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Stratigraphic context of the Vaca Muerta Formation, example of facies distribution in a well, trace-fossil descriptions, and XRD and TOC geochemical data.

Oceanic Anoxic Event-2 (OAE-2; Cenomanian-Turonian) is characterized by extensive deposition of organic carbon-rich deposits (black shales) in ocean basins worldwide as result of a major perturbation of the global carbon cycle. While the sedimentological, geochemical, and paleontological aspects of deep water expressions of OAE-2 have been intensively studied in the last few decades, much less attention has been given to the coeval shallow water deposits. In this study, we present the results of a detailed facies and petrographic (optical microscope and scanning electron microscopy) and geochemical studies (delta C-13(carb), delta C-13 (org), delta N-15(bulk), TOC, and Rock-Eval pyrolysis) on two key shallow marine sections from the Apennine Carbonate Platform (ACP; Italy). Here a continuous record of shallow water carbonates through the OAE-2 interval is preserved, offering the unique opportunity to document the archive of paleoenvironmental changes in a neritic setting, at a tropical latitude and far from the influence of a large continental block. Two conspicuous intervals are characterized by abundant and closely spaced dark microbial laminites found at correlative stratigraphic horizons in the two stratigraphic sections. These laminites contain elevated concentrations of TOC (up to 1%) relative to microbial capping cycles laminites stratigraphically above and below. The organic matter preserved in these fine-grained laminites is dominated by cyanobacteria remains, which accounted for most of the organic matter produced on the ACP in these intervals. Our study suggests that Tethyan carbonate platforms experienced significant biological changes during OAE-2, alternating, in few kiloyears, between eutrophic phases dominated by microbial communities and mesotrophic/oligotrophic conditions favoring normal carbonate production/sedimentation. The synchronous occurrence of microbialite facies at different locations across the ACP and on other platforms worldwide (e.g., Mexico and Croatia) suggests a causal link between Large Igneous Province volcanism and the environmental conditions necessary to trigger cyanobacterial proliferation on shallow carbonate platforms.

Oceanic Anoxic Event 2 (OAE 2), during the Cenomanian‐Turonian transition (∼94 Ma), was the largest perturbation of the global carbon cycle in the mid‐Cretaceous and can be recognized by a positive carbon‐isotope excursion in sedimentary strata. Although OAE 2 has been linked to large‐scale volcanism, several large igneous provinces (LIPs) were active at this time (e.g., Caribbean, High Arctic, Madagascan, Ontong‐Java) and little clear evidence links OAE 2 to a specific LIP. The Mid‐Cenomanian Event (MCE, ∼96 Ma), identified by a small, 1‰ positive carbon‐isotope excursion, is often referred to as a prelude to OAE 2. However, no underlying cause has yet been demonstrated and its relationship to OAE 2 is poorly constrained. Here we report sedimentary mercury (Hg) concentration data from four sites, three from the southern margin of the Western Interior Seaway and one from Demerara Rise, in the equatorial proto‐North Atlantic Ocean. We find that, in both areas, increases in mercury concentrations and Hg/TOC ratios coincide with the MCE and the OAE 2. However, the increases found in these sites are of a lower magnitude than those found in records of many other Mesozoic events, possibly characteristic of a marine rather than atmospheric dispersal of mercury for both events. Combined, the new mercury data presented here are consistent with an initial magmatic pulse at the time of the MCE, with a second, greater pulse at the onset of OAE 2, possibly related to the emplacement of LIPs in the Pacific Ocean and/or the High Arctic.

We present the preliminary results of the modern distribution of the benthic foraminifera in the Channel of Sicily (off Gela, 200-1000m w.d.) and in Malta escarpment (200-3000m w.d.). These areas are investigated within EC project HERMES to verify the possible impact on the biodiversity of two recent slope failures (the NW slides characterised by pressure ridges and the SE slides by blocks). The study of the slope failures was carried out with a multidisciplinary approach as seismic stratigraphy and sediment cores were available. The stratigraphic record of the cores (based on foraminifera micropaleontology, lithology, isotope stratigraphy, radiocarbon datings as well as magnetic properties) suggests that the age of the most recent failures is younger than 3.5 kyrs B.P. The foraminifera study has been carried out on samples collected by means of a box corer, subsequently subsampled with short tubes (or liners) to obtain sediment samples 0.5/1cm thick for the uppermost part. The sediment samples were treated with Bengal Rose to detect the living (=stained) assemblage, then results are presented as living and total (living + dead foraminifera) assemblage. Moreover, CTD data are available for each investigated site as well as the oxygen profile in the first centimetres of the sediment of the box cores. The preliminary results of this study are here summarised: 1) strong differences are present between samples collected in the slide scars (e.g. no living specimens and general bad preservation state of the microfauna in the SE slide scar), 2) the distal areas of the two slides present assemblage similar to the ones of the samples collected off the slides areas (samples assumed not affected by the failures and then representative of "normal" condition), 3) in general the samples of the NW slides are quite similar to the ones off the slide, 4) the samples of the SE slides are dominated by organically cemented agglutinants (in particular high abundance of tubular agglutinant specie) in the living as well as in the total assemblage, 5) in both the areas (Gela and Malta) infaunal forams such as Brizalina spp and Bulimina marginata are present only in the shallowest samples while oxic species, such as Cibicides spp/Cibicidoides spp and Buccella spp are present only in the deepest samples, and this is confirmed also by oxygen penetration depths in the sediment. These results seem to indicate that the SE slide represents an area somewhat still affected by sediment transport in comparison with the NW slide area. Acknowledgements: HERMES is an European Community funded project of the 6th Framework Programme. See http://www.eu-hermes.net

We investigate the impact of regional tectonic setting and sedimentary dynamics on the onset of Bari Canyon, the main sediment conduit on the Southwestern Adriatic Margin (SAM). Since the Middle Pleistocene, deposition on the SAM, a foreland basin relative to the Southern Apennines, was primarily controlled by glacio-eustatic cycles. However, a number of tectonic structures, active since the early Cenozoic, impacted on the stacking of progradational deposits and on the overall slope setting and stability along the SAM. Four depositional sequences accomplished the progradation of the shelf-margin between ca. 450 kyr BP and the Last Glacial Maximum lowstand (ca. 20 ka BP). These sequences are variably dissected by two large-scale erosional features on the upper slope: 1) Bari Canyon, and 2) Gondola Slide headscarp, further north. The shelf facing these two major erosional structures shows several, smaller-scale incisions that merge with the sequence boundaries between each of the four stacked depositional sequences. The distribution of these erosional features reflects the location of tectonic structures that are still active, suggesting that both the intense erosion and the sediment failure in these areas were enhanced by tectonic deformation. We define the age of these older episodes of shelf-edge erosion and mass wasting that were conducive to the inception of Bari Canyon as we know it today. Moreover, we envisage the following predisposing factors as responsible for the inception and subsequent evolution of Bari Canyon: a) long-term regional uplift and margin tilt, likely controlling the lateral variability in shelf width and shelf-slope profile; b) rapid margin progradation during the deposition of Middle-Late Pleistocene sequences; c) recent tectonic deformation resulting in gentle folds growing during the canyon evolution. (c) 2007 Elsevier B.V. All rights reserved.

The Bari Canyon System dissects the slope of the Southwestern Adriatic Margin from the shelf edge to the base of slope. The Bari Canyon System is a complex feature showing evidence of seafloor instability through repeated mass transport events up to very recent times. The location and geomorphology of the canyon system is controlled by the growth of a suite of gentle anticlines superimposed to a long term tectonic tilt of the margin induced by the uplift of the Apulian swell (onshore) during the last 500 ky. The margin tilt, together with the progressive margin progradation into steeper slope regions, favoured the potential instability of the slope. This instability likely represents a key predisposing factor leading to the formation of the Bari Canyon System. The Bari Canyon System displays three heads, comprised in a crescent-shaped region, and two main E-W trending conduits almost parallel to each other. Side scan sonar mosaics show a canyon floor with high backscatter corresponding to acoustically transparent deposits on Chirp sonar seismic profiles. This evidence suggests a markedly erosional canyon floor with coarse sediment from failed masses which deposited in very recent times, as indicated by the absence of draped sediment at the seafloor. A peculiar characteristic of the Bari Canyon System is its marked asymmetry: the left-hand canyon walls dip 5°, while the rigth-hand walls dip as much as 14°. This asymmetry allows strong bottom currents (up to 60 cm/s), flowing along slope from the North, to enter the canyon and interact with the complex topography. These interaction generates four main sedimentary features: a) bottom current deposits, representing sediment drifts exclusively distributed upcurrent on pre-existing morphologic irregularities ; b) mass wasting deposits, generally not-buried in the canyon thalwegs and gradually buried toward deeper waters the base of the slope; c) turbidite deposits, including a channel-levee complex overhanging on the canyon floors; and d) erosional areas, such as gullies along canyon walls and furrowed patches close to the canyon floor. Preliminary stratigraphic and biostratigraphic work on piston cores allow to infer a Last Glacial Maximum (LGM) age to the buried mass wasting deposits. Biostratigraphic data also indicate that sediment drifts have grown since the end of the LGM, likely, during at least part of the Holocene. The age determination of early phases of the canyon evolution are based on the presence of incised morphologies affecting Pleistocene regressive sequences on the shelfslope transition. These erosional features are part of the canyon heads that clearly cut through the deposits of the two most recent Pleistocene regressive sequences, which post-date the MIS 8 (230 ky). Thus, the whole data set suggests that the canyon system formed after MIS 8 (230 ky), that it became a major sediment conduit during the LGM lowstand, when mass failure deposits also accumulated at the base of the slope, and that the system is still active

The Southwestern Adriatic Margin (SAM) offshore Apulia is a key site to study bottom current activity and their effect on sedimentation. The SAM is impacted by the complex interaction of two southward-flowing bottom water masses: the cold North Adriatic dense Water (NAdDW), forming in the shallow northern Adriatic through cold wind forcing and winter heat loss, and the highly saline Levantine Intermediate Water (LIW), generated in the Eastern Mediterranean through intense evaporation and flowing along the slope in a depth range of 200-600 m. Chirp-sonar profiles, TOBI mosaics, multibeam data and sediment cores reveal distinctive sediment drifts types (elongated, plastered and isolated drifts along the SAM) and, in particular, extensive fields of sediment waves. Non-depositional and erosional features related to bottom current activity include moats, between the crest of sediment drifts and the steep upper slope, widespread upper-slope erosional areas and extensively furrowed areas, particularly where changes in slope orientation force the current circulation. Distribution, morphology and size of bottom-current features along the SAM results from an interaction between current regime and complex margin morphology, characterized by structural highs perpendicular to the slope contour, multiple slope incisions and extensive slide deposits (e.g. blocky slide deposits). Morphobatymetric and seismic stratigraphic data on the SAM evidence that bottom current deposits are best developed where the regional slope flattens seaward of a very steep, often erosional, upper slope. The roughness of the lower slope, in particular, seems to correlate with the complexity and decreasing size of the bottom current deposits. Like other land-locked basins, the Adriatic underwent dramatic paleogeographic and paleoceanographic re-arrangements during the Late Quaternary sea-level oscillations. Indeed, during the Last Glacial Maximum (LGM), most of the areas where NAdDW form today were subaerially exposed. Concurrently, during glacial times the LIW production was likely reduced or deepened compared to the present-day conditions. Seismic and cores data allow investigate the impact of changing current regime on late Quaternary slope deposits. These data show that during the glacial periods bottom current appear less intense than they appear during interglacial time. Other Mediterranean late-Quaternary contourite deposits are either in water depths compatible with the LIW, particularly in the case of shallow sill basins (e.g.: Sicily, Corsica Channel), or at the slope base reflecting the flow of Mediterranean deep waters. The SAM bottom-current deposits, instead, seems to record the changing interaction between these two distinctive bottom-hugging currents along a common pathway.