Continental weathering following a Cryogenian glaciation: Evidence from calcium and magnesium isotopes

Simone A. Kasemann*, Philip A. E. Pogge von Strandmann, Anthony R. Prave, Anthony E. Fallick, Tim Elliott, Karl-Heinz Hoffmann

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

64 Citations (Scopus)

Abstract

A marked ocean acidification event and elevated atmospheric carbon dioxide concentrations following the extreme environmental conditions of the younger Cryogenian glaciation have been inferred from boron isotope measurements. Calcium and magnesium isotope analyses offer additional insights into the processes occurring during this time. Data from Neoproterozoic sections in Namibia indicate that following the end of glaciation the continental weathering flux transitioned from being of mixed carbonate and silicate character to a silicate-dominated one. Combined with the effects of primary dolomite formation in the cap dolostones, this caused the ocean to depart from a state of acidification and return to higher pH after climatic amelioration. Differences in the magnitude of stratigraphic isotopic changes across the continental margin of the southern Congo craton shelf point to local influences modifying and amplifying the global signal, which need to be considered in order to avoid overestimation of the worldwide chemical weathering flux. (C) 2014 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)66-77
Number of pages12
JournalEarth and Planetary Science Letters
Volume396
DOIs
Publication statusPublished - 15 Jun 2014

Keywords

  • calcium isotopes
  • magnesium isotopes
  • continental weathering
  • cap carbonates
  • Neoproterozoic
  • ATMOSPHERIC CARBON-DIOXIDE
  • NEOPROTEROZOIC ICE AGES
  • SNOWBALL EARTH
  • CA ISOTOPES
  • INORGANIC CALCITE
  • AMAZON CRATON
  • LOW-LATITUDE
  • PORE-FLUID
  • CYCLE
  • FRACTIONATION

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