An early Proterozoic podiform chromitite in the Outokumpu ophiolite complex, Finland

Vuollo, Jouni; Liipo, Jussi; Nykänen, Vesa; Piirainen, T.; Pekkarinen, Lauri; Tuokko, I.; Ekdahl, E.

doi:10.2113/gsecongeo.90.2.445

Cited by 33 publications

(17 citation statements)

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“…The arrow refers to the depletion in iron toward the magnetite veins. Vuollo et al, 1995;Ahmed et al, 2001;Gahlan et al, unpublished), and not uncommon in the Phanerozoic ones (e.g. England and Davies, 1973;Arai, 1997;Tamura et al, 1999;Ishiwatari et al, 2003 and references therein).…”

Section: Characteristics Of the Serpentinized Peridotites Around Magnmentioning

confidence: 99%

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Origin of magnetite veins in serpentinite from the Late Proterozoic Bou-Azzer ophiolite, Anti-Atlas, Morocco: An implication for mobility of iron during serpentinization

Gahlan

Arai

Ahmed

et al. 2006

Journal of African Earth Sciences

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Section: Characteristics Of the Serpentinized Peridotites Around Magnmentioning

confidence: 99%

“…In addition, we describe in brief the host peridotite, because only limited number of studies on peridotites have been published for the Precambrian ophiolites (e.g. Quick, 1990;Bonavia et al, 1993;Liipo et al, 1995;Vuollo et al, 1995;Suita and Strieder, 1996;Ahmed et al, 2001;Gahlan, 2003;Kusky, 2004).…”

Section: Introductionmentioning

confidence: 99%

Origin of magnetite veins in serpentinite from the Late Proterozoic Bou-Azzer ophiolite, Anti-Atlas, Morocco: An implication for mobility of iron during serpentinization

Gahlan

Arai

Ahmed

et al. 2006

Journal of African Earth Sciences

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“…Limited petrological studies are available on Proterozoic ophiolite complexes in general, and their upper mantle in particular (Leblanc, 1981;Quick, 1990;Bonavia et al, 1993;Liipo et al, 1995;Vuollo et al, 1995;Zimmer et al, 1995;Suita and Strieder, 1996;Ahmed et al, 2001;Kusky et al, 2001;Hussein et al, 2004;Ahmed et al, 2005a). On the other hand, so many studies have been compiled on well-known Tethyan ophiolite complexes of late Paleozoic to Mesozoic age.…”

Section: Upper Mantle Behaviour In Proterozoic Ophiolites: a Comparismentioning

confidence: 99%

Platinum-group elements distribution and spinel composition in podiform chromitites and associated rocks from the upper mantle section of the Neoproterozoic Bou Azzer ophiolite, Anti-Atlas, Morocco

Ahmed

Arai

Abdel-Aziz

et al. 2009

Journal of African Earth Sciences

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“…Late Proterozoic podiform chromitites in ophiolites have been described in several areas, including Ethiopia, Saudi Arabia, Morocco, south China, and Egypt, and Phanerozoic examples are numerous . The oldest relatively intact podiform chromitite previously recognized is that from the Outokumpu ophiolite complex (2.0 Ga), Finland (Vuollo et al, 1995). The Zunhua chromite ores exhibit remarkable similarities to the podiform ores described from the examples mentioned above.…”

Section: What Does the Dongwanzi Ophiolite And Zunhua Ophiolitic Mélamentioning

confidence: 95%

Origin and emplacement of Archean ophiolites of the central orogenic belt, North China craton

Kusky

2010

J. Earth Sci.

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Understanding Archean crustal and mantle evolution hinges upon identification and characterization of oceanic lithosphere. We report and update here more than 10 years work on a complete, yet dismembered and metamorphosed Archean ophiolite sequence in the North China craton, in the Dongwanzi (东湾子)-Zunhua (遵化) structural belt and correlatives in the Wutaishan (五台山) area. Banded iron formation structurally overlies several tens of meters of variably deformed pillow lavas, mafic flows, and picritic amphibolites. These are in structural contact with a 2 km thick mixed gabbro and dike complex with gabbro screens, exposed discontinuously along strike for more than 20 km. The dikes consist of metamorphosed diabase, basalt, Hb-Cpx-gabbro, and pyroxenite. The dike/gabbro complex is underlain by several kilometers of mixed isotropic and foliated gabbro, which preserve compositional layering approximately 2 km below the dike complex, and then over several hundred meters merge into strongly compositionally layered gabbro and olivine-gabbro. The layered gabbro becomes mixed with layered pyroxenite/gabbro marking a transition zone into cumulate ultramafic rocks including serpentinized dunite, pyroxenite and wehrlite, and finally into strongly deformed and serpentinized olivine and orthopyroxene-bearing ultramafic rocks interpreted as depleted mantle harzburgite tectonites. A U/Pb zircon age of 2.505 Ga from gabbro of the Dongwanzi ophiolite makes it one of the world's oldest recognized, laterallyextensive complete ophiolite sequences, though older dismembered ophiolites are recognized in South Africa and Greenland, extending back to 3.8 Ga. This age is confirmed by a ca. 2.6 Ga Re-Os isochron from chromites from the belt, and a number of dated 2.5-2.4 Ga cross-cutting younger igneous units. The Dongwanzi ophiolite is one of the largest well-preserved greenstone belts in the central orogenic belt that divides the North China craton into eastern and western blocks. More than 1 000 other fragments of gabbro, pillow lava, sheeted dikes, harzburgite, Origin and Emplacement of Archean Ophiolites of the Central Orogenic Belt, North China Craton 745 and podiform-chromite bearing dunite occur as tectonic blocks (tens to hundreds of meters long) in a biotite-gneiss and BIF matrix, intruded by tonalite and granodiorite, in the Zunhua structural belt. Blocks in this metamorphosed Archean ophiolitic mélange preserve deeper levels of oceanic mantle than the Dongwanzi ophiolite. The ophiolite-related mélange marks a suture zone across the North China craton, traced for more than 1 600 km along the central orogenic belt. Many of the chromitite bodies are localized in dunite envelopes within harzburgite tectonite, and have characteristic nodular and orbicular chromite textures, known elsewhere only from ophiolites. The chromites have variable but high chrome numbers (Cr/(Cr+Al)=0.74-0.93) and elevated P, also characteristic of suprasubduction zone ophiolites. The high chrome numbers, coupled with TiO 2 <0.2 wt.% and V 2 O 5 <0.1 wt.% indicate ...

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An early Proterozoic podiform chromitite in the Outokumpu ophiolite complex, Finland

Cited by 33 publications

References 0 publications

Origin of magnetite veins in serpentinite from the Late Proterozoic Bou-Azzer ophiolite, Anti-Atlas, Morocco: An implication for mobility of iron during serpentinization

Origin of magnetite veins in serpentinite from the Late Proterozoic Bou-Azzer ophiolite, Anti-Atlas, Morocco: An implication for mobility of iron during serpentinization

Platinum-group elements distribution and spinel composition in podiform chromitites and associated rocks from the upper mantle section of the Neoproterozoic Bou Azzer ophiolite, Anti-Atlas, Morocco

Origin and emplacement of Archean ophiolites of the central orogenic belt, North China craton

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