Mineralogy and mineral chemistry of detrital heavy minerals from the Rhine River in Germany as evidence to their provenance, sedimentary and depositional history: focus on platinum‑group minerals and remarks on cassiterite, columbite‑group minerals and uraninite

Publikationen: Beitrag in FachzeitschriftArtikelForschung(peer-reviewed)

Autoren

  • Thomas Oberthür
  • Simon Goldmann
  • Hermann Wotruba
  • Axel Gerdes
  • Arjan Dijkstra
  • Christopher W. Dale

Externe Organisationseinheiten

  • RWTH Aachen, Lehr- und Forschungsgebiet Aufbereitung mineralischer Rohstoffe (AMR)
  • Bundesanstalt für Geowissenschaften und Rohstoffe (BGR)
  • Institut für Geowissenschaften, Facheinheit Mineralogie ‑ Petrologie und Geochemie, Universität Frankfurt
  • Faculty of Science and Technology, University of Plymouth
  • Department of Earth Sciences, Durham University

Abstract

In the course of studying the gold-bearing heavy mineral spectrum of sediments from the upper Rhine River, a distinct suite of detrital grains comprising platinum- group minerals (PGM), cassiterite, columbite-group minerals and uraninite was identified and investigated using conventional and modern analytical methods. This study aimed to characterize the selected mineral groups mineralogically and geochemically in order to identify possible source areas and to reconstruct different aspects of the complex sedimentary history of the Rhine River sediments. The PGM assemblage is dominated by grains of Ru–Os– Ir alloys (~70 %), followed by Pt–Fe alloys, sperrylite and rare other PGM. Accordingly, this PGM assemblage represents highly mature, physically and chemically extremely resistant compounds which may have experienced and survived repeated reworking during their sedimentary history. Pt–Fe alloys and sperrylite may originate from various sources; however, the predominant Ru–Os–Ir alloy grains point to an origin from ophiolite sequences of unknown age (but likely pre-Alpine; Variscan or older). The exact locations of the primary sources and the complex, prolonged sedimentary history of the detrital PGM with possibly multiple intermittent storages remain unknown. Detrital cassiterite grains were dated by the U–Pb method using LAICP- MS. The age dates of cassiterite largely overlap with zircon age distributions by peaking distinctly at ca. 325 Ma (majority of ages), thereby implying a predominantly Variscan age of the cassiterite grains and possible derivation from mineralization in the Black Forest area. Columbitegroup minerals are dominantly tapiolite originating from pegmatites. Rare uraninite grains attest that this mineral experienced rapid erosion, transport and deposition in a reducing environment.

Details

OriginalspracheEnglisch
Seiten (von - bis)637-657
FachzeitschriftInternational journal of earth sciences : Geologische Rundschau (GR ; Geologische Rundschau ; journal of Geologische Vereinigung)
Jahrgang105
Frühes Online-Datum9 Mai 2015
DOIs
StatusVeröffentlicht - 2016