Palynological evidence for astronomical forcing in early miocene lacustrine deposits from rubielos de mora basin (NE Spain)

摘要

Pollen and paleomagnetic analysis of the Rubielos de Mora-1 core (Rubielos de Mora basin, NE Spain) has been carried out with the aim of reconstructing floral, vegetational and climatic changes within an accurate time framework. Based on biostratigraphic information, the magnetostratigraphy of the Rubielos de Mora-1 core is calibrated to the Astronomical Tuned Neogene Time Scale (ATNTS04) resulting in an age of Early Miocene for the cored sedimentary sequence. The high percentages of thermophilous taxa and the diverse subarid flora in the pollen spectra points to a very dry subtropical climate with a marked seasonality, reflecting the onset of the Miocene climatic optimum. On the other hand, taxa with high water requirements (riparian) are also abundant. Alternation in pollen taxa (thenuophilous vs. mesothermic-riparian), coincide with sedimentological changes, which are related to lake level fluctuations and vegetation changes. In turn, the vegetational pattern indicates cyclic changes in temperature and precipitation which is controlled by astronomically forced obliquity cycles. (c) 2007 Elsevier B.V. All rights reserved.