Late Pleistocene–Holocene environmental and climatic history of a freshwater paramo ecosystem in the northern Andes

Abstract

This study presents the first multi-proxy palaeoenvironmental and palaeoclimatic history for northern South America based on the palaeolimnological reconstruction of a pond located in a dry paramo at 3570 masl. During the Last Glacial Maximum (LGM), the study area was under glacial conditions, then during global events Heinrich Stadial 1 (HS1), Bølling-Allerød (BA), and the Younger Dryas (YD), the pond expanded, accumulation rates and proxies for erosion reached the highest values, indicative of humid conditions, with maxima in humidity during the BA and YD. Dry conditions and pond desiccation occurred in the Greenlandian-Northgrippian and by 6010 cal a BP the area was transformed into the mire of today. Comparisons with records from other sites in South America indicate that changes in humidity are most likely controlled by the Intertropical Convergence Zone, mainly during the glacial and postglacial, and by changes in the Pacific Ocean, more pronounced after the YD.

Warm tropical oceans and ENSO flavours behind the late Holocene change in hydroclimates in northern South America

“…The two "paleo" environmental reconstructions are based on the record from Santurbán-Berlín (7° 6.6'N, 72° 49'W at 3,800 m asl) that covers the last 27,000 yr BP, and studied using diatoms, litho-stratigraphy and element concentrations (Patiño et al, 2020), and the record from Medellincito (5º 19'N, 75º 54'W at 2000 m asl) almost 7,000 years old interrupted by one hiatus from 3,710 to 1,560 yr BP, and analyzed using diatoms, isotope geochemistry, litho-stratigraphy and pollen (Jaramillo et al, 2021). The age models presented here are taken from the original articles (where they are discussed at length), based on Bayesian statistics of fifteen and eight 14 C dates for Santurbán-Berlín and Medellincito, respectively, processed through Bacon software (Blaauw and Christen, 2011).…”

“…In Santurbán-Berlín a decrease in detrital input, an increase in lake water levels and or an extension of the wetland and an increase in runoff, interpreted as an increase in precipitation and wetland productivity (Patiño et al, 2020) is dated between ~4,150 and lasted ~2,800 yr BP. This change was inferred from a sharp change in core lithology from pale silt to organic mud, a peak in Aulacoseira spp, a planktonic diatom previously absent from the record, and an increase in Ti:Ca (Patiño et al, 2020;Fig. 10).…”

“…1) (Poveda and Mesa, 2000;Yepes et al, 2019). These reconstructions indicate that Santurbán-Berlín, became wet between 4,150 and 2,500 yr BP (Patiño et al, 2020) while Medellincito witnessed very dry conditions between 3,700 and 1,750 yr BP (Jaramillo et al, 2021). This is, eastern Colombia became wet, while the western part turned dry.…”

Late Quaternary Abrupt Climate Change in the Tropics and Sub‐Tropics: The Continental Signal of Tropical Hydroclimatic Events (THEs)

“…The pollen data are more difficult to quantify in terms of hydroclimate, but during HE1 and HE3‐HE6, the area was relatively wet. During HE2, the evidence is less clear; it was certainly colder but may also have been relatively dry in some parts of the country where the complex topography makes it difficult to define the overall regional patterns of hydroclimatic changes (Groot et al., 2013; Patiño et al., 2020; Velásquez‐R & Hooghiemstra, 2013).…”

Tropical South America Diatom Database: a tool for studying the macroecology of microorganisms

“…In tropical South America the wide latitudinal, longitudinal, and elevational ranges, coupled with complex physiography and geology, produce notable climatic and limnological variability that structure species composition and diversity of diatom assemblages (Benito et al 2018a). Hence, lacustrine sediment cores from lakes of varied origins and ages have enabled the use of subfossil diatoms to track recent (10s-100s yr), historic (1000s yr), and geological (100,000s yr) change in ecosystems (Steinitz-Kannan et al 1993, Ekdahl et al 2008, Giles et al 2018, Patiño et al 2020. However, large-scale repositories of raw data combining modern and paleolimnological observations of Neotropical bioindicators are still scarce (e.g.…”