Showing papers on "Pull apart basin published in 2023"

Extensional tectonics, structural architecture modeling and geodynamic evolution in the Cretaceous Tinghir-Errachidia-Boudenib basin (pre-African trough, Morocco)

Abstract: Structural evolution of the Cretaceous Tinghir-Errachidia-Boudenib foreland basin in the south front of the Moroccan High Atlas belt is documented here. Fieldwork, lithostratigraphic and new structural analysis coupled with borehole and geoelectrical data identify two ENE-to NE-trending sub-basins in the large Cretaceous Tinghir-Errachidia-Boudenib (TEB) basin. One named Errachidia sub-basin is situated in the west and the other Boudenib sub-basin is located in the east. They are separated by a major NE-SW trending anticlinal, inherited from a paleohigh structure, where the thickening of the Cretaceous series increases towards the center of the sub-basins and in their northern borders with the central-eastern High Atlas. The Cretaceous series clearly show a considerable thickness variation, angular unconformities and lateral facies change that was related to the syn-sedimentary normal faulting activity. The Albian-Turonian period is characterized by the development of ENE- and NW-trending fault systems. These latter are linked to an extensional tectonics event responsible for half-graben basin geometry associated with significant sedimentary rates. This considerable thickness depocenters geometry is related to normal fault coupled with the intra-basin faults. The intensity of subsidence increases from south to north and from west to east, with a high rate in the Boudenib sub-Basin. The compressive Cenozoic events caused the inversion of these extensional faulting and the folding of the High Atlas area with ENE-trending structures.

Inversion of extensional basins parallel and oblique to their boundaries: inferences from analogue models and field observations from the Dolomites Indenter, European eastern Southern Alps

Abstract: Abstract. Polyphase deformation of continental crust is analysed through physical analogue models for settings wherein platform–basin geometries at passive continental margins are subject to subsequent shortening and orogenesis. In a first stage, segmentation of the brittle and brittle–ductile models into basins and platforms is achieved by extension. Basins are partly filled with brittle material to allow for a strength difference between basin and platform realms, simulating relatively weaker, incompetent deposits of grabens surrounded by competent pre-rift basement or carbonate platform rock, respectively. In a second stage of deformation, contraction parallel and oblique (10 to 20∘) to the basin axes has been applied, leading to the inversion of basins formed earlier. The experiments show that strength contrasts across platform–basin transitions control the localisation and overall style of compressional deformation, irrespective of the nature of the basal décollement (frictional versus viscous), the rheology of the basin fill, or changing platform–basin thickness ratios. Orientations of thrust faults change laterally across inherited platform–basin transitions throughout all experiments; higher obliquity of basin inversion leads to stronger alignment of thrust curvature with the orientation of pre-existing rift axes. At individual thrust faults, variations in the strike of thrust fronts are accompanied by changes in the shortening direction during incremental phases of deformation. Reactivation of normal faults occurs in oblique basin inversion settings only, favourably at platform–basin transitions where the normal faults face the shortening direction. The amount and style of fault reactivation depend on the material used. Our experiments are relevant for natural cases such as the Dolomites Indenter of the eastern Southern Alps, underlining the importance of inherited geologic features for the subsequent shortening geometries. Field structural data from the western segment of the Belluno thrust of the Valsugana fault system support predicted variations of thrust fault orientation and a lateral change in shortening direction (from SSW to SSE along-strike) along one single fault. Based on our modelling results, we suggest that this variability of thrust fault orientation and shortening directions, controlled by inherited structures, is consistent with strain partitioning during a single phase of deformation and does not necessarily reflect different deformation phases.

Geological interpretation of the offshore sedimentary basin of north central java based on spectral analysis and 2d gravity modeling

Abstract: The offshore sedimentary basin of North Central Java is a marine basin located in the northern part of North Serayu Basin. This basin was formed through the uplift of the southern part of Central Java (Bumiayu) caused by the movement of a pair of horizontal faults. Studies of sub-basin delineation and basement configuration are rarely carried out in this basin. Therefore, the gravity method referring to subsurface-density variations was carried out to obtain this information. This research aims to delineate sedimentary basins and interpret the geological subsurface based on gravity data using spectral analysis, highpass and lowpass filters, also 2D gravity modeling. An average estimation depth to the basement in the study area of about 2.22 km was determined using spectral analysis. Qualitative analysis shows the basement-high pattern, sub-basin, and structure lineament patterns. The 2D model shows three layers consisting of the upper sedimentary layer of Tertiary-Neogene and the middle layer of Tertiary-Paleogene sediment with a density value of 2.3 gr/cc and 2.5 gr/cc, respectively. The lower layer has the highest density of 2.67 gr/cc, assumed as a granitic basement. The results of the Second Vertical Derivative (SVD) analysis on the residual anomaly cross-sectional paths indicate the presence of thrust and normal faults which can be used to assist the interpretation of fault structures in subsurface geological models. Gravity analysis of the offshore North Central Java sedimentary basin indicates the occurrence of sub-basins and geological structure patterns that considered as a potential zone for the development of the petroleum system in this area.

Basin Structure for Earthquake Ground Motion Estimates in Urban Los Angeles Mapped with Nodal Receiver Functions

Abstract: Basin structures in the northern Los Angeles area have been identified from a nodal seismic array along 10 lines across three basins. The dense array of 758 geophones spaced at 250-300 m apart along the lines and recorded seismic response for 30-35 days. For basin structure investigation, the teleseismic receiver functions technique was used. The primary basin concerted phases were identified from the receiver functions. A shear wave velocity model produced in a separate study using the same dataset was incorporated to convert the basin time arrivals into depth. The deepest part of the San Bernardino basin was identified near Loma Linda fault at 2.8 km. San Gabriel basin exhibit larger basin depths and Ps arrival times of all with a maximum depth of 4 km. The high lateral resolution from the dense array helped revealing more continuous structures and reducing uncertainties in the RFs. We discovered a more complex basin structure than previously identified. Our findings show the basins’ core areas are not the deepest. Significant changes in basin depth were observed near some faults i.e. Rialto-Colton fault, Fontana fault, Red Hill fault and Raymond fault. Plain Language Summary Sedimentary basins can contribute to the damage caused by any earthquake. The seismic waves from an earthquake can get trapped and amplified within the basin which may result in a stronger ground shaking with longer duration. The three basins of our study area, San Bernardino, Chino and San Gabriel, are located in a seismically active region. The BASIN (Basin Amplification Seismic INvestigation) project aims to image the subsurface so that the seismic wave response within the basins for any earthquake can be assessed. As part of this project, we identified sedimentary basin shape and depth underneath this region. The P wave from an earthquake generates P to S conversions at boundaries. We used receiver functions to determine basin boundaries from those conversions. Arrival times of the P to S conversions were converted to depth using a velocity model.

Selective inversion of rift basins in lithospheric-scale analogue experiments

Abstract: Abstract. Basin inversion is commonly attributed to the reverse reactivation of normal basin-bounding faults. This association implies that basin uplift and inversion-related structures are mainly controlled by the frictional behaviour of pre-existing faults and associated damage zones. In this study, we use lithospheric-scale analogue experiments of orthogonal extension followed by shortening to explore how the flow behaviour of ductile layers underneath rift basins promote or suppress basin inversion. Our experiments show that the rheology of the ductile lower crust and lithospheric mantle, modulated by the imposed bulk strain rate, determine: (1) basin distribution in a wide rift setting and (2) strain accommodation by fault reactivation and basin uplift during subsequent shortening. When the ductile layers deformed uniformly during extension (i.e., stretching) and shortening (i.e., thickening), all of the basins were inverted. When viscous deformation was localised during extension (i.e., necking) and shortening (i.e., folding), only some basins – which were evenly spaced apart – were inverted. We interpret this selective basin inversion to be related to the superposition of crustal-scale and lithospheric-scale boudinage during the previous basin-forming extensional phase.

Transverse faults in the thrust belt-backarc hinge zone (Eastern Tyrrhenian Sea Margin, Italy)

Abstract: Stratigraphy and architecture of the fault bounding the sedimentary basins developed along the Eastern Tyrrhenian margin provide information on the kinematic of faults transversal to the Apennine chain. To understand how changes in geodynamic processes control the structural evolution of transverse faults in the thrust belt-backarc hinge zone, we performed the interpretation of a 2D strictly spaced seismic data set, tied to stratigraphic data of exploration wells and onshore data constrains, and a 3D basin analysis.On the basis of geometry and age of the basin infill, we dated three events of fault activity and a complex kinematics of Pliocene-Quaternary transverse faults. The first tectonic phase produced the oldest normal faults developed along the Latium margin. These faults, active between 5.1 and 3.2 Ma (MPL2-MPL3 and MPL4 succession), bound sedimentary basins filled by a Transgressive/Regressive succession made up of sands, silts and clays. They gradually migrated from the NE- trending (transversal to the Apennine chain), Pliocene in age, toward the NW-trending (parallel to the Apennine chain) during the Lower Pleistocene (1.8 MA, MPL6 succession). The displacement along these normal faults was transferred, or relayed, from one to the next one along accommodation zones, corresponding to transfer faults. Accommodation zones along major bounding structures are sites of intra-basinal highs, characterized by thinner sedimentary covers. The transfer faults, orthogonal to the normal faults, offset the basin depocenters. Whereas a positive inversion structure located near a transfer fault deforms the central basin rift. During the Lower Pleistocene the transform faults are transversal to the Apennines chain. These latter developed from the Latium margin to the Campania Margin.The third phase of the development of the transverse faults corresponds to a second episode of rifting of the Eastern Tyrrhenian margin. This event is linked to the activity of NE-trending normal faults, during the Middle Pleistocene since the 0.7 Ma, producing half-grabens and a deepening of the basement in the northwestern part of the Campania Plain and in Naples Bay. The stratigraphic succession architecture records the tilting of the fault block. During the middle Pleistocene along the Campania margin the transverse faults were reactivated as normal faults.The great variability in the tectonic evolution of the Tyrrhenian margin has been interpreted as strictly related to the complex and rapid geodynamic evolution of the area during Pliocene-Quaternary times: Pliocene slab retreat of the Adria plate, followed by Pleistocene growth of a Subduction-Transform-Edge-Propagator (STEP) fault along the northern margin of the Ionian slab.

Existence and Distribution of Basin-Wide Strike Slip Fault Systems in an Asymmetrical Back Arc Rift System: The Black Sea Basin

Abstract: The Black Sea Basin has been a focus of interest due to its economically promising hydrocarbon reserves and complex tectonic history. Several different theories were proposed to decipher its enigmatic basin formation and tectonic evolution processes.One important characteristic of the Black Sea Basin that makes it unique is its isolation from the world oceans, and global sea level changes for long periods during the geological time. This provides a good realm to correlate tectonic episodes with rapid sedimentation patterns in its thick sedimentary section. With the aim of modelling this sequence of events, we reviewed and reinterpreted previously proposed scenarios. We focus on the back-arc rifting and subsequent tectonic inversion that led the surrounding mountain belts to form. By reinterpreting 24 long-offset 2D seismic lines acquired by GWL in 2011, we propose a new structural framework for the Black Sea Basin.Our structural geology analyses show that in addition to basin-bounding normal faults and inversion tectonics, numerous flower structures occur in both the western and eastern Black Sea subbasins. These flower structures are typical indicators of strike-slip fault systems and in the Black sea Basin case, the orientation of these fault systems is roughly east-west. Our interpretations align with the hinge model that Stephenson and Schellart (Geological Society London Special Publications, 2010) proposed to explain the opening of the Black Sea Basin as one basin rather than the conventional interpretation of a two separate rifted basin configuration. The proposed tectonic framework sheds light on the geometry of the Black Sea Basin’s bounding faults, complex faulting and folding recognized in the sedimentary section, and complex ridge-depression geometry.

Comment on egusphere-2022-1530

Abstract: Abstract. Polyphase deformation of continental crust is analysed through physical analogue models for settings where platform-basin geometries at passive continental margins are subject to subsequent shortening and orogenesis. In a first stage, segmentation of the brittle and brittle-ductile models into basins and platforms is achieved by extension. Basins are partly filled with brittle material to allow for a strength differences between basin and platform realms, simulating relatively weaker, incompetent deposits of grabens surrounded by competent pre-rift basement or carbonate platform rock, respectively. In a second stage of deformation, contraction parallel to oblique (10 to 20 degrees) with respect to the basin axes has been applied leading to the inversion of earlier formed basins. The experiments show that the simple presence of an inherited platform-basin configuration controls the overall style of compressional deformation, no matter of including frictional or viscous basal décollements, of varying the rheology of the basin fill, or of changing platform-basin thickness ratios. Orientations of thrust faults change laterally across inherited platform-basin transitions throughout all experiments; higher obliquity of basin inversion leading to stronger curvature of thrusts with respect to the pre-existing rift axes. Variations in the strike of thrust fronts are accompanied by changes of the shortening direction along one single fault and time step. Furthermore, our models support localisation of deformation in areas of lateral strength contrasts, as platform-basin transitions represent. Reactivation of normal faults occurs in oblique basin inversion settings only, favourably at platform-basin transitions where the normal faults face the shortening direction. The amount and style of fault reactivation depend on the material used. Both parallel and oblique inversion experiments can be applied to polyphase deformed continental crust, as, e.g., the Dolomites Indenter of the eastern Southern Alps. Our models involving two phases of deformation, suggest that the whole tectonic evolution of the Dolomites Indenter is controlled by inherited features. Fault slip data and shortening directions from fold axes from our field case study along the western segment of the Belluno thrust of the Valsugana fault system support variations of thrust fault orientation and a lateral change in shortening direction (from SSW to SSE along strike) along one single fault. Based on our modelling results, we infer that this variability of shortening directions depends on inherited structures and do not necessarily reflect different deformation phases.

Analysis of a Pull-Apart Basin and Its Associated Fractures in the Woodford Shale, Central Oklahoma

Abstract: Pull-apart basins are faulting and folding zones with high intensity of fractures that strongly affect the production in unconventional shale gas. While most observations of pull-apart basins were from surface mapping or laboratory experiments, we investigated a nascent pull-apart basin in the subsurface. We characterized a nascent pull-apart basin along the strike-slip fault within the Woodford Shale by using seismic attributes analyses, including coherence, dip-azimuth, and curvature. The results indicate a 32 km long, N-S striking strike-slip fault that displays a distinct but young pull-apart basin, which is ~1.6 km by 3.2 km in size and is bounded by two quasi-circular faults. The curvature attribute map reveals two quasi-circular folds, which depart from the main strike-slip fault at ~25°, resulting in an elliptical basin. Inside the basin, a series of echelon quasi-circular normal faults step into the bottom of the basin with ~80 m of total subsidence. We propose that the controls of the shape of pull-apart basin are the brittleness of the shale, and we suggest proper seismic attributes as a useful tool for investigating high fracture intensity in the subsurface for hydrofracturing and horizontal drilling within the shale.

Tectonic dynamics of the Zhongjiannan Basin in the western South China Sea since the late Miocene

Abstract: The Zhongjiannan Basin is located west of the South China Sea (SCS) and was affected by the left-lateral strike-slip of the Red River Fault (RRF), the West Edge Fault of the South China Sea (WEFSCS) and the continental rifting of the South China Sea in the early Cenozoic. The Zhongjiannan Basin formed in a strike-pull basin with an S‒N distribution. During the middle Miocene, the sea spreading of the SCS stopped, but the dynamic mechanism of the Zhongjiannan Basin, which controlled the sedimentary and the structural evolution after the late Miocene, remains unclear. In this paper, through the segment interpretation of the latest seismic section in the Zhongjiannan Basin, we conduct a comparative study of the sedimentary structure in the southern and northern Zhongjiannan Basin since the late Miocene. Combined with the regional tectonic dynamics analysis, we propose that the sedimentary and structural evolution of the Zhongjiannan Basin since the late Miocene was mainly controlled by residual magmatic activity in the Southwest Subbasin (SWSB) after expansion stopped, and the compressional structure stress field weakened gradually from south to north. The compressional tectonic stress field from north to south was formed in the northern basin under the dextral strike-slip movement of the RRF. The sedimentary and structural environment was relatively stable in the middle basin. Therefore, the sedimentary-structure evolution of the Zhongjiannan Basin since the late Miocene was controlled by the two different structural stress fields. The above knowledge not only has guiding significance for oil and gas exploration in the Zhongjiannan Basin but also provides a reference for studying the initiation time of dextral strike-slip along the Red River Fault Zone, as well as the junction position between the RRF and the WEFSCS.

Reply on RC2

Abstract: Abstract. Polyphase deformation of continental crust is analysed through physical analogue models for settings where platform-basin geometries at passive continental margins are subject to subsequent shortening and orogenesis. In a first stage, segmentation of the brittle and brittle-ductile models into basins and platforms is achieved by extension. Basins are partly filled with brittle material to allow for a strength differences between basin and platform realms, simulating relatively weaker, incompetent deposits of grabens surrounded by competent pre-rift basement or carbonate platform rock, respectively. In a second stage of deformation, contraction parallel to oblique (10 to 20 degrees) with respect to the basin axes has been applied leading to the inversion of earlier formed basins. The experiments show that the simple presence of an inherited platform-basin configuration controls the overall style of compressional deformation, no matter of including frictional or viscous basal décollements, of varying the rheology of the basin fill, or of changing platform-basin thickness ratios. Orientations of thrust faults change laterally across inherited platform-basin transitions throughout all experiments; higher obliquity of basin inversion leading to stronger curvature of thrusts with respect to the pre-existing rift axes. Variations in the strike of thrust fronts are accompanied by changes of the shortening direction along one single fault and time step. Furthermore, our models support localisation of deformation in areas of lateral strength contrasts, as platform-basin transitions represent. Reactivation of normal faults occurs in oblique basin inversion settings only, favourably at platform-basin transitions where the normal faults face the shortening direction. The amount and style of fault reactivation depend on the material used. Both parallel and oblique inversion experiments can be applied to polyphase deformed continental crust, as, e.g., the Dolomites Indenter of the eastern Southern Alps. Our models involving two phases of deformation, suggest that the whole tectonic evolution of the Dolomites Indenter is controlled by inherited features. Fault slip data and shortening directions from fold axes from our field case study along the western segment of the Belluno thrust of the Valsugana fault system support variations of thrust fault orientation and a lateral change in shortening direction (from SSW to SSE along strike) along one single fault. Based on our modelling results, we infer that this variability of shortening directions depends on inherited structures and do not necessarily reflect different deformation phases.

Reply on RC1

Abstract: Abstract. Polyphase deformation of continental crust is analysed through physical analogue models for settings where platform-basin geometries at passive continental margins are subject to subsequent shortening and orogenesis. In a first stage, segmentation of the brittle and brittle-ductile models into basins and platforms is achieved by extension. Basins are partly filled with brittle material to allow for a strength differences between basin and platform realms, simulating relatively weaker, incompetent deposits of grabens surrounded by competent pre-rift basement or carbonate platform rock, respectively. In a second stage of deformation, contraction parallel to oblique (10 to 20 degrees) with respect to the basin axes has been applied leading to the inversion of earlier formed basins. The experiments show that the simple presence of an inherited platform-basin configuration controls the overall style of compressional deformation, no matter of including frictional or viscous basal décollements, of varying the rheology of the basin fill, or of changing platform-basin thickness ratios. Orientations of thrust faults change laterally across inherited platform-basin transitions throughout all experiments; higher obliquity of basin inversion leading to stronger curvature of thrusts with respect to the pre-existing rift axes. Variations in the strike of thrust fronts are accompanied by changes of the shortening direction along one single fault and time step. Furthermore, our models support localisation of deformation in areas of lateral strength contrasts, as platform-basin transitions represent. Reactivation of normal faults occurs in oblique basin inversion settings only, favourably at platform-basin transitions where the normal faults face the shortening direction. The amount and style of fault reactivation depend on the material used. Both parallel and oblique inversion experiments can be applied to polyphase deformed continental crust, as, e.g., the Dolomites Indenter of the eastern Southern Alps. Our models involving two phases of deformation, suggest that the whole tectonic evolution of the Dolomites Indenter is controlled by inherited features. Fault slip data and shortening directions from fold axes from our field case study along the western segment of the Belluno thrust of the Valsugana fault system support variations of thrust fault orientation and a lateral change in shortening direction (from SSW to SSE along strike) along one single fault. Based on our modelling results, we infer that this variability of shortening directions depends on inherited structures and do not necessarily reflect different deformation phases.

Inversion of extensional basins parallel and oblique to their boundaries: Inferences from analogue models and field observations from the Dolomites Indenter, eastern Southern Alps

Abstract: Abstract. Polyphase deformation of continental crust is analysed through physical analogue models for settings where platform-basin geometries at passive continental margins are subject to subsequent shortening and orogenesis. In a first stage, segmentation of the brittle and brittle-ductile models into basins and platforms is achieved by extension. Basins are partly filled with brittle material to allow for a strength differences between basin and platform realms, simulating relatively weaker, incompetent deposits of grabens surrounded by competent pre-rift basement or carbonate platform rock, respectively. In a second stage of deformation, contraction parallel to oblique (10 to 20 degrees) with respect to the basin axes has been applied leading to the inversion of earlier formed basins. The experiments show that the simple presence of an inherited platform-basin configuration controls the overall style of compressional deformation, no matter of including frictional or viscous basal décollements, of varying the rheology of the basin fill, or of changing platform-basin thickness ratios. Orientations of thrust faults change laterally across inherited platform-basin transitions throughout all experiments; higher obliquity of basin inversion leading to stronger curvature of thrusts with respect to the pre-existing rift axes. Variations in the strike of thrust fronts are accompanied by changes of the shortening direction along one single fault and time step. Furthermore, our models support localisation of deformation in areas of lateral strength contrasts, as platform-basin transitions represent. Reactivation of normal faults occurs in oblique basin inversion settings only, favourably at platform-basin transitions where the normal faults face the shortening direction. The amount and style of fault reactivation depend on the material used. Both parallel and oblique inversion experiments can be applied to polyphase deformed continental crust, as, e.g., the Dolomites Indenter of the eastern Southern Alps. Our models involving two phases of deformation, suggest that the whole tectonic evolution of the Dolomites Indenter is controlled by inherited features. Fault slip data and shortening directions from fold axes from our field case study along the western segment of the Belluno thrust of the Valsugana fault system support variations of thrust fault orientation and a lateral change in shortening direction (from SSW to SSE along strike) along one single fault. Based on our modelling results, we infer that this variability of shortening directions depends on inherited structures and do not necessarily reflect different deformation phases.