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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.

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.

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.