ALBERT

Description: 〈span〉Temperature-dependent clay mineral assemblages, vitrinite reflectance, and one-dimensional (1-D) thermal and three-dimensional (3-D) geological modeling of a Neogene wedge-top basin in the Sicilian fold-and-thrust belt and its pre-orogenic substratum allowed us to: (1) define the burial history of the sedimentary succession filling the wedge-top basin and its substratum, (2) reconstruct the wedge-top basin geometry, depocenter migration, and sediment provenance through time in the framework of a source-to-sink system, and (3) shed new light into the kinematic evolution of the Apennine-Maghrebian fold-and-thrust belt. The pre-orogenic substratum of the Scillato basin shows an increase in levels of thermal maturity as a function of stratigraphic age that is consistent with maximum burial to 3.5 km in deep diagenetic conditions. In detail, R〈sub〉o〈/sub〉% values range from 0.40% to 0.94%, and random ordered illite-smectite (I-S) first converts to short-range ordered structures and then evolves to long-range ordered structures at the base of the Imerese unit. The wedge-top basin fill experienced shallow burial (∼2 km) and levels of thermal maturity in the immature stage of hydrocarbon generation and early diagenesis. Vitrinite reflectance and mixed-layer I-S values show two populations of authigenic and inherited phases. The indigenous population corresponds to macerals with R〈sub〉o〈/sub〉% values of 0.33%−0.45% and I-S with no preferred sequence in stacking of layers, whereas the reworked group corresponds to macerals with R〈sub〉o〈/sub〉% values of 0.42%−0.47% and short-range ordered I-S with no correlation as a function of depth. Authigenic and reworked components of the Scillato basin fill allowed us to unravel sediment provenance during the Neogene, identifying two main source areas feeding the wedge-top basin (crystalline units of the European domain and sedimentary units of the African domain), and to detect an early phase of exhumation driven by low-angle extensional faults that predated Neogene compression. 〈/span〉

Description: A new data set of temperature-dependent clay mineral parameters and vitrinite reflectance of the Tuscan successions in the Northern Apennines (Italy) displays decreasing levels of thermal maturity from hinterland to foreland, and abrupt changes parallel to the strike of the chain which are structurally controlled by northeast-southwest–trending faults (e.g., Marecchia valley lineament). To the southeast of the Marecchia valley lineament, paleothermal indicators show deep diagenetic conditions in the hinterland and early diagenetic conditions in the foreland (R o % ranges from 0.80% to 0.30%; illite content in mixed-layer illite-smectite [I-S] from 86% to 38%). To the northwest of the Marecchia valley lineament, in the hinterland, R o % is up to 0.95% and mixed-layer I-S have an illite content of ~87%–88%, both gradually decreasing toward the northeast (to R o % of 0.33%, and illite in I-S of 50%). Thermal models allowed us to constrain the geometry of the Miocene thrust wedge with special regard to the original thickness and distribution of its allochthonous uppermost structural unit (Ligurian unit) across northeast-southwest–trending tectonic lineaments. The thickness of the Ligurian unit ranges from 1 to 1.5 km to the south of the Marecchia valley lineament, to 3 km to the north-northwest. This tectonic lineament affected wedge geometry, amounts of tectonic transport, and thickness of the uppermost structural unit, and, possibly, Neogene–Quaternary levels of exhumation.

Description: The Carpathian-Pannonian region is made up of the wide extensional Pannonian Basin surrounded by the Carpathian mountain belt. The Pannonian Basin formed in the Miocene by extension in a retro-wedge position while thrusting was still active at the Carpathian front. The Ukrainian region is an ideal area to reconstruct the relationship between the Pannonian Basin and the Carpathians, due to the relatively simple structural setting and to the progressive but neat transition between the two domains. This study uses low-temperature thermochronometry and vitrinite reflectance analysis to investigate the effect of the opening of the Pannonian Basin on the thermal and burial-exhumation histories of the Ukrainian Carpathians. The results show heating and burial maxima in the central units of the wedge (up to ~170 °C and 6 km, respectively), tapering out toward both the innermost and the outermost thrust sheets. Cooling and exhumation occurred by means of a first rapid stage between ca. 12 and 5 Ma (exhumation rates of up to ~1 mm/yr), followed by a slower stage from ca. 5 Ma to the present (exhumation rates within 0.5 mm/yr). Timing and spatial pattern of exhumation are compatible with post-thrusting erosion enhanced by isostatic uplift. The extent of exhumation progressively decreases toward the Pannonian Basin, characterized by a thinned crust. No further significant influence of the Pannonian Basin opening on the thermal and burial history of the Ukrainian Carpathians may be inferred based on our results, whereas the comparison of the tectonothermal evolution of the two domains suggests that they are both controlled by the same lithospheric processes.