Ultra-high temperatures from oxygen isotope thermometry of a coesite-sanidine grospydite
dc.contributor.author | Smyth, J. R. | en_US |
dc.contributor.author | Sharp, Z. D. | en_US |
dc.contributor.author | Essene, Eric J. | en_US |
dc.date.accessioned | 2006-09-11T18:49:11Z | |
dc.date.available | 2006-09-11T18:49:11Z | |
dc.date.issued | 1992-11 | en_US |
dc.identifier.citation | Sharp, Z. D.; Essene, E. J.; Smyth, J. R.; (1992). "Ultra-high temperatures from oxygen isotope thermometry of a coesite-sanidine grospydite." Contributions to Mineralogy and Petrology 112 (2-3): 358-370. <http://hdl.handle.net/2027.42/47301> | en_US |
dc.identifier.issn | 1432-0967 | en_US |
dc.identifier.issn | 0010-7999 | en_US |
dc.identifier.uri | https://hdl.handle.net/2027.42/47301 | |
dc.description.abstract | The oxygen isotope compositions of coesite, sanidine, kyanite, clinopyroxene and garnet were measured in an ultra-high pressure-temperature grospydite from the Roberts Victor kimberlite, South Africa. The δ 18 O values (per mil v. SMOW) of each phase and (1 σ) are as follows: coesite, 8.62 (0.31); sanidine, 8.31 (0.02); kyanite, 7.98 (0.08); pyroxene, 7.63 (0.11); garnet, 7.53 (0.03). In situ analyses of the coesite with the laser extraction system are δ 18 O=9.35 (0.08), n =4, demonstrating that the coesite is homogeneous. The coesite has partially inverted to polycrystalline quartz and the pyroxene is extensively altered during uplift. The larger scatter for the mineral separate coesite and pyroxene data may be due to partial reequilibration between the decompression-related breakdown products of these two phases. The anomalously high δ 18 O value of the grospydite (δ 18 O wholerock =7.7‰) is consistent with altered oceanic crust as a source rock. Temperature estimates from a linear regression of all the data to three different published calibrations correspond to an equilibrium temperature of 1310±80°C. The calculated isotopic pressure effect is to lower these estimates by about 40°C at 40 kb. The estimated temperature based on Al−Si disorder in sanidine is 1200±100°C and that from Fe−Mg exchange thermometry between garnet and clinopyroxene is 1100±50°C. Given the large errors associated with thermometry at such high temperatures, it is concluded that the xenolith equilibrated that 1200±100°C. Pressure estimates are 45±5 kb, based on dilution of the univariant equilibria albite = jadeite + coesite and 2 kyanite + 3 diopside = grossular + pyrope + 2 coesite . Zoning in the outer 20 μm of the feldspar from Ab 0.8 to Ab 16 indicates rapid decompression to 25 kb or less. The isotopic temperature estimates are the highest ever obtained and combined with the high degree of Al−Si disorder in sanidine require rapid cooling from ultra-high temperatures. It is inferred that the xenolith was sampled at the time of equilibration, providing a point on the upper Cretaceous geotherm in the mantle below South Africa. | en_US |
dc.format.extent | 1973072 bytes | |
dc.format.extent | 3115 bytes | |
dc.format.mimetype | application/pdf | |
dc.format.mimetype | text/plain | |
dc.language.iso | en_US | |
dc.publisher | Springer-Verlag | en_US |
dc.subject.other | Geosciences | en_US |
dc.subject.other | Geology | en_US |
dc.subject.other | Mineralogy | en_US |
dc.subject.other | Mineral Resources | en_US |
dc.title | Ultra-high temperatures from oxygen isotope thermometry of a coesite-sanidine grospydite | en_US |
dc.type | Article | en_US |
dc.subject.hlbsecondlevel | Geology and Earth Sciences | en_US |
dc.subject.hlbsecondlevel | Chemistry | en_US |
dc.subject.hlbtoplevel | Science | en_US |
dc.description.peerreviewed | Peer Reviewed | en_US |
dc.contributor.affiliationum | Institut de Minéralogie et de Pétrographie, Université de Lausanne, BFSH-2, CH-1015, Lausanne, Switzerland; Department of Geological Sciences, University of Michigan, 1006 C.C. Little Bldg, 48109-1063, Ann Arbor, MI, USA | en_US |
dc.contributor.affiliationother | Department of Geological Sciences, University of Colorado, Campus Box 250, 80309-0250, Boulder, CO, USA | en_US |
dc.contributor.affiliationother | Institut de Minéralogie et de Pétrographie, Université de Lausanne, BFSH-2, CH-1015, Lausanne, Switzerland | en_US |
dc.contributor.affiliationumcampus | Ann Arbor | en_US |
dc.description.bitstreamurl | http://deepblue.lib.umich.edu/bitstream/2027.42/47301/1/410_2004_Article_BF00310466.pdf | en_US |
dc.identifier.doi | http://dx.doi.org/10.1007/BF00310466 | en_US |
dc.identifier.source | Contributions to Mineralogy and Petrology | en_US |
dc.owningcollname | Interdisciplinary and Peer-Reviewed |
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