The responses of lake productivity, vegetation, and fire events in the Basin of Mexico to orbital changes from late MIS 6 to MIS 3 (146–35 ka) have been studied based on geochemical (Ti, TIC, TOC, C/N), charcoal (CHAR) and pollen data of the sediment core CHA08 from Lake Chalco. The paleoenvironmental reconstruction identifies the MIS 6 as a wetter period with episodes of dry conditions, low forest cover and low fire activity. A sudden change from wetter to dry environments with low to high forest cover and fire activity episodes characterized the end of the MIS 6 (132–130 ka) coincident with high spring insolation. Variations in vegetation composition, with a tendency towards higher forest cover, fire-activity, runoff, and organic matter availability, are recorded during the MIS 5, MIS 4, and MIS 3. However, a reduction in the fire-activity was recorded for the cold and dry MIS 4. Spectral analysis based on the titanium concentration record of Lake Chalco suggests a precessional forcing on runoff variations. We explored the impact of the Intertropical Convergence Zone latitudinal migrations which have been related to the summer insolation at 65° N by comparing runoff data with other sedimentary records from North and Central America. Our results highlight the sensitivity of the high altitude tropical basin to climate variations.
Bibliographical noteFunding Information:
This research was funded by UNAM DGAPA-PAPIIT IN103819 and by the US NSF (EAR-1462347). XRF core scanning was performed at the Large Lakes Observatory, University of Minnesota-Duluth. We would like to thank the authorities of the Ejido Tulyehualco for the support and access to the drilling site. Also we thank the technicians and students who helped during the different analysis: Mart?n Hern?ndez, Karla Zurizadae, Minerva L?pez and Erand? Rodr?guez.
© 2021 Elsevier Ltd
- Lake Chalco
- North America
- Z-Score analysis
Continental Scientific Drilling Facility tags