Abstract
The origin of Quaternary dolomites in continental environments (e.g. karst and lakes) is barely constrained compared to marine dolomites in sedimentary records. Here we present a study of dolomite and aragonite formations infilling young fractures of the ‘Erzberg’ iron ore deposit, Austria, under continental-meteoric and low temperature conditions. Two dolomite generations formed shortly after the Last Glacial Maximum (~20 kyr BP): dolomite spheroids and matrix dolomite. Clumped isotope measurements and U/Th disequilibrium ages reveal formation temperatures of 0–3 °C (±6 °C) and 3–20 °C (±5 °C) for the both dolomite types, and depositional ages around 19.21 ± 0.10 kyr BP and 13.97 ± 0.08 kyr BP or younger, respectively. Meteoric solution and carbonate isotope compositions (δ18O, δ13C and 87Sr/86Sr) indicate the dolomites formed via aragonite and high-Mg calcite precursors from CO2-degassed, Mg-rich solutions. Our study introduces low temperature dolomite formations and their application as a sedimentary-chemical archive.
Highlights
The origin of Quaternary dolomites in continental environments is barely constrained compared to marine dolomites in sedimentary records
The sedimentary and tectonic evolution of the Erzberg iron ore deposit is marked by Variscan age nappe stacking of Silurian and Carboniferous siliceous shales sandwiching lower Devonian limestones, which host the main iron ore body (Fig. 1c)
The sedimentary succession is cross-cut by numerous vertical fractures of variable width and length (Figs. 1d and 2a) that are interpreted to have been developed during fault tectonics or gravitational mass movements up to the Late Pleistocene[30]
Summary
The origin of Quaternary dolomites in continental environments (e.g. karst and lakes) is barely constrained compared to marine dolomites in sedimentary records. We present a case study of dolomite and prominent CaCO3 precipitates (i.e., laminated successions of aragonite and minor calcite; the so-called “erzbergite”30) infilling young vertical fractures within the Erzberg iron ore deposit, Eastern Alps, Austria (Fig. 1). This locality hosts the largest siderite [FeCO3] deposit worldwide[31]. Our results reveal a complex evolutionary history of the dolomite and erzbergite fracture mineralizations as well as the potential of these continental carbonate archives to be used in palaeoenvironmental and palaeo-climate studies, complementary to the widespread modern and ancient carbonate deposits of the marine realm
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
