The Paleocene-Eocene thermal maximum (PETM) in shallow-marine successions of the Adriatic carbonate platform (SW Slovenia)

Abstract

The Paleocene-Eocene thermal maximum represents one of the most rapid and extreme warming events in the Cenozoic. Shallow-water stratigraphic sections from the Adriatic carbonate platform offer a rare opportunity to learn about the nature of Paleocene-Eocene thermal maximum and the effects on shallow-water ecosystems. We use carbon and oxygen isotope stratigraphy, in conjunction with detailed larger benthic foraminiferal biostratigraphy, to establish a high-resolution paleoclimatic record for the Paleocene-Eocene thermal maximum. A prominent negative excursion in 13C curves of bulk-rock (~1‰-3‰), matrix (~4‰), and foraminifera (~6‰) is interpreted as the carbon isotope excursion during the Paleocene-Eocene thermal maximum. The strongly 13C-depleted 13C record of our shallow-marine carbonates compared to open-marine records could result from organic matter oxidation, suggesting intensified weathering, runoff, and organic matter flux. The Ilerdian larger benthic foraminiferal turnover is documented in detail based on high-resolution correlation with the carbon isotopic excursion. The turnover is described as a two-step process, with the first step (early Ilerdian) marked by a rapid diversifi-cation of small alveolinids and nummulitids with weak adult dimorphism, possibly as adaptations to fluctuating Paleocene-Eocene thermal maximum nutrient levels, and a second step (middle Ilerdian) characterized by a further specific diversification, increase of shell size, and well-developed adult dimorphism. Within an evolutionary scheme controlled by long-term biological processes, we argue that high seawater temperatures could have stimulated the early Ilerdian rapid specific diversification. Together, these data help elucidate the effects of global warming and associated feedbacks in shallow-water ecosystems, and by inference, could serve as an assessment analog for future changes. © 2012 Geological Society of America

Development of transient carbonate ramps in an evolving foreland basin

“…Biota can be a useful criterion for distinguishing palaeobathymetric zones with a predictive utility in palaeoenvironmental reconstructions, butas pointed out by Buxton & Pedley (1989) and Pomar (2001b) relatively little of such research has been conducted on the Cenozoic Tethyan carbonate ramps, particularly within the Alpine foreland basins. Case studies are few, including Scheibner et al (2007), Scheibner & Speijer (2008), Zamagni et al (2008Zamagni et al ( , 2012 and Pomar et al (2017).…”

Shallow marine response to global climate change during the Paleocene‐Eocene Thermal Maximum, Salisbury Embayment, USA

“…Previous studies of the event have largely focused on deep-sea or terrestrial sites [e.g., Kennett and Stott, 1991;Koch et al, 1995;Bowen et al, 2014]; relatively few shallow marine sections have been studied. However, shallow water sections offer the unique potential to evaluate how the PETM climate anomaly impacted coastal marine and terrestrial environments where ecosystems are sensitive to ocean chemistry and physical coastal processes [e.g., Zamagni et al, 2012;Afzal et al, 2011;Steurbaut et al, 2003].…”

Gradients in the carbon isotopic composition of Ordovician shallow water carbonates: A potential pitfall in estimates of ancient CO2 and O2

“…Despite the potential for ancient platform and periplatform  13 C carb to record trends unrelated to the global carbon cycle (e.g., Swart, 2008), there are many wellstudied examples in which positive or negative shifts in global  13 C DIC are clearly recorded. For example, prominent global  13 C excursions in pelagic carbonates have been traced into shallow carbonate settings for the early Cenozoic Paleocene-Eocene Thermal Maximum (PETM) (Robinson, 2011;Zamagni et al, 2012), the Late Cretaceous Cenomanian-Turonian Oceanic Anoxic Event (OAE) (Parente et al, 2007), and the Early Jurassic Toarcian OAE (Woodfine et al, 2008). However, the magnitudes of these  C excursions recorded in shallow water carbonates often appear to be exaggerated relative to the global signal (Immenhauser et al, 2008), which is problematic for use as a  13 C DIC proxy in global carbon cycle models.…”