Abstract: Tectonic events recorded during the Middle Jurassic to Late Cretaceous in the Linzhou Basin of the Lhasa Block are associated with the subduction closure process of the BangongCo - Nujiang Tethys Ocean. To constrain the subduction closure process of the BangongCo - Nujiang Tethys Ocean during this period, a detailed magnetic fabric study of five relatively continuous strata in the Linzhou Basin during the Middle Jurassic - Late Cretaceous was carried out. The results show that the Middle Jurassic Yeba Formation developed initial deformation magnetic fabric, pencil-like magnetic fabric and tensile lineation magnetic fabric; The Late Jurassic Duodigou and Linbuzong Formations developed initial deformation and pencil-like magnetic fabrics; The Early Cretaceous Tacna Formation developed strongly cleaved magnetic fabric and tensile lineation magnetic fabric with more intense deformation; The Late Cretaceous Shexing Formation developed initial deformation magnetic fabric and pencil-shaped magnetic fabric. Combining the movement of the fracture zone, the direction of the stress field and the analysis of the tectonic environment, it is concluded that the tectonic environment has undergone four processes of extension-extrusion-extension-extrusion from the Middle Jurassic Yeba Formation to the Late Cretaceous Shexing Formation. The fracture zone undergoes three main processes: clockwise dextral rotation - rotation stop – clockwise dextral rotation. There are also relatively frequent changes in the north-south direction of the extrusion stresses and plate drag forces to which they are subjected. Thus, under the continued northward subduction of the Neo-Tethys Ocean, the tectonic processes recorded in the Linzhou Basin are associated with altered subduction polarity of the BangongCo-Nujiang Tethys Ocean. The BangongCo-Nujiang Tethys Ocean shifted from southward subduction to northward subduction during the Middle Jurassic. It shifted again to southward subduction in the Early Cretaceous and eventually closed.

How to cite: Qinglong, C. and Wu, H.: Tectonic constraints on subduction closure processes of the BangongCo - Nujiang Tethys Ocean from the Middle Jurassic to the Late Cretaceous: A magnetic fabric study in the Linzhou Basin, Lhasa Block, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5556, https://doi.org/10.5194/egusphere-egu23-5556, 2023.

Surprisingly fast bedrock uplift of ~5 mm/yr is observed by both GNSS and InSAR measurements across the central Southern Alps where oblique convergence is accommodated by the Alpine fault and other tectonic structures. This mountain range also features anomalously heavy precipitation and high erosion on the western side of the main divide. Since vertical motion is sensitive to perturbations from surface processes, we first evaluate how surface processes operating at different time scales (e.g., erosion, (de)glaciation, and hydrological loading) impact the present-day GNSS measurements. Erosion-induced rebound might be significant, but with an upper limit below 2 mm/yr uplift across the central Southern Alps, whereas elastic rebound caused by modern glacier melting and hydrological loading are secondary, as the magnitude is below 0.3 mm/yr at the locations of GNSS stations. Next, we use elastic dislocation models to explore the geometry and kinematics of a ramp-décollement system consistent with the GNSS-derived shortening and remaining vertical motions. Our best-fit model has 5.5-6.5 mm/yr reverse slip on the 40-50°SE-dipping Alpine fault locked above ~9 km depth, connected to a flat décollement accommodating 7.5-11.0 mm/yr of shortening. The remaining far-field shortening might be taken up by folding near the ramp-décollement junction and/or reverse slip along a NW-dipping backthrust in the hinterland. Our results present how climate-related surface and endogenic tectonic processes modulate the present-day vertical deformation across the central Southern Alps, giving new insights into active mountain building for this mountain range.

How to cite: Liu, S. and Jónsson, S.: What is the cause of the present-day uplift across the central Southern Alps, New Zealand?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4274, https://doi.org/10.5194/egusphere-egu23-4274, 2023.

The interaction of subducted oceanic lithosphere with the upper-lower mantle transition zone has been documented to cause episodes of increased surface compression and extension at convergent continental margins. However, little is known about how these lithospheric-deep mantle interactions impact the evolution of arc-continent collision margins, where orogenic growth and basin formation/infilling can occur simultaneously. We use 2.5D subduction models that couple the evolution of Earth’s surface with the geodynamics of the mantle to investigate: (i) how the interactions between the lithosphere and the deep mantle affect the topography evolution of the orogen and basin infilling; and (ii) how sedimentation in the basin modulates the evolution of deformation. Results show that slab-folding in the upper-lower mantle transition zone triggers increased shortening and topographic growth in the orogen by causing the steepening of the subducting slab, which increases the sediment supply to the basin at punctuated times. Furthermore, results show that: (i) the effect of slab-folding in the topography evolution of the orogen and basin infilling increases with the efficiency of surface processes; and (ii) there is a spatial/temporal correlation between the cumulated sedimentation in the basin and the plastic strain. To quantify the strength of this correlation, we performed a Spearman correlation test, which displayed a high correlation between low values of sedimentation (200-1500 m) and low values of plastic strain (0.1-1.5) during the occurrence of slab-folding. In contrast, we found a high correlation between high values of sedimentation (> 1500 m) and plastic strain (>1.5) only when the sedimentation in the basin is 6000 m. We conclude that: (i) the effect of slab-folding in the topography evolution of the orogen and basin infilling is modulated by the efficiency of surface processes (ii) low sedimentation in the basin increases the activity of short wavelength deformation; and (iii) high sedimentation increase the activity of large wavelength deformation during slab-folding only when slab-steepening is maximum.

How to cite: Rodriguez Corcho, A. F., Mallard, C., Polanco, S., Farrington, R., Montes, C., and Moresi, L.: The role of lithospheric-deep mantle interactions in modulating the landscape evolution of arc-continent collision, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14201, https://doi.org/10.5194/egusphere-egu23-14201, 2023.

The stratigraphic development of foreland basins has mainly been related to surface loading in the adjacent orogens, whereas the controls of slab loads on these basins have received much less attention. This has also been the case for the Molasse basin situated on the northern side of the European Alps. Here we relate the evolution of this basin between Geneva (Switzerland) and Linz (Austria) to the subduction processes beneath the European Alps (Schlunegger and Kissling, 2022). At 30 Ma, the western and central portions of the basin (between Geneva and Munich) experienced a change from deep marine (underfilled Flysch stage) to terrestrial conditions (overfilled Molasse stage), while the eastern part in Austria remained a deep Flysch-type of basin and the final sedimentary sink. This is considered as response to oceanic lithosphere slab-breakoff beneath the Central and Western Alps, which resulted in a rise of the Alpine topography, in an increase of surface erosion rates and sediment discharge, and finally in the overfilling of the basin west of Munich. Beneath the Eastern Alps, however, the subducted oceanic slab remained attached to the European plate and down-warped the plate in the East, thereby controlling the east-directed routing of the clastic material and maintaining the Austrian part of the basin in underfilled conditions. The situation changed at 20 Ma, when an oceanic slab breakoff beneath the Eastern Alps resulted in a rebound of the European plate in the East. Beneath the Central and Western Alps, however, the buoyant crustal rocks of the European continental plate continued to be delaminated from the mantle lithosphere, which itself was further subducted by c. 60 km between 30 Ma (time of oceanic slab breakoff beneath the Central/Western Alps) and 20 Ma (Schmid et al., 1996). Because in the central/western part of the Alps, the mantle slab of the continental lithosphere remained attached to the European plate at 20 Ma, the foreland plate continued to be down-warped in its central and western portions. Accordingly, while in the Austrian Molasse basin, the facies changed at 20 Ma from deep underfilled (Flysch-type of sedimentation) to terrestrial filled/overfilled conditions (Molasse sedimentation), the central and western Molasse basin became the final sedimentary sink and remained in the Molasse stage of basin evolution. As a further consequence, the drainage direction in the basin axis changed from an E-directed material transport prior to 20 Ma to a W-directed sediment discharge thereafter. We thus propose that slab loads beneath the Alps were presumably the most important drivers for the development of the Molasse basin at the basin scale.

References:

Schmid, S.M., Pfiffner, O.A., Froitzheim, N., Schönborn, G., Kissling, E. (1996) Geophysical-geological transect and tectonic evolution of the Swiss-Italian Alps. Tectonics, 15, 1036–1064.

Schlunegger, F., Kissling, E. (2022). Slab load controls beneath the Alps on the source-to-sink sedimentary pathways in the Molasse Basin. Geosciences, 12, 226.

How to cite: Schlunegger, F. and Kissling, E.: Relationships between subduction tectonics beneath the Alps and the source-to-sink sedimentary pathways in the Molasse basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2356, https://doi.org/10.5194/egusphere-egu23-2356, 2023.

The Main Ethiopian Rift (MER) is characterized by a significant along-strike variation in rift evolution and strain accommodation mechanisms. The northern MER is at a transitional stage, whereas the central MER is at an intermediate stage of rifting. Previous geophysical and geological observations suggest that rift obliquity, age of onset of rifting and/or presence/absence of magma could be responsible for the observed difference in deformation style. Here, we use the geodynamic modelling software ASPECT that has recently been coupled with the landscape evolution model FastScape to understand the role that surface processes (such as erosion and sedimentation) play in controlling the style of deformation at the central and northern sectors of the MER. Our results show that the deformation in the central MER can be well explained by efficient surface processes. However, our models fail to fully capture the deformation in the northern MER implying that magma plays a significant role in this sector of the rift. We show that the MER is a unique plate boundary where surface and magmatic processes control the style of deformation at different sectors within the same tectonic setting. 

How to cite: Muluneh, A., Brune, S., Corti, G., and Keir, D.: Surface processes and rift evolution in the Ethiopian Rift, East Africa, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11421, https://doi.org/10.5194/egusphere-egu23-11421, 2023.

Basin inversion is usually associated with compressional uplift and erosion of the exhuming sedimentary succession, while the resulting uplift rates are governed by variable convergence rates and the inherited lithospheric structure. However, observations from the Pannonian Basin (Central Europe) record continuous basin-wide subsidence and deposition of anomalously thick sedimentary successions during its inversion. In this study, we investigate the controlling processes behind the subsidence and uplift patterns during the structural inversion of rifted basins.

We conducted a series of high resolution 3D numerical experiments to simulate the successive rifting and inversion stages of the Wilson cycle by applying the coupled I3ELVIS-FDSPM thermo-mechanical and surface processes numerical code. The code is based on staggered finite differences and marker-in-cell techniques to solve the mass, momentum and energy conservation equations for incompressible media, and it also takes into account simplified melting and surface processes.

The models show the successive stages of sedimentary basin formation during the extension. The variability of crustal and mantle thinning below the depocenters leads to spatial and temporal variations of subsidence rates during the syn-rift phase. At the onset of convergence, inversion localizes where the lithosphere is the hottest and thus the weakest. High convergence rate (i.e. 2 cm/yr) leads to localized uplift of the basin center above the asthenospheric upwelling, which also results in the flexural subsidence of the basin margins. This evolution ultimately leads to intraplate orogen formation and overprinting the former basin structure. In contrast, low convergence rate (i.e. 2 mm/yr) results in continuous thermal subsidence. Superimposed on this large-wavelength motion, localized contractional structures are formed. In this case, partial reactivation of the inherited extensional crustal fault zones is more dominant, while inversional structures are visible along the basin margins.

The modeling results are compared to the thermal and subsidence evolution of the Pannonian Basin during its Middle to Late Miocene rifting and Late Miocene to recent inversion.

How to cite: Oravecz, É., Balázs, A., Gerya, T., May, D., and Fodor, L.: Competing effects of post-rift thermal subsidence and contraction-induced tectonic uplift in inverted extensional basins: inferences from numerical models and observations from the Pannonian Basin, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-671, https://doi.org/10.5194/egusphere-egu23-671, 2023.

It is well-established that the mantle exerts a strong control on the geodynamic processes and their expressions observed at the surface. One of the key components in mantle-surface interaction is rheology, yet, the details of this rheological coupling remain not well understood. This is particularly true for large to global scales, which are difficult to assess in the field or in the lab. For instance, rheological inheritance is thought to influence the onset location of plate boundaries and their subsequent evolution. But the originating physical processes and timescales over which such rheological inheritance applies are still debated. Moreover, differences in the rheological coupling between mantle and surface are expected to change first-order surface observables, such as topography.

Here, we use numerical geodynamic models of whole-mantle convection to test the sensitivity of surface tectonics to different rheological assumptions, for instance in terms of deformation mechanisms at play and rheological inheritance. We show that the self-consistent generation of plate tectonics from mantle convection is altered by the use of a composite rheology (with co-existing diffusion and dislocation creep), by the consideration of mantle grain-size evolution, as well as by simple parameterisations of rheological memory such as strain-weakening. Using a set of quantitative diagnostics, we also demonstrate how such rheological complexities affect surface topography.

How to cite: Arnould, M., Manjón-Cabeza Córdoba, A., and Rolf, T.: Mantle controls on geodynamic processes and their surface expressions: a global approach, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6948, https://doi.org/10.5194/egusphere-egu23-6948, 2023.

The Zagros Mountains were formed in the Late Paleogene by the collision of the northern margin of the Arabian platform with the microplates of central Iran, after the closure of the Neotethys ocean. This fold-and-thrust belt extends in a NW-SE direction from eastern Turkey to the Makran subduction zone in southeastern Iran. The complex deformation of this collisional zone resulted in several parallel tectonic structures. From SW to NE, the Zagros belt can be divided into three elongated zones: the Zagros Fold and Thrust Belt (ZFTB), the Sanandaj–Sirjan Metamorphic Zone (SSZ), and the Urumieh–Dokhtar Magmatic Arc (UDMA). At NE, the ZFTB is bounded by an active thrust fault, the Main Zagros Thrust (MZT), which is considered a suture zone between the Arabian and Iranian plates.

In this study, conducted as part of the PRIN 2017 project, we analyze several types of recently acquired data, such as seismic tomography models of the crust and upper mantle, Moho depth, obtained from the inversion processes for Vs models [1], Curie point depth [2], derived from magnetic anomaly inversion, seismiciy distribution from the most updated seismic databse [3], and surface topography. Sharp lateral changes in velocities/temperatures occur at depths of ~100 km along the SSZ, where the crust reaches its greatest thickness (~60 km). These changes in deep structures are accompanied by a transition from high-frequency to smoother surface topography and an abrupt decrease in seismicity along the MZT. Velocity/temperature anomalies also allow identification of along-strike variations in the inclination of the subducting plate in the different sectors of the Zagros Collisional Zone: shallower in the northwest and steeper with possible slab detachment in the central part of the orogen. Looking at the transects perpendicular to the Zagros belt, the differences between the northwestern and central segments are also evident in the profiles of the surface topography and the distributions of the seismic events. We attribute these observations to the relamination process (i.e., the detachment of the Arabian crust from the subducting lithospheric mantle and its underthrusting beneath the crust of the overriding plate), which evolves to varying degrees along the Zagros belt, as it is controlled by the variable geometry of the subducting slab. To test this hypothesis, we use the numerical code I2VIS [4] to perform a series of numerical experiments that simulate the relamination process that occurs during the collisional phase, following subduction of an oceanic slab between two continents. We explore the influence of different convergence rates and slab dip angles on the final shape, viscosity structure, and topography of the orogen and compare the modelling outcomes with the available observations in the Zagros Collisional Zone. Finally, in order to verify the consistency of the results, the static gravity field of the modelled structures was forward modelled and compared with the present-day observed gravity.

References

[1] Kaviani et al., 2020. Geophys. J. Int., 221, 1349–1365, doi: 10.1093/gji/ggaa075.

[2] Li et al., 2019. Scientific Reports, 7:45129 DOI: 10.1038/srep45129.

[3] https://www.usgs.gov/programs/earthquake-hazards/national-earthquake-information-center-neic

[4] Gerya, T.V., 2019. Second edition. Book. Cambridge University Press. ISBN 978-0-521-88754-0.

How to cite: Tesauro, M., Maierova, P., Koptev, A., Pastrutti, A., Pivetta, T., Koulakov, I., and Braitenberg, C.: How did tectonics shape the Zagros Collisional Zone? Insights from data observations and numerical models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9427, https://doi.org/10.5194/egusphere-egu23-9427, 2023.

Deep (> 500 m below ground) geothermal energy is generated by heat sources within the Earth, including unusually high  lithospheric basal heat flow and/or intrusive bodies rich in radioactive isotopes, that heat the surrounding rocks and aquifers. This warm water can then be used for electricity production or to provide heat for buildings. These relatively high geothermal gradients can be found at depth in sedimentary basins where aquifers are surrounded by rocks with low thermal conductivity. Investigating the suitability of a basin for deep geothermal energy exploration requires, therefore, a thorough geological investigation of its spatially variable structure, stratigraphy and evolution. Low temperature thermochronology, namely apatite fission track and (U-Th-Sm)/He methods, are able to reconstruct the thermal structure of the shallow crust through time and, when data are available from boreholes, to quantify the evolution of the geothermal gradient, providing insights on the most promising areas where aquifers could be unusually warm.

We have applied low temperature thermochronology to the study of the Midland Valley (MV) Basin, an extensive sedimentary basin onshore Scotland, hosting many potential energy consumers in the cities of Glasgow and Edinburgh. The Midland Valley mainly consists of alternating succession of sandstone and siltstone with mudstone, limestone and coal, predominantly of Carboniferous and Devonian age. The MV also experienced folding and faulting throughout its geological history; therefore, the succession is spatially highly variable, difficult to reconstruct by simply using the sparse borehole-derived stratigraphic constraints. Apatite fission track data from across the eastern sector of the basin and the UK Geoenergy Observatories borehole in Glasgow indicate a 1) rapid burial in the Carboniferous-Permian; 2) Permian-Mesozoic cooling and a 3) a relatively rapid early Cenozoic cooling, an event that is asynchronous across the basin. Using a combination of forward and inverse modelling techniques, we constrain the palaeo-geothermal gradients and highlight areas where the thermal structure of the shallow crust could still be relatively hot for aquifer geothermal energy.

How to cite: Persano, C., Wildman, M., McKenna, E., Hattie, A., and Monaghan, A.: Low temperature thermochronology as an investigation tool for deep geothermal energy: insights from the Midland Valley sedimentary basin (Scotland)., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17462, https://doi.org/10.5194/egusphere-egu23-17462, 2023.

The Northern Apennines accretionary wedge has been extensively investigated by means of thermochronological studies to constrain its thermal history with respect to burial and exhumation. However, the Epiligurian wedge-top basins, which represent the shallowest portions of the orogenic wedge, have received less attention. These basins exhibit an internal complex structural architecture formed in response to the progressive growth of the Northern Apennines accretionary wedge during its progressive involvement in the fold-and-thrust belt. In this study, we combine a new structural characterisation of the Epiligurian stratigraphic succession with preliminary thermochronological data, with the aim to constrain the low-temperature thermal history of the Epiligurian system formation. We investigated the coarser arenaceous components of different middle Eocene to the upper Miocene Epiligurian formations (Loiano, Antognola, Pantano and Cigarello formations). We use both apatite fission-track (AFT) and (U-Th)/He (AHe) analyses. The majority of the AFT central ages cluster between 53 and 65 Ma (Paleocene-Lower Eocene). None of the samples passed the χ² test, indicating the presence of different population of grains. For all but one sample three to four detrital populations are characterised by the same range of ages, which varies from 140 to 41 Ma (Early Cretaceous-upper Eocene). The fact that these detrital populations are older than the depositional age of the hosting strata suggests minimal resetting of the AFT system and T generally lower than 120^°C post deposition. We interpret the AFT detrital populations consistent throughout the stratigraphic features as representative of cooling ages of the sediment source (alpine derivation source) that fed the Epiligurian basins. AHe ages show a more variable single grain age distribution ranging from 104 to 13 Ma (Late Cretaceous-middle Miocene) suggesting a significant degree of thermal resetting for the AHe system post deposition. AHe ages for the lowest part of the Epiligurian Units (Loiano and Antognola Fms) suggest a possible cooling/exhumation event of the basin at around 30-20 Ma. These preliminary results suggest that the Epiligurian basins experienced T ranging between >120 to 80°C post deposition. AFT data suggest rapid exhumation of the sediment source in the middle to late Eocene recorded by relatively short lag time of the youngest detrital population (~41 Ma). AHe data suggest subsequent Oligocene-Miocene exhumation consistent with deformation of the Northern Apennine.

How to cite: Stendardi, F., Viola, G., Carrapa, B., and Vignaroli, G.: Exhumation history of the Northern Apennines (Italy) recorded by low temperature thermochronology of Epiligurian wedge-top basins, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13209, https://doi.org/10.5194/egusphere-egu23-13209, 2023.

The Hellenides Fold and Thrust Belt (HFTB) is an arcuate shaped belt whose rocks were deposited in a series of platforms and basins that formed the southern rifted margin of the Apulian microcontinent. Despite a renew interest in the last years due to an international licensing round for the exploration and production of hydrocarbons in Greece, still little is published about its geometry, thermal maturity and hydrocarbon generation timing of the main source rocks hosted in the Mesozoic section. The External-most exposed part of the HFTB consists of the pre-Apulian and the Ionian geotectonic zones from West to East. Being part of the southern passive margin of Tethys from Triassic to Late Cretaceous, the Ionian zone represents a sedimentary basin which was differentiated from the adjacent platforms during the Jurassic rifting and consists of Triassic evaporites, Triassic-Eocene carbonates, and Oligocene-Early Miocene turbidites. The Pre-Apulian zone, as part of the slope of the Apulian platform to the Ionian basin, is made up of Triassic evaporites and up to Miocene carbonates. Organic rich layers are found across the Pre-Apulian and Ionian zones, and chiefly within Mesozoic. Present-day geometries have resulted from the mainly thin-skinned Miocene compressional deformation developed after the collision of the Apulian and Eurasian continental paleomargins. To understand the amount of overburden thickness across the chain, we performed Rock-Eval 6 pyrolysis, Gas Chromatography-Mass Spectrometry, MicroRaman spectroscopy and transmitted light petrography on Mesozoic-Cenozoic source rocks across an ENE-WSW transect in Western Greece where westward migrating intra-Ionian imbricate thrusts are evident. Overall, the data suggest that Cenozoic samples are immature, while Lower Cretaceous and Mid-Upper Jurassic thermal maturity reaches the onset of the oil window and further increases in Lower Jurassic and Triassic successions. Maturity data were used as input parameters to 1D thermal maturity modelling of wells and pseudo-wells across this transect. Model calibration by using present-day heat flow values and a Mesozoic rifting model, suggests that the eroded thickness at each studied location exceeds 1.5km. These erosion estimates better constrain our understanding of the geometry of the belt and the timing of maximum burial.

How to cite: Makri, V. I., Schito, A., Muirhead, D., Oikonomopoulos, I., and Bellas, S.: Preliminary results of a thermal maturity modelling study as a tool for understanding a structural setting – the case of the Fold and Thrust Belt of Western Greece., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-712, https://doi.org/10.5194/egusphere-egu23-712, 2023.

The Lower Cretaceous corresponds, in northwestern Europe, to a period of significant extension with the rifting of the Bay of Biscay and its eastern prolongation, the Parentis Basin. This basin has a long history of rifting and several important discontinuities between the uppermost Jurassic and the Albian (at the top of the Jurassic, top of the Barremian and at the Aptian-Albian boundary).

North of this basin i.e. the Aquitaine Platform, the sedimentation is very patchy, the few known Lower Cretaceous deposits suggest continental conditions during this period. Preliminary work carried out on some deep boreholes located on the Aquitaine platform reconstructed temperatures by thermochronology (apatite fission track on Triassic and Permian samples). The preliminary results show that these samples are not in equilibrium with the current sedimentary thickness taking into account a conventional geothermal gradient (35°/km). All these samples then show a significant cooling, from uppermost Jurassic to lower Cretaceous, consistent with a regional erosional event.

This preliminary work leads us to make two hypothesis:

-        The deposition of an upper Jurassic/lower Cretaceous sedimentary thickness that was then eroded from the Aptian. This hypothesis is in agreement with study carried out further east (French Massif Central) but not with the first order sedimentary outcropping characterization on the Aquitaine platform.

-        The high palaeotemperatures recorded are controlled by an increase in the geothermal gradient (a gradient of 50°/km must be considered) during the Upper Jurassic and Lower Cretaceous. This model does not consider the deposition and the erosion of a thick Cretaceous cover. This hypothesis is difficult to explain over such large area without significant crustal thinning.

These two-hypothesis lead to very different palaeogeographical situations and to very different vertical displacement. The answer to these questions is a key to understand the periods of karstification of the Jurassic carbonate platform and therefore to have a better knowledge of the water reservoir.

We presented in this work the results of an integrated study. The results are based on a combination of field study and the interpretation of subsurface data (boreholes and seismic). A wide range of methods has been applied to this dataset (sedimentology, sequence stratigraphy, well correlation, isotopic and geochemical analysis of carbonate, sand and clay, thermochronology, heavy mineral, U/Pb zircon, organic geochemistry).

How to cite: Ortiz, A., Husson, E., Barbarand, J., Lasseur, E., and Briais, J.: Understanding the thermal history of the North Aquitaine platform: implications on vertical motion and karstification, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1979, https://doi.org/10.5194/egusphere-egu23-1979, 2023.

Deciphering the tectono-thermal evolution of deformed foreland basins is fundamental for understanding the kinematics of mountain building processes. In orogenic systems, tectonic loading during early compressional stages produces the formation of foreland basins that, as compression progresses, are folded, exhumed and incorporated into the forming fold-and-thrust belts. These exhumed foreland basins represent excellent candidates for studying the early-orogenic burial conditions and geometries. The Jaca Basin, in the south-western Pyrenees, represents the primary south Pyrenean foreland basin that was latter deformed, piggy-back thrusted and embedded into the south Pyrenean fold-and-thrust belt. The basin displays a non-cylindrical geometry and it is filled by exceptionally preserved syn-orogenic sequences: early-middle Eocene turbidites that grade upwards to late Eocene marls and late Eocene-Oligocene and Miocene continental units. Debate exists on the timing of thrusting exhuming the basin, the geometry of basement thrusts and their link to syn-orogenic sedimentation and emerging cover structures. This debate sums up to the uncertainties on the basin thermal history, with previous paleo-thermal data being heterogeneously distributed and mostly concentrated in the eastern part of the basin.

To reduce these uncertainties and contribute into the understanding of debated kinematic aspects, we carried out a combined structural and paleo-thermal study covering the eastern and central part of the deformed Jaca basin. Four sequential, seismic-based cross sections have been constructed whereas thermal and burial conditions along section traces have been constrained through Raman Spectroscopy on Carbonaceous Material (RSCM). Samples for RSCM have been collected from the Eocene turbidites and indicate maximum burial temperatures of ~200ºC at the base of the sedimentary sequence (northern part of the cross-sections) that decrease progressively to the south where younger turbidites crop-out. In the considered area, RSCM temperature estimates along specific cover thrusts indicate a westward increase of peak temperatures. Along-strike thermal variations are in line with seismic-based cross-sections that depict strong lateral changes in the geometry of the basement soling the Jaca basin. The top of the basement is at shallower positions in the central Jaca basin where the number of basement thrusts increases. Basement thrusts partly derive from the reactivation of inherited Permian-Triassic extensional faults and partition the eastern-central Jaca basin into two structural domains separated by a main, oblique basement ramp. From cross-sections and thermal estimates, this contribution allows reconstructing the tectono-thermal history of the Jaca basin from the early foreland basin stages to the advanced shortening stages both along its central and eastern segments.

How to cite: Izquierdo Llavall, E., Calvín, P., Toro, R., Pueyo, E., Casas, A., Larrasoaña, J. C., Muñoz Ochando, I., Sierra, P., and Orera, A.: Burial and structural evolution of a deformed foreland basin: the south-western Pyrenees, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9217, https://doi.org/10.5194/egusphere-egu23-9217, 2023.

Geothermal energy capacity in Europe has doubled in the last decade and will grow more over the next ten years, according to the 2020’s market report of the European Geothermal Energy Council. This brings great potential for development in Europe as the global energy demand is turning to greener, more reliable, and non-intermittent options besides oil and gas. As of 2022, Italy is the second country in Europe with the biggest number of geothermal plants (installed, in development, or planned) with a capacity of more than 800 MWe, but this capacity almost didn't increase in the last decade with only small additions in capacity in the 2010-2020 period, according to the EGEC report. This data shows the great potential for geothermal energy development, and a thorough evaluation of new study areas in Italy with geothermal potential is necessary.

One of these potential areas is the Po Plain, in northern Italy; a complex geological area that represents the foreland basin of two opposite verging orogens: the Southern Alps and Northern Apennines. This region experienced E-W extensional events during the Mesozoic, leading to the formation of several carbonatic platforms divided by relatively deep carbonate basins, followed by a tectonic inversion since the Cenozoic that changed the regime to a N-S compressive setting which deposited a clastic sedimentary succession of up to 8 km in thickness, thus hiding the outer thrust fronts both from the Northern Apennines and the Southern Alps. Because of this complexity, several hydrocarbon provinces have been discovered associated mainly with oil and thermogenic gas. These discoveries have led to extensive amounts of thermal subsurface data, especially Bottom Hole Temperatures (BHT), Drill Stem Tests (DST), and extrapolated data from temperature maps at different depths that are mainly available from public databases like the Geothopica Project. Although obtained mainly for the oil and gas industry, these data have become very important for the exploration of geothermal reservoirs. For a reliable use of BHT data, they need to be corrected before any interpretation because they are usually obtained at the bottom of the borehole right after the perforation, leading to the change of the true formation temperature due to the cooling effect of the perforation mud.

We present here a basin-scale depth to the isotherm maps for the Po Plain subsurface obtained for 40°, 60°, 80° and 100°C based on the extensive database of BHT data from Geothopica integrated with other public thermal data. All the temperature values were corrected using the equations proposed in the scientific literature for the Po Plain. The isothermal maps provide a new large-scale baseline for the most common temperatures used for low-enthalpy geothermal energy applications. The temperature distribution analysis, both in a map and along the regional cross-section through the Po Plain, allows preliminary considerations about how the heat flow is transferred and distributed in the Plio-Pleistocene deposits compared with deep carbonate structures.

How to cite: Barrera, D., Toscani, G., Amadori, C., Meda, M., Catellani, D., Gorla, M., and Di Giulio, A.: Thermal state of the Po Plain subsurface: a first overview, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13895, https://doi.org/10.5194/egusphere-egu23-13895, 2023.

The Rif belt (Northern Morocco) represents the western termination of the Maghrebides system. It is subdivided into three tectono-stratigraphic domains known as: Internal domain (i.e., Alboran domain), the Maghrebian flysch domain (i.e., the sedimentary cover of the Maghrebian Tethys) and the external domain (i.e., north African passive paleo-margin and its sedimentary infill. The Rif fold-and-thrust belt derives from the deformation of the North African passive Paleo-margin and its sedimentary infill since the onset of Africa-Eurasia convergence. The compressional setting led to the progressive closure of the Maghrebian Tethys and westward translation of the Alboran Domain and its docking onto the Northwest African rifted margin during the Late Burdigalian. However, field structural survey revealed the presence of an important Paleogene unconformity in the External domain, attesting for a deformation older than the Miocene Alpine compression.

Thus, to unravel the Cenozoic history of the Rif fold-and-thrust belt and its burial paths, a regional transect NE-SW-oriented crossing the Rif fold-and-thrust belt is studied. The methodological approach consists in combining organic petrography, micro-Raman spectroscopy on organic matter, clay mineralogy and 1D thermal modelling, together with field structural data.

A new paleo-thermal data set of vitrinite reflectance (Ro%), Raman micro-spectroscopy and %I in I/S mixed layers has been provided. The obtained results show a thermal jump between the Miocene deposits in the Mesorif (External Domain) and their Eocene substratum. In order to fit the paleo-thermal data, the thermal modelling indicates the erosion of about 1300-1900 m of sedimentary and/or tectonic pile before the deposition of Lower Miocene siliciclastic. The obtained results have been used to highlight a disregarded tectonic event affecting the north African paleo-margin and how it is influencing the Miocene orogenic processes.

How to cite: Atouabat, A., Schito, A., Leprêtre, R., Mohn, G., and Corrado, S.: Paleogene-Neogene evolution of the central-western Rif fold-and-thrust belt (Northern Morocco) by means of thermal modeling, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17511, https://doi.org/10.5194/egusphere-egu23-17511, 2023.