A subduction origin for komatites and cratonic lithospheric mantle
| dc.contributor.author | Parman, Stephen W | |
| dc.contributor.author | Grove, Timothy L | |
| dc.contributor.author | Dann, Jessc C | |
| dc.contributor.author | De Wit, Maarten J | |
| dc.date.accessioned | 2017-03-22T10:55:52Z | |
| dc.date.available | 2017-03-22T10:55:52Z | |
| dc.date.issued | 2004 | |
| dc.date.updated | 2016-01-07T10:06:04Z | |
| dc.description.abstract | We present a model in which the generation of komatiites in Archaean subduction zones produced depleted mantle residues that eventually formed the highly depleted portions of the Kaapvaal lithospheric mantle. The envisioned melting process is similar to that which has formed boninites in Phanerozoic subduction zones such as the Izu-Bonin-Mariana arc. The primary differences between the Archaean and Phanerozoic melting regimes are higher mean melting temperatures (1450 versus 1350 °C) and higher mean melting pressures (2.5 versus 1.5 GPa) for the komatiites. The komatiites from the Komati Formation in the Barberton greenstone belt are mafic enough to have produced the depletion seen in most Kaapvaal granular peridotite xenoliths. However, the most highly depleted Kaapvaal xenoliths require an even more Mg-rich magma than the Komati komatiites (Kk). Samples of boninite mantle residues from the fore-arc of the Marianas subduction zone are nearly as depleted as the Kaapvaal cratonic mantle, indicating that buoyant, craton-like mantle is being produced today. We speculate that production rates of cratonic mantle were greater in the Archaean due to the greater depth of melting for komatiites (relative to boninites) and greater worldwide arc length. The high production rates and high buoyancy of the komatiite mantle residues gave rise to the rapid growth and stabilization of the Kaapvaal craton in the Archaean. | |
| dc.identifier.apacitation | Parman, S. W., Grove, T. L., Dann, J. C., & De Wit, M. J. (2004). A subduction origin for komatites and cratonic lithospheric mantle. <i>South African Journal of Geology</i>, http://hdl.handle.net/11427/24075 | en_ZA |
| dc.identifier.chicagocitation | Parman, Stephen W, Timothy L Grove, Jessc C Dann, and Maarten J De Wit "A subduction origin for komatites and cratonic lithospheric mantle." <i>South African Journal of Geology</i> (2004) http://hdl.handle.net/11427/24075 | en_ZA |
| dc.identifier.citation | Parman, S. W., Grove, T. L., Dann, J. C., & De Wit, M. J. (2004). A subduction origin for komatiites and cratonic lithospheric mantle. South African Journal of Geology, 107(1-2), 107-118. | |
| dc.identifier.ris | TY - Journal Article AU - Parman, Stephen W AU - Grove, Timothy L AU - Dann, Jessc C AU - De Wit, Maarten J AB - We present a model in which the generation of komatiites in Archaean subduction zones produced depleted mantle residues that eventually formed the highly depleted portions of the Kaapvaal lithospheric mantle. The envisioned melting process is similar to that which has formed boninites in Phanerozoic subduction zones such as the Izu-Bonin-Mariana arc. The primary differences between the Archaean and Phanerozoic melting regimes are higher mean melting temperatures (1450 versus 1350 °C) and higher mean melting pressures (2.5 versus 1.5 GPa) for the komatiites. The komatiites from the Komati Formation in the Barberton greenstone belt are mafic enough to have produced the depletion seen in most Kaapvaal granular peridotite xenoliths. However, the most highly depleted Kaapvaal xenoliths require an even more Mg-rich magma than the Komati komatiites (Kk). Samples of boninite mantle residues from the fore-arc of the Marianas subduction zone are nearly as depleted as the Kaapvaal cratonic mantle, indicating that buoyant, craton-like mantle is being produced today. We speculate that production rates of cratonic mantle were greater in the Archaean due to the greater depth of melting for komatiites (relative to boninites) and greater worldwide arc length. The high production rates and high buoyancy of the komatiite mantle residues gave rise to the rapid growth and stabilization of the Kaapvaal craton in the Archaean. DA - 2004 DB - OpenUCT DO - 10.2113/107.1-2.107 DP - University of Cape Town J1 - South African Journal of Geology LK - https://open.uct.ac.za PB - University of Cape Town PY - 2004 T1 - A subduction origin for komatites and cratonic lithospheric mantle TI - A subduction origin for komatites and cratonic lithospheric mantle UR - http://hdl.handle.net/11427/24075 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/24075 | |
| dc.identifier.uri | http://dx.doi.org/10.2113/107.1-2.107 | |
| dc.identifier.vancouvercitation | Parman SW, Grove TL, Dann JC, De Wit MJ. A subduction origin for komatites and cratonic lithospheric mantle. South African Journal of Geology. 2004; http://hdl.handle.net/11427/24075. | en_ZA |
| dc.language.iso | eng | |
| dc.publisher.department | Department of Geological Sciences | en_ZA |
| dc.publisher.faculty | Faculty of Science | en_ZA |
| dc.publisher.institution | University of Cape Town | |
| dc.source | South African Journal of Geology | |
| dc.source.uri | http://sajg.geoscienceworld.org/ | |
| dc.title | A subduction origin for komatites and cratonic lithospheric mantle | |
| dc.type | Journal Article | en_ZA |
| uct.type.filetype | Text | |
| uct.type.filetype | Image | |
| uct.type.publication | Research | en_ZA |
| uct.type.resource | Article | en_ZA |