A 400 ka-multi-centennial record from Lake Petén Itzá reveals mechanisms of moisture transport across Central America
Abstract
Continuous and undisturbed sediment sequences from Lake Petén Itzá provide an opportunity to test how tropical ecosystems react to long-term and abrupt climate changes over several interglacial/glacial cycles. We established a ~400 ka-multi-centennial paleoecological, paleoenvironmental and paleoclimatic record from Lake Petén Itzá by combining geophysical, geochemical and biological proxies. Our results suggest that Lake Petén Itzá was an open-basin lake during 400-85 ka BP, and became a closed-basin lake after 85 ka. Biological and geochemical evidence for the period ~400-85 ka BP show that Marine Isotope Stage (MIS) 11-MIS 5 are expressed in the lake record and follow global trends in temperature. Humid and dry periods are characterized by lake level high and low stands occurring during both warm and cold stages. Climatic conditions during MIS 11 at ~ 400 ka BP and MIS 7 at ~200 ka BP were relatively dry and lake levels dropped between 30 and 50 m. For the last 85 ka, sedimentological, geochemical and biological (pollen, ostracodes) evidence demonstrate that MIS 5, MIS 4 and early MIS 3 where periods of relative climatic stability. Late MIS 3, MIS 2 and MIS 1, on the contrary, were periods characterized by abrupt climatic changes. The most important pulses of alteration occurred during the period 85 to 83 ka BP, Heinrich Stadials (HS) and the Younger Dryas, all characterized by severe lake level lowering of ~50 m. HS1 was the period of strongest climatic and environmental alteration of the last 85 ka, and probably the coldest event during the last glacial. Ostracodes suggest a maximum temperature decrease of 5°C below present in the terrestrial environment and 3°C in the lake. During 85 to 50 ka BP, we inferred warmer and wetter conditions, similar to the marine record MD02-2529 in the Pacific, suggesting a Pacific-modulation of climate conditions in the continental northern Neotropics. After 50 ka BP the record mimics North Atlantic events (HS dry and cold). The Petén Itzá paleoclimatic record combined with other continental and marine archives in the region have great potential in disentangling mechanisms of moisture transport across Central America.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMPP31D1674S
- Keywords:
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- 1616 Climate variability;
- GLOBAL CHANGE;
- 4943 Paleolimnology;
- LIMNOLOGY;
- 4914 Continental climate records;
- PALEOCEANOGRAPHY;
- 4954 Sea surface temperature;
- PALEOCEANOGRAPHY