A metasomatic origin for late Archean eclogitic diamonds: Implications from internal morphology of diamonds and Re-Os and S isotope characteristics of their sulfide inclusions from the late Jurassic Klipspringer kimberlites
| dc.contributor.author | Westerlund, K J | |
| dc.contributor.author | Gurney, J J | |
| dc.contributor.author | Carlson, R W | |
| dc.contributor.author | Shirey, S | |
| dc.contributor.author | Hauri, E H | |
| dc.contributor.author | Richardson, S H | |
| dc.date.accessioned | 2016-11-16T13:59:23Z | |
| dc.date.available | 2016-11-16T13:59:23Z | |
| dc.date.issued | 2004 | |
| dc.date.updated | 2016-01-07T10:34:08Z | |
| dc.description.abstract | The majority of the Klipspringer eclogitic diamonds display complex crystal zonation with zones of N- and H-rich cubic diamond alternating with zones of N-poor octahedral diamond. These growth features were likely related to different levels of carbon supersaturation in the diamond forming fluid(s). The diamonds are younger than their host rock and formed through differential flux of fluids into the eclogite. Re-Os isotope systematics of sulfide inclusions yield an isochron age of 2554 ± 150 Ma. The age overlaps the break-up of the Vaalbara supercontinent, the formation of the Ventersdorp lavas and a major re-activation of the Thabazimbi-Murchinson lineament into which the Klipspringer kimberlites intruded 148 ± 4 Ma ago. While a separate, relatively older generation of Klipspringer diamonds (Westerlund and Gurney, 2004) may be related to a proposed ~2.9 Ga craton-wide eclogitic diamond formation event (Shirey et al., 2001; 2002), a temporal connection between the current diamonds and the Ventersdorp lavas is inferred. Sulfur isotope compositions (δ34S = −1.8 to +2.4 ‰) of the sulfide inclusions overlap mantle values and large S isotope excursions indicative of altered MORB and associated sediment protoliths are absent. The data are compatible with slightly altered oceanic basalt or sub-lithospheric mantle sources for the S in these inclusions. The radiogenic initial Os isotope composition of the sulfide inclusions (187Os/188Os of 0.187 ± 0.046; γOs = +69) is not compatible with an origin of the PGE in the sulfides from the Ventersdorp lavas. The diamond growth characteristics along with the S and Os isotopic composition of their sulfide inclusions could be accounted for by the remobilization of local fluids in or proximal to the pre-existing eclogite host rock. We propose that the event that generated the Ventersdorp lavas may have raised the ambient lithospheric temperature and triggered fluid remobilization and the formation of the diamonds. | |
| dc.identifier | http://dx.doi.org/10.2113/107.1-2.119 | |
| dc.identifier.apacitation | Westerlund, K. J., Gurney, J. J., Carlson, R. W., Shirey, S., Hauri, E. H., & Richardson, S. H. (2004). A metasomatic origin for late Archean eclogitic diamonds: Implications from internal morphology of diamonds and Re-Os and S isotope characteristics of their sulfide inclusions from the late Jurassic Klipspringer kimberlites. <i>South African Journal of Geology</i>, http://hdl.handle.net/11427/22568 | en_ZA |
| dc.identifier.chicagocitation | Westerlund, K J, J J Gurney, R W Carlson, S Shirey, E H Hauri, and S H Richardson "A metasomatic origin for late Archean eclogitic diamonds: Implications from internal morphology of diamonds and Re-Os and S isotope characteristics of their sulfide inclusions from the late Jurassic Klipspringer kimberlites." <i>South African Journal of Geology</i> (2004) http://hdl.handle.net/11427/22568 | en_ZA |
| dc.identifier.citation | Westerlund, K. J., Gurney, J. J., Carlson, R. W., Shirey, S. B., Hauri, E. H., & Richardson, S. H. (2004). A metasomatic origin for late Archean eclogitic diamonds: Implications from internal morphology of diamonds and Re-Os and S isotope characteristics of their sulfide inclusions from the late Jurassic Klipspringer kimberlites. South African Journal of Geology, 107(1-2), 119-130. | |
| dc.identifier.issn | 1012-0750 | |
| dc.identifier.ris | TY - Journal Article AU - Westerlund, K J AU - Gurney, J J AU - Carlson, R W AU - Shirey, S AU - Hauri, E H AU - Richardson, S H AB - The majority of the Klipspringer eclogitic diamonds display complex crystal zonation with zones of N- and H-rich cubic diamond alternating with zones of N-poor octahedral diamond. These growth features were likely related to different levels of carbon supersaturation in the diamond forming fluid(s). The diamonds are younger than their host rock and formed through differential flux of fluids into the eclogite. Re-Os isotope systematics of sulfide inclusions yield an isochron age of 2554 ± 150 Ma. The age overlaps the break-up of the Vaalbara supercontinent, the formation of the Ventersdorp lavas and a major re-activation of the Thabazimbi-Murchinson lineament into which the Klipspringer kimberlites intruded 148 ± 4 Ma ago. While a separate, relatively older generation of Klipspringer diamonds (Westerlund and Gurney, 2004) may be related to a proposed ~2.9 Ga craton-wide eclogitic diamond formation event (Shirey et al., 2001; 2002), a temporal connection between the current diamonds and the Ventersdorp lavas is inferred. Sulfur isotope compositions (δ34S = −1.8 to +2.4 ‰) of the sulfide inclusions overlap mantle values and large S isotope excursions indicative of altered MORB and associated sediment protoliths are absent. The data are compatible with slightly altered oceanic basalt or sub-lithospheric mantle sources for the S in these inclusions. The radiogenic initial Os isotope composition of the sulfide inclusions (187Os/188Os of 0.187 ± 0.046; γOs = +69) is not compatible with an origin of the PGE in the sulfides from the Ventersdorp lavas. The diamond growth characteristics along with the S and Os isotopic composition of their sulfide inclusions could be accounted for by the remobilization of local fluids in or proximal to the pre-existing eclogite host rock. We propose that the event that generated the Ventersdorp lavas may have raised the ambient lithospheric temperature and triggered fluid remobilization and the formation of the diamonds. DA - 2004 DB - OpenUCT DP - University of Cape Town J1 - South African Journal of Geology LK - https://open.uct.ac.za PB - University of Cape Town PY - 2004 SM - 1012-0750 T1 - A metasomatic origin for late Archean eclogitic diamonds: Implications from internal morphology of diamonds and Re-Os and S isotope characteristics of their sulfide inclusions from the late Jurassic Klipspringer kimberlites TI - A metasomatic origin for late Archean eclogitic diamonds: Implications from internal morphology of diamonds and Re-Os and S isotope characteristics of their sulfide inclusions from the late Jurassic Klipspringer kimberlites UR - http://hdl.handle.net/11427/22568 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/22568 | |
| dc.identifier.uri | http://sajg.geoscienceworld.org/content/107/1-2/119 | |
| dc.identifier.vancouvercitation | Westerlund KJ, Gurney JJ, Carlson RW, Shirey S, Hauri EH, Richardson SH. A metasomatic origin for late Archean eclogitic diamonds: Implications from internal morphology of diamonds and Re-Os and S isotope characteristics of their sulfide inclusions from the late Jurassic Klipspringer kimberlites. South African Journal of Geology. 2004; http://hdl.handle.net/11427/22568. | 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 metasomatic origin for late Archean eclogitic diamonds: Implications from internal morphology of diamonds and Re-Os and S isotope characteristics of their sulfide inclusions from the late Jurassic Klipspringer kimberlites | |
| dc.type | Journal Article | |
| uct.type.filetype | Text | |
| uct.type.filetype | Image | |
| uct.type.publication | Research | en_ZA |
| uct.type.resource | Article | en_ZA |