Please use this identifier to cite or link to this item:
Title: Aragonite-calcite veins of the ‘Erzberg’ iron ore deposit (Austria) : environmental implications from young fractures
Authors: Boch, Ronny
Wang, Xianfeng
Kluge, Tobias
Leis, Albrecht
Lin, Ke
Pluch, Hannes
Mittermayr, Florian
Baldermann, Andre
Böttcher, Michael E.
Dietzel, Martin
Keywords: Science::Geology
Issue Date: 2019
Source: Boch, R., Wang, X., Kluge, T., Leis, A., Lin, K., Pluch, H., ... Dietzel, M. (2019). Aragonite-calcite veins of the ‘Erzberg’ iron ore deposit (Austria) : environmental implications from young fractures. Sedimentology, 66(2), 604-635. doi:10.1111/sed.12500
Journal: Sedimentology
Abstract: The well-known Erzberg site represents the largest siderite (FeCO 3 ) deposit in the world. It consists of various carbonates accounting for the formation of prominent CaCO 3 (dominantly aragonite) precipitates filling vertical fractures of different width (centimetres to decimetres) and length (tens of metres). These commonly laminated precipitates are known as ‘erzbergite’. This study focuses on the growth dynamics and environmental dependencies of these vein fillings. Samples recovered on-site and from mineral collections were analyzed, and these analyses were further complemented by modern water analyses from different Erzberg sections. Isotopic signatures support meteoric water infiltration and sulphide oxidation as the principal hydrogeochemical mechanism of (Ca, Mg and Fe) carbonate host rock dissolution, mobilization and vein mineralization. Clumped isotope measurements revealed cool formation temperatures of ca 0 to 10°C for the aragonite, i.e. reflecting the elevated altitude Alpine setting, but unexpectedly low for aragonite nucleation. The 238 U– 234 U– 230 Th dating yielded ages from 285·1 ± 3·9 to 1·03 ± 0·04 kyr bp and all samples collected on-site formed after the Last Glacial Maximum. The observed CaCO 3 polymorphism is primarily controlled by the high aqueous Mg/Ca ratios resulting from dissolution of Mg-rich host rocks, with Mg/Ca further evolving during prior CaCO 3 precipitation and CO 2 outgassing in the fissured aquifer. Aragonite represents the ‘normal’ mode of erzbergite formation and most of the calcite is of diagenetic (replacing aragonite) origin. The characteristic lamination (millimetre-scale) is an original growth feature and mostly associated with the deposition of stained (Fe-rich) detrital particle layers. Broader zonations (centimetre-scale) are commonly of diagenetic origin. Petrographic observations and radiometric dating support an irregular nature for most of the layering. Open fractures resulting from fault tectonics or gravitational mass movements provide water flow routes and fresh chemical reaction surfaces of the host rock carbonates and accessory sulphides. If these prerequisites are considered, including the hydrogeochemical mechanism, modern water compositions, young U-Th ages and calculated precipitation rates, it seems unlikely that the fractures had stayed open over extended time intervals. Therefore, it is most likely that they are geologically young.
ISSN: 0037-0746
DOI: 10.1111/sed.12500
Rights: © 2018 The Authors. Sedimentology published by John Wiley & Sons Ltd on behalf of International Association of Sedimentologists. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:EOS Journal Articles

Citations 20

Updated on Mar 10, 2021

Citations 20

Updated on Mar 4, 2021

Page view(s)

Updated on May 21, 2022

Download(s) 50

Updated on May 21, 2022

Google ScholarTM




Items in DR-NTU are protected by copyright, with all rights reserved, unless otherwise indicated.