Development and dolomitization of Anisian isolated carbonate platforms in the Transdanubian Range, Hungary

In the Middle Anisian, extensional tectonic movements led to the development of isolated carbonate platforms in the area of the southwestern part of the Transdanubian Range. The platforms are made up of meter-scale peritidal–lagoonal cycles bounded by subaerial exposure surfaces. One of the platform successions (Tagyon Platform) consists predominantly of limestone that contains partially and completely dolomitized intervals, whereas the other one (Kádárta Platform) is completely dolomitized. Drowning of the platforms took place in the latest Pelsonian to the early Illyrian interval when submarine highs came into existence and then condensed pelagic carbonate successions with volcanic tuff interbeds were deposited on the top of the drowned platforms from the late Illyrian up to the late Ladinian. The comparative study of dolomitization of the coeval platforms, affected by different diagenetic histories, is discussed in the current paper. Traces of probably microbially-mediated early dolomitization were preserved in the slightly dolomitized successions of the Tagyon Platform. This might also have been present in the successions of the Kádárta Platform, but was overprinted by geothermal dolomitization along the basinward platform margin and by pervasive reflux dolomitization in the internal parts of the platform. The Carnian evolution of the two submarine highs was different, and this may have significantly influenced the grade of the shallow to deeper burial dolomitization.

A Normal Faults System in the Monte Nerone area and its significance in the recent seismo-tectonic setting of the Northern Umbria-Marche Apennines (Italy)

The faults system mapped in the northern Marche Apennines, the NW sector of Monte Nerone, Italy, shows many indications of recent activity. This area has been affected by some strong historical earthquakes, such as the Cagli earthquake of 1781, similar to seismic events close by affecting the southern Marche, Umbria, Lazio, and Abruzzi areas in recent years, we focused our investigation on this sector. The original field mapping work integrated with seismic and subsurface data suggests very similar genesis and kinematics to those of the recent seismic events in the south of Marche region. In addition, this interpretation could also attest the extensional tectonic activity affecting the whole Adriatic side of the watershed backbone of this sector of the Apennines, with probable inversion of involved previous compressional features, such as thrust ramps.

Timing of magmatism of the Ditrău Alkaline Massif, Romania – A review based on new U–Pb and K/Ar data

The timing of Triassic magmatism of the Ditrău Alkaline Massif (Eastern Carpathians, Romania) is important for constraining the tectonic framework and emplacement context of this igneous suite during the closure of Paleotethys and coeval continental rifting, as well as formation of back-arc basins.Our latest geochronological data refine the previously reported ages ranging between 237.4 ± 9.1 and 81.3 ± 3.1 Ma. New K/Ar and U–Pb age data combined with all recently (post-1990) published ages indicate a relatively short magmatic span (between 238.6 ± 8.9 Ma and 225.3 ± 2.7 Ma; adding that the most relevant U–Pb ages scatter around ∼230 Ma) of the Ditrău Alkaline Massif. The age data complemented by corresponding palinspastic reconstructions shed light on the paleogeographic environment wherein the investigated igneous suite was formed.The magmatism of the Ditrău Alkaline Massif could be associated with an intra-plate, rift-related extensional tectonic setting at the southwestern margin of the East European Craton during the Middle–Late Triassic (Ladinian–Norian) period.

SUBSURFACE STRUCTURE OF BATURAGUNG ESCARPMENT REVEALED THROUGH THREE-DIMENSIONAL GRAVITY INVERSION

Baturagung Escarpment is an essential tectonic element of Java Island because it represents a transition from the Southern Mountain Block to the Kendeng Basin. This study has succeeded in producing a three-dimensional model of the Baturagung Escarpment subsurface using gravity anomaly data. The data are distributed along a regional scale transect, whose resolving capability has been tested using a checkerboard test. Our proposed geophysical model can fit the observed data very well, with a 0.77% RMS error. This model exhibits a structural depression bounded by high basement blocks below the Baturagung Escarpment, one of the basement block outcrops at Jiwo Hills. The maximum width of the depression is 10 km, with a depth exceeding 3 km in some places. The depression might be formed because of an extensional tectonic regime that prevailed during the Palaeogene, followed by volcanic arc loads' emplacement up to the early Miocene.

Timan-Pechora Composite Tectono-Sedimentary Element

Timan-Pechora Composite Tectono-Sedimentary Element represents a significant part of the Timan-Pechora petroleum province, which is the second largest in the Circum-Arctic. It contains as much as up to 10 km of Paleozoic and Mesozoic strata hosting world-class hydrocarbon source rock, the Domanik Formation, and a variety of hydrocarbon plays prolific for both, oil and natural gas. Complex tectonic structure of the composite tectono-sedimentary element formed as result of several tectonic phases: two extensional events, post-rift thermal sag in a passive margin setting, and a series of late Paleozoic and early Mesozoic compressional events. The latter modified the extensional fabric and led to the formation of a number of inverted swells and smaller anticlinal structures providing the major trapping capacities. The deposition of source and reservoir facies occurred during the extensional tectonic phases, while the main reservoir-prone sedimentary units were deposited during late Paleozoic and early Mesozoic orogenic phases.

The first result of geodetic implications on intra-graben subsidence along the eastern part of the Gediz graben

<p>The Western Anatolian extensional tectonic regime results in developing a set of approximately E-W trending Horst-Graben morphology. The Gediz graben accommodating many fertile lands is one of the significant tectonic structures associated with that regime. Intensive grape cultivation requiring irrigation has been conducted in these lands for many years, which causes a permanent decrease in the water budget as a consequence of increasing farming activities. Hence, we have aimed to clarify better spatial subsidence of the eastern part of the Gediz graben and performed at first InSAR data to obtain land-surface deformations. Towards the middle of graben, the line-of-sight deformation rates of InSAR from LiCSAR products reach gradually up to nearly 10 cm/yr. To confirm these rates, we monumented four continuous GNSS stations.  One of which was located out of the graben while the rest were at the graben in June 2020. Analysis of such a short time-series does not make sense; however, the vertical displacements for the closest stations to the center of the graben reach up to about 8 cm. while out of the graben station seems to be stable visually. It is worth stating that the givens are biased due most likely to the periodic signals. Consequently, the gradually increasing subsidence rates towards the graben center showed that have not been driven only by tectonic settlements but could also be driven by other phenomena. These results are the first results of the ongoing project no 119Y180 supported by TUBITAK.</p><p><strong>Keywords:</strong> Land subsidence, GPS, InSAR, Gediz Graben</p>

Strain Analysis of Transfer Faults in Extending Regions: Inferences from Micropolar Theory

<p>Transfer faults are generally identified as transversely oriented discrete faults linking normal fault segments in extensional tectonic settings.  The presence of the transfer faults in fault networks provides displacement transfer between the normal faults. The role and tectonic significance of transfer faults in overall extensional deformation of the upper crust is however not known very well. Micropolar theory extended by J-2 plasticity facilitates evaluation of a deforming medium in which cataclastic flow takes place with respect to each component of deformation. In this study, a series of experiments based on the Micropolar theory are performed, using fault-slip patterns, to better understand interplay among dip angle of normal and transfer faults connecting to each other, angle of linkage, and extensional direction. Synthetic linkage cases are created systematically considering various orientation of both faults sharing common stretching direction.<br>Our findings reveal that in orthogonal and oblique linkage cases, 3D strain field is mostly observed; a few cases exhibit plane strain. All cases are subjected to simple shearing. In cases of orthogonal linkage, extensional direction is predominantly oblique to the strike of the normal faults. Many of these cases have no block rotation (microrotation) independent from macrorotation. No particular relationship between changing dip amount of faults and direction of extension is observed. In cases of oblique linkage, (sub)orthogonal direction of extension appear in nearly half of experiments, especially those including normal faults dipping less than 60˚. The frequency of non-zero microrotation is seen apparently more than that in orthogonal linkage cases.<br>The study represents that structural togetherness of the transfer and normal faults essentially can accommodate complete micropolar strain in a region. This further suggests that not only the normal faults but the transfer faults should also be considered as major primary structural elements in extending domains.</p>

Mantle flow and orography: the effect of basal lithospheric shearing and lateral erosion gradients on continental rifting

<p><span>Mantle plume-lithosphere interactions modulated by surface processes across extensional tectonic settings give rise to outstanding topographies and sedimentary basins. However, the nature of these interactions and the mechanisms through which they control the evolution of continental rifts are still elusive. Basal lithospheric shearing due to plume-related mantle flow leads to extensional lithospheric rupturing and associated magmatism, rock exhumation, and topographic uplift away from the plume axis by a distance inversely proportional to the lithospheric elastic thickness. When moisturized air encounters a topographic barrier, it rises, decompresses, and saturates, leading to enhanced erosion on the windward side of the uplifted terrain. Orographic precipitation and asymmetric erosional unloading facilitate strain localization and lithospheric rupturing on the wetter and more eroded side of an extensional system. This simple model is validated against petro-thermo-mechanical numerical experiments where a rheologically stratified lithosphere above a mantle plume is subject to fluvial erosion proportional to stream power during extension. These findings are consistent with Eocene mantle upwelling and flood basalts in Ethiopia synchronous with distal initiation of lithospheric stretching in the Red Sea and Gulf of Aden as well as asymmetric topography and slip along extensional structures where orography sets an erosional gradient in the Main Ethiopian Rift (MER). I conclude that, although inherently related to the lithosphere rheology, the evolution of continental rifts is even more seriously conditioned by the mantle and surface dynamics than previously thoughts.</span></p>