Juan I . Soto | The University of Texas at Austin (original) (raw)
Papers by Juan I . Soto
From swath bathymetry data and high-resolution acoustic profiles (TOPAS) several slides have been... more From swath bathymetry data and high-resolution acoustic profiles (TOPAS) several slides have been imaged in the Alboran Ridge in the western Mediterranean. This submarine relief is the most prominent morphological feature (> 130 km in length) in the Alboran Sea and its elongated SW-NE shape results is enhanced from the recent convergence between the African and Eurasian plates. The identified gravitational deposits show transparent and chaotic facies, and appear in depths ranging between 640 and 1810 m. Occurrence of slides deposits along fault escarpments affecting the seafloor reveals that submarine instability processes are mainly controlled by tectonics. Mass-transport deposits are generally composed by several overhead lobes of sediments. These observations suggest collectively that instability processes are frequent and may be related with faulting pulses. Instability processes represent therefore a geological risk in the region that should be surveyed and analyzed in the f...
Authorea (Authorea), Jun 23, 2023
El terremoto principal de la serie sísmica tuvo lugar el 25 de enero de 2016, con una magitud Mw ... more El terremoto principal de la serie sísmica tuvo lugar el 25 de enero de 2016, con una magitud Mw 6.3, que fue precedido por un premonitorio de magnitud Mw 5.1 el día 21 de enero. Hemos utilizado 41 mecanismos focales para analizar las características sismotectónicas y estructurales de la serie. Para agrupar los mecanismo focales hemos utilizado un algoritmo de agrupamiento jerárquico espacial y por el tipo de rotura del mecanismo. De cada agrupación hemos obtenido el mecanismo focal medio y lo hemos asociado a una estructura o familia de estructuras. Hemos comprobado la compatibilidad mecánica de estas estructuras mediante transferencia de esfuerzos de Coulomb. El evento principal de la serie se produjo en la Falla de Al Idrisi intersectando la cresta de Alborán. Este evento disparó réplicas y series independientes en fallas de desgarre asociadas al sistema de Falla de Al Idrisi hacia el sur, pero también en fallas inversas asociadas al levantamiento de la Cresta de Alborán hacia el...
GSA Bulletin, 2019
Passive-margin salt basins tend to be much more deformed than their nonsalt equivalents, but they... more Passive-margin salt basins tend to be much more deformed than their nonsalt equivalents, but they are by no means all the same. We used seismic data to study the Salina del Bravo region, northeast Mexico, to investigate the ways in which margin configuration and postsalt uplift history can influence passive-margin salt tectonics. The Salina del Bravo area contains four main structural systems, all of which trend NNE across the entire region. These structures are the Bravo trough, Sigsbee salt canopy, Perdido fold-and-thrust belt, and BAHA high. Gravity-driven deformation did not begin until more than 130 m.y. after salt deposition, because of buttressing against the BAHA high. We suggest that deformation was ultimately triggered in the Cenozoic by Cordilleran uplift that tilted the margin seaward and created a major sediment source terrane. Sediments shed from the uplift expelled salt seaward to form the Sigsbee canopy. At the same time, tilted and loaded sediments were translated s...
Permo-Triassic Salt Provinces of Europe, North Africa and the Atlantic Margins, 2017
A three dimensional rheological model has been developed in the Betic-Rif and Alboran Sea region ... more A three dimensional rheological model has been developed in the Betic-Rif and Alboran Sea region to characterize the brittle-ductile transition (BDT) in the upper crust; calculating a multiple set of regularlyspaced strength profiles based on a synthetic 3D lithospheric structure that gathers most of the available geological and geophysical data in the region. This is the first numerical modelling calculated in the region, for either compressional or tensional tectonic regimes, to characterize the rheological layering of the crust in the Betic-Rifean belt. The model results in a BDT topology highly constrained by the lithospheric thickness. The upper-crust brittle domain gets thinnest in the East Alboran Basin and the transition to the South Balearic Basin (7 and 6 km for tensional and compressional tectonic regimes), and becomes thicker westwards, getting the major values in the West Alboran Basin, near the Gibraltar Arc (18-16 km). In the onshore Betics, the BDT deeps towards the ...
A backstripping analysis is presented for the different scientific ODP wells in the Alboran Sea (... more A backstripping analysis is presented for the different scientific ODP wells in the Alboran Sea (Leg 161, Holes 976B, 977A, 978A, and 979A). The study has been performed for the complete Pliocene-to- Quaternary sedimentary sequence, based on the detailed paleontological dataset available in these wells. Logging data together with in-situ determinations of porosity and density have been fitted to obtain robust estimates of the appropriate variables to perform the backstripping study (e.g., porosity, density). The total subsidence pattern shows a remarkable coincidence in all the wells (Y=310-355 m) equivalent to a subsidence rate of 0.06-0.07 mm/y for the last 5.1 Ma. In regions where a significant intra-Pliocene hiatus (2.2-5.0 Ma) occurred, like the Site 976-basement high in the West Alboran Basin or the Alboran Ridge, we infer the existence of a major tectonic pulse with high subsidence rates (2.2-5.0 mm/y) that diminished towards the Quaternary (0.07-0.11 mm/y). According to thes...
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Structural systems involving mobile shale represent one of the most difficult challenges for geos... more Structural systems involving mobile shale represent one of the most difficult challenges for geoscientists dedicated to exploring the subsurface structure of continental margins. Mobile-shale structures range from surficial mud volcanoes to deeply buried shale diapirs and shale-cored folds. Where mobile shales occur, seismic imaging is typically poor, drilling is hazardous, and established principles to guide interpretation are few. The central problem leading to these issues is the poor understanding of the mechanical behaviour of mobile shales. Here we propose that mobile shales are at critical state, and discuss how this proposition can explain key observations associated with mobile shales. The critical-state model can explain the occurrence of both fluidized shales (e.g., in mud volcanoes) and more viscous shales flowing with grain-to-grain contact (e.g., in mud diapirs), mobilization of cemented or compacted materials, and the role of overpressure in shale mobility. Our model ...
Basin Research, 2021
[Abstract Shortening styles in salt‐influenced basins can vary markedly, with the volume and dist... more [Abstract Shortening styles in salt‐influenced basins can vary markedly, with the volume and distribution of salt prior to shortening being a key control. Here, we use a suite of physical models to examine styles of thin‐skinned regional shortening in settings where the preshortening structure comprised minibasins surrounded by salt (‘isolated‐minibasin’ provinces). Our models show that the high volume of mechanically weak salt localizes lateral regional shortening, with shortening inducing salt flow towards the foreland that subsequently contributes to three key processes – translation, tilting and rotation of minibasins. First, we demonstrate that the flowing salt pushes against minibasins, propelling them in the regional shortening direction. Minibasin translation is enhanced by fast‐flowing salt streams and impeded by basal friction due to welding and base‐salt buttresses. Second, we show how minibasin tilt directions and magnitudes vary spatially and temporally during regional shortening. Minibasins tilt away from zones of pressurized salt, the locations of which may shift due to changes in salt flow regimes. Tilt directions may also change as minibasins pivot on primary welds, or due to forces associated with minibasin collision. Third, minibasins can rotate around sub‐vertical axes during regional shortening. We speculate that this rotation is caused by a combination of: (a) traction imparted on the minibasin boundary by differential horizontal flow of adjacent salt; and (b) pivoting on primary and secondary welds. We synthesize our results in a series of 3‐D conceptual models, before we compare and contrast regional shortening styles and processes in salt‐influenced basins with different preshortening salt configurations. Our findings contribute to the understanding of the geometry and kinematics of shortened salt basins, as well as a deeper understanding of the tectono‐stratigraphic evolution of minibasins., 3‐D conceptual block model synthesising the structural styles and processes that occur in isolated‐minibasin provinces at low regional shortening strain. ]
Basin Research, 2021
We have identified seven mechanisms by which mobile shales can pierce their roofs. The operative ... more We have identified seven mechanisms by which mobile shales can pierce their roofs. The operative piercement mechanism depends on mobile-shale viscosity, roof strength, and stress state. For mobile shales at depths of several kilometers, three mechanisms are possible: fracture piercement, thrust piercement, and ductile "piercement." However, injection up fractures and faults appears to be the dominant mechanism by which mobile shales rise towards the surface. In this process, mobile shales behave similarly to magmas rising through the Earth's crust. Nearer the surface, a wider range of piercement mechanisms becomes possible: passive piercement, reactive piercement, active piercement, and erosional piercement. These mechanisms all have salt-tectonics analogs. Although shale tectonics and salt tectonics share common piercement mechanisms, in many cases the resulting structures are different. This is because near-surface mobile shales can have much lower viscosities than salt. Mobile shales that reach the surface extrude very rapidly, in many cases leading to caldera collapse of the underlying shale chamber. This instability in the near-surface means that long-term, stable growth of passive shale diapirs is unlikely, in contrast to the behavior of salt. A key question in seismic interpretation of mobile-shale structures is whether large-volume mobile-shale diapirs exist. We show that both active piercement and ductile "piercement" can create such structures. Both of these mechanisms create steeply upturned beds on diapir flanks, which are diagnostic. However, active shale diapirs appear to be rare, and ductile "piercements" are not documented. We therefore suggest that large-volume shale diapirs should be interpreted with caution on seismic data.
Journal of Structural Geology, 2018
Marine and Petroleum Geology, 2015
Abstract The internal structure of one of the common fold structures in the western margin of the... more Abstract The internal structure of one of the common fold structures in the western margin of the South Caspian Basin (SCB) has been characterized in 3D using a depth-migrated seismic cube in offshore Azerbaijan. The fold corresponds to a NNW-SSE anticline with a basinward vergence; i.e., eastwards, because in this direction of the margin the SCB is floored by a probable oceanic crust. The anticline has two culminations cut by mud-diapirs and is bounded by two parallel rim synclines with contrasting sedimentary thickness. This anticline deforms congruently the thick Productive Series (PS; Messinian to Late Pliocene), whereas the most recent sequences ( We reconstruct the existence of two episodes of folding. During deposition of the uppermost PS sequences (ca. 3.5–3.4 to 3.1 Ma), fold uplift initiated with a significantly lower rate than sedimentation. During this epoch, folding was accompanied by basin tilting and by faulting in a basinward normal fault with a limited right lateral, strike-slip component. Motion along this fault zone promoted the downdip flow of a weak layer formed by fluid- and mud-rich sediments (Maykop Formation), which also migrated along strike to build-up the growing anticline. Henceforth, fold growth accelerated and sedimentary units like the Akchagyl (3.1–1.7 Ma) were deposited preferentially in the subsiding flanks. Seafloor upwarping due to folding conditioned the sediment transport, and large deltas adapted their prograding pattern to the growing anticline crest. This structure resembles a detachment fold with a leading, East-vergent forelimb. Nevertheless, the occurrence of progressive tilting accompanying sedimentation and folding, or the mud inflation of the fold core by deep flow parallel to the anticline axis, make this example in the SCB a special example of this fold type.
Earth-Science Reviews, 2021
American Mineralogist, 1993
ABSTRACT
From swath bathymetry data and high-resolution acoustic profiles (TOPAS) several slides have been... more From swath bathymetry data and high-resolution acoustic profiles (TOPAS) several slides have been imaged in the Alboran Ridge in the western Mediterranean. This submarine relief is the most prominent morphological feature (> 130 km in length) in the Alboran Sea and its elongated SW-NE shape results is enhanced from the recent convergence between the African and Eurasian plates. The identified gravitational deposits show transparent and chaotic facies, and appear in depths ranging between 640 and 1810 m. Occurrence of slides deposits along fault escarpments affecting the seafloor reveals that submarine instability processes are mainly controlled by tectonics. Mass-transport deposits are generally composed by several overhead lobes of sediments. These observations suggest collectively that instability processes are frequent and may be related with faulting pulses. Instability processes represent therefore a geological risk in the region that should be surveyed and analyzed in the f...
Authorea (Authorea), Jun 23, 2023
El terremoto principal de la serie sísmica tuvo lugar el 25 de enero de 2016, con una magitud Mw ... more El terremoto principal de la serie sísmica tuvo lugar el 25 de enero de 2016, con una magitud Mw 6.3, que fue precedido por un premonitorio de magnitud Mw 5.1 el día 21 de enero. Hemos utilizado 41 mecanismos focales para analizar las características sismotectónicas y estructurales de la serie. Para agrupar los mecanismo focales hemos utilizado un algoritmo de agrupamiento jerárquico espacial y por el tipo de rotura del mecanismo. De cada agrupación hemos obtenido el mecanismo focal medio y lo hemos asociado a una estructura o familia de estructuras. Hemos comprobado la compatibilidad mecánica de estas estructuras mediante transferencia de esfuerzos de Coulomb. El evento principal de la serie se produjo en la Falla de Al Idrisi intersectando la cresta de Alborán. Este evento disparó réplicas y series independientes en fallas de desgarre asociadas al sistema de Falla de Al Idrisi hacia el sur, pero también en fallas inversas asociadas al levantamiento de la Cresta de Alborán hacia el...
GSA Bulletin, 2019
Passive-margin salt basins tend to be much more deformed than their nonsalt equivalents, but they... more Passive-margin salt basins tend to be much more deformed than their nonsalt equivalents, but they are by no means all the same. We used seismic data to study the Salina del Bravo region, northeast Mexico, to investigate the ways in which margin configuration and postsalt uplift history can influence passive-margin salt tectonics. The Salina del Bravo area contains four main structural systems, all of which trend NNE across the entire region. These structures are the Bravo trough, Sigsbee salt canopy, Perdido fold-and-thrust belt, and BAHA high. Gravity-driven deformation did not begin until more than 130 m.y. after salt deposition, because of buttressing against the BAHA high. We suggest that deformation was ultimately triggered in the Cenozoic by Cordilleran uplift that tilted the margin seaward and created a major sediment source terrane. Sediments shed from the uplift expelled salt seaward to form the Sigsbee canopy. At the same time, tilted and loaded sediments were translated s...
Permo-Triassic Salt Provinces of Europe, North Africa and the Atlantic Margins, 2017
A three dimensional rheological model has been developed in the Betic-Rif and Alboran Sea region ... more A three dimensional rheological model has been developed in the Betic-Rif and Alboran Sea region to characterize the brittle-ductile transition (BDT) in the upper crust; calculating a multiple set of regularlyspaced strength profiles based on a synthetic 3D lithospheric structure that gathers most of the available geological and geophysical data in the region. This is the first numerical modelling calculated in the region, for either compressional or tensional tectonic regimes, to characterize the rheological layering of the crust in the Betic-Rifean belt. The model results in a BDT topology highly constrained by the lithospheric thickness. The upper-crust brittle domain gets thinnest in the East Alboran Basin and the transition to the South Balearic Basin (7 and 6 km for tensional and compressional tectonic regimes), and becomes thicker westwards, getting the major values in the West Alboran Basin, near the Gibraltar Arc (18-16 km). In the onshore Betics, the BDT deeps towards the ...
A backstripping analysis is presented for the different scientific ODP wells in the Alboran Sea (... more A backstripping analysis is presented for the different scientific ODP wells in the Alboran Sea (Leg 161, Holes 976B, 977A, 978A, and 979A). The study has been performed for the complete Pliocene-to- Quaternary sedimentary sequence, based on the detailed paleontological dataset available in these wells. Logging data together with in-situ determinations of porosity and density have been fitted to obtain robust estimates of the appropriate variables to perform the backstripping study (e.g., porosity, density). The total subsidence pattern shows a remarkable coincidence in all the wells (Y=310-355 m) equivalent to a subsidence rate of 0.06-0.07 mm/y for the last 5.1 Ma. In regions where a significant intra-Pliocene hiatus (2.2-5.0 Ma) occurred, like the Site 976-basement high in the West Alboran Basin or the Alboran Ridge, we infer the existence of a major tectonic pulse with high subsidence rates (2.2-5.0 mm/y) that diminished towards the Quaternary (0.07-0.11 mm/y). According to thes...
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Logging data are measurements of physical properties of the formation surrounding a borehole, acq... more Logging data are measurements of physical properties of the formation surrounding a borehole, acquired in situ after completion of coring (wireline logging) or during drilling (Logging-While-Drilling, LWD). The range of data (resistivity, gamma radiation, velocity, density, borehole images,…) in any hole depends on the scientific objectives and operational constraints.
Structural systems involving mobile shale represent one of the most difficult challenges for geos... more Structural systems involving mobile shale represent one of the most difficult challenges for geoscientists dedicated to exploring the subsurface structure of continental margins. Mobile-shale structures range from surficial mud volcanoes to deeply buried shale diapirs and shale-cored folds. Where mobile shales occur, seismic imaging is typically poor, drilling is hazardous, and established principles to guide interpretation are few. The central problem leading to these issues is the poor understanding of the mechanical behaviour of mobile shales. Here we propose that mobile shales are at critical state, and discuss how this proposition can explain key observations associated with mobile shales. The critical-state model can explain the occurrence of both fluidized shales (e.g., in mud volcanoes) and more viscous shales flowing with grain-to-grain contact (e.g., in mud diapirs), mobilization of cemented or compacted materials, and the role of overpressure in shale mobility. Our model ...
Basin Research, 2021
[Abstract Shortening styles in salt‐influenced basins can vary markedly, with the volume and dist... more [Abstract Shortening styles in salt‐influenced basins can vary markedly, with the volume and distribution of salt prior to shortening being a key control. Here, we use a suite of physical models to examine styles of thin‐skinned regional shortening in settings where the preshortening structure comprised minibasins surrounded by salt (‘isolated‐minibasin’ provinces). Our models show that the high volume of mechanically weak salt localizes lateral regional shortening, with shortening inducing salt flow towards the foreland that subsequently contributes to three key processes – translation, tilting and rotation of minibasins. First, we demonstrate that the flowing salt pushes against minibasins, propelling them in the regional shortening direction. Minibasin translation is enhanced by fast‐flowing salt streams and impeded by basal friction due to welding and base‐salt buttresses. Second, we show how minibasin tilt directions and magnitudes vary spatially and temporally during regional shortening. Minibasins tilt away from zones of pressurized salt, the locations of which may shift due to changes in salt flow regimes. Tilt directions may also change as minibasins pivot on primary welds, or due to forces associated with minibasin collision. Third, minibasins can rotate around sub‐vertical axes during regional shortening. We speculate that this rotation is caused by a combination of: (a) traction imparted on the minibasin boundary by differential horizontal flow of adjacent salt; and (b) pivoting on primary and secondary welds. We synthesize our results in a series of 3‐D conceptual models, before we compare and contrast regional shortening styles and processes in salt‐influenced basins with different preshortening salt configurations. Our findings contribute to the understanding of the geometry and kinematics of shortened salt basins, as well as a deeper understanding of the tectono‐stratigraphic evolution of minibasins., 3‐D conceptual block model synthesising the structural styles and processes that occur in isolated‐minibasin provinces at low regional shortening strain. ]
Basin Research, 2021
We have identified seven mechanisms by which mobile shales can pierce their roofs. The operative ... more We have identified seven mechanisms by which mobile shales can pierce their roofs. The operative piercement mechanism depends on mobile-shale viscosity, roof strength, and stress state. For mobile shales at depths of several kilometers, three mechanisms are possible: fracture piercement, thrust piercement, and ductile "piercement." However, injection up fractures and faults appears to be the dominant mechanism by which mobile shales rise towards the surface. In this process, mobile shales behave similarly to magmas rising through the Earth's crust. Nearer the surface, a wider range of piercement mechanisms becomes possible: passive piercement, reactive piercement, active piercement, and erosional piercement. These mechanisms all have salt-tectonics analogs. Although shale tectonics and salt tectonics share common piercement mechanisms, in many cases the resulting structures are different. This is because near-surface mobile shales can have much lower viscosities than salt. Mobile shales that reach the surface extrude very rapidly, in many cases leading to caldera collapse of the underlying shale chamber. This instability in the near-surface means that long-term, stable growth of passive shale diapirs is unlikely, in contrast to the behavior of salt. A key question in seismic interpretation of mobile-shale structures is whether large-volume mobile-shale diapirs exist. We show that both active piercement and ductile "piercement" can create such structures. Both of these mechanisms create steeply upturned beds on diapir flanks, which are diagnostic. However, active shale diapirs appear to be rare, and ductile "piercements" are not documented. We therefore suggest that large-volume shale diapirs should be interpreted with caution on seismic data.
Journal of Structural Geology, 2018
Marine and Petroleum Geology, 2015
Abstract The internal structure of one of the common fold structures in the western margin of the... more Abstract The internal structure of one of the common fold structures in the western margin of the South Caspian Basin (SCB) has been characterized in 3D using a depth-migrated seismic cube in offshore Azerbaijan. The fold corresponds to a NNW-SSE anticline with a basinward vergence; i.e., eastwards, because in this direction of the margin the SCB is floored by a probable oceanic crust. The anticline has two culminations cut by mud-diapirs and is bounded by two parallel rim synclines with contrasting sedimentary thickness. This anticline deforms congruently the thick Productive Series (PS; Messinian to Late Pliocene), whereas the most recent sequences ( We reconstruct the existence of two episodes of folding. During deposition of the uppermost PS sequences (ca. 3.5–3.4 to 3.1 Ma), fold uplift initiated with a significantly lower rate than sedimentation. During this epoch, folding was accompanied by basin tilting and by faulting in a basinward normal fault with a limited right lateral, strike-slip component. Motion along this fault zone promoted the downdip flow of a weak layer formed by fluid- and mud-rich sediments (Maykop Formation), which also migrated along strike to build-up the growing anticline. Henceforth, fold growth accelerated and sedimentary units like the Akchagyl (3.1–1.7 Ma) were deposited preferentially in the subsiding flanks. Seafloor upwarping due to folding conditioned the sediment transport, and large deltas adapted their prograding pattern to the growing anticline crest. This structure resembles a detachment fold with a leading, East-vergent forelimb. Nevertheless, the occurrence of progressive tilting accompanying sedimentation and folding, or the mud inflation of the fold core by deep flow parallel to the anticline axis, make this example in the SCB a special example of this fold type.
Earth-Science Reviews, 2021
American Mineralogist, 1993
ABSTRACT
AAPG Memoir 93 (Shale tectonics. L. Wood, ed.), 2010
The Alboran Basin is a back-arc basin in the Mediterranean developed during the Miocene by the ex... more The Alboran Basin is a back-arc basin in the Mediterranean developed during the Miocene by the extensional collapse of the thick continental orogen known as the Betic-Rif arc. Collision and basin formation occurred in the Neogene as a result of oblique convergence of the Eurasian and African plates. A major, curved depocenter (with sedimentary accumulations >10 km [>6 mi]) is located to the west of this basin, containing a diapiric province with overpressured shales and mud volcanoes. This study presents a detailed reconstruction of the three-dimensional ge- ometry of the diapirs and associated minibasins in the northern margin of this major depo- center (offshore Spain). Basin formation began in the early Miocene when rapid initial subsi- dence of the basin floor was accompanied by massive sedimentation and burial of fine-grained sediments. Gravity-driven tectonics and continuous basement subsidence during the Miocene led to downslope migration of mobile shales, whereas the basin margins were affected by syn- sedimentary extension, and associated shale-cored thrusts occurred in the basin depocenter. Extension occurred by means of low-angle normal faults coalescing with the basement surface, which represents a master detachment surface. Thin-skinned extension during the Miocene was accompanied by punctuated diapir ascent and the advance of shale sheets. Downslope shale advance was enhanced by counterregional high-angle normal faults isolating noncylin- drical minibasins in the overburden. The Alboran Basin therefore is a useful area for analysis of the structural pattern associated with shale tectonic processes and a key basin for comparing the geometries and evolution of shale with structures formed in salt basins.
