Pliocene-Quaternary chronology of the sediments of the high plain of Bogota, Eastern Cordillera, Colombia Andriessen, P.A.M.; Helmens, K.F.; Hooghiemstra, H.; Riezebos, P.A.; van der Hammen, T. Published in:Quaternary Science Reviews DOI:10.1016/0277-3791(93)90066-U Link to publicationCitation for published version (APA): Andriessen, P. A. M., Helmens, K. F., Hooghiemstra, H., Riezebos, P. A., & van der Hammen, T. (1994). Pliocene-Quaternary chronology of the sediments of the high plain of Bogota, Eastern Cordillera, Colombia. Quaternary Science Reviews, 12, 483-501. DOI: 10.1016/0277-3791(93)90066-U General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. A revised geochronological framework is presented for the sequence of unconsolidated sediments present in the Bogot~i area (Eastern Cordillera, Colombia). This is based on 11 fission track dates on zircons that were obtained both from exposed ash layers and from a series of ashes from the Funza II borehole, which reached 586 m below the surface of the high plain. The 3 dates obtained from the exposed ash layers provide control for the older part of the sequence (6-2.5 Ma). The 8 dates from the Funza II core give control for the younger part of the sequence (3--0 Ma). Acceptance of these new fission track dates on volcanic zircons means that many of the tephra dates obtained from the Funza I core (that included fission track dates on glass shards and K-Ar dates using the mineral fractions in the ashes, published in 1984), are rejected. It also confirms earlier climate-stratigraphical dating.The Neogene-Quaternary sediments of the Bogotfi area span a period of at least the last 6 Ma. The fluvial-lacustrine sediment record registers major tectonic uplift of the Eastern Cordillera for the period between 5 and 3 Ma, the development of the large sedimentary basin of Bogot~i after 3.5 Ma, with an important phase of tectonic adjustment at about 1 Ma, and a long period of strong climatic fluctuations that started shortly after 2.7 Ma.

The clay mineral composition of a number of Saalian till samples from The Netherlands shows a large variation in smectite and illite abundances. The samples were selected according to their source area, as inferred from coarse erratic components. Specimens containing primarily rock fragments indicative of East and East‐Central Baltic areas are associated with no or low smectite percentages in their clay fractions. Those with mainly flint and rock fragments indicative of the West Baltic areas have high smectite contents in the clay. In general the smectite‐rich material is found in the lower portions of the Saalian till bed, whereas the smectite‐poor occurs in the upper portions. The linkage between very fine and coarse till components in the upper smectite‐free parts of the till suggests that this entire till has been subjected to englacial transport over distances of at least 1000 km.

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A pollen diagram of a calcareous travertine bed near Kirf (West Germany) shows a tripartition of the Allerød chronozone. In northwestern and central‐European diagrams this is not an uncommon phenom‐enon. Arguments supporting a deduced climatic oscillation may also be derived from the average ice recession in southern Sweden, the Coleoptera assemblages in northwestern England, the isotope 180/16O curve from the Gerzensee in Switzerland, and the Camp Century Ice Core in Greenland. The included sandy Laachcr See ash may suggest explosive volcanism again to be somehow related to inferred climatic changes.

Pollen analysis and radiocarbon dating of a core section from the valley head of the Husterbaach near Hosingen (Oesling) provides a very detailed record of the successive vegetations from 1200 A. D. until today. This palynological record agrees largely with the consecutive events known from the agricultural history of that area. Particularly significant are the curves obtained of several cultivated and ruderal plants. In this section it could be demonstrated that the interruption of peat growth by deposition of minerogenic material corresponds with a comparatively high arable land/pasture ratio. As well as being intrinsically interesting for assessing which features of the present landscape are due to former human activities, a detailed knowledge of the Subatlantic evolution of the vegetation and land use in the Oesling is indispensable, as its geomorphological development in the immediate past has largely been influenced by man.