Abstract
Scientific drill cores recovered from Lake Malawi exhibit a remarkable down-core lithologic variability, and are indicative of radically changing environmental conditions forced by large-amplitude lake-level shifts over the past 150kyr. Here we present detailed lithologic and sedimentary fabric descriptions of the key sedimentary units, along with down-core physical properties data, down-core organic matter geochemistry (TOC, C/N, and δ13C data sets), and images and descriptions from core sections and from sediment smear slide microscopy. These data reveal a fundamental change in Lake Malawi's limnology and regional climate at ca. 60-70ka. Prior to this time the lake was characterized by large-amplitude variations in lake level and water chemistry, but after 60ka the lake remained comparatively high, and the central basin drill site accumulated mainly organic-rich, laminated sediments. Organic matter sources changed dramatically during the different lake stages. During major lake high stands, a mixed assemblage of algal (diatom-dominated), woodland and aquatic macrophyte (C4-pathway), and grassland (C3-pathway) organic matter was deposited, whereas during extreme low lake stages (water depths <200m), when saline, alkaline lakes persisted in the basin, sediments with minimal amounts of algal-dominated organic matter accumulated and were preserved.
Original language | English (US) |
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Pages (from-to) | 38-50 |
Number of pages | 13 |
Journal | Palaeogeography, Palaeoclimatology, Palaeoecology |
Volume | 303 |
Issue number | 1-4 |
DOIs | |
State | Published - Apr 1 2011 |
Keywords
- East African Rift
- Lake Malawi
- Lithostratigraphy
- Paleoclimatology
- Paleolimnology
- Pleistocene
ASJC Scopus subject areas
- Oceanography
- Ecology, Evolution, Behavior and Systematics
- Earth-Surface Processes
- Palaeontology