Paleoenvironmental signature of the Selandian-Thanetian Transition Event (STTE) and Early Late Paleocene Event (ELPE) in the Contessa Road section (western Neo-Tethys)

Abstract

Sedimentary records of the Early Cenozoic indicate a series of events with climatic and carbon cycle variability known as hyperthermals. A ~350-kyr-long event of environmental disruption during the Paleocene, not described before and here named Selandian-Thanetian Transition Event (STTE), has been recognized and well constrained in the western Tethys Contessa Road section (Gubbio, Italy) through high-resolution biostratigraphic, geochemical, and rock-magnetic data. The STTE exhibits peculiar stressed ecological responses among calcareous nannofossils and foraminifera, which highlight marked environmental perturbation affecting the biosphere. The environmental instability is not confined within the photic zone but extends to the seafloor leading to little more trophic conditions of the sea surface waters with an enhanced, but of short measure, nutrient availability on the seafloor conditions and marked rise of lysocline. Magnetic Susceptibly (MS) is dominantly controlled by the balance between carbonate productivity and detrital supply, as evidenced by the strong correlation between MS and CaCO3 (%) (r2 = −0.72). However, we also document two components in the isothermal remanent magnetization (IRM) and first-order reversal curves (FORC) diagrams that prove the occurrence of biogenic magnetite throughout the STTE. Systematic variations in bio-geochemical and magnetic parameters show the relative abundance of carbonate production (or inversely dissolution of carbonate) versus detrital supply during the STTE, which induced higher populations of magnetotactic bacteria through increased terrigenous input and, therefore, increased nutrient supply. Noteworthy, the uppermost part of the STTE includes the equivalent of the suspected hyperthermal, short-lived Early Late Paleocene Event (ELPE). The ELPE event shows an episode of increase in magnetic properties of the sediments, including an increase in magnetofossil concentration, as indicated by IRM components and FORC diagrams. The comparison of biotic and abiotic records throughout the STTE at Contessa Road section with available data across the ELPE from former investigated ocean and land-based sites provides lines of evidence that this latter event might be indeed only the terminal part of a long-lasting environmental change than hitherto supposed.

The Birth of a Connected South Atlantic Ocean: A Magnetostratigraphic Perspective

“…From an ocean circulation perspective, our results indicate that during the Early Paleogene, the Rio Grande Rise -Walvis Ridge alignment was overcome, and deep-water currents from South Atlantic toward the North Atlantic were established. The geographical distribution of the Dan-C2 anomalies (Kroon et al, 2007;Quillevere et al, 2008;Westerhold et al, 2011;Coccioni et al, 2019) matches the areas that would be affected by the northward flow of South Atlantic deep waters. This raises the question of whether Dan-C2 may actually be an expression of this connectivity change in the South Atlantic.…”

“…The slumps likely induced an offset in our age model, visible as slight delays of LDE, when compared with the Walvis Ridge data. No similar anomalies can be correlated with ELPE (Coccioni et al, 2019) due to the presence of a large sedimentation gap, the onset which can be confidently correlated with ELPE, indicating a change in sedimentation occurred at the time.…”

“…From the top: magnetic susceptibility and S-ratio for Deep Sea Drilling Program (DSDP) Site 356 obtained in this study, stage and magnetic polarity, and benthic δ 13 C from Barnet et al (2019). Marked are the major recognized events reported in the literature discussed in the text: the Cretaceous-Paleogene boundary (blue) and suspected hyperthermal-like events (red): the Cretaceous-Paleogene boundary (K/Pg), the Dan-C2 event (Dinarès-Turell et al, 2014;Jehle et al, 2015), L.C29n (Barnet et al, 2019), M.27Cr (Barnet et al, 2019), Late Danian Events (LDEs) LDE1 and LDE2 (Sprong et al, 2012;Jehle et al, 2015;Deprez et al, 2017), L.C26r (Barnet et al, 2019), Danian/Selandian Transition Event (D/STE) (Arenillas et al, 2008), Early-Late Paleocene Event (ELPE) (Coccioni et al, 2019).…”

“…Although the study of early Paleogene Carbon Isotope Excursions (CIE) and hyperthermals are somewhat overshadowed by the more spectacular End-Cretaceous Chicxulub cataclysm and the subsequent Cretaceous-Paleogene Extinction event, robust work has been conducted to determine the amplitude and duration of these climatic anomalies in the early Paleogene time. Our understanding of early Paleogene climate anomalies is based on key reference sites such as Walvis ridge (Leg 208, in particular, Hole 1262) in the South Atlantic (Barnet et al, 2019), Shatsky Rise (in particular Hole 1209) in the Central Pacific (Westerhold et al, 2011), Zumaia (Spain) in the North Atlantic (Dinarès-Turell et al, 2014), Gubbio-Contessa (Italy) in the western Tethys (Coccioni et al, 2012(Coccioni et al, , 2019Sinnesael et al, 2016; Figure 9), North-Eastern Desert and Sinai region (Egypt) in the south Tethys (Schulte et al, 2013), Boltysh crater lake (Ukraine) continental Eurasia in north Tethys (Gilmour et al, 2014) and Wombat plateau (IODP Leg 122, Hole 761) in the Indian Ocean (Quillevere et al, 2002). A particular feature of the early Paleogene climate anomalies (CIEs and hyperthermal events) is that unlike their Eocene counterparts, the Paleogene climate anomalies are much more complex and often consist of multiple minor events, creating a sawtoothlike appearance in climatic and rock magnetic proxies, similar to behavior also described in the Early Paleogene in the Tethyan region (Coccioni et al, 2012).…”

Biostratigraphy and Paleoenvironmental Reconstruction at the Gebel Nezzazat (Central Sinai, Egypt): A Paleocene Record for the Southern Tethys

“…The Paleocene Epoch (Series) has been formally divided into Danian, Selandian, and Thanetian Stages [1,2]. This epoch was characterized by short and extremely warm episodes (known as hyperthermal events) associated with sedimentological and isotopic changes as well as variations in calcareous nannofossil assemblages [3][4][5][6][7][8][9]. These Paleocene events comprise the Late Danian Event (LDE) [10][11][12][13]; the Danian/Selandian (D/S) transition event [14,15]; the early-late Paleocene event (ELPE, [3]), also known as the mid-Paleocene biotic event (MPBE, [4]); and likely part of the long-lasting environmental disruption during the Paleocene (i.e., the Selandian-Thanetian Transition Event, STTE, [8]).…”