Astronomical tuning of long pollen records reveals the dynamic history of montane biomes and lake levels in the tropical high Andes during the Quaternary

Online Access: Get full text
doi: 10.1016/j.quascirev.2012.11.004
Author(s): Torres, Vladimir; Hooghiemstra, Henry; Lourens, Lucas; Tzedakis, P. Chronis
Author Affiliation(s): Primary:
University of Amsterdam, Institute for Biodiversity and Ecosystem Dynamics, Amsterdam, Netherlands
Utrecht University, Netherlands
University College London, United Kingdom
Volume Title: Quaternary Science Reviews
Source: Quaternary Science Reviews, Vol.63, p.59-72. Publisher: Elsevier, International. ISSN: 0277-3791
Note: In English. 59 refs.; illus., incl. 3 tables, sketch map
Summary: Long pollen records from two sediment cores of the basin of Bogota (Colombia) are presented, reflecting the dynamic history of environmental and vegetation changes in the tropical high Andes during the Quaternary. An astronomically tuned age model has been developed by using the visual correlation of the temperature-constrained record of Alnus with the benthic δ18O stacked record of ODP Site 846 and 849 for the last 1 million year (Ma). In addition, spectral analysis of the arboreal pollen percentages (AP%) prior to 1 Ma shows two consistent peaks at 7.6 and 9.5 m, which could either be interpreted as reflecting the 19 and 23-kyr components of the precession cycle or the 41-kyr cycle of obliquity. Evidence for precession forcing comes from the sum of the filtered 7.6 and 9.5 m cycles, revealing a long-term modulation that can be linked to the short-term (100-kyr) and long-term (400-kyr) eccentricity cycles. A precession-forced scenario, however, is not consistent with zircon fission-track ages and is difficult to explain in terms of climate forcing mechanisms. On the contrary, an obliquity control of the AP% record is consistent with the fission-track ages and with glacial-interglacial-bound temperature changes within the study region. Accordingly, it appears that the Funza09 record extends back to ∼2.25 Ma during which four periods with distinct different depositional environments could be identified, following a chronological poorly constrained interval of fluvial and fluvio-lacustrine sediments. From ∼2.25 to ∼1.47 Ma sediment deposition occurred in an area of wetlands dissected by fluvial channels and swamps. The strongest subsidence of the basin occurred between ∼1.47 and ∼1.23 Ma when a proper lake developed. Lacustrine sediments accumulated in water up to 50 m deep between ∼1.23 and ∼0.86 Ma. Hereafter, water depth was generally lower than 50 m, but fluctuated in conjunction with the 100-kyr dominated glacial-interglacial variability during the middle and late Pleistocene. The evolutionary changes of the paramo and montane forest biomes are described in terms of five characteristic stages. Most of the Pleistocene vegetation has no analogue to modern assemblages principally due to the late immigration events of Alnus (1.01 Ma) and Quercus (0.43 Ma) and we conclude that forest composition similar to modern was not established until the Last Interglacial. However, modern ecological constraints of suites of taxa that formed the vegetation of the pre-MIS 5 part of the record allow a reconstruction of environmental and climate change. Abstract Copyright (2013) Elsevier, B.V.
Year of Publication: 2013
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Andes; Biostratigraphy; Cenozoic; Chronostratigraphy; Climate change; Climate forcing; Colombia; Cores; Cyclostratigraphy; East Pacific; Equatorial Pacific; Funza Colombia; Lake-level changes; Leg 138; Lithostratigraphy; Microfossils; Miospores; North Pacific; Northeast Pacific; Northern Andes; ODP Site 846; ODP Site 849; Ocean Drilling Program; Orbital forcing; Pacific Ocean; Paleoclimatology; Paleoecology; Palynomorphs; Pleistocene; Pollen; Quaternary; Sabana de Bogota; Sediments; South America; South Pacific; Southeast Pacific; Vegetation
Coordinates: S030549 S030541 W0904904 W0904906
S030549 S030541 W0904904 W0904906
N045000 N045000 W0741200 W0741200
Record ID: 2013095040
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands