Oxygen isotopic study of the nature and provenance of large quartz and chert clasts in gold-bearing conglomerates of South Africa and Stable isotope compositions of quartz pebbles and their fluid inclusions as tracers of sediment provenance: Implications for gold-and uranium-bearing quartz pebble conglomerates: Comment and Replies
R. W. HutchinsonR. P. ViljoenTorsten VennemannStephen E. KeslerJames R. O’NeilJ. M. BartonDavid B. WennerD. K. Hallbauer
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Research Article| September 01, 1993 Oxygen isotopic study of the nature and provenance of large quartz and chert clasts in gold-bearing conglomerates of South Africa and Stable isotope compositions of quartz pebbles and their fluid inclusions as tracers of sediment provenance: Implications for gold-and uranium-bearing quartz pebble conglomerates: Comment and Replies R. W. Hutchinson; R. W. Hutchinson 1Department of Geology and Geological Engineering, Colorado School of Mines, Golden, Colorado 80401 Search for other works by this author on: GSW Google Scholar R. P. Viljoen; R. P. Viljoen 275 Fox Street, Johannesburg 2001, South Africa Search for other works by this author on: GSW Google Scholar Torsten W. Vennemann; Torsten W. Vennemann 3Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109 Search for other works by this author on: GSW Google Scholar Stephen E. Kesler; Stephen E. Kesler 3Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109 Search for other works by this author on: GSW Google Scholar James R. O'Neil; James R. O'Neil 3Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109 Search for other works by this author on: GSW Google Scholar J. M. Barton, Jr.; J. M. Barton, Jr. 4Department of Geology, Rand Afrikaans University, P.O. Box 524, Johannesburg 2000, South Africa Search for other works by this author on: GSW Google Scholar D. B. Wenner; D. B. Wenner 5Department of Geology, University of Georgia, Athens, Georgia 30602 Search for other works by this author on: GSW Google Scholar D. K. Hallbauer D. K. Hallbauer 6Department of Geology, University of Stellenbosch, Stellenbosch 7600, South Africa Search for other works by this author on: GSW Google Scholar Author and Article Information R. W. Hutchinson 1Department of Geology and Geological Engineering, Colorado School of Mines, Golden, Colorado 80401 R. P. Viljoen 275 Fox Street, Johannesburg 2001, South Africa Torsten W. Vennemann 3Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109 Stephen E. Kesler 3Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109 James R. O'Neil 3Department of Geological Sciences, University of Michigan, Ann Arbor, Michigan 48109 J. M. Barton, Jr. 4Department of Geology, Rand Afrikaans University, P.O. Box 524, Johannesburg 2000, South Africa D. B. Wenner 5Department of Geology, University of Georgia, Athens, Georgia 30602 D. K. Hallbauer 6Department of Geology, University of Stellenbosch, Stellenbosch 7600, South Africa Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1993) 21 (9): 858–861. https://doi.org/10.1130/0091-7613(1993)021<0858:OISOTN>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation R. W. Hutchinson, R. P. Viljoen, Torsten W. Vennemann, Stephen E. Kesler, James R. O'Neil, J. M. Barton, D. B. Wenner, D. K. Hallbauer; Oxygen isotopic study of the nature and provenance of large quartz and chert clasts in gold-bearing conglomerates of South Africa and Stable isotope compositions of quartz pebbles and their fluid inclusions as tracers of sediment provenance: Implications for gold-and uranium-bearing quartz pebble conglomerates: Comment and Replies. Geology 1993;; 21 (9): 858–861. doi: https://doi.org/10.1130/0091-7613(1993)021<0858:OISOTN>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract No abstract available First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.Keywords:
Chalcedony
ABSTRACT The extent of quartz cementation in shallow marine sandstones of the Brora Arenaceous Formation (Oxfordian) is closely related to the occurrence and abundance of Rhaxella perforata sponge spicules. Three cement morphologies are identified, chalcedonic quartz, microquartz and mesoquartz. Chalcedonic quartz forms matrix‐supported cements which preserve moulds of Rhaxella spicules. Chalcedonic quartz crystals have inequant development of crystal faces, on average 0·1 μm in diameter, and are the first formed cement and reveal homogeneous dark grey tones on the SEM‐CL/BEI. Microquartz forms 5–10 μm diameter crystals, which commonly grow on chalcedonic quartz substrates and show various grey tones under SEM‐CL/BEI. Mesoquartz crystals grow in optical continuity with their host grains, have >20 μm a ‐axial diameter crystals, and exhibit distinctly zoned luminescence. Although no opaline silica is preserved, the quartz cement is interpreted to have formed from an opaline precursor. Detrital quartz has an average δ 18 O composition of + 12·2‰ and mesoquartz (syntaxial overgrowth) has an average δ 18 O composition of +20·0‰. Estimates of the δ 18 O compositions of microquartz and chalcedonic quartz are complicated by the problem of isolating the two textural types; mixtures of the two give consistently higher δ 18 O compositions than mesoquartz, the higher estimate being +39·2‰. From oxygen isotope data the formation of quartz, microquartz and chalcedonic quartz is interpreted to have taken place between 35 and 71°C in marine derived pore waters. Organic and inorganic maturation data constrain the upper temperature limit to less than 60°C.
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Results of evaluation of natural aggregates which can be classified as slow/late expanding alkali-silica reactive rocks are presented. One common feature in these rocks was the presence of strained quartz; on the other hand, metastable silica minerals like opal or chalcedony etc, were not detected. Taking into account past service records, results of mortar-bar tests at 38 and 60 degrees C and rapid chemical tests up to 7 days, revised criteria for assessment of such aggregates are proposed. (A) For the covering abstract see IRRD 871351.
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The use of gamma radiation to induce or enhance c olor centers in g emstones is a widespread technique and applied worldwide on a industrial scale since a t l east 1970. The presence of defects and d efect structures in quartz from a border region of southern Brazil and Uruguay are the reason for the creation of a new color variety of quartz ca lled “Prasiolite” in the gem trade. This quartz has a pleasant green color produced b y gamma irradiation. The procedures of irradiation at IPEN show that the activation of these color producing defects can be monitored b y detailed chemical and spectroscopic a nalysis. For the first t ime UV-VIS-NIR spectra of this new color variety of quartz a re shown. They revealed special features of these quartz c rystals coming from basaltic terraines of the Parana Basin. Contrary to most specimen of quartz from other parts of Brazil, they have such a high water and OH content that they resemble more chalcedony or opal, but not highly crystalline quartz specimens. The cause of the color are broken bonds of Si-OH defining the so-called dangling bonds.
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Described are Miocene bivalves of species Megacardita jouanneti (Basterot, 1825) and quartz crystals of the »rocks crystal« variety. Both were found in clastics - quartz conglomerates and sandstones at Dobrina in Haloze. Until recently in rocks from this area no fossil remains were known. Also the well shaped quartz crystals of moderate sizes and various inclusions are new for Slovenia.
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