Source-to-sink response to high-amplitude lake level rise driven by orbital-scale climate change: An example from the Pleistocene Lake Malawi (Nyasa) Rift, East Africa

M. Tan, C.A. Scholz

Research output: Contribution to journalArticlepeer-review

Abstract

Sedimentary systems respond to environmental forcings in dissimilar ways over different timescales. The Lake Malawi (Nyasa) Rift is an ideal natural laboratory for evaluating the overall functioning of lacustrine source-to-sink systems on orbital or younger scales. These closed sedimentary systems exhibited high spatiotemporal climate variability, and their responses to two late Pleistocene lake-level stillstands are evaluated. The coarse-grained deposits documented a dramatic transgression from 350 to 200 m below present lake-level (BPLL) developed during an important climate transition in tropical Africa. Based on an integrated analysis of a digital elevation model and high-resolution single/multi-channel seismic profiles, catchment geomorphology has been linked with sediment delivery in the sink area. The coarse-grained deposition of each source-to-sink system is quantified through a sediment mass calculation. A modified empirically-derived ‘BQART’ predictor with a bedload equation to assess the sediment discharge is employed based on a Monte Carlo simulation, considering temperature lapse rate and topographic effects. The river discharges are estimated by specific empirical relationships that associate catchment area to various climate systems, developed using a global modern river database. The results show that the total sediment discharge increases from 7.53 to 9.50 Mt year−1; likewise, the preserved coarse-grained deposits also record a significant increase in deposition rate from 350 to 200 m BPLL stage, indicating that the short length-scale source-to-sink systems are sensitive to the high-amplitude lake transgression developed from the climate shift. The volume of upstream buffered deposits may decrease within the progressively wetter climate, while the buffering degree was substantially influenced by the pre-existing landforms. Moreover, the substantial deep-water mud dispersal is not well-developed, despite the relatively higher lake-level and slightly wetter climate. This quantitative source-to-sink analysis with the modified sediment predictor yields preliminary constraints for system functioning in response to high-amplitude climate change in a closed sedimentary system. © 2021 International Association of Sedimentologists
Original languageEnglish (US)
Pages (from-to)3494-3522
Number of pages29
JournalSedimentology
Volume68
Issue number7
DOIs
StatePublished - Dec 2021

Bibliographical note

Funding Information:
This study was supported by China Scholarship Council (201706440095), National Natural Science Foundation of China (42002117), National Natural Science Foundation of Jiangsu Province (BK20200529), and Lacustrine Rift Basin Research Program of Syracuse University. We thank Peter Cattaneo for his technological assistance, and Corporation for providing the latest versions of software for conducting seismic interpretation and geomorphological research in the sediment mass‐balance study. Dr Stéphanie Girardclos, Prof. Christopher Fielding, Dr Brian Romans and Dr Tor Sømme are thanked for their comments on an earlier version of the manuscript. We also thank journal editors Dr Ian Kane, Prof. Zhifei Liu, and anonymous reviewers for their constructive suggestions. Landmark Graphics, ESRI

Funding Information:
This study was supported by China Scholarship Council (201706440095), National Natural Science Foundation of China (42002117), National Natural Science Foundation of Jiangsu Province (BK20200529), and Lacustrine Rift Basin Research Program of Syracuse University. We thank Peter Cattaneo for his technological assistance, Landmark Graphics, and ESRI Corporation for providing the latest versions of software for conducting seismic interpretation and geomorphological research in the sediment mass-balance study. Dr St?phanie Girardclos, Prof. Christopher Fielding, Dr Brian Romans and Dr Tor S?mme are thanked for their comments on an earlier version of the manuscript. We also thank journal editors Dr Ian Kane, Prof. Zhifei Liu, and anonymous reviewers for their constructive suggestions.

Publisher Copyright:
© 2021 International Association of Sedimentologists

Keywords

  • BQART model
  • climate fluctuation
  • river discharge
  • sediment flux
  • sediment mass-balance
  • source-to-sink

Continental Scientific Drilling Facility tags

  • GLAD7

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