter, and Zr/Rb. The abrupt transition between units 1 and 2 likely signals a hiatus followed by a period of reduced erosion in the watershed, perhaps because the landscape became more vegetated based on pollen records from a neighboring kettle lake. The transition to unit 3, comprised of interbedded carbonate mud with abundant mollusks and sapropel, was gradual. Higher Zr/Rb in unit 3 suggests the aquatic system became shallower as coarser grained sediment, silt- and sand-sized siliciclastic sediment, accumulated. Overall, siliciclastic inputs continued to decrease as evident from the decline in MS, % lithogenous, and Ti. Ca/Ti and % carbonate values are high, indicative of calcite precipitation in the lake-water column. Higher % organic matter and Si/Ti values suggest higher levels of primary productivity, including diatoms, increased during this interval. It is possible that higher Mn/Ti indicates Mn mobilization and precipitation as a result of changes in oxic-anoxic conditions at the sediment-water interface. Unit 4 (sapropel) and unit 5 (peat) signal a transition to predominantly organic-sediment deposition. The % organic matter steadily increased up-core. The overall shift in sediment composition reflects the progressive in-filling of the water body since ~13 ka. Superimposed on this gradual trend are variations in Ti, Ca/Ti, and Zr/Rb. These likely reflect changes in sediment influx, likely from changes in precipitation and runoff.