Mr. R. McIlwaine, E. Ross Townsend, Mr. R. McIlwaine,
... Accused Again Remanded, Natal & Light Railways, Gold at Vredefort, O. R. C., Tuesday Not Guilty, A Prophesy, ...
1904 - Gale Group | NCCO EuropeAfrica
W. U. Reimold, Roger L. Gibson,
... km), and widespread regional mining activity make the Vredefort impact structure in South Africa an exceptional laboratory ... of impact-generated melt rock occur in the Vredefort Structure: the Vredefort Granophyre – impact melt rock – and pseudotachylitic breccias. Along ... melting. On the other hand, rocks in the Vredefort Dome – the central uplift of the impact structure – ... term “pseudotachylitic breccia” has been adopted for these Vredefort occurrences. These breccias formed during the impact in ... pseudotachylitic breccias, nine clast-laden impact melt dikes (Vredefort Granophyre), each up to several kilometers long, occur ...
Tópico(s): Geology and Paleoclimatology Research
2005 - Elsevier BV | Geochemistry
JONATHAN HUTCHINSON., HINDLIP., K. M., J. H. VINES., G. D. LESLIE., T. L. PAPILLON, , W. C. D. WHETHAM., DAVID CUNNINGHAM ANDERSON., ALGERNON E. ASPINALL, , J. J. COXHEAD., S. B. TRISTRAM., R. V. F. D., R. T. WATKIN WILLIAMS., JOHN HOLT SCHOOLING., F. W. HAINE., GEORGE KEBBELL., GEORGE HERRING., ALFRED DAVIES., G. C. WILTON, , JOHN C. MEDD.,
... China And Yun-Nan Rail-, Lord Milner At Vredefort.-A corre-, Fiscal Policy. Mr. Chamberlain's Visit ...
1903 - Gale Group | TDA
W. U. Reimold, Roger L. Gibson,
... the Earth's surface. The origin of the Vredefort dome, a ca 70 kilometre wide structural uplift ... 2023 ± 4 Ma) known terrestrial impact structures. The Vredefort structure is not only of importance because of ... for its abundant shatter cones and the enigmatic Vredefort granophyre. A wealth of new data on the Vredefort structure have become available in recent years: detailed ... impact and have permitted temporal separation of the Vredefort impact event from the emplacement of the 2050 ... regional metamorphic evolution. As continued study of the Vredefort structure has the potential to contribute much more ...
Tópico(s): Paleontology and Stratigraphy of Fossils
1996 - Elsevier BV | Journal of African Earth Sciences
... A Brutal Murder Woman Hacked to Pieces, The Vredefort Meeting Points Which Require Explanation, St. George's ...
1906 - Gale Group | NCCO EuropeAfrica
Christian Koeberl, W. U. Reimold, Steven B. Shirey,
... Re-Os isotope and geochemical study of the Vredefort Granophyre: Clues to the origin of the Vredefort structure, South Africa Christian Koeberl; Christian Koeberl 1Institute ... Re-Os isotope and geochemical study of the Vredefort Granophyre: Clues to the origin of the Vredefort structure, South Africa. Geology 1996;; 24 (10): 913– ... Abstract The origin of granophyric rock dikes (the Vredefort Granophyre) at the 2 Ga Vredefort structure in South Africa has been controversial. They ... as either impact melt or igneous intrusions. Most Vredefort Granophyre samples have considerably higher Os contents than ...
Tópico(s): Geological and Geophysical Studies Worldwide
1996 - Geological Society of America | Geology
R. J. Hart, H. J. Welke, L. O. Nicolaysen,
... an updomed and overturned sequence of strata at Vredefort, South Africa, has been known for over 70 ... to view and that radial traverses in the Vredefort basement penetrate through a ∼15 km thick section ... of the dome. The upper levels of the Vredefort crust are dominated by a relatively homogeneous outer ... granulite facies metamorphism. The deeper levels of the Vredefort crust exposed in the central parts of the ... of Archean crust forming processes. In the upper Vredefort crust, whole rock isochron ages of ∼3050 m. ...
Tópico(s): Geochemistry and Elemental Analysis
1981 - American Geophysical Union | Journal of Geophysical Research Atmospheres
A. M. Therriault, W. U. Reimold, A. M. Reid,
The Vredefort impact structure contains a suite of granophyric dykes, referred to as the Vredefort Granophyre, occurring within and at the edge of ... the Granophyre occurrences. These data show that the Vredefort Granophyre has a remarkable chemical homogeneity, within and ... and least-squares mixing calculations to reproduce the Vredefort Granophyre composition. The best-fit mixture is made ... of the pre-impact regional stratigraphic succession at Vredefort, but they do not conform with the clast ... melted to form the melt. Characteristics of the Vredefort Granophyre are similar to those of terrestrial impact ...
Tópico(s): Geological and Geochemical Analysis
1997 - Geological Society of South Africa | South African Journal of Geology
W. U. Reimold, W. P. Collision,
The Vredefort Structure is the type locality for pseudotachylite, a type of clast-laden melt breccia often observed in ... northern part of the Witwatersrand Basin surrounding the Vredefort Dome. In order to facilitate comparison between pseudotachylites from Vredefort and from impact structures and tectonic settings, the ... petrographic appearance, the distribution and orientation data for Vredefort and Witwatersrand pseudotachylite, as well as the complex temporal relationships between Vredefort pseudotachylite and other deformation phenomena in the structure ...
Tópico(s): Geotechnical and construction materials studies
1992 - Geological Society of America | Geological Society of America Special Papers
Produção Nacional
Revisado por pares
W. U. Reimold, Natalia Hauser, Bent Hansen, M.F. Thirlwall, Marie C. Hoffmann,
... terrestrial impact structures, notably the Sudbury (Canada) and Vredefort (South Africa) structures, exhibit considerable occurrences of a ... melt in shear or fault zones). At the Vredefort Dome, the eroded central uplift of the largest ... typified by the breccias of the Sudbury and Vredefort structures has so far remained entirely speculative. The ... Sm-Nd, and U-Pb isotopic data for Vredefort pseudotachylitic breccias and their host rocks, in comparison to data for Vredefort Granophyre (impact melt rock), are presented. They strongly ...
Tópico(s): Geological and Geochemical Analysis
2017 - Elsevier BV | Geochimica et Cosmochimica Acta
T. Mohr‐Westheide, W. U. Reimold, Ulrich Riller, Roger L. Gibson,
... Archean gneiss of the central uplift of the Vredefort Impact Structure, South Africa T. Mohr-Westheide; T. ... Archean gneiss of the central uplift of the Vredefort Impact Structure, South Africa. South African Journal of ... Geology Search Advanced Search Abstract Since 1916 the Vredefort Dome, the erosional remnant of the central uplift of the Vredefort Impact Structure, has been known as the type ... The structures apparent in the rocks of the Vredefort Dome constitute relative time indicators for different stages ...
Tópico(s): Geological and Geochemical Analysis
2009 - Geological Society of South Africa | South African Journal of Geology
The ∼ 50 km wide Vredefort structure appears to present the eroded roots of an area affected by rapid uplift and violent rock deformation—widely regarded ... agencies have been suggested. This note introduces the Vredefort structure and its geological environment, emphasizing information published ... Geological Record, with a Special Focus on the Vredefort Structure. This typical cryptoexplosion structure has a central ... than one “shock event” in the evolution of Vredefort. Analysis of the character of the faulting of ...
Tópico(s): Geochemistry and Geologic Mapping
1990 - Elsevier BV | Tectonophysics
B. Corner, Raymond Durrheim, L. O. Nicolaysen,
... and to investigate other features such as the Vredefort structure, the Bethlehem gravity high, and the Colesberg ... in three regions: in the centre of the Vredefort structure, along the Kaapvaal craton boundary, and centrally ... apex of this broad arch is termed the Vredefort axis and plunges northwestwards beneath the Witwatersrand basin. The Vredefort structure lies at the intersection of this axis ... are discussed. With either scenario, genesis of the Vredefort structure should be integrated with the genesis and ...
Tópico(s): Geomagnetism and Paleomagnetism Studies
1990 - Elsevier BV | Tectonophysics
C. Roering, J. M. Barton, Hanna Winter,
The deformational history of the area surrounding the Vredefort structure in South Africa is long and complex, ... time span of 1000 Ma is established. The Vredefort deformation is identified as a separate structural event ... therefore, that deformational structures related to the pre-Vredefort event should be identified and subtracted from the ... related with certainty to the formation of the Vredefort structure are defined. This approach could influence interpretations of the origin of the Vredefort structure which attribute most structural and geological associations ...
Tópico(s): Geological formations and processes
1990 - Elsevier BV | Tectonophysics
Rodger J. Hart, M. A. G. Andreoli, M. Tredoux, Maarten J. de Wit,
The central region of the Vredefort structure consists of a semi-circular multi-layered sequence of crystalline rocks which are nearly vertical in attitude, and which increase ... craton (36 km). The upper part of the Vredefort crystalline crust consists of a 3.0-Ga ... is separated from the lower crust by the Vredefort discontinuity, a brittle-ductile shear zone characterised by ... the upper and the lower parts of the Vredefort crystalline crust were juxtaposed during intracratonic thrusting ∼2. ... entire 36-km section of crust, including the Vredefort discontinuity, were rotated and uplifted into their present ...
Tópico(s): Geological and Geophysical Studies
1990 - Elsevier BV | Chemical Geology
W. U. Reimold, E. K. Jeßberger, T. Stephan,
To date, six pseudotachylite samples from the Vredefort dome have been analysed by the stepheating 40Ar39Ar technique. The resulting ages (Ga) (2.25 ± 0.04 (KAr), 2.01 ± 0. ... understood as suggesting several pseudotachylite-forming events at Vredefort. This, and other chronological and field evidence, may be interpreted as supporting the possibility that Vredefort pseudotachylite is not derived from a single catastrophic, ... 1.1 Ga in the region of the Vredefort structure. On the contrary, field and laboratory observations ...
Tópico(s): High-pressure geophysics and materials
1990 - Elsevier BV | Tectonophysics
L. Carporzen, B. P. Weiss, Stuart A. Gilder, Anne Pommier, Rodger J. Hart,
The Vredefort impact crater in South Africa is one of the oldest and largest craters on Earth, making it ... oriented remanent magnetization observed in surface samples at Vredefort has been attributed to impact‐generated magnetic fields. ... found along shock‐generated planar deformation features in Vredefort granites has been widely attributed to the 2. ... unusual magnetization and/or rock magnetic properties of Vredefort rocks are the products of recent lightning strikes. ... rocks are superficial phenomena produced by lightning. Because Vredefort is the only terrestrial crater that has been ...
Tópico(s): Geology and Paleoclimatology Research
2011 - American Geophysical Union | Journal of Geophysical Research Atmospheres
Cristiano Lana, Roger L. Gibson, W. U. Reimold,
... September 01, 2006 The Broodkop shear zone, southeast Vredefort dome (South Africa): a Dominion-related extensional feature? ... Wolf Uwe Reimold; The Broodkop shear zone, southeast Vredefort dome (South Africa): a Dominion-related extensional feature?. ... C) greenstones in the southeastern part of the Vredefort dome. The mylonitic fabric transposes 3.09 to ... effects, particularly those associated with formation of the Vredefort dome, suggests that the shear zone formed as ... greenstone-TTG formation in the core of the Vredefort dome and the initiation of a series of ...
Tópico(s): earthquake and tectonic studies
2006 - Geological Society of South Africa | South African Journal of Geology
I.T. Graham, S. A. de Waal, Roy A. Armstrong,
... Palaeoproterozoic sub-vertical supracrustal collar rocks of the Vredefort Dome, South Africa. The alkali granite intruded the ... Schurwedraai alkali granite places it statistically before the Vredefort impact event at 2023 ± 4 Ma and within ... and associated small ultramafic-mafic intrusions in the Vredefort collar rocks extends the southern extremity of Bushveld- ... pronouncedly steep pre-impact geothermal gradient in the Vredefort area, and to the amphibolite-grade metamorphism observed in the supracrustal collar rocks of the Vredefort Dome.
Tópico(s): High-pressure geophysics and materials
2005 - Elsevier BV | Journal of African Earth Sciences
Rodger J. Hart, Iain McDonald, M. Tredoux, Maarten J. de Wit, Richard W. Carlson, M. A. G. Andreoli, D. E. Moser, Lewis D. Ashwal,
... isotope data from lower crustal sections of the Vredefort Dome and a reinterpretation of its "crust on ... isotope data from lower crustal sections of the Vredefort Dome and a reinterpretation of its "crust on ... Abstract Granulites exposed in the core of the Vredefort Dome are generally thought to represent components of ... 1 Ga. However, near the core of the Vredefort Dome across a major shear zone, other ~3. ... different metamorphic history in the core of the Vredefort structure requires a modified "crust on edge" model ...
Tópico(s): Geological and Geophysical Studies
2004 - Geological Society of South Africa | South African Journal of Geology
B. O. Dressler, W. U. Reimold,
... the center of large impact structures (e.g., Vredefort Dome, South Africa) appear to have a random ... as ring and terrace collapse features. In the Vredefort Dome, networks of randomly distributed pseudotachylite veins accompany ... the lower part of the excavation cavity. At Vredefort, erosion has removed the coherent melt sheet, but melt breccia dikes (Vredefort Granophyre) in the crater floor are preserved. They ... represent the initial, undifferentiated impact melt. Near the Vredefort collar, the Granophyre forms more or less concentric ...
Tópico(s): Geology and Paleoclimatology Research
2004 - Elsevier BV | Earth-Science Reviews
Rebecca M. Flowers, D. E. Moser, R. J. Hart,
... the amphibolite‐granulite facies boundary exposed in the Vredefort impact structure of the central Kaapvaal Craton. Our ... to 380 Ma. Our results suggest that the Vredefort amphibolite‐granulite facies transition can shed valuable insight ... cratonic crust. The nature and paleodepth of the Vredefort metamorphic transition are compatible with the seismic characteristics ... tectonic activity post–3.08 Ga in the Vredefort crystalline basement is consistent with the presence of ... between amphibolite and granulite facies rocks in the Vredefort crystalline basement may be typical of this metamorphic ...
Tópico(s): High-pressure geophysics and materials
2003 - University of Chicago Press | The Journal of Geology
A Friese, W. U. Reimold, Paul W. Layer,
... the age of breccia development due to the Vredefort impact event. Most of these mylonites record ~1. ... portion of the basin.Besides geological evidence for Vredefort-related generation of ultracataclastic-pseudotachylitic breccias along some ... Goldfield, ages that could be related to the Vredefort impact event at ~2.02 Ga were obtained ... Merriespruit Thrust Zone. Ages <~2 Ga represent post-Vredefort tectono-thermal or hydrothermal events that have previously ... their isotopic systems during later (pre-Bushveld, Bushveld, Vredefort, post-Vredefort) tectono-thermal events. These results clearly ...
Tópico(s): Geochemistry and Geologic Mapping
2003 - Geological Society of South Africa | South African Journal of Geology
Rodger J. Hart, D. E. Moser, M. A. G. Andreoli,
... granulite facies metamorphism near the center of the Vredefort structure, South Africa Rodger Hart; Rodger Hart 1Schonland ... granulite facies metamorphism near the center of the Vredefort structure, South Africa. Geology 1999;; 27 (12): 1091– ... near the center of the 2.02 Ga Vredefort impact structure previously have been interpreted either as ... high-grade metamorphic event in the crust beneath Vredefort at 2060 Ma. Instead, the preimpact, high-temperature metamorphic history observed in the Vredefort lower crustal rocks indicates an enigmatic high-temperature ...
Tópico(s): Geological formations and processes
1999 - Geological Society of America | Geology
M. S. Huber, Elizaveta Kovaleva, Martin D. Clark, Ulrich Riller, F. Fourie,
... 10 km of erosion since its formation, the Vredefort impact structure, South Africa, is an ideal testing ... we present geophysical and geochemical evidence from the Vredefort Granophyre Dikes, which were derived from the - now eroded - Vredefort impact melt sheet. The dikes have been studied ... least 104 years. The sequential formation of the Vredefort Granophyre Dikes points to horizontal extension of crust ...
Tópico(s): Geology and Paleoclimatology Research
2021 - Elsevier BV | Icarus
Denis Fougerouse, Aaron J. Cavosie, Timmons M. Erickson, Steven M. Reddy, M. A. Cox, David W. Saxey, William D.A. Rickard, M.T.D. Wingate,
... by atom probe tomography (APT). Shocked monazite from Vredefort (South Africa; ∼300 km crater diameter), Araguainha (Brazil; ∼ ... with a different post-impact thermal history. The Vredefort sample is a thermally recrystallised foliated felsic gneiss ... sample is an impact melt-bearing bedrock. Both Vredefort and Araguainha samples record temperatures > 900 °C, whereas ... twins and shock-specific (1¯01) twins in Vredefort monazite was defined at 1979 ± 150 Ma, consistent ... monazite during shock twin formation at high temperature (Vredefort and Araguainha), and also that Pb is not ...
Tópico(s): Mineralogy and Gemology Studies
2021 - Elsevier BV | Geochimica et Cosmochimica Acta
M. S. Huber, Elizaveta Kovaleva, Ulrich Riller,
Abstract The Vredefort impact structure, South Africa, is comparable to the Sudbury impact structure, Canada, in size, age, and target rock ... offset dikes in the underlying target rock. At Vredefort, the melt sheet was eroded so that only ... one of the dikes. The results from the Vredefort granophyre dikes are compared to the Sudbury offset ... by its emplacement following some differentiation of the Vredefort melt sheet.
Tópico(s): Geological and Geochemical Analysis
2020 - Wiley | Meteoritics and Planetary Science
Elizaveta Kovaleva, M. S. Huber, Federica Zaccarini,
Abstract Vredefort Granophyre dykes are generally considered to be a part of impact melt, which intruded downward from the melt sheet of the Vredefort impact structure (South Africa). This work reports enigmatic ... granophyre dykes located in the core of the Vredefort impact structure, and in the Kopjeskraal core-collar ...
Tópico(s): Geology and Paleoclimatology Research
2018 - Geological Society of South Africa | South African Journal of Geology
Stephanie D. Montalvo, Aaron J. Cavosie, Timmons M. Erickson, Cristina Talavera,
... Africa, detrital shocked minerals from the 2020 Ma Vredefort impact structure have been documented in the Vaal ... to search for the presence of far-traveled Vredefort-derived detrital shocked zircon grains in different modern ... are consistent with derivation from bedrock at the Vredefort impact structure. These results demonstrate the transport of Vredefort-derived shocked zircon to the coast via the ...
Tópico(s): Geology and Paleoclimatology Research
2017 - Mineralogical Society of America | American Mineralogist
Produção Nacional
Revisado por pares
W. U. Reimold, Marie C. Hoffmann, Natalia Hauser, R-T. Schmitt, P. T. Zaag, T. Mohr-Westerheide,
... in the Otavi and Kudu Quarries of the Vredefort Dome support the "In Situ Formation" hypothesis W. ... in the Otavi and Kudu Quarries of the Vredefort Dome support the "In Situ Formation" hypothesis. South ... quarries of the outer crystalline core of the Vredefort Dome (South Africa) have been investigated petrographically and ... not indicate that additional components, such as a Vredefort Granophyre-like impact melt intrusive phase, contributed to ...
Tópico(s): Geology and Paleoclimatology Research
2016 - Geological Society of South Africa | South African Journal of Geology