Iron isotope investigation of hydrothermal and sedimentary pyrite and their aqueous dissolution products

Amy L. Wolfe, Brian W. Stewart, Rosemary C. Capo, Ran Liu, David A. Dzombak, Gwyneth Gordon, Ariel Anbar

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Oxidative dissolution experiments were carried out on pyrite from multiple petrogenetic environments (hydrothermal, sedimentary, and coal-related nodules) to investigate possible variations in the iron isotopic composition of pyrite and the products of pyrite dissolution. The experimental materials were leached under carefully controlled abiotic conditions, and a subset of leachates and starting materials from these experiments was analyzed for 56Fe/54Fe by multicollector ICP-MS. Bulk pyrite δ56Fe values (relative to IRMM-014) ranged from -0.1 to +1.3‰, with hydrothermal bulk pyrite values 56Fe continental source, such as Fe derived from dissolution of Fe(III) oxides. This interpretation is consistent with pyrite rare earth element (REE) patterns. This could allow differentiation of Fe contributed from coal- and shale-related pyrite at abandoned mine drainage sites. Leachates from oxidative dissolution of the pyrite at pH = 3 yielded, with few exceptions, δ56Fe values equal to or lower than those of the coexisting bulk pyrite, by up to about 1‰. These shifts are consistent in direction (but not magnitude) with equilibrium isotope fractionation predictions from theory, with possible second order effects from isotopic heterogeneity within individual natural pyrite samples.

Original languageEnglish (US)
Pages (from-to)73-82
Number of pages10
JournalChemical Geology
Volume427
DOIs
StatePublished - Jun 1 2016

    Fingerprint

Keywords

  • Coal
  • Fe isotope
  • Mass fractionation
  • Pyrite
  • Rare earth element
  • REE

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geology

Cite this