 | | Journal (article/letter/editorial) | | shocked metaquartzites from the Vredefort impact structure, South Africa John G. SPRAY * and Suporn BOONSUE...~30 km from the center of the 2.02 Ga Vredefort impact structure. This work focuses on deploying analytical...deep crust from 20 to 30 km depth (coesite) and impact INTRODUCTION The polymorphs of silica are of considerable...Chao et al. (1960). Coesite can be an indicator of impact, though not exclusively so, due to its occurrence...surface can only be attributed to the hypervelocity impact of asteroids or comets, where suitably high P–T |  | Kovaleva, E., Huber, M.S., Roelofse, F., Tredoux, M., Praekelt, H. (2018) Pseudotachylite vein hosted by a clast in the Vredefort Granophyre: characterization, origin and relevance. South African Journal of Geology, 121 (1) 51-68 doi:10.25131/sajg.121.0002 | Journal (article/letter/editorial) | | Pseudotachylite vein hosted by a clast in the Vredefort Granophyre: characterization, origin and relevance...University of the Free State, 205 Nelson Mandela Drive, 9300 Bloemfontein, South Africa e-mail: kovalevae@ufs...praekehe@ufs.ac.za © 2018 March Geological Society of South Africa Abstract A small, meta-granitic clast with...microcrystalline vein was found enclosed within the Vredefort Granophyre. Semi-quantitative chemical analyses...vein within the granophyre. Introduction Meteorite impact structures are the most important features of rocky |  | | Journal (article/letter/editorial) | | 20, 57±70 Impact-induced melting of Archean granulites in the Vredefort Dome, South Africa. I: anatexis...Private Bag 3, P O WITS, Johannesburg 2050, South Africa (065rlg@cosmos.wits.ac.za) ABSTRACT Mid-crustal...Mid-crustal Archean pelitic granulites in the Vredefort Dome experienced a static, low-P granulite facies...associated with the formation of the dome by meteorite impact at 2.02 Ga. Heating and exhumation were virtually...energy released from nonadiabatic decay of the impact shock wave. Maximum temperatures within a radius |  | | Journal (article/letter/editorial) | | felsic and mafic rocks from the Vredefort impact structure, South Africa. Implications for the experimental...University of the Free State, 205 Nelson Mandela Drive, 9300 Bloemfontein, South Africa e-mail: kovalevae@ufs...University of the Free State, 205 Nelson Mandela Drive, 9300 Bloemfontein, South Africa e-mail: fouriefd@ufs...ac.at © 2018 December Geological Society of South Africa Abstract While the formation of tectonic PTs...for all rock types, the mechanism of formation of impact-related pseudotachylites (PTs) is strongly debated |  | Wilk, Jakob, Hamann, Christopher, Fazio, Agnese, Luther, Robert, Hecht, Lutz, Langenhorst, Falko, Kenkmann, Thomas (2018) Petrographic investigation of shatter cone melt films recovered from MEMIN impact experiments in sandstone and iSALE modeling of their formation boundary conditions. Meteoritics & Planetary Science, 53 (8) 1569-1593 doi:10.1111/maps.13179 | Journal (article/letter/editorial) | | of shatter cone melt films recovered from MEMIN impact experiments in sandstone and iSALE modeling of...are diagnostic for the recognition of meteorite impact craters. They are unambiguously identifiable in...cone fragments from the ejecta of hypervelocity impact experiments. Here, we focus on silicate melt films...melting and mixing of quartz, phyllosilicates, and rutile in this overlying texture, we infer high, but very...Society, 2018. 2 J. Wilk et al. INTRODUCTION Impact structures are exposed to resurfacing and recycling |  | | Report (chapter) | | Downloaded from http://sp.lyellcollection.org/ at Ohio State University Library on September 16, 2012 Geological...Basin, South Africa: evidence for a modified placer origin, and the role of the Vredefort impact event...02 Email alerting service click here to receive free e-mail alerts when new articles cite this article... Downloaded from http://sp.lyellcollection.org/ at Ohio State University Library on September 16, 2012 Gold mineralization...Basin, South Africa: evidence for a modified placer origin, and the role of the Vredefort impact event |  | | Journal (article/letter/editorial) | | the southeastern Vredefort dome, South Africa Cristiano Lana* and Roger L. Gibson Impact Cratering Research...Johannesburg, South Africa *Present address: Department of Earth Sciences and Engineering, South Kensington...gibsonr@geosciences.wits.ac.za Wolf U. Reimold Impact Cratering Research Group, School of Geosciences...Witwatersrand, P.O. Wits 2050, Private Bag 3, Johannesburg, South AfricaCorresponding author: Fax: +27 11 3391697;...Johannesburg, South Africa e-mail: minnitt@egoli.min.wits.ac.za © 2003 Geological Society of South Africa ABSTRACT |  | | Journal (article/letter/editorial) | | high stress in quartz from the impact site of Vredefort, South Africa KAI CHEN1, MARTIN KUNZ2, NOBUMICHI...stishovite-bearing quartzite from the Vredefort meteorite impact site in South Africa reveals features that are attributed...Average lattice strains of 1400 microstrains in Vredefort quartz are much higher compared to values (500)...compressive and tensile residual stresses, in Vredefort quartz, shear stresses associated with lamellar...lamellar boundaries dominate. Key-words: Vredefort impact site, quartz, Dauphiné twinning, residual stress |  | | Journal (article/letter/editorial) | | margin of the Kaapvaal Craton in present-day AC South Africa and Botswana. In addition, there exist remnants...area, which were affected by a 2.02 Ga asteroid impact (Fig. 1) CE (Kamo et al 1996; Buchanan and Reimold...performed under PT contract at the Washington State University Radiogenic Isotope Facility. Samples...for a retention pond on a private farm ~1 km CR south of the town of Marble Hall. The sample is a ~30...perthite, AN and ilmenite with minor amounts of rutile, sphene, and zircon. This assemblage is identical |  | Reimold, W. U., K�ber, C., Fletcher, P., Killick, A. M., Wilson, J. D. (1999) Pseudotachylitic breccias from fault zones in the Witwatersrand Basin, South Africa: evidence of autometasomatism and post-brecciation alteration processes. Mineralogy and Petrology, 66 (1) 25-53 doi:10.1007/bf01161721 | Journal (article/letter/editorial) | | from fault zones in the Witwatersrand Basin, South Africa: evidence of autometasomatism and post-brecciation...University of the Witwatersrand, Johannesburg, South Africa 2 Institute of Geochemistry, University of Vienna...Austria 3 Fochville, South Africa 4 The Mineral Corporation, Cramerview, South Africa 5 CORSTOR Pry. Ltd...Ltd, Fourways, South Africa With 12 Figures Received July 14, 1998; revised version accepted February 9...Basin in South Africa. They are particularly abundant in a zone tangential to the Vredefort Dome, a structure |  | | Journal (article/letter/editorial) | | signatures and magmatic stability of terrestrial impact produced zircon Matthew M. Wielicki ⁎, T. Mark...Editor: R.W. Carlson Keywords: zircon early Earth impact Hadean Late Heavy Bombardment Jack Hills a b s...REE abundances and Ti-in-zircon thermometry for impact produced zircon are reported here. These results...thermometry indicates an average of 773 °C for impact-produced zircon, ~ 100 °C higher than the average...record actual crystallization temperatures for impact melts. Zircon saturation modeling of Archean crustal |  | | Journal (article/letter/editorial) | | veins in the central uplift of the Manicouagan impact structure: Context and genesis Marc B. Biren ⁎, John...anorthositic central uplift of the Manicouagan impact structure. They occur as thin (b 2.5 mm wide), linear...predominantly trend radially from the point of impact. The shock veins are distinguished by the development...within the collar rocks of the Vredefort impact structure of South Africa (Martini, 1978, 1991; Spray et...of the structure (i.e., it is now accepted that Vredefort was formed by hypervelocity impact). Only a |  | | Journal (article/letter/editorial) | | the Central Kaapvaal Craton Andreas E.W. Friese Impact Cratering Research Group, School of Geosciences... Private Bag 3, PO Wits 2050, Johannesburg, South Africa Present address: Rock Engineering Department...PO Box 55291, Northlands 2116, South Africa Wolf Uwe Reimold Impact Cratering Research Group, School... Private Bag 3, PO Wits 2050, Johannesburg, South Africa Corresponding author, Fax: +27 (11) 339 1697;...99775-7320, USA © 2003 Geological Society of South Africa ABSTRACT Tectonites from ~2.7-Ga-old Platberg |  | | Journal (article/letter/editorial) | | coesite in lithic clasts from suevite of the Ries impact crater (Germany) Volker Stähle Æ Rainer Altherr...non-porous lithic clasts from suevite of the Ries impact structure were studied in transmitted light and under...They formed from silica melt as well as by solid-state transformation. In weakly shocked rocks (stage I)...phase and PDFs to diaplectic glass in the solid state. Coesite formed during unloading occurs in two textural...is mostly replaced by amorphous silica. Keywords Impact metamorphism Stishovite Coesite Suevite |  | O’Callaghan, J. W., Osinski, G. R., Lightfoot, P. C., Linnen, R. L., Weirich, J. R. (2016) Reconstructing the Geochemical Signature of Sudbury Breccia, Ontario, Canada: Implications for Its Formation and Trace Metal Content. Economic Geology, 111 (7) 1705-1729 doi:10.2113/econgeo.111.7.1705 | Journal (article/letter/editorial) | | 85719-2395 Abstract The Sudbury breccia is an impact-generated pseudotachylitic breccia formed in the...target rocks, and/or (3) injection of allochthonous impact melt from the Sudbury Igneous Complex into the...from six different locations around the Sudbury structure. A mixing model was used to construct the composition...with no requirement for a contribution from the impact melt sheet. Instead, we propose a dynamic, parautochthonous...described by Shand (1916) in the Vredefort impact structure, South Africa, as a rock that originated by |  | Huber, Matthew S., Koeberl, Christian, Smith, Frank C., Glass, Billy P., Mundil, Roland, McDonald, Iain (2019) Geochemistry of a confirmed Precambrian impact ejecta deposit: The Grænsesø spherule layer, South Greenland. Meteoritics & Planetary Science, 54 (10) 2254-2272 doi:10.1111/maps.13271 | Journal (article/letter/editorial) | | confirmed Precambrian impact ejecta deposit: The Grænsesø spherule layer, South Greenland Matthew S. HUBER... University of the Free State, 205 Nelson Mandela Dr., Bloemfontein, South Africa 2 Department of Lithospheric...outcrop of the Graenseso spherule layer, Midternaes, South Greenland, consist of a spherule-bearing dolomixtite...possible that both layers are related to the Vredefort impact event. The samples containing spherules, as...have elevated REEs compared to the underlying pre-impact layer, suggestive of a new continental source of |  | | Journal (article/letter/editorial) | | hornblende in shock veins of crustal rocks from the Ries impact crater (Germany) Volker Stähle • Rainer Altherr...from suevite breccia of the Nördlinger Ries impact structure. These veins were studied by optical microscopy...the chemical compositions of both phases, a solid-state mechanism is deduced for the hornblende to majorite...described for the first time from a terrestrial impact crater. Along with stishovite, majorite constitutes...respectively. Stishovite aggregates, produced by solid-state reaction, along with shock-induced high-pressure |  | Campanale, Fabrizio, Mugnaioli, Enrico, Folco, Luigi, Gemmi, Mauro, Lee, Martin R., Daly, Luke, Glass, Billy P. (2019) Evidence for subsolidus quartz-coesite transformation in impact ejecta from the Australasian tektite strewn field. Geochimica et Cosmochimica Acta, 264. 105-117 doi:10.1016/j.gca.2019.08.014 | Journal (article/letter/editorial) | | for subsolidus quartz-coesite transformation in impact ejecta from the Australasian tektite strewn field...for subsolidus quartz-coesite transformation in impact ejecta from the Australasian tektite strewn field...for subsolidus quartz-coesite transformation in impact ejecta from the Australasian tektite strewn field...silica polymorph, is a diagnostic indicator of impact cratering in quartz-bearing target rocks. The formation...impacts has been debated since its discovery in impact rocks in the 1960s. Electron diffraction analysis |  | | Journal (article/letter/editorial) | | PLATINIFEROUS MERENSKY REEF, BUSHVELD COMPLEX, SOUTH AFRICA, BY THE U-Pb ZIRCON CHEMICAL ABRASION ID-TIMS...V6T-1Z4, Canada Abstract The Bushveld Complex, South Africa, is the world’s largest layered intrusion and...proven to be difficult. In this study, zircon and rutile were identified in thin section and separated from...and is locally in direct contact with sulfide. Rutile occurs mainly as inclusions within or overgrowths...U-Pb dating of zircon, and multigrain fractions of rutile yielded a U-Pb cooling age of 2055.0 ± 3.9 Ma. |  | Fazio, Agnese, Folco, Luigi, D'Orazio, Massimo, Frezzotti, Maria Luce, Cordier, Carole (2014) Shock metamorphism and impact melting in small impact craters on Earth: Evidence from Kamil crater, Egypt. Meteoritics & Planetary Science, 49 (12) 2175-2200 doi:10.1111/maps.12385 | Journal (article/letter/editorial) | | 1111/maps.12385 Shock metamorphism and impact melting in small impact craters on Earth: Evidence from Kamil...August 2014) Abstract–Kamil is a 45 m diameter impact crater identified in 2008 in southern Egypt. It...It was generated by the hypervelocity impact of the Gebel Kamil iron meteorite on a sedimentary target...including fracturing, planar deformation features, and impact melt lapilli and bombs, and (2) localized shock...abundant) including high-pressure phases and localized impact melting in the form of intergranular melt, melt |  | | Journal (article/letter/editorial) | | Processes in Planetary Materials: From Hypervelocity Impact to Earthquakes John G. Spray Planetary and Space...rates, it forms shock veins in meteorites and in impact craters, which may contain high-pressure mineral...faults, facilitate the post-shock modification of impact craters, and make landslides more hazardous. 221...tectonic collapse of craters formed by hypervelocity impact. Frictional melting is an important transient phenomenon...(1916) following his work on the Vredefort Structure of South Africa. Shand described anastomosing veins |  | Robb, L. J., Charlesworth, E. G., Drennan, G. R., Gibson, R. L., Tongu, E. L. (1997) Tectono‐metamorphic setting and paragenetic sequence of Au‐U mineralisation in the Archaean Witwatersrand Basin, South Africa. Australian Journal of Earth Sciences, 44 (3) 353-371 doi:10.1080/08120099708728317 | Journal (article/letter/editorial) | | mineralisation in the Archaean Witwatersrand Basin, South Africa a a a a L. J. Robb , E. G. Charlesworth...Witwatersrand, Private Bag 3, Wits 2050, Republic of South Africa Version of record first published: 09 May 2007...mineralisation in the Archaean Witwatersrand Basin, South Africa, Australian Journal of Earth Sciences: An International...mineralisation in the Archaean Witwatersrand Basin, South Africa L. J. ROBB, E. G. CHARLESWORTH, G. R. DRENNAN...Witwatersrand, Private Bag 3, Wits 2050, Republic of South Africa. The Witwatersrand Basin is a structural remnant |  | | Journal (article/letter/editorial) | | petrography of impact breccias and target rocks from the 145 Ma Morokweng impact structure, South Africa CHRISTIAN...Vienna, Althanstrasse 14, A-1090 Vienna, Austria Impact Cratering Research Group, School of Geosciences...Witwatersrand, Private Bag 3, Johannesburg 2050, South Africa (Received October 5, 2001; accepted in revised...a large, 145 Ma impact structure in the Northwest Province of South Africa. The impact origin of this...this structure and its melt rock has been confirmed by ample evidence of shock metamorphism in clasts within |  | | Journal (article/letter/editorial) | | University of the Free State, 205 Nelson Mandela Drive, Bloemfontein 9300, Free State, South Africa; kovalevae@ufs...reported polycrystalline zircons from magmatic and impact settings. This work shows how appearance, crystallographic...EBSD; shear zones; Eastern Alps; Southern Alps; impact recrystallization; granitoids 1. Introduction...µm in diameter [15–19], but attempts to date an impact event with this polygranular zircon were not entirely...after reidite and can be dated for the age of an impact event [28,29]. The fine granules in such zircon |  | | Journal (article/letter/editorial) | | 1111/maps.12682 Formation of shatter cones in MEMIN impact experiments J. WILK* and T. KENKMANN Institute...diagnostic for the discovery and verification of impact structures. The occurrence of shatter cones is...boundary conditions of shatter cone formation in impact experiments and test a novel approach to qualitatively...pressures of up to 86 GPa. In experiments with lower impact velocities shatter cones could not be found. A...the poorest sample of the record of hypervelocity impact throughout geologic time” (Grieve and Therriault |
|
