Interglacial–glacial Fuquene-3 pollen record from Colombia: an Eemian to Holocene climate record

Abstract

Pollen analysis of the 43-m-long Fuquene-3 core from Lake Fuquene (5°27′N, 73°46′W), located at 2580-m elevation in the Eastern Cordillera of Colombia, shows a record of vegetational and climatic change since the last interglacial. The upper 13 m of lake sediments include six 14C ages ranging from 44,100±200 to 8920±200 14C years BP, and this core interval is correlated to pollen record Fuquene-2. The lower part of the core is compared with pollen record Fuquene-7 and with the marine oxygen isotope stages (MIS) of the general δ 18O stratigraphy. Cold episodes, corresponding to MIS 2 and MIS 4, are clearly identifiable, whereas a long period with mainly interglacial conditions has been identified as corresponding to MIS 5. The pollen record does not show the transition to the penultimate glacial and is thought to start in the beginning of the last interglacial (‘Eemian’ or ‘Palo Blanco’ interglacial). The formalised chronostratigraphy of Colombia is partly based on core Fuquene-3: three stadials and three interstadials of early Pleniglacial (73–60 k.y. BP) and middle Pleniglacial (60–28 k.y. BP) time have been recognised. During the two periods, sediments were eroded causing a hiatus from about 36–25 to 18–10 k.y. BP. The upper forest line oscillated between 3300 (max. 14 °C at 2550 m) during the last interglacial and about 2000 m (min. 6 °C at 2550 m). Compared to today, an LGM temperature depression of 8 °C and an Eemian maximum temperature of +1 °C at 2550 m have been inferred. Sediment accumulation rates vary from 8 to 3.8 cm/100 years; highest accumulation rates coincide with shallow lake conditions. Upper Andean vegetation is dominated by Quercus forest during the Holocene and by Weinmannia forest during the last interglacial. A slow transition is observed from mild MIS 5 conditions to cool MIS 4 conditions during which period a temperature depression of 4 °C compared to today is reconstructed. The temperature record shows two maxima during stage 5a, two minima during stage 5b, stage 5c is relatively short, stage 5d is not represented, and in stage 5e (‘Palo Blanco’ or ‘Eemian’ interglacial) two maxima are represented: Weinmannia forest dominated during the oldest and Quercus forest dominated during the youngest episode.