FREQUENCY-SPECTRA AND PALEOCLIMATIC VARIABILITY OF THE HIGH-RESOLUTION 30-1450-KA FUNZA I POLLEN RECORD (EASTERN CORDILLERA, COLOMBIA)

The evolution of orbital periodicities during the Quaternary has been studied in the 30-1450 ka Funza I pollen record from cores through the sedimentary basin of Bogota, Eastern Cordillera, Colombia. The 1178 pollen samples analysed between 2.90 and 340.00 m generate 5 time series with an average time resolution of ca. 1200 years. Our geochronological framework is based on fission track ages on zircon in combination with correlation of the pollen record with the oxygen isotope record of ODP Site 677 from the Eastern Pacific. The 5 data sets were analysed in the frequency domain with Maximum Entropy Spectrum Analysis (MESA) and Thomson Multi-Taper Spectrum Analysis (TMT) using a moving 400 ka window with steps of 20 ka. Frequencies closely related to the Milankovitch theory were detected in all 5 data sets. The 100 ka period in the arboreal pollen record is restricted to the last ca. 800 ka of the Quaternary at a confidence level largely higher than 90%. Periodicities close to 23 ka occur throughout the record at a high significance level (above 90%) and are strongest in the subparamo data. A statistically significant period centred at ca. 40 ka also occurs in the Funza I record. Four frequency bands centred at ca. 30, ca. 15, ca. 13 and ca. 10 ka were also detected. The 5 principle data sets from the Funza I pollen record reveal an evolution of orbital frequencies in the Middle and Late Quaternary which are in general agreement with other marine (e.g. Imbrie et al., 1984) and continental (e.g. Kukla et al., 1990) records.