Last edited by Tezil
Monday, July 20, 2020 | History

1 edition of Archean variolitic lavas found in the catalog.

Archean variolitic lavas

Archean variolitic lavas

  • 264 Want to read
  • 40 Currently reading

Published in Kingston .
Written in English

    Subjects:
  • Variolite,
  • Rocks, Igneous

  • Classifications
    LC ClassificationsQE 191 R356 1978 thesis
    The Physical Object
    Pagination69 p.
    Number of Pages69
    ID Numbers
    Open LibraryOL22025103M

    quartz in both pillowed and massive Archean volcanic rocks, interpreting it as an igneous feature. Alternatively, this feature can be interpreted as devitrification (Barker ). However, since basalts exhibit granophiric texture the latter hypothesis is not favored. Ladeira () was the first to describe the existence of variolitic. The interdisciplinary approach of examining the evolution of the Archean crust, oceans, and life that we adopt in this book sets it apart from previous publications on Precambrian geology. The book will be attractive to researchers in academia and in industry, and to senior undergraduate students, graduate students and faculty in earth and.

    Revista Brasileira de Geociências 30(3), setembro de VOLCANIC AND VOLCANICLASTIC FEATURES IN ARCHEAN ROCKS AND THEIR TECTONIC ENVIRONMENTS, RIO DAS VELHAS GREENSTONE BELT, QUADRILÁTERO FERRIFERO, MG - BRAZIL MARCIA ZUCCHETTI1, LYDIA M. LOBATO2 AND ORIVALDO F. BALTAZAR1 ABSTRACT Rocks of Rio das . This paper presents an integrated major and trace element data and crystal size distribution analysis for zoned clinopyroxene phenocrysts hosted in variolitic and massive picrobasalts of the Suisaari Formation, Karelian Craton, Eastern Fennoscandian Shield. Clinopyroxenes in variolitic and massive lavas occur as unzoned, reverse, and normally zoned crystal. Oscillatory-zoned clinopyroxenes are.

    PDF | This paper presents an integrated major and trace element data and crystal size distribution analysis for zoned clinopyroxene phenocrysts hosted | Find, read and cite all the research you.   Microbial corrosion textures in volcanic glass are well studied in Cenozoic seafloor basalts, they are distinct from the well-understood abiotic alteration textures, and they are considered an indication of an active deep oceanic biosphere down to at least m below the seafloor (Fig. 1 A–C and Figs. S1–S4) (1, 2).Such corrosion textures were proposed to be preserved in the form of.


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Archean variolitic lavas Download PDF EPUB FB2

Variolitic basalts and variolitic komatiites occur commonly as Archean lava flows in the greenstone belts of South Africa and the Canadian Shield. [7] [8] Finally, there is a group of spotted volcanic rocks formerly known to French petrographers as the variolites du Drac from the locality in which they are found in Parc National des Ecrins.

Archean variolitic lavas contain matrix fractions possessing spectacularly high iron contents (up to 24 wt.% total FeO). The amount of iron contained in a single variolite horizon is greater than 1 × 10 12 kg, a source of magmatic iron large enough to account for the iron required to form banded iron formation (BIF) early in the earth's history.

In Archean greenstone belts, variolitic lavas are commonly found as distinct stratigraphic horizons which can be traced for many kilometers, and aided in the mapping of the Abitibi Belt (Ferguson et al., ).

PILL01rJED FLOWS ; Varioles tend to coalesce when they are present in. sufficient concentrations and commonly show a size zoning Author: David Saunders. Archean variolitic lavas contain matrix fractions possessing spectacularly high iron contents (up to 24 wt.% total FeO).

The amount of iron contained in a single variolite horizon is greater than. Variolitic lavas from Archean tholeiitic series north and south of Rouyn–Noranda (Abitibi Metavolcanic belt, Canada) contain large, sharply defined, spheroidal to subspheroidal felsic varioles (up to 5 cm in diameter) set in a ferruginous matrix of more mafic by: The Mäkinen Member consists of basaltic and pyroxenitic komatiites (MgO variolitic pillow lavas.

The Raivio Member is composed of ultramafic to mafic metatuffs. The lavas are generally massive or amygdaloidal, but flow-top breccias and Archean variolitic lavas book lavas are also found. Laterally, different lava flows of this formation can be followed up to several hundred meters.

Diagnostic pseudoforms after primary minerals and volcanic glass in the lavas are used in identifying crystallizing phases. Archean;Variolitic Lavas;Munro Township;Ontario: Publication Date: May Abstract: Chemical variations between the matrix and variole fractions of variolitic lavas are quite distinct.

Analyses for major. and trace elements and trace gold content was carried out on separated fractions of matrix and varioles from several handspecimens. The location of lavas is limited to the northernmost part of the Kurkikylä, where the most representative section of it is in the Matinvaara area.

The lavas are generally massive or amygduloidal, but flow-top breccias and variolitic lavas are also found (Fig. 3C–E). Laterally, different flows in this formation can be followed up to several. Earth and Planetary Science Letters, 27 () Elsevier Scientific Publishing Company, Amsterdam - Printed in The Netherlands SUBDIVISION OF THE ARCHEAN LAVAS OF THE ABITIBI AREA, CANADA, FROM Fe-Mg-Ni-Cr RELATIONS WAYNE T.

JOLLY Department of Geological Sciences, Brock University, St. Catharines, Ont. (Canada) Received Janu Revised version received July, 7, The lavas. The best outcrops of the variolitic lavas are west of Wedela (Fig. 2c). Field observations Variolitic lava flows.

Each variolitic lava flow of the Hekpoort Formation consists of two distinct layers of similar thickness (Fig. 3a, b). The upper V-layer is mostly rich in well-formed spherical varioles, whereas the lower C-layer appears. Exceptionally well-preserved pillowed and massive phenocryst-free metabasaltic lava flows in the uppermost part of the Palaeoarchaean Hooggenoeg Complex of the Barberton Greenstone Belt exhibit both flow banding and large leucocratic varioles.

The flow banding is defined by blebs and bands of pale and dark green metabasalt and was the result of mingling of two types of basalt (Robins et al.

Precambrian Res., Archean ( Ga old) subaqueous basalt flows of the lower Blake River group, at Lava Flow Mountain, Ontario, are dominantly of a thick, massive flow morphology with hya- loclastic flow-top breccias.

Pillow lavas are. Variolitic lavas from Archean tholeiitic series north and south of Rouyn–Noranda (Abitibi Metavolcanic belt, Canada) contain large, sharply defined, spheroidal to subspheroidal felsic varioles.

The RZ clinopyroxenes from the variolitic and massive lavas displayed a positive correlation between Mg# and Cr 2 O 3, and a negative correlation between Mg# and TiO 2, although this was better in the clinopyroxenes from the massive lavas (R = and R = −) than from the variolitic lavas (R = and R = −).

These data provide. Flow banding in basaltic pillow lavas from the Early Archean Hooggenoeg Formation, Barberton Greenstone Belt, variolitic metabasalt, which we interpret as the result of.

The komatiitic basalt flows are subdivided into flowtop breccia, zone of variolitic lavas, and a massive lower part exhibiting columnar jointing, while dacitic lavas are mostly massive throughout. Two komatiitic basalt samples were collected from the massive zone of a 25 m thick lava flow, and a dacite sample from a thick massive flow.

The geochemistry and alteration of variolitic rocks were studied within the Archean Abitibi Greenstone Belt in Harker Township, Ontario and in the Dome Mine area, Timmins, Ontario.

The study demonstrates that there is a connection between the anomalously high Fe/Mg ratio of the variolites and disseminated sulphide-Au mineralization.

including Paleoproterozoic and Archean volcanic associations (Smol’kin, ; Hanski, ; Fowler et variolitic, and other volcanic series, large intrusive Variolitic Lavas in the Axial. Well-preserved pillow lavas in the uppermost part of the Early Archean volcanic sequence of the Hooggenoeg Formation in the Barberton Greenstone Belt exhibit pronounced flow banding.

The banding is defined by mm to several cm thick alternations of pale green and a dark green, conspicuously variolitic variety of aphyric metabasalt.

Concentrations of relatively immobile TiO2, Al2O3 and Cr in. Archean Vedlozero–Segozero greenstone belt in central Karelia. The overall thickness of the rocks of the komatiite–tholeiite associations ranges from (at Koikary) to – km (at Palasel’ga and Sovdozero).

The sequences are made up of massive, pillow, and variolitic differentiated lava flows with thin beds of .Clinopyroxenes in variolitic and massive lavas occur as unzoned, reverse, and normally zoned crystal.

Oscillatory-zoned clinopyroxenes are only observed in variolitic lavas.Well-preserved pillow lavas in the uppermost part of the Early Archean volcanic sequence of the Hooggenoeg Formation in the Barberton Greenstone Belt exhibit pronounced flow banding.

The banding is defined by mm to several cm thick alternations of pale green and a dark green, conspicuously variolitic variety of aphyric metabasalt.