Abstract
A new detailed pollen record of the penultimate glacial–interglacial–glacial cycle corresponding to the late marine isotopic stages (MISs) 6–3 (146–35 ka ago) has been obtained from Lake Chalco, in the Basin of Mexico. This record provides an insight into vegetation dynamics and climate variability at the northern limit of the American tropics. The pollen record displays a high temporal resolution with a mean sampling interval of ∼230 years. The changes in plant composition were reconstructed by pollen analysis and differences in plant composition between distinct periods were established. The wettest cold stage, indicated by a combination of diverse open vegetation and mesophytic taxa correlates with the penultimate late glacial MIS 6 (146–130 ka), when Lake Chalco was a deep freshwater lake. The penultimate interglacial MIS 5e (126.5–123.6 ka) shows a dominance of Pinus forests, with tropical taxa suggesting warmer than present conditions; environmental proxies indicate drier conditions and that the lake transitioned into a saline water body. Open communities and Pinus and Quercus forests with mesophytic taxa and, during the stadial periods, MIS 5 d, 5c, and 5 b (125–90 ka), with tropical taxa, characterize the record of interstadials. Pinus-dominated forests characterize the landscape during MIS 5a. MIS 5c to MIS 3 showed lower and variable evenness and palynological richness, along with an increase in fire activity. During MIS 4 and 3, a trend towards drier conditions was also recorded with enhanced carbonate precipitation and proxies indicating saline conditions. Tree-line changes in response to climate change and taxa migration were documented. A comparison with long records from the Greenland ice cores, the marine Cariaco Basin and insolation parameters revealed that the pollen data and the Pinus pollen accumulation rates evidence the response of the vegetation to glacial and interglacial changes and to millennial-scale variability. Wetter conditions were inferred to exist during the Greenland interstadials, while drier conditions persisted during Heinrich events.
Original language | English (US) |
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Article number | 107830 |
Journal | Quaternary Science Reviews |
Volume | 297 |
DOIs | |
State | Published - Dec 1 2022 |
Bibliographical note
Funding Information:This work is dedicated to Enrique Santoyo Villa an outstanding engineer who worked in soil mechanics and geotechnics in the Basin of Mexico. Thanks to his creativity we drilled 250 m of high-quality cores in Lake Chalco. We thank an anonymous reviewer and Vera Markgraf for thoughtful reviews that strengthened this manuscript. Financial support was provided by projects UNAM PAPIIT (Universidad Nacional Autónoma de México, México) IN103819 and IN106620 . Also, we want to express our recognition to the Ejido de Tulyehualco for the support and access to the drilling site. We thank Erik Brown for the XRF core scanning performed at the Large Lakes Observatory, University of Minnesota, Duluth.
Publisher Copyright:
© 2022 Elsevier Ltd
Keywords
- Basin of Mexico
- Climate change
- Last glacial
- Millennial-scale variability
- Penultimate interglacial
- Plant diversity
- Pollen analysis
- Vegetation dynamics
Continental Scientific Drilling Facility tags
- CHALCO