Holocene carbonate record of Lake Kivu reflects the history of hydrothermal activity

Jillian E. Votava, Thomas C. Johnson, Robert E. Hecky

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

Abstract

The sediment record of Lake Kivu reveals a complex volcanogenic and climatic Holocene history. Investigation of the inorganic carbonate record dates the onset of carbonate deposition in the midHolocene in Kivu's deep northern and eastern basins and identifies conditions enabling deposition. The magnitude and timing of carbonate-rich sedimentation is not so much controlled by climate but, instead, linked strongly to hydrothermal activity in the basin. Sublacustrine springs supply the vast majority of the calcium and carbonate ions required for supersaturation with respect to aragonite. This major hydrothermal activity that permanently stratifies Lake Kivu today was initiated ∼3,100 y before present (3.1 ka), when carbonate-rich sediments first appeared in the Holocene record. Aragonite is the dominant CaCO3 mineral present in the lake deposits. Both δ13C and δ18O of the aragonite are enriched above the expected kinetic fractionation of meteoric waters, suggesting a volcanogenic influence on the formation waters. Repeated major fluctuations in the carbonate record after 3.1 ka therefore most likely reflect the historical variation in hydrothermal inputs.

Original languageEnglish (US)
Pages (from-to)251-256
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume114
Issue number2
DOIs
StatePublished - Jan 10 2017

Bibliographical note

Copyright:
Copyright 2019 Elsevier B.V., All rights reserved.

Keywords

  • CaCO
  • East Africa
  • Holocene
  • Lake Kivu hydrothermal activity

Continental Scientific Drilling Facility tags

  • MANGO
  • MANGO2

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