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The Reykjanes Ridge is located in the North Atlantic Ocean, southwest of Iceland. Here, the oceanic crust is characterized by a series of V-shaped ridges (VSRs) and V-shaped troughs (VSTs), the formation of which has been linked to three alternative hypotheses: i) thermal pulsing, ii) propagating rifts, and iii) buoyant mantle upwelling. During International Ocean Discovery Program Expeditions 384 and 395C, a transect of five sites were drilled eastwards of the modern Mid-Atlantic Ridge (between 20-30°W) at a latitude of ~60°N, to investigate VSTs/VSRs formation. In this preliminary study, we analyze basalt samples from four sites, two from VSRs and two from VSTs, using rock magnetic and anisotropy of magnetic susceptibility (AMS) techniques, to investigate the differences between VSRs and VSTs. We analyzed the samples at the CIMaN-ALP (Peveragno) and INGV (Rome) Laboratories of paleomagnetism through bulk susceptibility, AMS, stepwise demagnetization of natural remanent magnetization through alternating field and temperature, hysteresis loops and FORC diagrams, and susceptibility vs temperature curves. Rock magnetism was used to determine the rock magnetic properties of each sample and investigate its correlation with the degree of alteration observed in the basalts. The AMS was measured to determine the magnetic fabric as a proxy of the magmatic fabric, where, for instance, lava flow-like fabric would be typical of an unaltered basalt. Preliminary results suggest that basalts from VSTs are generally characterized by higher susceptibility values, while the AMS shows a mixed behavior (well defined or dispersed) independently from the structural position. Further rock magnetic data, integrated with petrological, structural and geochemical data will be correlated to the pervasiveness of alteration in each site, the age of basalts and their distance from the Mid-Atlantic Ridge to test the three hypotheses.

Throughout its history, the Earth’s magnetic field has undergone changes in its polarity. These changes vary in scale, from millennial (excursions) to hundreds of thousands or millions of years (reversal). Constraining the chronology of these geomagnetic instabilities is fundamental to understanding Earth’s dynamo processes and their surface expressions. Moreover, a detailed geomagnetic instability time scale (GITS) refines its applicability as an accurate correlation and dating tool (magnetostratigraphy) for sedimentary and volcanic sequences and it is fundamental to understanding several aspects of past climate. Indeed, periods of geomagnetic instability are usually associated with a weak field. This in turn weakens the efficiency of the Earth’s magnetic field shielding enhancing the production of cosmogenic isotopes which play a significant role on modulating climate by either directly or indirectly influencing factors such as the total or spectral solar irradiance. In this study, we present a preliminary record of geomagnetic instabilities during the Brunhes (0-0.778 Ma), based on intercorrelation of paleomagnetic data from five marine sedimentary cores collected during the IODP Expeditions 384 and 395C from the North Atlantic Ocean along the Reykjanes ridge. Two of the drilling sites are nearby the ODP Sites 983 and 984 (Channell et al., 2002) providing an opportunity to cross correlate our preliminary results.

Introduction Parkinson’s disease (PD) patients in chronic levodopa treatment may experience motor and non-motor fluctuations, which may affect their quality of life. Safinamide is a new monoamine oxidase B inhibitor, also exerting a non-dopaminergic effect, recently approved as add-on therapy in fluctuating PD patients. Methods We performed a longitudinal prospective study in a cohort of 20 fluctuating PD patients, to test whether safinamide 50 mg may improve non-motor, cognitive, and behavioral symptoms over a 6-month treatment period. At each timepoint, clinical features were assessed by means of validated PD-specific scales. Neuropsychological assessment was performed by exploring all five cognitive domains. Results Compared to baseline, significant improvement was found in PD patients at 6-month follow-up in items investigating interest (p = 0.02), motivation (p = 0.02), and urinary disturbances (p = 0.03). Moreover, neuropsychiatric assessment showed a significant decrease in fatigue and apathy scores (p = 0.02 and p = 0.01, respectively). Motor assessment revealed a significant reduction in the total wake-up time spent in OFF state (p = 0.01). Follow-up neuropsychological evaluation did not reveal any change compared to baseline. Conclusions Our data reveal that, along with motor fluctuation improvement, treatment with safinamide 50 mg may significantly decrease non-motor symptom burden in PD patients. Interestingly, non-dopaminergic mechanisms, such as glutamatergic overdrive, have been demonstrated to play a role in many pathways underlying these symptoms. Thus, we hypothesize that the neurotransmitter receptor-binding profile of safinamide may explain our findings.

The aim of this study is to investigate how structural deformation in shear zones is documented by the anisotropy of magnetic susceptibility (AMS). The study area is located in the Pliocene outer thrust of the Northern Apennines, which involved Cretaceous to Neogene calcareous and marly rocks. Here, brittle-ductile tectonites show different characteristics along two differently oriented thrust ramps: the NNE-SSW-trending oblique thrust ramp is characterized by the presence of S tectonites, while the NW-SE-trending frontal ramp is characterized by the presence of SC tectonites.Samples for AMS fabric investigation were collected on shear zones from three sectors of the belt, at different distance from the main thrust to detect possible magnetic fabric variations. The three study area are characterized by different combinations of simple and pure shear, thus different degree of non-coaxiality, which has been quantified through the vorticity number Wk.Specimens were measured with an AGICO KLY-3 Kappabridge at the CIMaN-ALP Laboratory (Italy) on 15 different directions mode. Only measurements with all three F-statistics of the anisotropy tests higher than 5 were accepted as reliable. Moreover, outliers characterized by ± 2σ difference with respect to the mean value of AMS scalar parameters were excluded from further analysis. In order to distinguish groups of specimens affected by different sedimentary or tectonic processes, we identified clusters of AMS scalar parameters; when clusters were not defined by these parameters, we applied a combination of contouring and cluster analysis on each principal axis to identify different subfabrics.The magnetic fabric revealed straightforward correlations with structural data and specific changes of AMS axis orientation depending upon the increasing of deformation (lower vorticity number) and proximity to the main thrust. Similar evolution was detected in different deformation regimes. Overall, the magnetic fabric is more sensitive to the simple shear deformation, as the magnetic lineation tends to parallelize mostly with the computed slip vector; however in pure-shear dominated regimes, the magnetic lineation becomes parallel to the transport direction when the deformation is really intense (sites at less than 15-30 cm from the thrust plane).The applied combination of density diagrams and cluster analysis on AMS data successfully allowed discriminating subfabrics related to different events, and shows a great potential to unravel mixed sedimentary and/or tectonic features in magnetic fabrics.

Paleomagnetic data are used in different data formats, adapted to data output of a variety of devices and specific analysis software. This includes widely used openly available software, e.g. PMag.py/MagIC, AGICO/.jr6 & .ged, and PuffinPlot/.ppl. Besides these, individual software and data formats have been established by individual laboratories.Here we compare different data formats, identify similarities and create a common and interchangeable data basis. We introduce the idea of a paleomagnetic object (pmob), a simple data table that can include any and all data that would be relevant to the user. We propose a basic nomenclature of abbreviations for the most common paleomagnetic data to merge different data formats. For this purpose, we introduce a set of automatization routines for paleomagnetic data conversion. Our routines bring several data formats into a common data format (pmob), and also allow reversion into selected formats. We propose creating similar routines for all existing paleomagnetic data formats; our suite of computation tools will provide the basis to facilitate the inclusion of further data formats. Furthermore, automatized data processing allows quality assessment of data.

Arcuate fold-and-thrust belts have been extensively studied in the literature. Less attention, however, has been paid to the characteristics of local-scale arcuate structures, meaning 5–10 km long fold or thrust traces that display map-view curvature. Nevertheless, detailed investigation of small arcuate structures hosted in major arcs can contribute to understanding the pervasiveness of deformation mechanisms. We performed a combined geological and palaeomagnetic study on 21 sites from ac. 60 km2area in the Northern Apennines in order to analyse minor arcs at a kilometric scale. As evidenced by the geological and structural analysis performed on the 21 sites, the fold axial trend changes from N–S to NW–SE in the study area. The comparison with palaeomagnetic results shows the lack of correlation between vertical axis rotations and fold axial trends. As a consequence, the minor arcuate shapes of thrusts and related folds are interpreted as mostly primary features inherited from the geometry of the palaeomargin, represented by pre-orogenic faults, according to a context of inversion tectonics.

The early Toarcian sedimentary record is frequently characterized by the occurrence of marls, shales, and organic rich facies comprising the Toarcian oceanic anoxic event (T-OAE), which are broadly synchronous to the emplacement of the Karoo-Ferrar large igneous province (LIP) with a main pulse at ~181.7 Ma. Here we describe the chronology and rock magnetic properties of the early Toarcian Marne del Serrone Formation (Serrone Marls) from the Monte Serrone section in the Northern Apennines of Italy, and interpret them as reflecting the local environmental response to the transient CO2 rise and accelerated hydrological cycle most likely induced by the emplacement of the Karoo-Ferrar LIP. The studied 62 m-thick section is characterized by a succession of micritic limestones and marls, interrupted by a few slumps, and contains a record of the T-OAE represented by posidonia beds and a ~40 cm-thick black shale interval. The age of the section has been constrained using magnetostratigraphy and ammonite biostratigraphy to the Spinatum to Variabilis zones. Rock-magnetic properties have been used to characterize fluctuations in the magnetite and hematite input throughout the section. Spectral analysis of continuous IRM2.5T and IRM0.1T/IRM2.5T records indicates a duration of the studied marly interval of ca. 3.5 Myr, regarded as a first-order estimate of the duration of the response of the environmental system (hydrological cycle) to the transient climate perturbation triggered by the emplacement of the Karoo-Ferrar LIP, and a duration of the Bifrons zone of ca. 3.4 Myr.

We present the results of an integrated structural and anisotropy of magnetic susceptibility (AMS) investigation in calcareous and marly rocks from thrust shear zones. A total of 17 sites from six localities along the frontal and oblique ramp of the Olevano-Antrodoco-Sibillini thrust and back thrust (Northern Apennines, Italy) were studied to investigate both magnetic fabric and structural characteristics of Cretaceous to Neogene calcareous and marly rocks. In most of the sites AMS is controlled by the paramagnetic minerals (prevailingly phyllosilicates), with minor contribution of ferromagnetic (sensu latu) ones. Structural analysis shows the presence of SC- and S-tectonites associated to predominant simple and pure shear, respectively. The combination of density diagrams and cluster analysis allowed discriminating the contributions of sedimentary and tectonic processes to the bulk magnetic fabric. Six different subfabrics were distinguished, related to the structural data and associated to deformation stages and regimes: A. sedimentary fabric; B. intersection lineation; C. magnetic foliation parallel to S planes with k1 parallel to the S/C intersection; D. k1 moving toward the slip vector; E. magnetic foliation parallel either to the S or the C planes, with k1 parallel to the slip vector or the transport direction; F. k1 parallel to extensional planes intersection. The magnetic foliation has a double tendency to parallelize to pressure solution cleavage (S) and shear planes (C), while the magnetic lineation tends to progressively align with the slip vector, except for pure-shear-dominated sites at less than 15–20 cm from the thrust, where it aligns with the transport direction. The magnetic fabric is dominated by simple shear deformation. The protocol applied for AMS analysis shows a great potential to unravel mixed sedimentary and/or tectonic features in magnetic fabrics. AMS can be considered as a useful tool in unravelling the variation of simple-pure shear deformation regime in shear zones.

Background Anxiety symptoms are common in Parkinson's disease (PD). A link between anxiety and cognitive impairment in PD has been demonstrated. Objectives Using resting-state functional magnetic resonance imaging, we investigated intrinsic brain network connectivity correlates of anxiety symptoms in a cohort of drug-naive, cognitively unimpaired patients with PD. Methods The intrinsic functional brain connectivity of 25 drug-naive, cognitively unimpaired PD patients with anxiety, 25 without anxiety, and 20 matched healthy controls was compared. All patients underwent a detailed behavioral and neuropsychological evaluation. Anxiety presence and severity were assessed using the Parkinson's Disease Anxiety Scale. Single-subject and group-level independent component analyses were used to investigate functional connectivity differences within and between the major resting-state networks. Results Decreased connectivity within the default-mode and sensorimotor networks (SMN), increased connectivity within the executive-control network (ECN), and divergent connectivity measures within salience and frontoparietal networks (SN and FPN) were detected in PD patients with anxiety compared with those without anxiety. Moreover, patients with anxiety showed a disrupted inter-network connectivity between SN and SMN, ECN, and FPN. Anxiety severity was correlated with functional abnormalities within these networks. Conclusions Our findings demonstrated that an abnormal intrinsic connectivity within and between the most reported large-scale networks may represent a potential neural correlate of anxiety symptoms in drug-naive PD patients even in the absence of clinically relevant cognitive impairment. We hypothesize that these specific cognitive and limbic network architecture changes may represent a potential biomarker of treatment response in clinical trials. © 2020 International Parkinson and Movement Disorder Society.

Continental breakup represents the successful process of rifting and thinning of the continental lithosphere, leading to plate rupture and initiation of oceanic crust formation. Magmatism during breakup seems to follow a path of either excessive, transient magmatism (magma-rich margins) or of igneous starvation (magma-poor margins). The latter type is characterized by extreme continental lithospheric extension and mantle exhumation prior to igneous oceanic crust formation. Discovery of magma-poor margins has raised fundamental questions about the onset of ocean-floor type magmatism, and has guided interpretation of seismic data across many rifted margins, including the highly extended northern South China Sea margin. Here we report International Ocean Discovery Program drilling data from the northern South China Sea margin, testing the magma-poor margin model outside the North Atlantic. Contrary to expectations, results show initiation of Mid-Ocean Ridge basalt type magmatism during breakup, with a narrow and rapid transition into igneous oceanic crust. Coring and seismic data suggest that fast lithospheric extension without mantle exhumation generated a margin structure between the two endmembers. Asthenospheric upwelling yielding Mid-Ocean Ridge basalt-type magmatism from normal-temperature mantle during final breakup is interpreted to reflect rapid rifting within thin pre-rift lithosphere.

International Ocean Discovery Program Expedition 368 is the second of two consecutive cruises that form the South China Sea Rifted Margin program. Expeditions 367 and 368 share the common key objectives of testing scientific hypotheses of breakup of the northern South China Sea (SCS) margin and comparing its rifting style and history to other nonvolcanic or magma-poor rifted margins. Four primary sites were selected for the overall program: one in the outer margin high (OMH) and three seaward of the OMH on distinct, margin-parallel basement ridges. These three ridges are informally labeled A, B, and C. They are located within the continent-ocean transition (COT) zone ranging from the OMH to the interpreted steady-state oceanic crust (Ridge C) of the SCS. The main scientific objectives include 1. Determining the nature of the basement within crustal units across the COT of the SCS that are critical to constrain style of rifting, 2. Constraining the time interval from initial crustal extension and plate rupture to the initial generation of igneous ocean crust, 3. Constraining vertical crustal movements during breakup, and 4. Examining the nature of igneous activity from rifting to seafloor spreading. In addition, the sediment cores from the drill sites targeting primarily tectonic and basement objectives will provide information on the Cenozoic regional environmental development of the Southeast Asia margin. Expedition 368 was planned to drill at two primary sites (U1501 and U1503) at the OMH and Ridge C, respectively. However, based on drilling results from Expedition 367, Expedition 368 chose to insert an alternate site on Ridge A (Site U1502). In total, the expedition completed operations at four sites (U1501, U1502, U1504, and U1505). Site U1503, however, was not completed beyond casing to 990 m because of mechanical problems with the drilling equipment that limited the expedition from 25 May 2017 to the end of the expedition to operate with a drill string not longer than 3400 m. New alternate Site U1504 proposed during Expedition 367 met this condition. Site U1505 also met the operational constraints of the 3400 m drill string (total) and was an alternate site for the already drilled Site U1501. At Site U1501, we cored to 697.1 m in 9.4 days, with 78.5% recovery. We also drilled ahead for 433.5 m in Hole U1501D and then logged downhole data from 78.3 to 399.3 m. In 19.3 days at Site U1502, we penetrated 1679.0 m, set 723.7 m of casing and cored a total of 576.3 m with 53.5% recovery, and collected downhole log data from 785.3 to 875.3 m and seismic data through the 10¾ inch casing. At Site U1503, we penetrated 995.1 m, setting 991.5 m of 10¾ inch casing, but no cores were taken. At Site U1504, we took 40 rotary core barrel (RCB) cores over two holes. The cored interval between both holes was 277.3 m with 26.8% recovery. An 88.2 m interval was drilled in Hole U1504B. At Site U1505, we cored 668.0 m with 101.1% recovery. Logging data was collected from 80.1 to 341.2 m. Operations at this site covered 6.1 days. Except for Site U1505, we drilled to acoustic basement, which prior to the expedition, except for Site U1501, had been interpreted to be crystalline basement. A total of 6.65 days were lost due to mechanical breakdown or waiting on spare supplies for repair of drilling equipment. At Site U1501 on the OMH, coring ~45 m into the acoustic basement sampled highly lithified sandstone to conglomerate of presumed Mesozoic age overlain by siliciclastic Eocene pre- to synrift sediments of Oligocene age and topped by primarily carbonaceous postrift sediments of early Miocene to Pleistocene age. Site U1502 on Ridge A was cased to 723.7 m. At this site, we recovered 180 m of hydrothermally altered brecciated basalts comprising sheet and pillow lavas below deep-marine sediments of Oligocene to late Miocene age. Coring was not performed within the upper 380 m (~Pliocene-Pleistocene) at Site U1502. At Site U1503 on Ridge C, 991.5 m of casing was installed in preparation for the planned deep drilling to ~1800 m, but no coring was performed due to mechanical failures, and the site was abandoned without further activity. Coring at Site U1504 on the OMH ~45 km east of Site U1501 recovered metamorphic schist to gneiss (greenschist facies) below late Eocene (?) carbonate rocks (partly reef debris) and early Miocene to Pleistocene sediments. At Site U1505, we cored to 480.15 m through Pleistocene to late Oligocene mainly carbonaceous ooze followed at depth by early Oligocene to late Eocene siliciclastic sediments. Efforts were made at every drill site to correlate the core with the seismic data and seismic stratigraphic unconformities interpreted within the Eocene to Plio-Pleistocene sedimentary sequence prior to drilling. The predrilling interpretation of ages of these unconformities was in general confirmed by drilling results. As a result of the constraints on the length of drill string that could be deployed during the later part of Expedition 368, the secondary expedition objectives addressing the environmental history of the SCS and Southeast Asia received more focus than planned because these sites are located in shallower water depths and required less penetration depth. This forced change in emphasis, however, was without fatal consequences for the primary tectonic objectives. The two expeditions together provided solid evidence for a process of breakup that included vigorous synrift magmatism as opposed to the often-favored interpretation of the SCS margin as a magma-starved margin.

In foreland thrust belts, abrupt lateral changes in tectonic style, structural–stratigraphic features, and topography usually occur across cross-strike faults. The Central Apennines of Italy offer an exceptional scenario of lateral variations in tectonic setting. Here, the Sangro Volturno oblique thrust ramp (SVOTR) represents the outer thrust front of the Pliocene–Quaternary foreland thrust system, confining southward the axial culmination of the orogen that occurs in the Central Apennines. We present an interpretation of the Pliocene–Quaternary evolution of this cross-strike fault through an integrated dataset including structural-geological mapping and subsurface onshore seismic reflection profiles. The interpretation of the structural framework is augmented by the analysis of low-temperature thermochronometers from 32 new sites extending across the subsurface transverse structure. As evidenced by seismic line interpretation, the localization and development of the SVOTR have been influenced by inherited extensional faults within a positive inversion tectonics context. The regional distribution of the maximum paleotemperature values across the SVOTR constrains the original extent of the allochthonous thrust sheet over all its hanging-wall and footwall blocks. The Pliocene–Quaternary thrusting and inversion of SVOTR caused the strong hanging-wall uplift, which brought to the complete erosion of the allochthonous units and the exhumation of the Adria units. The integrated analysis of low-temperature thermochronometers and structural evidence as applied in the study case can define the role of major cross-strike discontinuities in foreland thrust belts, by constraining and verifying their tectonics inversion significance and the amount of related exhumation.

[1] We report on a paleomagnetic study of the southern sector of the Olevano-Antrodoco-Sibillini (OAS) thrust front, which corresponds to the southern limb of the Northern Apennines (Italy) orogenic salient. A lively debate has developed regarding the oroclinal/progressive-arc versus non-rotational nature of the OAS, which has been alternatively interpreted as a dextral strike-slip fault, dextral transpressive fault, or frontal to oblique ramp that reactivated pre-existing Jurassic normal faults. Here, we document the paleomagnetism, integrated with biostratigraphic and structural data, of 52 new sites from both the OAS hanging wall and footwall. On the basis of 39 retained sites, we find a peculiar pattern of tectonic rotations along the OAS thrust that evidences four rotational domains. The thrust footwall is characterized by a southern domain that undergoes an approximately 30° counterclockwise rotation with respect to the stable foreland, and an approximately non-rotated domain. The data from the hanging wall indicate the occurrence of a dextral strike-slip component along the southern sector of the OAS thrust supported by a strong clockwise rotation close to the NE-SW lateral ramp, which rapidly fades 1 km from the thrust front. A slight but significant CW rotation observed in the remaining sites from the hanging wall confirms the progressive nature of the OAS, and its structural position as the southern limb of the Northern Apennines salient. Our detailed paleomagnetic study is crucial in discriminating between progressive-arc- and strike-slip-related components in the main curved orogenic front of the Northern Apennines.

This work reports the results of our analysis of the brittle-ductile shear zone associated with the Olevano-Antrodoco-Sibillini (OAS) curved-shape thrust in the Central/Northern Apennines of Italy. Its southern sector is characterized by NNW–SSE trending footwall anticlines, which also affect the OAS thrust surface. S tectonites in the NNE–SSW trending sector are crenulated by conjugate extensional surfaces (extensional crenulation cleavage). The NW–SE trending segment of the OAS thrust is characterized by SC tectonites developed along the thrust-related shear zone. Both the SC and S tectonites are consistent with a top-to-the N60–70°E direction of tectonic transport. The SC tectonites are associated with a simple-shear-dominated deformation (Wn = 0.86–0.98). On the other hand, the S tectonites and their related extensional shear planes document two stages of strain: (i) sub-simple shear (Wn = 0.34–0.50, related to OAS thrusting contemporaneous to growing incipient footwall anticlines, and (ii) pure-shear-dominated deformation (Wn = 0.17–0.00), subsequent to the OAS thrusting and caused by the definitive growth of footwall anticlines within an in-sequence deformation context. The present study proposes the analysis of shear zones to: (i) discriminate in-sequence against out-of-sequence evolution, and (ii) use as a tool to constrain the modes and timing of the curved belt's development.

The relationships between thrusts and normal faults represent primary constraints in the reconstruction of the modes and timing of pre-, syn- and post-orogenic deformation events in fold-and-thrust belts. Such relationships are well exposed in curved orogenic belts where the thrusts are oblique to the trend of normal faults. We study the NNE–SSW-trending Olevano-Antrodoco-Sibillini oblique thrust and its crosscutting relationships with NW–SE-trending normal faults in order to constrain the Neogene–Quaternary deformation history of the Central-Northern Apennine (Italy). The analysis of structural and geological data allowed us to reconstruct the geometric and kinematic constraints of two inversion events: 1 – During the Pliocene, positive inversion reactivated the NNE–SSW-trending pre-existing Ancona-Anzio normal fault as the Olevano-Antrodoco-Sibillini oblique thrust ramp and caused the shortcut of NW–SE-oriented normal faults; 2 – During the Quaternary, negative inversion reactivated NW–SE-trending pre-thrusting normal faults. The growth of the NW–SE Quaternary normal faults causes seismicity and is responsible of the development of wide Quaternary intramontane basins. Their distribution and the related seismicity have been controlled and compartmentalized by NNE–SSW-trending oblique thrusts. Thus, the crosscutting relationships between thrusts and normal faults are crucial in seismic hazard assessment.

Terra Nova, 24, 396–406, 2012 Abstract Fault-bend and fault-propagation folds have unique profiles in foreland fold-and-thrust belts that are caused by different fault-related folding models and controlled by the mechanical characteristic of the multilayer and/or by reactivation of normal faults in a positive inversion tectonics context. In this work, NNE–SSW- and NW–SE-trending anticlines, related to the Neogene curve-shaped Olevano-Antrodoco-Sibillini thrust (Northern Apennines, Italy), are investigated to reconstruct fault-related folding mechanisms. Geological and structural analysis allows us to interpret the NNE–SSW-trending anticlines as fault-bend reactivation folds and the NW–SE-trending anticlines as fault-propagation shortcut anticlines. The coexistence of fault-bend and fault-propagation folding processes involving the same multi-layered succession in different arms of a curve-shaped thrust is explained in an inversion tectonics context. This along-strike variation of different folding mechanisms might be recognised in similar curve-shaped orogenic thrust-belts controlled by structural inheritance.

The geometry of the Apennine fold-and-thrust belt has been strongly influenced by the original architecture of the Adria paleomargin. In the Central Apennines, pre-thrusting normal faults (pre-orogenic Permian(?)/Triassic–Jurassic and synorogenic Neogene) were reactivated with compressional kinematics during the Neogene–Quaternary orogenesis. We present a study of the control of preexisting extensional faults on thrust tectonics in the Central Apennines. We describe positive inversion geometries of some salient fold-and-thrust structures from the Central Apennines (Setteporte, the Sabini Mountains, the Sibillini Mountains, Montagna dei Fiori, the Gran Sasso range, Maiella Mountain, and Casoli-Bomba) by integrating surface geological data and seismic-line interpretation. In these structures, different styles of fault reactivation depend on their orientation with respect to the subsequent compressional NE-SW-trending stress field. The NW-SE– and WNW-ESE–trending pre-thrusting normal faults in the backlimbs of the anticlines were displaced and passively translated in the hanging-wall blocks of the thrust planes, thus exhibiting a classical shortcut geometry (shortcut anticlines). Differently, pre-orogenic normal faults in the N-S–trending anticlines were reactivated in a transpressive deformational context, as documented by the mainly dip-slip and strike-slip kinematics along the thrusts and back thrusts, respectively (reactivation anticlines). The cases studied document differences in geometry in fold-and-thrust structures related to the trend of preexisting extensional faults, showing that different reactivation geometries linked to the same inversion event can coexist at regional scale in curved fold-and-thrust belts. The proposed inversion tectonic model and the resulting geometry of the fold-and-thrust belt could possibly be applied to analogous orogenic belts.

We computed a new 120 to 100 Ma high-resolution Apparent Polar Wander Path (APWP) for Adria from magnetostratigraphic studies in the Northern Apennines (Italy). We analyzed 274 cores from three Early Aptian–Late Albian sections of the Marne a Fucoidi Fm., belonging to the sedimentary succession deposited above the Adria passive margin during Meso-Cenozoic time. To solve the problem of tectonic rotations induced during the Apennine orogenesis, we computed relative rotations between sections and realigned them into a common declination reference frame (Bosso, Italy). These new data were added to the previous 150–125 Ma segment computed from the same region [Satolli, S., Besse, J., Speranza, F., Calamita, F., 2007. New 125–150 Ma high-resolution Apparent Polar Wander Path for Adria from magnetostratigraphic sections in Umbria-Marche (Northern Apennines, Italy): Timing and duration of the global Jurassic–Cretaceous hairpin turn. Earth Planet. Sci. Lett. 257, 329–342. doi:10.1016/j.epsl.2007.03.009.] to get a very high-resolution 100 to 150 Ma APWP for Adria. The comparison of our APWP with the African APWP segment of Besse and Courtillot computed with 10 Myr sliding window [Besse, J., Courtillot, V., 2002. Apparent and true polar wander and the geometry of the geomagnetic field over the last 200 Myr. J. Geophys. Res. 107. doi:10.1029/2000JB000050.] leads to the following conclusions: 1) our segment (after a 25° clockwise rotation of the Bosso reference frame) is in very good agreement with the African APWP, as shown by a very similar time evolution of inclinations and declinations, most often statistically indistinct; 2) this agreement vindicates our previous model of structural unit rotation for older periods [Satolli, S., Besse, J., Speranza, F., Calamita, F., 2007. New 125–150 Ma high-resolution Apparent Polar Wander Path for Adria from magnetostratigraphic sections in Umbria-Marche (Northern Apennines, Italy): Timing and duration of the global Jurassic–Cretaceous hairpin turn. Earth Planet. Sci. Lett. 257, 329–342. doi:10.1016/j.epsl.2007.03.009.] 3) the concept of “synthetic” APWP construction is strongly validated; 4) the good agreement found strengthens the fact that Adria has been a promontory of Africa at the lithospheric level during Late Jurassic–Early Cretaceous (150–100 Ma), affected by tectonic rotations linked to the Apennines orogenic phases during Neogene; 5) our data evidence a possible ca. 105 Ma southward motion of Adria undetected from classical African APWPs. Finally, we have not found evidence for reversals interrupting the long normal Cretaceous superchron in our sections.

[1] The Apennines consists of the following two major first-order arcuate features: the northern Apennines Arc and the southern Apennines-Calabrian Arc, separated by the Sangro-Volturno line. In this paper we compare and discuss these major arcs, which are characterized by several differences. These are mainly related to differences in paleogeographic domains, stratigraphic successions, structural setting, and geodynamic evolution. We describe with particular emphasis the following two main salients: the Gran Sasso Range and the Matese-Frosolone Mountains, geographically belonging to the central and the southern Apennines, respectively. We analyze existing geological, structural, and paleomagnetic information from both salients and provide new paleomagnetic and magnetic anisotropy data for eight Messianian-Tortonian sites from the Matese-Frosolone Mountains. The aim of the work is to reconstruct the Tortonian-Quaternary kinematic evolution of the central Apennines, which represents the junction zone between the northern Apennines Arc and the southern Apennines-Calabrian Arc. Furthermore, we propose to use the different style of paleomagnetic rotations in arcuate shapes as a tool to discriminate if structures located in the central Apennines geologically belong to the northern Apennines Arc or to the southern Apennines-Calabrian Arc. Finally, the results of this study allowed us to interpret the Sangro-Volturno line as an oblique ramp of the Pliocene-Quaternary frontal thrusts.

International audience; A new high-resolution Apparent Polar Wander Path (APWP) segment has been obtained from the magnetostratigraphy of four Kimmeridgian to Lower Aptian sections in the Northern Apennines (Italy). The use of paleomagnetic data for determination of the Adria APWP was hampered by the large local rotations linked to Apennine tectonics, characterized by folds and thrusts developed during the Neogene. To overcome this problem, we have computed relative rotations between time overlapping sections and realigned them in a common declination reference frame (namely the Bosso section). We synthesized a new high-resolution 150 to 125 Ma APWP for Adria, which has a similar shape to the time-equivalent segment of the synthetic APWP of Africa of Besse and Courtillot [J., Besse, V., Courtillot, Apparent and true polar wander and the geometry of the geomagnetic field over the last 200 Myr, J. Geophys. Res. 107(B11) (2002), doi:10.1029/200JB000050]. A 26° clockwise rotation of our combined Adria APWP places it in almost perfect overlap with African data of same age, confirming that the Adria promontory moved coherently with Africa during this time span, whereas the counterclockwise rotation of Adria with respect to Africa was introduced later, most probably during Apennines orogenesis. Finally, we discuss in relation with worldwide plate evolution the peculiar shape of our APWP, which displays a hairpin turn during Berriasian time, and dates the main Late Jurassic/Early Cretaceous change in plate motion at around anomaly M16.

[1] We report on the paleomagnetism (39 new sites) of Gran Sasso, an indenter-controlled salient of the external central Apennines formed by two orthogonal limbs. We find that Gran Sasso is a complex salient, paleomagnetically corresponding to neither a nonrotating nor an oroclinal end-member. Data from the core of the arc show that the indenter itself did not undergo any rotation. Conversely, rotations of variable magnitude and sign are observed along the curve-shaped thrust fronts. Rotations are virtually absent at both end points of the arc. Moving toward the apex, progressively greater counterclockwise (CCW) and clockwise (CW) rotations occur along the E-W and N-S fronts, respectively. The rotations increase continuously and more than linearly, reaching their maximum values (∼80° CCW and ∼50° CW) around the apex. Here, the more strongly CCW and CW rotated fronts are separated by a domain characterized by local block rotations. The inequality between the maximum CCW and CW rotation values is likely a consequence of the asymmetry of the indenter displacement direction (N70°E) with respect to the preorogenic trends of its margins (E-W and N-S). From an oroclinal point of view, the fronts close to the end points virtually define a nonrotating arc, while the pattern around the apex is similar to that of an orocline. We conclude that close to end points, nonrotational thrusting normal to the indenter margins occurred, while in the vicinity of the apex, the peritidal carbonates acted as an “ice breaker”, pushing apart (and strongly rotating) the weaker multilayer located ahead.

International audience; The magnetic stratigraphy of the Maiolica and Calcari ad Aptici pelagic limestones is documented from four Umbro-Marchean land sections (Italy). The overall biostratigraphic age of the sampled strata encompasses the whole Kimmeridgian-Lower Aptian. The data were gathered from two new sections (Arcevia, Contessa) and by resampling more densely than in the past two additional classical sections (Bosso, Gorgo a Cerbara). A detailed record of the polarity chrons M21n-M14 and M9-M0 was derived, and no difference was observed with respect to the sequence of M polarity chrons inferred from oceanic magnetic anomalies. Barely measurable remanent magnetization from chron M14 to M10n at Contessa concurred with previous evidence from Bosso, indicating that the Maiolica from Umbria-Marche is characterized by a ''recording gap'' during chrons M14n to M11, possibly due to diagenetic magnetite dissolution related to the Late Valanginian carbon isotope event. At Arcevia and Bosso, the boundary between Maiolica and Calcari ad Aptici occurs at the top of chron M19n and in the upper part of chron M20n, respectively, showing that the onset of Maiolica sedimentation may be diachronous by 1.5-2 Myr along the Umbria-Marche domain. Arcevia is the most expanded Mid-Upper Tithonian land section documented so far. Here, the subchrons M20n-1 and M19n-1 are found to represent 3.2% and 10.1% in time of chrons M20n and M19n, respectively. Evidence is also provided for a reversal excursion occurring within the M20n-1 subchron. At Bosso, an excursion and a reversal excursion were found within chrons M16n and M16, respectively.