Resources in the Upper Zone of the Bushveld Complex, South Africa
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Timeline of Natural History
Timeline of natural history This timeline of natural history summarizes significant geological and Life timeline Ice Ages biological events from the formation of the 0 — Primates Quater nary Flowers ←Earliest apes Earth to the arrival of modern humans. P Birds h Mammals – Plants Dinosaurs Times are listed in millions of years, or Karo o a n ← Andean Tetrapoda megaanni (Ma). -50 0 — e Arthropods Molluscs r ←Cambrian explosion o ← Cryoge nian Ediacara biota – z ←Earliest animals o ←Earliest plants i Multicellular -1000 — c Contents life ←Sexual reproduction Dating of the Geologic record – P r The earliest Solar System -1500 — o t Precambrian Supereon – e r Eukaryotes Hadean Eon o -2000 — z o Archean Eon i Huron ian – c Eoarchean Era ←Oxygen crisis Paleoarchean Era -2500 — ←Atmospheric oxygen Mesoarchean Era – Photosynthesis Neoarchean Era Pong ola Proterozoic Eon -3000 — A r Paleoproterozoic Era c – h Siderian Period e a Rhyacian Period -3500 — n ←Earliest oxygen Orosirian Period Single-celled – life Statherian Period -4000 — ←Earliest life Mesoproterozoic Era H Calymmian Period a water – d e Ectasian Period a ←Earliest water Stenian Period -4500 — n ←Earth (−4540) (million years ago) Clickable Neoproterozoic Era ( Tonian Period Cryogenian Period Ediacaran Period Phanerozoic Eon Paleozoic Era Cambrian Period Ordovician Period Silurian Period Devonian Period Carboniferous Period Permian Period Mesozoic Era Triassic Period Jurassic Period Cretaceous Period Cenozoic Era Paleogene Period Neogene Period Quaternary Period Etymology of period names References See also External links Dating of the Geologic record The Geologic record is the strata (layers) of rock in the planet's crust and the science of geology is much concerned with the age and origin of all rocks to determine the history and formation of Earth and to understand the forces that have acted upon it. -
The Rustenburg Layered Suite Formed As a Stack of Mush with Transient Magma Chambers ✉ Zhuosen Yao1, James E
ARTICLE https://doi.org/10.1038/s41467-020-20778-w OPEN The Rustenburg Layered Suite formed as a stack of mush with transient magma chambers ✉ Zhuosen Yao1, James E. Mungall 1 & M. Christopher Jenkins 1 The Rustenburg Layered Suite of the Bushveld Complex of South Africa is a vast layered accumulation of mafic and ultramafic rocks. It has long been regarded as a textbook result of fractional crystallization from a melt-dominated magma chamber. Here, we show that most 1234567890():,; units of the Rustenburg Layered Suite can be derived with thermodynamic models of crustal assimilation by komatiitic magma to form magmatic mushes without requiring the existence of a magma chamber. Ultramafic and mafic cumulate layers below the Upper and Upper Main Zone represent multiple crystal slurries produced by assimilation-batch crystallization in the upper and middle crust, whereas the chilled marginal rocks represent complementary supernatant liquids. Only the uppermost third formed via lower-crustal assimilation–fractional crystallization and evolved by fractional crystallization within a melt-rich pocket. Layered intrusions need not form in open magma chambers. Mineral deposits hitherto attributed to magma chamber processes might form in smaller intrusions of any geometric form, from mushy systems entirely lacking melt-dominated magma chambers. 1 Department of Earth Sciences, Carleton University, 2115 Herzberg Laboratories, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada. ✉ email: [email protected] NATURE COMMUNICATIONS | (2021) 12:505 | https://doi.org/10.1038/s41467-020-20778-w | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | https://doi.org/10.1038/s41467-020-20778-w ayered mafic intrusions represent portions of the plumbing derived by incremental crystallization must be removed. -
The Bushveld Igneous Complex
The Bushveld Igneous Complex THE GEOLOGY OF SOUTH AFRICA’S PLATINUM RESOURCES By C. A. Cousins, MSC. Johannesburg Consolidated Investment Company Limited A vast composite body of plutonic and volcanic rock in the central part of the Transvaal, the Bushveld igneous complex includes the platinum reef worked by Rustenburg Platinum Mines Limited and constituting the world’s greatest reserve of the platinum metals. This article describes the geological and economic aspects of this unusually interesting formation. In South Africa platinum occurs chiefly in square miles. Two of these areas lie at the the Merensky Reef, which itself forms part of eastern and western ends of the Bushveld and the Bushveld igneous complex, an irregular form wide curved belts, trending parallel to oval area of some 15,000 square miles occupy- the sedimentary rocks which they overlie, and ing a roughly central position in the province dipping inwards towards the centre of the of the Transvaal. A geological map of the Bushveld at similar angles. The western belt area, which provides the largest known has a flat sheet-like extension reaching the example of this interesting type of formation, western boundary of the Transvaal. The is shown on the facing page. third area extends northwards and cuts out- The complex rests upon a floor of sedi- side the sedimentary basin. Its exact relation- mentary rocks of the Transvaal System. This ship to the other outcrops within the basin floor is structurally in the form of an immense has not as yet been solved. oval basin, three hundred miles long and a As the eastern and western belts contain hundred miles broad. -
Attributes of Skaergaard-Type PGE Reefs
Attributes of Skaergaard-Type PGE Reefs James D. Miller, Jr.1 and Jens C. Ø. Andersen2 1Minnesota Geological Survey, c/o NRRI, University of Minnesota-Duluth, 5013 Miller Trunk Hwy., Duluth, MN, 55811 , USA 2Camborne School of Mines, University of Exeter, Redruth, Cornwall, TR15 3SE UK e-mail: [email protected], [email protected] Stratiform, platinum group element (PGE) peridotite, pyroxenite, and dunite are usually deposits have long been known to occur in quantitatively minor. When well-differentiated, ultramafic-mafic intrusive complexes such as such intrusions display a simplified cumulus Bushveld and Stillwater (Naldrett, 1989b). stratigraphy following the scheme: Ol or Pl only-> Commonly known as PGE reefs, such deposits are Ol + Pl -> Pl + Cpx + FeOx ± Ol -> Pl + Cpx + typically found near the transition from ultramafic FeOx + Ol + Ap. They have a strong cryptic to mafic cumulates where they occur as 1-3 meter layering towards iron-enrichment indicative of thick intervals enriched in PGEs (1-20 ppm) and Fenner-type differentiation. They differ from trace to moderate amounts of sulfide (0.5-5 wt %). classic PGE reef-bearing intrusions by lacking a However, relatively recent discoveries have significant ultramafic component (early olivine- demonstrated that potentially economic stratiform only crystallization is minor to absent in most PGE mineralization may also occur in tholeiitic tholeiitic intrusions) and by being poor in mafic layered intrusions. Au- and PGE-bearing orthopyroxene (inverted pigeonite is rarely a layers -
Monchegorsk Layered Intrusion, Fennoscandian Shield)
minerals Article Chromite Mineralization in the Sopcheozero Deposit (Monchegorsk Layered Intrusion, Fennoscandian Shield) Artem V. Mokrushin 1,* and Valery F. Smol’kin 2 1 Geological Institute—Subdivision of the Federal Research Centre “Kola Science Centre of the Russian Academy of Sciences”, 14 Fersman Street, 184209 Apatity, Russia 2 Vernadsky State Geological Museum of the Russian Academy of Sciences, 11/11 Mokhovaya Street, 125009 Moscow, Russia; [email protected] * Correspondence: [email protected]; Tel.: +7-(902)133-39-95 Abstract: In 1990, the Sopcheozero Cr deposit was discovered in the Monchegorsk Paleoprotero- zoic layered mafic-ultramafic layered intrusion (Monchepluton). This stratiform early-magmatic deposit occurs in the middle part of the Dunite Block, which is a member of the Monchepluton layered series. The Cr2O3 average-weighted content in ordinary and rich ores of the deposit is 16.65 and 38.76 wt.%, respectively, at gradually changing concentrations within the rich, ordinary and poor ore types and ore body in general. The ores of the Sopcheozero deposit, having a ratio of Cr2O3/FeOtotal = 0.9–1.7, can serve as raw materials for the refractory and chemical industries. The ore Cr-spinel (magnochromite and magnoalumochromite) is associated with highly magnesian olivine (96–98 Fo) rich in Ni (0.4–1.1 wt.%). It confirms a low S content in the melt and complies with the low oxygen fugacity. The coexisting Cr-spinel-olivine pairs crystallized at temperatures ◦ from 1258 to 1163 C, with accessory Cr-spinel crystallizing at relatively low, while ore Cr-spinel at higher temperatures. The host rock and ore distinguish with widespread plastic deformations of ◦ Citation: Mokrushin, A.V.; Smol’kin, olivine at the postcrystallization phase under conditions of high temperature (above 400 C) and V.F. -
Open Kosei.Pdf
The Pennsylvania State University The Graduate School Department of Geosciences GEOCHEMISTRY OF ARCHEAN–PALEOPROTEROZOIC BLACK SHALES: THE EARLY EVOLUTION OF THE ATMOSPHERE, OCEANS, AND BIOSPHERE A Thesis in Geosciences by Kosei Yamaguchi Copyright 2002 Kosei Yamaguchi Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy May 2002 We approve the thesis of Kosei Yamaguchi Date of Signature ____________________________________ _______________________ Hiroshi Ohmoto Professor of Geochemistry Thesis Advisor Chair of Committee ____________________________________ _______________________ Michael A. Arthur Professor of Geosciences ____________________________________ _______________________ Lee R. Kump Professor of Geosciences ____________________________________ _______________________ Raymond G. Najjar Associate Professor of Meteorology ____________________________________ _______________________ Peter Deines Professor of Geochemistry Associate Head for Graduate Program and Research in Geosciences iii ABSTRACT When did the Earth's surface environment become oxic? The timing and mechanism of the rise of atmospheric pO2 level in the early Precambrian have been long debated but no consensus has been reached. The oxygenation of the atmosphere and oceans has significant impacts on the evolution of the biosphere and the geochemical cycles of redox-sensitive elements. In order to constrain the evolution of the atmosphere, oceans, biosphere, and geochemical cycles of elements, a systematic and multidisciplinary -
The Uranium Potential of the Bushveld Igneous Complex
(GEA748| June 1987 THE URANIUM POTENTIAL OF THE BUSHVELD IGNEOUS COMPLEX A CRITICAL REAPPRAISAL Investigators: MAG Andreoli R J Hart H J Brynard F A G M Camisani-Calzolari ATOMIC ENERGY CORPORATION OF SOUTH AFRICA LIMITED PRETORIA THIS DOCUMENT MAY NOT BE COPIED IN ANY WAY WHATSOEVER PER 158 GEA 748 ATOMIC ENERGY CORPORATION/UNIVERSITY OF PRETORIA WORKING GROUP ON URANIUM IN THE BUSHVELD COMPLEX Progress Report No. 4 THE URANIUM POTENTIAL OF THE BUSHVELD IGNEOUS COMPLEX A CRITICAL REAPPRAISAL Investigators: MAG Andreoli R J Hart H J Beynard F A G M Camisani-Calzolari POSTAL ADDRESS: Department of Geotechnology P 0 Box 582 PELINDABA PRETORIA June 1987 0001 ISBN 0 86960 848 7 PER-158 GEA-748 ATOMIC ENERGY CORPORATION/UNIVERSITY OF PRETORIA WORKING GROUP ON URANIUM IN THE BUSHVELD COMPLEX Progress Report No. 4 THE URANIUM POTENTIAL OF THE BUSHVELD IGNEOUS COMPLEX A CRITICAL REAPPRAISAL Investigators: MAG Andreoli R J Hart H J Brynard F A G M Camisani-Calzolari DEPARTMENT OF GEOTECHNOLOGY ATOMIC ENERGY CORPORATION OF SOUTH AFRICA LIMITED P 0 BOX 582, PRETORIA (0001) June 1987 ISBN 086960 848 7 PER-158- i - CONTENTS Page Samevatting/Abstract vi LIST OF ABBREVIATIONS ii-iii LIST OF TABLES iv LIST OF FIGURES v 1 INTRODUCTION 1 2 ON THE POSSIBILITY OF A GIANT OLYMPIC DAM-TYPE DEPOSIT JN THE BUSHVELD COMPLEX 3 3 THE WATERBERG COVER: A TARGET FOR UNCOMFORMITY-TYPE DEPOSITS? 19 4 ADDITIONAL TARGETS FOR URANIUM EXPLORATION 25 5 DISCUSSION & RECOMMENDATIONS 27 6 ACKNOWLEDGEMENTS 30 7 REFERENCES 30 LIST OP IBBEKVIAÏIOIIS All allanite amp amphibole -
The Nakhlite Meteorites: Augite-Rich Igneous Rocks from Mars ARTICLE
ARTICLE IN PRESS Chemie der Erde 65 (2005) 203–270 www.elsevier.de/chemer INVITED REVIEW The nakhlite meteorites: Augite-rich igneous rocks from Mars Allan H. Treiman Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, TX 77058-1113, USA Received 22 October 2004; accepted 18 January 2005 Abstract The seven nakhlite meteorites are augite-rich igneous rocks that formed in flows or shallow intrusions of basaltic magma on Mars. They consist of euhedral to subhedral crystals of augite and olivine (to 1 cm long) in fine-grained mesostases. The augite crystals have homogeneous cores of Mg0 ¼ 63% and rims that are normally zoned to iron enrichment. The core–rim zoning is cut by iron-enriched zones along fractures and is replaced locally by ferroan low-Ca pyroxene. The core compositions of the olivines vary inversely with the steepness of their rim zoning – sharp rim zoning goes with the most magnesian cores (Mg0 ¼ 42%), homogeneous olivines are the most ferroan. The olivine and augite crystals contain multiphase inclusions representing trapped magma. Among the olivine and augite crystals is mesostasis, composed principally of plagioclase and/or glass, with euhedra of titanomagnetite and many minor minerals. Olivine and mesostasis glass are partially replaced by veinlets and patches of iddingsite, a mixture of smectite clays, iron oxy-hydroxides and carbonate minerals. In the mesostasis are rare patches of a salt alteration assemblage: halite, siderite, and anhydrite/ gypsum. The nakhlites are little shocked, but have been affected chemically and biologically by their residence on Earth. Differences among the chemical compositions of the nakhlites can be ascribed mostly to different proportions of augite, olivine, and mesostasis. -
Abstract Booklet
DSI-NRF CIMERA Annual COLLOQUIUM 26-27 NOVEMBER 2020 ABSTRACT BOOKLET Image: Transvaal Supergroup, banded iron formation, Kuruman Kop, Northern Cape. 26-27 November 2020 ONLINE & IN PERSON School of Tourism and Hospitality (STH) University of Johannesburg Auckland Park Bunting Road Campus 2 Dear All, Dear All, We would like to extend a warm welcome to the annual DSI-NRF CIMERA Colloquium, hosted by the University of We would like to extend a warm welcome to the annual DSI-NRF CIMERA Colloquium, hosted by the University of Johannesburg. Johannesburg. DSI-NRF Centre of Excellence (CoE) for Integrated Mineral and Energy Resource Analysis (CIMERA) is hosted by the Department DSI-NRF Centre of Excellence (CoE) for Integrated Mineral and Energy Resource Analysis (CIMERA) is hosted by the Department of Geology at the University of Johannesburg (UJ), and co-hosted by the School of Geosciences at the University of the of Geology at the University of Johannesburg (UJ), and co-hosted by the School of Geosciences at the University of the DearWitwatersrand All, (Wits). DSI-NRF CIMERA is a virtual centre of research that concentrates existing research excellence, capacity Witwatersrand (Wits). DSI-NRF CIMERA is a virtual centre of research that concentrates existing research excellence, capacity Weand extend resources a warm welcome to enable to the researchersannual DSI-NRF toCIMERA collaborate Colloquium, across hosted disciplinesby the University and of Johannesburg. institutions on long-term projects of economic and/ or and resources to enable researchersThe to Colloquiumcollaborate will acrossrun as a hybriddisciplines event this and year, institutions triggered by the on COVID-19 long-term pandemic projects lockdown of economic situation and and/ or societal benefit in geology, that are locally relevant and internationally competitive. -
Timeline of Natural History
Timeline of natural history Main articles: History of the Earth and Geological his- chondrules,[1] are a key signature of a supernova ex- tory of Earth plosion. See also: Geologic time scale and Timeline of evolution- ary history of life • 4,567±3 Ma: Rapid collapse of hydrogen molecular For earlier events, see Timeline of the formation of the cloud, forming a third-generation Population I star, Universe. the Sun, in a region of the Galactic Habitable Zone This timeline of natural history summarizes signifi- (GHZ), about 25,000 light years from the center of the Milky Way Galaxy.[2] • 4,566±2 Ma: A protoplanetary disc (from which Earth eventually forms) emerges around the young Sun, which is in its T Tauri stage. • 4,560–4,550 Ma: Proto-Earth forms at the outer (cooler) edge of the habitable zone of the Solar Sys- tem. At this stage the solar constant of the Sun was only about 73% of its current value, but liquid wa- ter may have existed on the surface of the Proto- Earth, probably due to the greenhouse warming of high levels of methane and carbon dioxide present in the atmosphere. Early bombardment phase begins: because the solar neighbourhood is rife with large planetoids and debris, Earth experiences a number of giant impacts that help to increase its overall size. Visual representation of the history of life on Earth as a spiral 2 Hadean Eon cant geological and biological events from the formation of the Earth to the rise of modern humans. Times are listed in millions of years, or megaanni (Ma). -
Per-20 Geochemical Aspects of the Megacryst Suite
PER-20 GEOCHEMICAL ASPECTS OF THE MEGACRYST SUITE FROM THE MONASTERY KIMBERLITE PIPE by W. R.O.JAKOB | ATOMIC ENERGY BOARD I pelindal..) / i PRETORIA 30 i*~\'$'.- j Republic of South Africa August 1977 3 i •:>:'::. MiK!ëliitebai!!gi88u»<(á$:<HHffl iliiiiiil Illi IflU.^SIÏilïiíïïjíl PER20-1 ATOMIC ENERGY BOARD GEOCHEMICAL ASPECTS Of THE MEGACRYST SUITE FROM THE MONASTERY KIMBERLITE PIPE by W.R.O. JAKOB* "Chemistry Division POSTAL ADDRESS: Private Rag X256 Pelindaba Preto.-ia August 1977 0001 ISBN 0 86960 667 0 GEOCHEMICAL ASPECTS OF THE MEGACRYST SUITE FROM THE MONASTERY KIMBERLITE PIPE W. R.O.JAKOB Thesis submitted in fulfilment of the requirements for the degree of Master of Science at the Department of Geochemistry of the University of Cape Town October 1977 2 CONTENTS Page SAMEVATTING 3 ABSTRACT 4 ACKNOWLEDGEMENTS 5 1. INTRODUCTION 6 2. SAMPLING AND LOCALITY DESCRIPTION 7 3. ANALYTICAL METHODS 9 4. ANALYTICAL RESULTS 9 4.1 Olivine 9 4.2 Orihopyroxene 10 4.3 Clinopyroxene 11 4.4 Garnet 12 4.5 llmenite 13 5. DISCUSSION 15 5.1 Clinopyroxene 15 5.2 Garnet 16 53 llmenite 18 5.4 Orthopyroxene 19 5.5 Olivine 22 6. GENERAL DISCUSSION AND CONCLUSIONS 26 7. REFERENCES 28 8. APPENDICES: 34 APPENDIX I: DIAGRAMS 34 APPENDIX II: PLATES 47 APPENDIX III: TABLES 11 TO 2B 51 3 5AMEVATTING 3 Die Monastery kimberlietpyp in die Distrik Marquard, Oranje-Vrystaat, Suid-Afrika, het groot belangstclling in kimberlietstudies gaande gemaak omdat dit groot enkelkristalle (2— 20 cm) van olivien, enstaiiet, diopsied, granaat, ilmeniet en flogopiet/vermikuliet bevat- Daar is vasgestel dat at die silikate (behalwe flogopiet wat nie bestudeer is nie) met ilmeniet verband nou. -
Igneous Intrusive Rocks of the Peake and Denison Ranges Within the Adelaide Geosyncline
tl-io' -GIÜEOIJS IìÜTFÈIJSIVE R.OCKS OF TI;IE PE.ã,KE .ã.¡ÜED DEDÜTSO¡Ü FI.ãNGES T'i'ITIT-¡Ü 1FI:[E .â'EDEI,.â'IDE GEOSYIÜCI,IìÜE \/OLL[&fE I f = Figrures, Plates, Captions, Irfaps, Tabl.es and Appendicies. By: Robert Sinclair Irlorrison B.Sc. (Acadia, L98L) B.Sc. Hons. (Adelaide, 1982) The Department of Geology and Geophysics The University of Adelaide South Australia. This thesis is submitted as fulfilment of the requirements for the degree of Doctor of Philosophy in GeologY at The University of Adelaide South Australia. February 298à, l-988. Resubmitted March 3L-t, 1989. n¡ q: t c! Jr '"f.' .''ì r ll,r.-¡. lci- I\ \, \ , .' ì T.ã.BI,E OF COIÜTEIÜTS Chapter One: Symopsis of tlre Adelaide Geoslmcline. Figure 1.1: General Geology of Èhe Adelaide Geosynclj-ne. Figure L.2= Structural Geology of the Adelaide Geosybcline. Figure l-.3: Stratigraphic Nomenclature for the Adelaide Geosyncline. Figure L.5.4: Cross-Section of Adelaidean Evaporite Deformation. Plate 1.1-: Diapiric Breccia. Plate L.2z Diapiric Breccia and Contacts. Table L.3.1: RepresentaÈive Geochemistry of Callanna Group Volcanics in the Adelaide Geosyncline. Table 1.3.2: Representative Geochemistry of Burra Group Volcanics in the Adelaide Geosyncline. Table 1.3.3: Representative Geochernistry of the Umberatana Group Volcanic Equivalents. Table l-. 3.5: Representative Geochemistry of Moralana Supergroup Volcanics in the Adelaide Geosyncline. Chapter thtos Igmeous Intn¡sions of the Adelaide Geoslmcline: A Revies. Figure 2.Lz lgneous Rocks of the Adelaide Geosyncline and Kanmantoo Trough. Figure 2.7.1-'. Geology of a Northern Section in the willouran Ranges.