Evidence for a Neoproterozoic ocean in south-central Africa from mid-oceanic-ridge–type geochemical signatures and pressure-temperature estimates of Zambian eclogites

Research Article| March 01, 2003 Evidence for a Neoproterozoic ocean in south-central Africa from mid-oceanic-ridge–type geochemical signatures and pressure-temperature estimates of Zambian eclogites Timm John; Timm John 1Institut für Geowissenschaften, Universität Kiel, Olshausenstrasse 40, 24098 Kiel, Germany, and Institut für Mineralogie, Universität Münster, Corrensstrasse 24, 48149 Münster, Germany Search for other works by this author on: GSW Google Scholar Volker Schenk; Volker Schenk 2Institut für Geowissenschaften, Universität Kiel, Olshausenstrasse 40, 24098 Kiel, Germany Search for other works by this author on: GSW Google Scholar Karsten Haase; Karsten Haase 2Institut für Geowissenschaften, Universität Kiel, Olshausenstrasse 40, 24098 Kiel, Germany Search for other works by this author on: GSW Google Scholar Erik Scherer; Erik Scherer 3Institut für Mineralogie, Universität Münster, Corrensstrasse 24, 48149 Münster, Germany Search for other works by this author on: GSW Google Scholar Francis Tembo Francis Tembo 4School of Mines, University of Zambia, P.O. Box 32379, Lusaka, Zambia Search for other works by this author on: GSW Google Scholar Geology (2003) 31 (3): 243–246. https://doi.org/10.1130/0091-7613(2003)031<0243:EFANOI>2.0.CO;2 Article history received: 27 May 2002 rev-recd: 25 Oct 2002 accepted: 02 Nov 2002 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 Timm John, Volker Schenk, Karsten Haase, Erik Scherer, Francis Tembo; Evidence for a Neoproterozoic ocean in south-central Africa from mid-oceanic-ridge–type geochemical signatures and pressure-temperature estimates of Zambian eclogites. Geology 2003;; 31 (3): 243–246. doi: https://doi.org/10.1130/0091-7613(2003)031<0243:EFANOI>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 Precambrian eclogites, metagabbros, and gabbros occur in an ∼200-km-long by 40-km-wide zone in central Zambia. Pressure-temperature (P-T) estimates of kyanite-bearing eclogites (kyanite eclogites) throughout the zone give temperatures of 590–750 °C at minimum pressures of 20 kbar. Phengite-bearing eclogites equilibrated at 720–755 °C and 26–28 kbar and show evidence for a clockwise P-T path. These P-T conditions imply a low geothermal gradient of ∼8 °C/km and a subduction depth of ∼90 km. The eclogites, metagabbros, and gabbros show incompatible element patterns similar to those of recent mid-oceanic-ridge basalts, and thus are interpreted to represent former oceanic crust. The low geothermal gradient indicates a cold subducted oceanic lithosphere, implying long-lived, fast convergence and a relatively large (>1000 km) associated ocean basin. A Sm-Nd isochron defines an age of 595 ± 10 Ma for the eclogite facies metamorphism. These results imply that a Neoproterozoic suture zone exists between the Congo and Kalahari cratons. Suturing occurred during the same orogenic cycle that formed the Zambezi belt and is related to the assembly of Gondwana. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.