Chapter 10 Alteration of Opaque Heavy Minerals as a Reflection of the Geochemical Conditions in Depositional and Diagenetic Environments

Rikke Weibel, Henrik Friis

Research output: Chapter in Book/Report/Conference proceedingChapter in bookResearchpeer-review

18 Citations (Scopus)

Abstract

Detrital opaque heavy minerals are minor but common constituents of most detrital sediments. It is sometimes possible to map the diagenetic paths of those opaques that are readily altered through changing oxidising and reducing geochemical environments, both depositional, post-depositional and diagenetic. The alteration of opaque heavy minerals from different depositional and diagenetic environments, reflecting various geochemical regimes, is reviewed and evaluated. The investigated deposits span from Triassic red beds (Skagerrak and Bunter Sandstone Formations) with early oxidising conditions (including local reduction spots representing early reducing conditions) through weakly reducing conditions of the Miocene Odderup Formation to the strongly reducing environment of the Gassum Formation, where abundant iron and organic matter, and thus related sulphate reduction, have influenced the alteration products. Extreme sulphur-dominated local environments are represented by Holocene carbonate-cemented sandstone pillars. When successive phases of oxidation and reduction occur, the resulting assemblage of primary detrital opaque heavy minerals and their alteration products converge; a detailed study can sometimes reveal the sequence of events. A comparison of the alteration sequence of detrital Fe-Ti oxides, together with identification of authigenic opaques, from red and drab parts of the succession in Triassic red beds (Skagerrak and Bunter Sandstone Formations), has enabled us to distinguish primarily oxidised horizons, primarily reduced areas, secondarily reduced originally oxidised areas, and secondarily oxidised originally reduced areas.

Original languageEnglish
Title of host publicationHeavy Minerals in Use
EditorsMaria Mange, David Wright
Pages277-303
Number of pages27
DOIs
Publication statusPublished - 2007

Publication series

NameDevelopments in Sedimentology
Volume58
ISSN (Print)0070-4571

Keywords

  • alteration
  • diagenetic environment.
  • Fe-Ti oxides
  • geochemical conditions
  • hematite
  • ilmenite
  • magnetite
  • opaque heavy minerals
  • oxidising conditions
  • reducing conditions
  • titanomagnetite

Programme Area

  • Programme Area 3: Energy Resources

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