Last edited by Arashik
Thursday, November 12, 2020 | History

2 edition of Metamorphism in the Witwatersrand Basin found in the catalog.

Metamorphism in the Witwatersrand Basin

Gary Stevens

Metamorphism in the Witwatersrand Basin

a review of recent advances and some predictions on gold remobilization by metamorphic fluid flow

by Gary Stevens

  • 60 Want to read
  • 29 Currently reading

Published by University of the Witwatersrand in Johannesburg .
Written in English

    Places:
  • South Africa,
  • Witwatersrand.
    • Subjects:
    • Metamorphism (Geology) -- South Africa -- Witwatersrand.,
    • Gold ores -- Geology -- South Africa -- Witwatersrand.

    • Edition Notes

      Statementby Gary Stevens, Rudy Boer, and Roger Gibson.
      SeriesInformation circular / Economic Geology Research Unit ;, no. 303, Information circular (University of the Witwatersrand. Economic Geology Research Unit) ;, no. 303.
      ContributionsBoer, Rudy., Gibson, Roger.
      Classifications
      LC ClassificationsIN PROCESS (UTILITY LOAD) (lccopycat)
      The Physical Object
      Pagination34 leaves :
      Number of Pages34
      ID Numbers
      Open LibraryOL778146M
      LC Control Number97179474
      OCLC/WorldCa36443331

      recycling of major and trace elements mobilized during basin maturation and metamorphism. The mineralogical and petrological processes that characterise diagenetic and low-grade metamorphic reactions in sedimentary basins have been widely studied and documented (e.g. The Witwatersrand gold - uranium mines in north-central South Africa, between Johannesburg in Gauteng and Welkom in the Free State, have contributed over 50% of all of the gold produced in the world to date. These mines are distributed around the arcuate, active, fault bounded, north to north-western to western margins of the northeast-southwest elongated, x m Witwatersrand Basin . Contact metamorphism of Silurian black shales by a basalt sill: geological evidence and thermal modeling in the Barrandian Basin Figure 2. Schematic view of the northeastern face of the Kosov quarry, showing the location of the sills and the samples studied. The values of organic matter reflectance and illite crystallinity have also been plotted.


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Metamorphism in the Witwatersrand Basin by Gary Stevens Download PDF EPUB FB2

Regional metamorphism in the Witwatersrand gold fields has been inferred to be synchronous with large-scale alteration on the basis of mineralogical and geochemical trends in pelites involving chlorite, chloritoid and pyro- phyUite (Phillips, ).

rally distinct on the basis of his published by: A Review of the Witwatersrand Basin - The World’s Greatest Goldfield Article (PDF Available) in Episodes 39(2) June with 8, Reads How we measure 'reads'. Although there is a pattern of higher metamorphic temperatures toward the northwest corner of the Witwatersrand basin (Phillips and Law,Fig.

10), for the whole –km length around the Witwatersrand basin margin, from Welkom to Johannesburg to Evander, the maximum metamorphic temperature in the Central Rand Group was consistently. The Witwatersrand Basin fill was subjected to a series of alteration events, ranging from burial and regional low-grade metamorphism to heating in the course of the emplacement of the Ma Bushveld Igneous Complex and catastrophic shattering during the Ma Vredefort impact, which enabled renewed fluid flow long after primary rock Cited by: 2.

Tectonically, the basin evolved in response to processes occurring within a Wilson cycle, associated with the encroachment and ultimate collision of the Zimbabwe and Kaapvaal cratons. Metamorphism of the Witwatersrand Basin occurred at ca.

and by: The Witwatersrand Basin is a largely underground geological formation which surfaces in the Witwatersrand, South holds the world's largest known gold reserves and has produced over billion ounces (o metric tons), which represents about 50% of all the Metamorphism in the Witwatersrand Basin book ever mined on earth.

The basin straddles the old provinces of Transvaal and the Orange Free State, and consists of a Country: South Africa. Abstract— Historically, there have been a range of diameter estimates for the large, deeply eroded Vredefort impact structure within the Witwatersrand Basin, South Africa.

Here, we estimate the diameter Cited by: Conditions of gold remobilization in the Ventersdorp Contact Reef, Witwatersrand Basin: in Reimold W.U., ed., The economic significance of metamorphism and fluid movement within the Witwatersrand Basin: Johannesburg, Economic Geology Research Unit, University of.

Metamorphism is the change of minerals or geologic texture (distinct arrangement of minerals) in pre-existing rocks (), without the protolith melting into liquid magma (a solid-state change).

The change occurs primarily due to heat, pressure, and the introduction of chemically active fluids. The chemical components and crystal structures of the minerals making up the rock may change even.

The word "Metamorphism" comes from the Greek: meta = after, morph = form, so metamorphism means the after form. In geology this refers to the changes in mineral assemblage and texture that result from subjecting a rock to conditions such pressures, temperatures, and chemical environments different from those under which the rock originally formed.

0BREGIONAL LOCAL 1Borogenic burial ocean-floor hydrothermal contact dislocation impact hot-slab combustion lightning pyrometamorphism Fig. Main types of metamorphism Regional metamorphism is a type of metamorphism which occu rs over an area of wide extent, that is, affecting a large rock vo lume, and is associated with large-scale tectonic processes, such.

The evolution of the Witwatersrand basin includes the depositional stage at ~ to Ga, followed by a complex history of metamorphism and hydrothermal activity spanning several hundred million.

Metamorphism, mineralogical and structural adjustments of solid rocks to physical and chemical conditions differing from those under which the rocks originally formed. Changes produced by surface conditions such as compaction are usually excluded.

The most important agents of Metamorphism in the Witwatersrand Basin book include temperature, pressure, and fluids. The most common sulfide ore minerals associated with contact metamorphism are bornite (copper), chalcopyrite (copper), galena (lead), pyrite (iron), and sphalerite (zinc); two common iron oxide ore minerals are hematite and magnetite.

Other economically important metamorphic minerals includes asbestos, talc, graphite, garnets, corundum. Stevens G, Boer R, Gibson R (b) Metamorphism, fluid-flow, and gold mineralization in the Witwatersrand Basin: towards a unifying model.

S Afr J Geol – Google Scholar Tweedie KAM () The Evander by: 7. Metamorphism as the result of slow cooling of magma. A _____ metamorphism tends to occur in regions where massive amounts of sedimentary or volcanic materials accumulate in a subsiding basin.

Burial B. Contact C. Regional D. Hydrothermal. c _____ is a widespread type of metamorphism typically associated with mountain building. Regional Metamorphism As described above, regional metamorphism occurs when rocks are buried deep in the crust.

This is commonly associated with convergent plate boundaries and the formation of mountain ranges. Because burial to 10 km to 20 km is Author: Steven Earle. Metamorphism and Metamorphic Rocks. Definition of Metamorphism.

The word "Metamorphism" comes from the Greek: meta = after, morph = form, so metamorphism means the after form. In geology this refers to the changes in mineral assemblage and texture that result from subjecting a rock to pressures and temperatures different from those under which.

Regional metamorphism occurs when rocks are buried deep in the crust. This is commonly associated with convergent plate boundaries and the formation of mountain ranges.

Because burial to 10 km to 20 km is required, the areas affected tend to be large. Most regional metamorphism takes place within continental crust. the basin is covered by younger sedimentary and volcanic rocks such as those making up the Ventersdorp and Karoo Supergroups.

Mining here in this basin has attracted, and continues to attract worldwide attention. Fig. 1 Location of goldfields within the Witwatersrand Basin () with limits of Witwatersrand strata (Pretorius, ).

metamorphism, rift basin metamorphism, regional and substantially thicker basin sequences to the east of the Cobar Basin.

Metamorphism during basin inver-sion is believed to have taken advantage of the earlier formed burial metamorphic thermal profile, and as a result, rocks subject to deeper, hotter (biotite-zone. Regional metamorphism covers large areas of continental crust typically associated with mountain ranges, particularly those associated with convergent tectonic plates or the roots of previously eroded mountains.

Conditions producing widespread regionally metamorphosed rocks occur during an orogenic event. The collision of two continental plates or island arcs with continental plates produce. Some Ultra-High Grade Gold Ore from what was at the time the highest grade mine outside of the Witwatersrand Basin.

Close. it all, but these archaen deposits are thought to be primarily formed from metamorphic fluids (fluids generated during metamorphism serve to transport gold). My great-grandpa's book, written by the man himself.

The Witwatersrand Basin is approximatly km long and km wide. The gold mines in this area are possibly the deepest mines in the world (mining operations at m and exploration core-drilling up to m).

Peak gold production occured in when over metric tommes were mined, generating US $1, billion in sales, however gold. Contact Metamorphism and Hydrothermal Processes Contact metamorphism takes place where a body of magma intrudes into the upper part of the crust. Any type of magma body can lead to contact metamorphism, from a thin dyke to a large : Steven Earle.

Metamorphic rock - Metamorphic rock - Regional metamorphism: Regional metamorphism is associated with the major events of Earth dynamics, and the vast majority of metamorphic rocks are so produced. They are the rocks involved in the cyclic processes of erosion, sedimentation, burial, metamorphism, and mountain building (orogeny), events that are all related to major convective processes in.

1 Tectonic Control of Basin Development .2 Tindouf and Reggane Basins .3 Central and Southern Algerian Basins Bechar-Timimoun Basin Illizi Basin .4 Petroleum in Algerian Paleozoic Basins .5 Ghadames Basin File Size: 1MB.

Abstract— The occurrence of shock metamorphosed quartz is the most common petrographic criterion for the identification of terrestrial impact structures and lithologies. Its utiCited by: METAMORPHIC PETROLOGY METAMORPHISM: Process of mineralogical and structural (textural) changes of rocks in the solid state in response to physical and chemical conditions which differ from those under which they originated.

Mineral assemblages change. Textural Changes (foliations, cleavage, etc). • Physical Conditions = Pressure File Size: 45KB. What causes metamorphism of rocks. Imagine going down a very deep mine-shaft. The deeper you go, the greater the pressure on the tunnels because of the weight of rock above.

Also, it gets hotter as you go down, because the Earth’s interior is very hot. At a depth. Regional metamorphism definition is - geological metamorphism involving a wide area.

Contact metamorphism (also called thermal metamorphism) is the process by which the country rock that surrounds a hot magma intrusion is metamorphosed by the high heat flow coming from the intrusion. The zone of metamorphism that surrounds the intrusion is called the halo (or aureole) and rarely extends more than meters into the country rock.

@article{osti_, title = {Chemistry of sands from the modern Indus River and the Archean Witwatersrand basin: Implications for the composition of the Archean atmosphere}, author = {Maynard, J B and Ritger, S D and Sutton, S J}, abstractNote = {Both the Indus River and the Witwatersrand basin contain sand with grains of detrital uraninite.

Dynamic metamorphism: Processes and products in Devonian carbonate rocks, Canning Basin, Western Australia (Special publication - Geological Society of Australia Incorporated ; no. 6) [Logan, Brian W, Semeniuk, V.] on *FREE* shipping on qualifying offers. Dynamic metamorphism: Processes and products in Devonian carbonate rocks, Canning Basin, Western Australia (Special Cited by: Contact Metamorphic Rocks Recommendations by the IUGS Subcommission on the Systematics of Metamorphic Rocks: Web version 1E.

Callegari and 2N.N. Pertsev 1 E. Callegari, Department of Science, Mineralogy and Petrology, University of Torino, Italy 2 File Size: KB.

From inside the book. Borehole stylolites sub-siliceous thin Transvaal tuff UK9A Upper Witwatersrand usually varies in colour vein quartz Veldschoen Reef Witwatersrand Basin Witwatersrand sediments Witwatersrand Sequence yellow-green 5GY 5/2 The Stratigraphy of the Witwatersrand Sequence in the Delmas Area, Transvaal Issue 58 of.

Impact metamorphism synonyms, Impact metamorphism pronunciation, Impact metamorphism translation, English dictionary definition of Impact metamorphism. The process by which rocks are altered in composition, texture, or internal structure by extreme heat. Geography Notes Form 1; Geography Notes KCSE Form 1 - Topics - Form 1 Geography Syllabus.

KLB Geography Form 1. Geography Form 1 Questions and Answers. Geography Notes Form One Free Download.

Notes za Geography Form 1. Geography Notes Form One Pdf. Form 1 Geography Notes KLB. Metamorphism and Metamorphic Rocks – Chapter Questions 1. **What are the agents of metamorphism. **When metamorphic rocks form, what main factors dictate the rock that will form. **Where does water in hydrothermal (chemically active) fluids come from.

Size: KB. This is called contact metamorphism. Contact metamorphism can either happen deep underground or at the Earth's surface. Underground, hot magma, fills areas within the crust; large areas are called batholiths.

The hot magma alters the surrounding rocks. The amount of rock that is changed depends on how much magma there is producing heat. Burial Metamorphism Hypothesis - Deep burial may result from either sedimentation or tectonic thickening of the crust via faulting.

The tectonic setting of high P/T metamorphic belts is consistent with this hypothesis. In particular, the presence of Blueschist Facies Series rocks in paired metamorphic belts suggests that subduction and.Regional metamorphism is generally independent of igneous intrusions and tends to happen in places where tectonic forces have compressed the crust and put high pressure on the rocks.

Since contact metamorphism requires that the affected rocks exist within a local temperature gradient, it is necessarily limited to small areas.Reddit gives you the best of the internet in one place.

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