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The southern tip of South America off Chile has suffered a long phase of ocean-continent convergence which has shaped the continental margin through different phases of accretion and tectonic erosion. The present accretionary wedge is a discontinuous geological record of plate convergence and records only part of the accretionary processes resumed after Chile ridge consumption (14 Ma). The structural style of the subduction complex, such as rates of sediment accretion and tectonic erosion, structural vergence, width of the accretionary wedge, taper angle and deformation in the forearc basin, varies along the margin. Large taper values are related to narrow wedges and seaward vergent structures. Low tapers occur where deformation at the toe of the accretionary complex is spread over wide areas and is related both to landward and seaward vergent thrust faults. Seismic data interpretation contributes to define more accurately frontal wedge morphology and geometry of subduction and suggests that different modes of accretion together with tectonic erosion may be active concurrently along the trench at different locations. In areas of subduction driven accretionary processes the majority of trench sediments are involved in accretionary processes and sediments are uplifted and piled up in the form of imbricate thrust sheets. In areas where the wedge is non-accretionary the continental margin shows steeper continental slopes associated with narrow accretionary wedges, more intense sediment disruption and very shallow décollement levels. Variation in structural style and in the geometry of the forearc region setting off Southernmost Chile, has been interpreted as related to the existence of different structural domains: the nature of their boundaries is still unclear mainly for the lack of high resolution bathymetric data. They have been tentatively related to tectonic lineaments belonging to the Magellan Fault system and/or to the character and morphology of the converging plates (lateral heterogeneities, sea-mounts and fracture zones), which produce a segmentation of the margin.

We are investigating the effects of earthquakes and tsunamis on the sedimentary record in the Ionian Sea through the analysis of turbidite deposits. A comparison between radiometric dating and historical earthquake catalogs suggests that turbidite emplacement triggered by great earthquakes represents over 90% of the deposits in this region. Seismo-turbidite beds can be correlated with major earthquakes such as the AD 1908 Messina, AD 1693 Catania, AD 1169 Eastern Sicily and AD 365 Crete earthquakes.

Highlights • Plate boundary re-organization in the central Mediterranean Sea • Segmentation of the subduction complex along lithospheric transverse faults • STEP faults in the Ionian Sea • Pleistocene active faulting and Mt. Etna formation Abstract The Calabrian Arc is a narrow subduction-rollback system resulting from Africa/Eurasia plate convergence. While crustal shortening is taken up in the accretionary wedge, transtensive deformation accounts for margin segmentation along transverse lithospheric faults. One of these structures is the NNW-SSE transtensive fault system connecting the Alfeo seamount and the Etna volcano (Alfeo-Etna Fault, AEF). A second, NW-SE crustal discontinuity, the Ionian Fault (IF), separates two lobes of the CA subduction complex (Western and Eastern Lobes) and impinges on the Sicilian coasts south of the Messina Straits. Analysis of multichannel seismic reflection profiles shows that: 1) the IF and the AEF are transfer crustal tectonic features bounding a complex deformation zone, which produces the downthrown of the Western lobe along a set of transtensive fault strands; 2) during Pleistocene times, transtensive faulting reactivated structural boundaries inherited from the Mesozoic Tethyan domain which acted as thrust faults during the Messinian and Pliocene; 3) the IF and the AEF, and locally the Malta escarpment, accommodate a recent tectonic event coeval and possibly linked to the Mt. Etna formation. Regional geodynamic models show that, whereas AEF and IF are neighboring fault systems, their individual roles are different. Faulting primarily resulting from the ESE retreat of the Ionian slab is expressed in the northwestern part of the IF. The AEF, on the other hand, is part of the overall dextral shear deformation, resulting from differences in Africa-Eurasia motion between the western and eastern sectors of the Tyrrhenian margin of northern Sicily, and accommodating diverging motions in the adjacent compartments, which results in rifting processes within the Western Lobe of the Calabrian Arc accretionary wedge. As such, it is primarily associated with Africa-Eurasia relative motion.

A geological transect from the abyssal plain of the Ligurian Sea to the Po Plain, realised integrating seismic profiles (ENI, BG Group and CROP data set), well data and surface geology, is presented and discussed in order to highlight Messinian deposits and their structural-stratigraphic features in different structural domains, as a contribute to better define the geodynamic and tectonic implication of the Messinian salinity crisis (MSC) within the Northern Apennines (NA) evolution. In late Tortonian-early Pliocene time three main tectonic pulses caused the uplift of the emerging NA orogenic wedge and the outward migration of its associated basins (foredeep and wedge top basins), while a coeval extensional tectonic regime developed in hinterland areas (Tuscany region and Northern Tyrrhenian sea). The frontal zone of the NA orogenic wedge, thrusting over the west-dipping Adriatic monocline, is imaged in the NE part of the transect. Its thrust front is now buried under a thick succession of Plio-Pleistocene synorogenic deposits in the subsurface of the Po Plain. The Ligurian Units, the uppermost nappe of the tectonic pile, overly Oligo-Miocene foredeep turbidites which are tectonically stacked and accreted to the chain, together with their Mesozoic carbonatic substratum. In the NA foreland basin system two distinctive wedge-top basin types, with different morphostructural setting and Messinian stratigraphy, have been recognised: 1) closed marginal basins, where shallow-water primary evaporites, deposited during the first phase of the MSC, underwent deformation, uplift and erosion during the intra-Messinian tectonic phase (i.e. the Vena del Gesso basin, western Romagna area); 2) deeper and more subsiding basins where organicrich shales and thin limestones, coeval to marginal basins evaporites, were overlain by relatively deep-water resedimented evaporites during the intra-Messinian tectonic phase (i.e. the Cortemaggiore basin, in the Emila area). In deep basinal settings primary evaporites are never found. During the intra-Messinian tectonic phase the main foredeep depocentre shifted toward the NE and the late Tortonian-early Messinian foreland ramp areas were drowned. The axial zone of the chain occurs in the central part of the transect. No Messinian deposits are found here because this area underwent strong uplift and emersion during this time interval. Hinterland areas of the NA chain, characterised by peculiar Messinian deposits, occur in the SW portion of the transect: the Ligurian Basin and extensional basins pertaining to the Northern Tyrrhenian Sea and Tuscany region. The late Oligocene-early Miocene Ligurian Basin syn-rift sequences are highlighted in the Ligurian Basin. The Alpine units are interested by extensional west-dipping listric faults. An undifferentiated Messinian unit, including evaporites, salt and late Messinian deposits, has been recognised. Its deposition is related to a post-rift thermal subsidence regime that took place after the counterclockwise rotation of the Corsica-Sardinia Block. This well-stratified seismic unit shows evidence of deformations due to salt diapirism and gravitational tectonics, driven by shallow low-angle listrict faults that sole out at its base or immediately beneath. Moving NE-ward the intra-Messinian unconformity is sealed by the latest Messinian “Lago Mare” units, as recognized in the Gorgona High. The Northern Tyrrhenian Sea and Tuscany region in upper Tortonian-lower Pliocene time underwent extensional tectonic regime, with the developement of basins bounded by main west-dipping low-angle listric faults. In these basins, actually poor represented in our transect, primary evaporites are preserved under upper Messinian-Pliocene deposits. The Viareggio basin, imaged on this transect, displays evidence of important extensional tectonic regime only in Plio-Pleistocene time. At the base of these syn-rift deposits a probable undifferentiated Messinian unit has been traced. These sediments may represent the onset of the extensional tectonic phase in this area.

The Calabrian arc, is a 200 to 400 km wide accretionary wedge which connects the Southern Apennine chain, to the North, with the Sicilian-Maghrebian chain, to the Southwest. This wedge is still forming, as testified by seismic activity and by recent sea-bottom morphologies including tectonic lineaments, mud volcanoes and deep-incised canyons. In particular, mud volcanoes and mud diapirs show a strict relationship with the Late Pliocene to Recent tectono-sedimentary evolution of the accretionary wedge (Artoni et al, 2009). In order to better understand their origin and evolution, we focused on the Gulf of Squillace. This latter is located in the northern part of the Crotone-Spartivento forearc basin. The studied area was selected because of the consistent available data base which consists of 10 well logs, 330 km of public seismic reflection lines and about 350 km of higher resolution seismic profiles (Sparker lines “J”, ISMAR CNR, 1971-75). The latter profiles have been extensively analyzed because they clearly show diapiric structures, also having a sea-bottom expression. In the Gulf of Squillace the reconstructed complex structural setting shows the occurrence of a system consisting of transpressive and transtensive lines oriented WNW-ESE, which has been interpreted as the off-shore prosecution of the Catanzaro-Squillace transcurrent system (Tansi et al., 2007). All the available WSW-ENE seismic profiles show a wide basin which is confined to the South by WNW-ESE system of deep rooted normal faults, dipping to the North, associated with antithetic faults developing in the northern side of the basin. These latter faults flatten on shallower layers, interpreted as Late Miocene clays with intervening clastic gypsum intervals. The displacement along the southern master fault is associated to an increase in sediment accumulation, of Late Pliocene to Recent age, arranged in a growth geometry on the hanging-wall and documenting the fault activity during this period. Mud diapirs are mainly grouped in this sector of the basin, characterized by the increase in sediment thickness. These diapirs, in turn, are bounded by the major faults. The WNW-ESE seismic profiles also evidence another normal fault system oriented SW-NE, dipping toward the basin, which cuts the upper and middle slope of the gulf. These faults account for hundred of meters of displacement and are associated with significant gravitative processes. In this frame, the occurrence of mud diapirism is related at least to two favorable conditions: 1) overpressure generated by the asymmetric sediment accumulation on the underlying unconsolidated muds and 2) the propagation of the active normal faults system. This activity, in fact, represents the main trigger for fluid and mud rising up to the seafloor. Mud diapirs could be originated from Late Miocene succession, but also from deeper sources. The progressive extensional deformation associated with mud diapirs significantly influences the morphologic evolution of the slope and of the basin. Deep erosion occurs in canyons, that are aligned along the main faults and in some cases are also laterally bounded by the mud diapirs relief. The retrogressive and landward migration of the canyon heads is also strictly associated to the evolution of normal faults, oriented near parallel to the coastline, and associated to gravitative slope failures.

The Calabrian Arc (CA) subduction system is part of the complex African-Eurasian plate boundary in the central Mediterranean Sea and connects the NW/SE trending Apennine with the E-W trending Magrebian thrust belt. Previous studies have outlined the overall architecture of the subduction complex in the Ionian Sea through the analysis of high penetration seismic lines (Cernobori et al., 1996; Doglioni et al. 1999; Finetti, 2005). None of these studies focuses on the outermost part of the CA system, i.e. the transition between the accretionary wedge and the Ionian abyssal plain, and we believe this is the reason why a major question remains unanswered: “is the CA subduction still active”? The lack of seismicity along the subduction fault plane (with a characteristic shallow dipping thrust-type focal mechanism) can be explained by one of the following occurrences: 1) subduction has ceased; 2) subduction is active but aseismically, or 3) subduction is active and there is a large locked seismogenic zone. Diverse earthquake scenarios can be envisioned depending on which of these three hypotheses is taken into account. Understanding the present-day tectonics of the CA is thus important to understand the geological risk in central Mediterranean region.

Coeval extensional and contractional tectonics are a common feature in orogenic belts, especially in post-collisional phases. The attempt to constrain their relative timing and the responsible mechanisms led to several models taking into account different geodynamic contexts of various mountain chains. In peri-Mediterranean collisional orogens, extension and compression are commonly associated and coeval to the emplacement of far-travelled/allochthonous units. Therefore their internal deformation acquired during the translation across collisional belts is likely imprinted by the extensional and contractional tectonics affecting the orogen.In the western portion of the Northern Apennines of Italy, one of the northernmost peri-Mediterranean Tertiary orogens, the far-travelled/allochthonous units, i.e., the Ligurian and Subligurian units, are widely exposed. The present study integrates published and newly acquired surface geological data (geological maps, cross-sections), subsurface boreholes data, and paleothermal (vitrinite reflectance, mixed layer illite-smectite and Kübler index) and thermochronological data (apatite fission-tracks) in order to investigate the deformation history and, consequently, the record of the extension-compression relationships within these far-travelled/allochthonous units.The study of modes and timing of reshaping of the far-travelled/allochthonous units allowed us to strengthen the hypothesis that extensional and contractional tectonics were coeval in the Northern Apennines and tightly connected by a cause/effect relationship. In particular, the late orogenic low- and high-angle extensional tectonics represent the response to an overall contractional regime which induced episodes of gravitational instability in the orogenic wedge. © 2013 Elsevier B.V.

AIM:Completion axillary lymph node dissection (CALND) performed as a standard procedure after a positive sentinel node biopsy (SLNB) in breast cancer patients results, in almost 40-70% of cases, in no additional positive nodes. A nomogram has been developed at Memorial Sloan Kettering Cancer Center (MSKCC) to predict the likelihood of nonsentinel node metastases (NSLNM) after a positive SLNB. Aim of study was to assess the accuracy of MSKCC nomogram in our community breast cancer population. MATERIAL OF STUDY: From a retrospective database of 276 breast cancer patients we evaluated 62 consecutive cases who underwent CALND after a positive SLNB. Patient and tumor characteristics were collected and the nomogram was used to calculate the probability of NSLNM. The accuracy of MSKCC nomogram was tested by the Receiver Operating Characteristic (ROC) curve. The Area Under the Curve (AUC), sensitivity and specificity were calculated for a 10% cut-off value. RESULTS: Presence of macrometastases (p=0.03) and its extranodal extension (p=0.013) in sentinel node were associated with NSLNM, while other tumor and patient characteristics were not. The accuracy of MSKCC nomogram as measured by AUC was 0.67. The nomogram showed 95% sensitivity and 14% specificity. We revised the nomogram by incorporating the presence of extranodal extension and we obtained a new test with improved specificity (84%). DISCUSSION: The modified predictive model is a useful tool in predicting the likelihood of NSLNM in our cohort of patients and may help decision regarding the need of completion axillary lymph node dissection

We analyzed the structure and evolution of the external Calabrian Arc (CA) subduction complex through an integrated geophysical approach involving multichannel and single‐channel seismic data at different scales. Pre‐stack depth migrated crustal‐scale seismic profiles have been used to reconstruct the overall geometry of the subduction complex, i.e., depth of the basal detachment, geometry and structural style of different tectonic domains, and location and geometry of major faults. High‐resolution multichannel seismic (MCS) and sub‐bottom CHIRP profiles acquired in key areas during a recent cruise, as well as multibeam data, integrate deep data and constrain the fine structure of the accretionary wedge as well as the activity of individual fault strands. We identified four main morpho‐structural domains in the subduction complex: 1) the post‐Messinian accretionary wedge; 2) a slope terrace; 3) the pre‐Messinian accretionary wedge and 4) the inner plateau. Variation of structural style and seafloor morphology in these domains are related to different tectonic processes, such as frontal accretion, out‐of-sequence thrusting, underplating and complex faulting. The CA subduction complex is segmented longitudinally into two different lobes characterized by different structural style, deformation rates and basal detachment depths. They are delimited by a NW/SE deformation zone that accommodates differential movements of the Calabrian and the Peloritan portions of CA and represent a recent phase of plate re‐organization in the central Mediterranean. Although shallow thrust‐type seismicity along the CA is lacking, we identified active deformation of the shallowest sedimentary units at the wedge front and in the inner portions of the subduction complex. This implies that subduction could be active but aseismic or with a locked fault plane. On the other hand, if underthrusting of the African plate has stopped recently, active shortening may be accommodated through more distributed deformation. Our findings have consequences on seismic hazard, since we identified tectonic structures likely to have caused large earthquakes in the past and to be the source regions for future events.

AIM: The aim of this study was to determine factors that predict non-sentinel axillary lymph nodes (NSLNs) metastases in breast cancer patients with positive sentinel node biopsy (SLNB). MATERIAL OF STUDY: We reviewed the records of a consecutive series of 176 breast cancer patients who underwent SLNB at our institution. From the database we analysed those cases with one or more positive sentinel lymph nodes (SLNs) in order to determine factors predicting NSLN metastases. RESULTS: From a series of 176 consecutive patients, we evaluated 41 cases (23.3%) with positive SLNB. Subsequent completion axillary lymph node dissection (CALND) revealed NSLN metastases in 15 cases (36.6%). The significant variables predictive of NSLN involvement were the presence of macrometastases with extranodal extension (p = 0.048), the presence of more than one positive SLN (p = 0.08) and a ratio between positive SLN and SLNs globally dissected higher than 0.5 (p = 0.05). DISCUSSION: CALND is the gold standard for patients with positive SLNB, but results, in almost 40-70% of cases, in no additional positive nodes and its therapeutic benefit remains controversial. Clinicopathologic factors predictive of NSLN metastases may be useful in identifying a subset of patients with lower risk of further axillary involvement. CONCLUSIONS: In patients with early breast carcinoma and a positive SLNB, the size of SLN metastases, the presence of extranodal extension, more than one positive SLN and a nodal ratio higher than 0.5 are the factors that significantly increase the frequency of additional axillary positive lymph nodes.

The southern tip of South America off Chile has suffered a long phase of ocean-continent convergence which has shaped the continental margin through different phases of accretion and tectonic erosion. The present accretionary wedge is a discontinuous geological record of plate convergence and records only part of the accretionary processes resumed after Chile ridge consumption (14 Ma). The structural style of the subduction complex, such as rates of sediment accretion and tectonic erosion, structural vergence, width of the accretionary wedge, taper angle and deformation in the forearc basin, varies along the margin. Large taper values are related to narrow wedges and seaward vergent structures. Low tapers occur where deformation at the toe of the accretionary complex is spread over wide areas and is related both to landward and seaward vergent thrust faults. Seismic data interpretation contributes to define more accurately frontal wedge morphology and geometry of subduction and suggests that different modes of accretion together with tectonic erosion may be active concurrently along the trench at different locations. In areas of subduction driven accretionary processes the majority of trench sediments are involved in accretionary processes and sediments are uplifted and piled up in the form of imbricate thrust sheets. In areas where the wedge is non-accretionary the continental margin shows steeper continental slopes associated with narrow accretionary wedges, more intense sediment disruption and very shallow décollement levels. Variation in structural style and in the geometry of the forearc region setting off Southernmost Chile, has been interpreted as related to the existence of different structural domains: the nature of their boundaries is still unclear mainly for the lack of high resolution bathymetric data. They have been tentatively related to tectonic lineaments belonging to the Magellan Fault system and/or to the character and morphology of the converging plates (lateral heterogeneities, sea-mounts and fracture zones), which produce a segmentation of the margin.