Aragonite and calcite cementation in boulder-controlled meteoric environments on the Fern Pass rockslide (Austria): Implications for radiometric age dating of catastrophic mass movements

Marc Ostermann, Diethard Sanders, Christoph Prager, Jan Kramers

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)

Abstract

On the Fern Pass rockslide (Eastern Alps, Austria), projecting boulders collected surface runoff and delayed percolation of water into the rockslide mass, leading to decimetre-scale, fluctuating, phreatic/vadose diagenetic systems along their contact. In these systems, aragonite and calcite precipitation were nourished mainly by dissolution of carbonate-rock flour. Cement precipitation was limited to southern- and eastern-exposed "runoff haloes" of boulders and mainly resulted in cemented breccias. Aragonite precipitation was related to dissolved Mg2+ and/or to high CaCO3 supersaturation in evaporative-concentrated pore waters. Early aragonite cement yielded a 234U/230Th age of 4,150 ± 100 years. Relative to other radiometric ages (36Cl, 14C; by other authors) for the rockslide event, the U - Th age of the aragonite is the most precise proxy of depositional age. Carbonate cements are present in other rockslide and rockfall deposits also. U - Th dating of such cements is thus a comparatively rapid and inexpensive method of minimum-age dating catastrophic mass movements.

Original languageEnglish
Pages (from-to)189-208
Number of pages20
JournalFacies
Volume53
Issue number2
DOIs
Publication statusPublished - May 2007
Externally publishedYes

Keywords

  • Aragonite
  • Eastern Alps
  • Holocene
  • Rockslide
  • Sturzstrom
  • Thorium-uranium
  • Vadose diagenesis

ASJC Scopus subject areas

  • Geology
  • Stratigraphy
  • Paleontology

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