T15 Lakes Past, Present, and Future—Archives of Climate Variability, Paleoenvironment, Geohazards, and Economic Resources I

Sunday, 9 October 2022
8:00 AM - 12:00 PM
607

A NEW LUMINESCENCE DATED AGE MODEL FOR 1.3 MA LAKE MALAWI DRILL CORE

Paper number: T15-5
Program: Technical Sessions
Time: 8:50 AM – 9:05 AM

Authors

Abstract

The 2005 Lake Malawi deep scientific drill core is one of the longest and most continuous high-resolution records from the continental tropics, extending to 1.3 Ma. While extensive sets of paleoclimate proxy data have been generated from this core, a gap in absolute ages, between ~74 ka and ~590 ka (28-167 m core depth), has limited our understanding of climate drivers in this system. Previous age models fill the gap using paleomagnetic excursions and tuning to the global 18O stack, but these methods and the resulting age models remain disputed. We fill this gap in chronology using luminescence dating, with 39 samples collected at ~4 m resolution in this section of the core. All dates are on fine silt and all but the youngest samples use feldspar grains. Though luminescence dates have a large error of ~7%, the high density of dates produces a robust age model. While some of the dates agree with published ages, our age model is unique and indicates changes in sedimentation rates not discernible in prior age models. Our model yields smooth changes in sedimentation rates, rather than abrupt shifts as suggested previously. This new age model allows for a reassessment of the existing proxy records and will aid in a more quantitative evaluation of tropical continental climate drivers.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-382928

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