GSA Connects 2021 in Portland, Oregon

Paper No. 172-5
Presentation Time: 2:40 PM


MONGOL, Erdoo, Missouri University of Science and Technology, Department of Geosciences and Geological and Petroleum Engineering, Rolla, MO 65401-2000, OBOH-IKUENOBE, Francisca, Geosciences and Geological and Petroleum Engineering, Missouri University of Science and Technology, 129 McNutt Hall, Rolla, MO 65409, OBRIST-FARNER, Jonathan, Department of Geosciences and Geological and Petroleum Engineering, Missouri University of Science and Technology, Rolla, MO 65409 and CORREA-METRIO, Alex, Instituto de Geología, Universidad Nacional Autónoma de México, CDMX, 04510, Mexico

Pollen and spores are used for paleovegetation reconstructions in lake sediments due to their excellent preservation potential. In this study, the pollen and spores from a new 760-cm long core from Lake Izabal in eastern Guatemala have been used to reconstruct vegetation changes in the country’s lowlands. Palynological study involved the analysis of 39 palynomorph samples to determine their abundance and diversity as a viable proxy for paleovegetation reconstruction. The core spans approximately 9.5 Ka BP based on the extrapolation of 10 AMS 14C dates of woody debris within the sediments. Detailed synthesis of the results show that the palynomorph assemblage is dominated by different bisaccate gymnospermous pollen (Pinus and Podocarpus), followed by forest taxa (Quercus, Malvaceae, Malpighiaceae, Euphorbiaceae, etc.). The abundance and diversity of the forest taxa are highest at 760 – 500 cm (9.5-4.5 Ka BP), indicative of conditions that probably favored forest expansion in line with higher precipitation rates across the region about 8.2 Ka BP, as widely reported in literature. Well-preserved and abundant spores also occur in this interval, suggestive of proximity to source plants. The interval from 500-350 cm (4.5-3.0 Ka BP) appears to be transitional due to the alternating abundances of forest and disturbance vegetation species observed. From 350-0 cm (3.0-present- Ka BP); disturbance taxa (Poaceae, Solanaceae, Asteraceae) dominate in abundance. Insights from this study will be juxtaposed with climate models and other proxy records in the northern Neotropics to reconstruct past vegetation trends to unravel paleoenvironmental change patterns that could have impacted Guatemala and other parts of the neotropical area.