Description: Highlights • Dextral strike-slip faulting occurs offshore E Sicily above a lateral slab tear fault. • Proposed dextral Ionian Fault becomes sinistral to the south, in external wedge. • Compressional (folding and thrusting) tectonics occur throughout the wedge. • Morpho-tectonics indicate ongoing subduction and advance of Calabrian backstop. The detailed morphology and internal structure of the Calabrian accretionary wedge and adjacent Eastern Sicily margin are imaged in unprecedented detail by a combined dataset of multi-beam bathymetry and high-resolution seismic profiles. The bathymetric data represent the results of 6 recent marine geophysical surveys since 2010 as well as a compilation of earlier surveys presented as a 2 arc-sec (60 m) grid. Several distinct morpho-tectonic provinces are identified including: the deeply incised Malta–Hyblean Escarpment, numerous submarine canyons, broad regions of relatively flat seafloor dominated by fields of sediment waves, the gently undulating anticlinal fold-and-thrust belts of the external Calabrian accretionary wedge and the adjacent portion of the Western Mediterranean Ridge. The Calabrian arc can be divided into 4 domains (from SE to NW): 1) the undeformed Ionian abyssal plain, 2) the external evaporitic wedge, 3) the internal clastic wedge, 4) the Calabrian backstop (Variscan crystalline basement). The Calabrian accretionary wedge can also be divided laterally into two major lobes, the NE- and the SW lobes, and two minor lobes. The kinematics of the limit between the two major lobes is investigated and shown to be sinistral in the external (evaporitic) wedge. A network of radial slip lines within the southernmost external wedge unequivocally demonstrate ongoing dextral displacement of a rigid indenter (representing the corner of the clastic wedge) into the evaporitic wedge thereby confirming the geodynamic model of an active lateral slab tear fault here off eastern Sicily. The slab tear produces a series of major sub-parallel dextral strike-slip faults offshore Mt. Etna and south of the Straits of Messina consistent with the relative motions between Calabria and the Peloritan domain (NE Sicily). Abundant strike-slip faulting, and wide-spread folding and thrusting observed throughout the entire accretionary wedge, indicate regional shortening between the Ionian abyssal plain (foreland) and the Calabrian–Peloritan backstop caused by active subduction.

Description: The Ionian Sea, due to the presence of two accretionary prisms, the Calabrian Arc and the Mediterranean Ridge, associated with the subduction of the Nubia plate and the Eurasia plate, is the witness of large and catastrophic turbidite events. These events are associated with high magnitude earthquakes and tsunamis. They lead an important gravity-driven sedimentary deposit in the Ionian basin. In this study, we analysed turbidite deposits in order to establish a calendar of the palaeoseismicity and volcaniclastic events from Etna on the Calabrian Arc. Two gravity cores collected in a slope basin on the Calabrian Arc and in the Ionian abyssal plain record more than two hundred turbidites over the last 60,000 years. These turbidites were dated with a multi-proxy approach: radiometric dating, tephrochronology and sapropels. The origin of the turbidites was studied with a sedimentary approach: grain-size, lithology, thin section, and geochemistry of volcanic glass. The results suggest that three triggers are responsible for the deposits of turbidites. There are siliciclastic turbidites triggered by earthquakes and tsunamis waves, and volcaniclastic turbidites triggered by the Etna volcano eruptions or flank collapses. Co-seismic turbidites present different recurrence times depending on the location of the core. On the Calabrian Arc, recurrence times vary between 450 and 1000 years according to the periods in time. On the abyssal plain, recurrence times are shorter and more regular: around every 240 years.

Description: This paper documents the last 10 ka evolution of one of the key parameters of climate: sea-surface temperatures (SST) in the subpolar North Atlantic. We focus on the southern Bay of Biscay, a highly sensitive oceanographic area because of its strategic and nodal position regarding the dynamics of the North Atlantic subpolar and subtropical gyres. This site furthermore offers unique sedimentary environments characterized by exceptional accumulation rates, enabling the study of Holocene archives at (infra)centennial scales. Our results mainly derive from planktonic foraminiferal association analysis on two cores from the southern Landes plateau. These associations were used as quantitative tools (thanks to the Modern Analog Technique) to track past hydrographical changes. SST reconstructions were thus obtained at an unprecedented resolution and compared to a compilation of Holocene records from the northern North Atlantic. From this regional perspective are shown fundamental timing differences between the gyre dynamics, nuancing classical views of a simple meridional overturning cell.

Description: The last glacial period was punctuated by abrupt climatic events with extrema known as Heinrich and Dansgaard-Oeschger events. These millennial events have been the subject of many paleoreconstructions and model experiments in the past decades, but yet the hydrological processes involved remain elusive. In the present work, high-resolution analyses were conducted on the 12-42 ka BP section of core MD99-2281 retrieved southwest of the Faeroe Islands, and combined with analyses conducted in two previous studies (Zumaque et al., 2012; Caulle et al., 2013). Such a multiproxy approach, coupling micropaleontological, geochemical and sedimentological analyses, allows us to track surface, subsurface, and deep hydrological processes occurring during these rapid climatic changes. Records indicate that the coldest episodes of the studied period (Greenland stadials and Heinrich stadials) were characterized by a strong stratification of surface waters. This surface stratification seems to have played a key role in the dynamics of subsurface and deep-water masses. Indeed, periods of high surface stratification are marked by a coupling of subsurface and deep circulations which sharply weaken at the beginning of stadials, while surface conditions progressively deteriorate throughout these cold episodes; conversely, periods of decreasing surface stratification (Greenland interstadials) are characterized by a coupling of surface and deep hydrological processes, with progressively milder surface conditions and gradual intensification of the deep circulation, while the vigor of the subsurface northward Atlantic flow remains constantly high. Our results also reveal different and atypical hydrological signatures during Heinrich stadials (HSs): while HS1 and HS4 exhibit a "usual" scheme with reduced overturning circulation, a relatively active North Atlantic circulation seems to have prevailed during HS2, and HS3 seems to have experienced a re-intensification of this circulation during the middle of the event. Our findings thus bring valuable information to better understand hydrological processes occurring in a key area during the abrupt climatic shifts of the last glacial period.

Description: Data set of dinocyst assemblages (% of 71 taxa) and corresponding location and sea-surface parameters.