Stromatolitic carbonates from the Middle Miocene of the western Pannonian Basin reflect trace metal availability in microbial habitats during the Badenian Salinity Crisis

Exploring the Effects of Residence Time on the Utility of Stable Isotopes and S/C Ratios as Proxies for Ocean Connectivity

“…As noted above, paleontological data have been interpreted as indicating continuously hypersaline conditions in a lagoon restricted from the open ocean, rather than waxing and waning seawater influence or even brackish conditions. However, the REY signatures seen here differ from those of hypersaline fluids and their precipitates . Paired with the lack of gypsum and other salt deposits in the stratigraphic section of the Ritzing area, the REY data thus suggest a lack of hypersaline conditions in the Rabenkopf section.…”

“…However, for the remainder of the section, δ 34 S CAS does not replicate the trends seen in Yb SN /Pr SN and other typical seawater proxies (this study, ref ), meaning that like TRS/TOC this proxy fails to capture the environmental transitions that affected the trace element record. The lack of correlation between Yb SN /Pr SN and δ 34 S CAS (Figure D) further supports this conclusion.…”

“…Instead, the relatively low TRS/TOC ratios and the strong correlation with TOC suggest that sulfate levels in the water column were probably lower than those in the open ocean and that most sulfide is organic-bound. However, the absence of stratigraphic trends (Figure A) means that this proxy is not as sensitive to the transition from open-marine to restricted conditions as the trace elements (this study, ref ). In other words, this proxy is similarly invariable as the paleontological data across the section, though not showing evidence of hypersalinity in the form of TRS/TOC ratios well above the marine/nonmarine threshold.…”

“…Middle Miocene stromatolitic limestones of the Oberpullendorf Basin crop out at the Rabenkopf section (N47°37′0.155″, E16°30′08.53″) near the village Ritzing close to the Austrian–Hungarian border (Figure A). The Rabenkopf section was described sedimentologically, petrographically, and geochemically in detail by Harzhauser et al and Viehmann et al In short, chemo-clastic sediments of this section were deposited at the northern margin of the Oberpullendorf Basin, a western sub-basin of the Parathethys Sea. Marine deposition in this area started during the Badenian (Langhian and early Serravallian), reflected by three consecutive marine depositional cycles, and ended during the late Serravallian. , The first cycle, which is only poorly exposed at the study site and was not sampled, can be identified as a Langhian in age due to characteristic foraminifera and is composed of fossil-rich marls, sands, and limestones that reflect a marine transgression …”

“…These siliciclastic sediments were deposited during the late Badenian (early Serravallian) and suggest a reflooding of the southern area of the Oberpullendorf Basin. 21 We obtained off-cuts from the same stromatolite hand specimens and sampling regions as described in Viehmann et al 10 Each stromatolite sample comprised multiple laminae, which was necessary to have enough material for analyses. The samples were prepared for analyses of carbonate-associated sulfate, total reduced sulfide, organic carbon isotopes, bulk nitrogen isotopes, and carbonate-hosted trace elements (see Supporting Information for details).…”