Age of porphyry-type deposits in the Skellefte District, northern Sweden

Weihed, Pär; Schöberg, Hans

doi:10.1080/11035899109453203

Cited by 23 publications

(12 citation statements)

References 21 publications

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“…The zircon cores would hence represent recycling of Palaeoproterozoic rocks while Archaean material is lacking, which is consistent with previous studies of the SD González Roldán, 2010;Wilson et al, 1987). The QFP emplacement age is younger, and within the analytical error of the previously reported 1886 +15/−9 Ma age of Weihed and Schöberg (1991). The disagreement between the new SIMS and the older TIMS data is suggested to be due to a mixed age between zircon rim and zircon core in the latter, a problem also noted by Weihed and Schöberg (1991).…”

Section: The Heterogeneous Gi Magmatic Phasesupporting

confidence: 86%

“…The QFP emplacement age is younger, and within the analytical error of the previously reported 1886 +15/−9 Ma age of Weihed and Schöberg (1991). The disagreement between the new SIMS and the older TIMS data is suggested to be due to a mixed age between zircon rim and zircon core in the latter, a problem also noted by Weihed and Schöberg (1991). The porphyritic, quartz vein brecciated intrusion at Tallberg (sample ALA24-89), yields a considerably younger rim age (1871±9 Ma) compared to most of the QFP dykes in the study area, but also a significantly larger error, overlapping with all QFP dyke ages.…”

Section: The Heterogeneous Gi Magmatic Phasementioning

confidence: 53%

“…The QFP dykes in the Tallberg area ( Fig. 1) have previously been dated with ID-TIMS (isotope dilution thermal ionization mass spectrometry), yielding a U-Pb age of 1886 + 15/−9 Ma (Weihed and Schöberg, 1991). This result suggests that formation of porphyry-style mineralisation and VMS deposits in the SD was spatially and, in a broad sense, temporally related.…”

Section: Introductionmentioning

confidence: 67%

“…It is associated with a younger intrusive at depth (Fig. 2) and multiple generations of quartz-feldspar porphyritic (QFP) dykes dated by the TIMS U-Pb zircon method at 1886+15/−9 Ma (Weihed and Schöberg, 1991). The QFP dykes consist of quartz plagioclase and hornblende ±biotite phenocrysts in a matrix of similar mineralogy with minor chlorite, epidote, apatite and zircon (Bejgarn et al, 2011;Weihed, 1992b).…”

Section: Southern Jicmentioning

confidence: 99%

“…This result suggests that formation of porphyry-style mineralisation and VMS deposits in the SD was spatially and, in a broad sense, temporally related. However, Weihed and Schöberg (1991) noted the presence of inherited cores, indicating that the intrusive age of the QFP dykes may be younger than ca. 1886 Ma.…”

Section: Introductionmentioning

confidence: 96%

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Palaeoproterozoic porphyry Cu–Au, intrusion-hosted Au and ultramafic Cu–Ni deposits in the Fennoscandian Shield: Temporal constraints using U–Pb geochronology

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Section: The Heterogeneous Gi Magmatic Phasesupporting

confidence: 86%

Section: The Heterogeneous Gi Magmatic Phasementioning

confidence: 53%

Section: Introductionmentioning

confidence: 67%

Section: Southern Jicmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Geochemical, Microtextural, and Mineralogical Studies of the Samba Deposit in the Zambian Copperbelt Basement

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Nature, origin and evolution of the granitoid-hosted early Proterozoic copper-molybdenum mineralization at Malanjkhand, Central India

et al. 1996

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At Malanjkhand, Central India, lode-type copper (-molybdenum) mineralization occurs within calcalkaline tonalite-granodiorite plutonic rocks of early Proterozoic age. The bulk of the mineralization occurs in sheeted quartz-sulfide veins, and K-silicate alteration assemblages, defined by alkali feldspar (K-feldspar >> albite) + dusty hematite in feldspar + biotite + muscovite, are prominent within the ore zone and the adjacent host rock. Weak propylitic alteration, defined by albite + biotite + epidote/zoisite, surrounds the K-silicate alteration zone. The mineralized zone is approximately 2 km in strike length, has a maximum thickness of 200 m and dips 65~ ~ along which low-grade mineralization has been traced up to a depth of about 1 km. The ore reserve has been conservatively estimated to be 92 million tonnes with an average Cu-content of 1.30%. Supergene oxidation, accompanied by limited copper enrichment, is observed down to a depth of 100m or more from the surface. Primary ores consist essentially of chalcopyrite and pyrite with minor magnetite and molybdenite. 634S (Too) values in pyrite and chalcopyrite (-0.38 to +2.90) fall within the range characteristic of granitoid-hosted copper deposits. 61sO (Too) values for vein quartz (+ 6.99 to + 8.80) suggest exclusive involvement of juvenile water. Annealed fabrics are common in the ore. The sequence of events that led to the present state of hypogene mineralization is suggested to be as follows: fracturing of the host rock, emplacement of barren vein quartz, pronounced wall-rock alteration accompanied by disseminated mineralization and the ultimate stage of intense silicification accompanied by copper mineralization. Fragments of vein quartz and altered wall rocks and striae in the ore suggest post-mineralization deformation. The recrystallization fabric, particularly in chalcopyrite and sphalerite, is a product of dynamic recrystallization associated with the post-mineralization shearing. The petrology of the host rocks, hydrothermal alteration assemblages, ore mineral associations, fluid inclusions and the sulfur and oxygen isotopes of ores are Correspondence to: S.C. Sarkar comparable to those in Phanerozoic (and reported Precambrian) porphyry-copper systems, and the Malanjkhand deposit has important implications for both metallogenic models for, and mineral exploration in, Precambrian terrains.

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Age of porphyry-type deposits in the Skellefte District, northern Sweden

Cited by 23 publications

References 21 publications

Palaeoproterozoic porphyry Cu–Au, intrusion-hosted Au and ultramafic Cu–Ni deposits in the Fennoscandian Shield: Temporal constraints using U–Pb geochronology

Palaeoproterozoic porphyry Cu–Au, intrusion-hosted Au and ultramafic Cu–Ni deposits in the Fennoscandian Shield: Temporal constraints using U–Pb geochronology

Geochemical, Microtextural, and Mineralogical Studies of the Samba Deposit in the Zambian Copperbelt Basement

Nature, origin and evolution of the granitoid-hosted early Proterozoic copper-molybdenum mineralization at Malanjkhand, Central India

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