Research Article| August 01, 1987 Altered former alkalic carbonatite lava from Oldoinyo Lengai, Tanzania: Inferences for calcite carbonatite lavas J. B. Dawson; J. B. Dawson 1Department of Geology, University of Sheffield, Sheffield S1 3JD, England Search for other works by this author on: GSW Google Scholar M. S. Garson; M. S. Garson 2Geological Survey, P.O. Box 8039, Causeway, Harare, Zimbabwe Search for other works by this author on: GSW Google Scholar B. Roberts B. Roberts 3Department of Geology, Birkbeck College, London W1P 1PA, England Search for other works by this author on: GSW Google Scholar Geology (1987) 15 (8): 765–768. https://doi.org/10.1130/0091-7613(1987)15<765:AFACLF>2.0.CO;2 Article history first online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation J. B. Dawson, M. S. Garson, B. Roberts; Altered former alkalic carbonatite lava from Oldoinyo Lengai, Tanzania: Inferences for calcite carbonatite lavas. Geology 1987;; 15 (8): 765–768. doi: https://doi.org/10.1130/0091-7613(1987)15<765:AFACLF>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The active volcano Oldoinyo Lengai, Tanzania, is well known for its extrusions of alkalic carbonatite lava, first witnessed in 1960. An older carbonatite flow from the volcano was originally also rich in Na and K, but replacement of nyerereite by pirssonite as a result of leaching of these elements (together with soluble components such as SO3, Cl, and Rb) and addition of Ca has resulted in a rock intermediate in bulk composition between the unique 1960 Lengai lavas and calcite-rich carbonatite flows reported from other localities. Further replacement of Na by Ca could theoretically result in a pure calcite rock, and we suggest that the partially altered alkalic lava described here is the “missing link” between lavas that are now calcitic but which had a high alkali content when originally extruded. The suggested link between alkali carbonate precursors and present-day calcium carbonate “lavas” explains the apparent paradox between the existence of calcite-rich “flows” and the experimental evidence that denies the possibility of hot, liquid calcium carbonate. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.