Re–Os isotopic constraints on the source of platinum-group minerals (PGMs) from the Vestřev pyrope-rich garnet placer deposit, Bohemian Massif

Pašava, Jan; Malec, Jan; Griffin, William L.; Gonzáléz-Jiménez, José María

doi:10.1016/j.oregeorev.2015.01.013

Cited by 7 publications

(7 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The observations above clearly are in disagreement with previous studies suggesting that the Re-Os system in Os-rich PGM remains unchanged [6,7,9,10,25]. The differences between high-temperature and lateritic PGM in the Ni-rich laterites from Falcondo led us to speculate that a significant part of the Os-isotopic heterogeneity described in many placer PGM, and interpreted to be mantle-derived, may be actually due to post-magmatic disturbance by low-temperature fluids.…”

Section: Discussioncontrasting

confidence: 76%

Open System Re-Os Isotope Behavior in Platinum-Group Minerals during Laterization?

et al. 2021

Self Cite

View full text Add to dashboard Cite

In this short communication, we present preliminary data on the Re-Os isotopic systematics of platinum-group minerals (PGM) recovered from different horizons in the Falcondo Ni-laterite in the Dominican Republic. The results show differences in the Os-isotope composition in different populations of PGM: (i) pre-lateritic PGM yield 187Os/188Os varying from 0.11973 ± 0.00134 to 0.12215 ± 0.00005 (2σ uncertainty) whereas (ii) lateritic PGM are more radiogenic in terms of 187Os/188Os (from 0.12390 ± 0.00001 to 0.12645 ± 0.00005; 2σ uncertainty). We suggest that these differences reflect the opening of the Re-Os system in individual grains of PGM during lateritic weathering. The implications of these results are twofold as they will help to (1) elucidate the small-scale mobility of noble metals in the supergene setting and therefore the possible formation of PGM at these very low temperatures, (2) better refine the Os-isotopic datasets of PGM that are currently being used for defining dynamic models of core–mantle separation, crustal generation, and fundamental plate-tectonic processes such as the opening of oceans.

show abstract

Section: Discussioncontrasting

confidence: 76%

Open System Re-Os Isotope Behavior in Platinum-Group Minerals during Laterization?

et al. 2021

Self Cite

View full text Add to dashboard Cite

show abstract

“…6b). However, a good correlation exists between the Os-poor Os-Ir-Ru alloys of this study and the Vestřev pyrope-rich garnet placer (Pašava et al, 2015). Similarly, inclusions of Pt-Fe alloys and Os-Ir-Ru alloys were observed in this study (Fig.…”

Section: Source Regions Of Pgm Au and Other Heavy Mineralssupporting

confidence: 81%

“…The geochemical character of Au and PGM rather requires ultramafic and gabbroic lithologies. Minor and smaller occurrences of gabbroic and ultramafic rocks are known from the drainage system (Ackerman et al, 2013;Fediuk, 2005;Járóka et al, 2019Járóka et al, , 2021Járóka et al, , 2023Pašava et al, 2003Pašava et al, , 2015 and are described below.…”

Section: Source Regions Of Pgm Au and Other Heavy Mineralsmentioning

confidence: 99%

“…In the Vestřev pyrope-rich garnet placer (Krkonoše Piedmont Basin) in the Bohemian Massif, Pt-Fe alloy particles are accompanied by Os-Ir-Ru minerals (native osmium, iridium, and ruthenium) with inclusions of Pt-Fe alloy and hongshiite (Pašava et al, 2015). The Os-Ir-Ru alloys are dominated by Ru, which is typical for ophiolites (Pašava et al, 2015). The PGM composition at the Vestřev pyrope-rich garnet placer therefore differs from Sohland-Rožany, Kunratice, Ransko and Angstberg.…”

Section: Source Regions Of Pgm Au and Other Heavy Mineralsmentioning

confidence: 99%

“…Near the confluence with the Elbe, mainly sedimentary rocks of the North Bohemian Basin exist (Walter, 1995). The source of the Elbe is located in the Krkonoše mountains in Czech Republic, intersecting granites, sediments, and volcanic and metamorphic rocks (Hladil et al, 2003;Pašava et al, 2015;Plasil et al, 2009). Further downstream the Elbe covers various additional geological units such as the gabbroic and ultramafic rocks of the Lusatia (Járóka et al, 2019(Járóka et al, , 2021 and sedimentary, plutonic and metamorphic rocks, including the Erzgebirge and the Granulitgebirge (Hofmann et al, 2018;Zieger et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mineralogy and mineral chemistry of detrital platinum-group minerals and gold particles from the Elbe, Germany

2023

View full text Add to dashboard Cite

Abstract. In heavy mineral concentrates of the Elbe, gold and platinum-group minerals (PGMs) are observed. Two fractions (> 63 and < 63 µm) of the concentrate are analyzed by reflected-light microscopy, scanning electron microscopy with automated mineralogy software and electron microprobe analysis (EPMA). Other heavy minerals are cassiterite, ferberite, monazite, uraninite, columbite–tantalite, magnetite, zircon and cinnabar. Scanning electron microscopy determined the modal abundance of PGMs, gold and the other heavy minerals. The PGMs are mainly Os–Ir–Ru–(Pt) alloys, Pt–Fe alloys, sperrylite and rustenburgite. Compositional variation of PGMs and gold was analyzed by EPMA. This showed that Pt–Fe alloys are (1) native platinum (> 80 atom %), (2) ferroan Pt (20 atom % to 50 atom % Fe), (3) isoferroplatinum (2.64 to 3.04 apfu of sum PGE, platinum-group element), (4) tetraferroplatinum group with Ni + Cu + Fe ≈ 50 atom %, and (5) γ(Pt,Fe) with sum PGE > 3.04 apfu. The Os–Ir–Ru–(Pt) alloys show large compositional variations. Platinum and Fe enrichment is typically observed for Ir-rich Os–Ir–Ru alloys. Gold particles often show compositional zoning of Ag-rich cores and Ag-poor rims due to selective leaching of Ag. Similarly, Hg-rich rims of gold particles are analyzed. These are interpreted as the results of in situ amalgamation due to mobilization of Hg from the associated cinnabar particles. The size and shape of the gold particles generally argue for short transportation distances. Similarly, almost euhedral sperrylite and Pt–Fe alloys suggest a source region close to the sampling site. However, roundish Os–Ir–Ru–(Pt) alloys presumably have experienced longer transportation in the river. Gabbroic dikes of the Lusatia block contain sperrylite and gold particles, which can be the source for these particles found in the concentrate. The composition of the Os–Ir–Ru–(Pt) alloys is similar to previous studies on the Vestřev placer in Czech Republic. Both locations are within the drainage area of the Elbe and can therefore be the source of the PGM and gold particles in the concentrate.

show abstract

Rhenium–osmium isotopes in pervasively metasomatized mantle xenoliths from the Bohemian Massif and implications for the reliability of Os model ages

et al. 2016

View full text Add to dashboard Cite

Re–Os isotopic constraints on the source of platinum-group minerals (PGMs) from the Vestřev pyrope-rich garnet placer deposit, Bohemian Massif

Cited by 7 publications

References 59 publications

Open System Re-Os Isotope Behavior in Platinum-Group Minerals during Laterization?

Open System Re-Os Isotope Behavior in Platinum-Group Minerals during Laterization?

Mineralogy and mineral chemistry of detrital platinum-group minerals and gold particles from the Elbe, Germany

Rhenium–osmium isotopes in pervasively metasomatized mantle xenoliths from the Bohemian Massif and implications for the reliability of Os model ages

Contact Info

Product

Resources

About