ABSTRACT Advancing ice sheets have a strong impact on the earth’s topography. For example, they l... more ABSTRACT Advancing ice sheets have a strong impact on the earth’s topography. For example, they leave behind an erosional unconformity, bulldozer the underlying strata and form tunnel valleys, primarily by subglacial melt-water erosion and secondarily by direct glacial erosion. The conceptual models of the reactivation of faults within the upper crust, due to the ice sheets’ load, are also established. However, this phenomenon is also rather under-explored. Here, we propose a causal link between ice-load induced tectonics, the generation of near-vertical faults in the upper crust above an inherited deep-rooted fault and the evolution of tunnel valleys. The Kossau tunnel valley in the southeastern Bay of Kiel has been surveyed by means of high-resolution multi-channel seismic and echosounder data. It strikes almost south to north and can be mapped over a distance of ca. 50 km. It is 1200 to 8000 m wide with a valley of up to 200 m deep. Quaternary deposits fill the valley and cover the adjacent glaciogenic unconformity. A near-vertical fault system with an apparent dip angle of >80°, which reaches from the top Zechstein upwards into the Quaternary, underlies the valley. The fault partially pierces the seafloor and growth is observed within the uppermost Quaternary strata only. Consequently, the fault evolved in the Late Quaternary. The fault is associated with an anticline that is between 700 and 3000 m wide and about 20 to 40 m high. The fault–anticline assemblage neither resembles any typical extensional, compressional or strike-slip deformation pattern, nor is it related to salt tectonics. Based on the observed position and deformation pattern of the fault–anticline assemblage, we suggest that these structures formed as a consequence of the differential ice-load induced tectonics above an inherited deep-rooted sub-salt fault related to the Glückstadt Graben. Lateral variations in the ice-load during the ice sheet’s advance caused differential subsidence, thus rejuvenating the deep-rooted fault. As a result, the inherited fault propagated upwards across the Zechstein and post-Permian overburden and further grew during the ice sheet’s retreat. The developing fault and anticline system under the ice sheet created a weakness zone that facilitated erosion by pressurized glacial and subglacial melt-water, as well as by the glaciers themselves. Near-vertical faults cutting through the post-Permian are abundant in the southwestern Baltic realm, which implies that the ice-load induced tectonic activity described above was not an isolated incident.
Abstract In this study we investigate the Late Cretaceous to recent tectonic evolution of the sou... more Abstract In this study we investigate the Late Cretaceous to recent tectonic evolution of the southwestern Baltic Sea based on a dense grid of seismic reflection profiles. This area covers the Baltic Sea sector of the salt influenced North German Basin and its transition to the salt free Baltic Shield across the Tornquist Zone. The Upper Cretaceous to recent structural evolution is discussed by means of individual seismic sections and derived high-resolution time-structure maps of the main horizons, i.e., the Upper Cretaceous, Tertiary and Pleistocene. The Upper Cretaceous and Tertiary layers reveal numerous significant faults throughout the study area. Several of these faults propagate upwards across the unconsolidated Pleistocene sediments and occasionally penetrate the surface. The salt influenced North German Basin reveals three major fault trends: NW-SE, N-S and NNE-SSW. Several of these faults are located directly above basement (sub-salt) faults and salt pillows. The majority of these faults are trending N-S to NNE-SSW and parallel the direction of the Gluckstadt Graben faults. In the salt free Tornquist Zone, we identify two major shallow fault trends, which are NW-SE and NE-SW. The majority of these faults are located above basement faults, following the direction of the Tornquist Zone. We conclude that generally basement tectonics controls activation and trends of shallow faults. If salt is present, the ductile salt layer causes a lateral shift between the sub- and supra-salt faults. Major plate reorganisation related to the Africa-Iberia-Europe convergence and the subsequent Alpine Orogeny caused reactivation of pre-existing faults and vertical salt movement in the Late Cretaceous. The change of stress orientation from NE-SW to a NW-SE during Neogene caused another phase of fault and salt tectonic reactivation. We explain that the ice-sheet loading and/or present-day stress field may have acted in combination, causing the recent tectonics and upward extension of the faults.
Based on integration of seismic reflection and well data analysis this study examines two major c... more Based on integration of seismic reflection and well data analysis this study examines two major contourite systems that developed during the late Creta-ceous in the southern Baltic Sea. The evolution of these Chalk Sea con-tourite systems between the Kattegat and the southern Baltic Sea started when Turonian to Campanian inversion tectonics overprinted the rather flat sea floor of the epeiric Chalk Sea. The Tornquist Zone and adjacent smaller blocks were uplifted and formed elongated obstacles that influenced the bottom currents. As a consequence of the inversion, the sea floor west of the Tornquist Zone tilted towards the northeast , creating an asymmetrical sub-basin with a steep marginal slope in the northeast and a gentle dipping slope in the southwest. A southeast directed contour current emerged in the Coniacian or Santonian along the southwestern basin margin, creating contourite channels and drifts. The previously studied contourite system offshore Stevns Klint is part of this system. A second, deeper and northwest directed counter-flow emerged along and parallel to the Tornquist Zone in the later Campanian, but was strongest in the Maastrichtian. This bottom current moderated the evolution of a drift-moat system adjacent to the elevated Tornquist Zone. The near surface Alnarp Valley in Scania represents the Danian palaeo-moat that linked the Pomeranian Bay with the Kattegat. The previously studied contourite system in the Kattegat represents the northwestern prolongation of this system. This study links previous observations from the Kattegat and offshore Stevns Klint to the here inferred two currents, a more shallow, southeast directed and a deeper, northwest directed flow.
In this study we investigate faulting above a salt wall in the Glückstadt Graben / North German B... more In this study we investigate faulting above a salt wall in the Glückstadt Graben / North German Basin. Two supra-salt faults are mapped from coast to coast over a distance of 6–9 km based on offshore and onshore seismic data. These faults form a ca. 2 km wide crestal collapse graben and pierce the seafloor. Salt wall evolution started in the early Late Triassic to Early Jurassic due to regional extension and resulting sub-salt faulting. The salt wall was eroded following exposure to costal and sub-aerial erosion by the regional Mid-Late Jurassic to Early Cretaceous uplift. Late Cretaceous to Early Paleogene compressional tectonics reactivated the vertical salt movement and shortened the salt wall, creating a salt-cored anticline with the crestal collapse graben above. The supra-salt faults were reactivated between the Late Eocene and Middle Miocene when the principal horizontal stress orientation changed from a NE-SW to a NW-SE, the present-day orientation. Stratigraphic data indicate that these faults moved mainly in the Cenozoic. Several observations strongly suggest that the faults continued developing during the Pleistocene until today: (i) the Pleistocene Unconformity is concave upwards and cut by faults; (ii) growth strata within the marine Holocene deposits above the graben imply recent tectonic movements; (iii) onshore high-resolution P-wave vibroseis data of the south-eastern Eckernförde Bay suggest about 10 m of faulted Holocene strata; and (iv) marine seismic data show the faults piercing the seafloor. We suggest that the recent salt tectonics and upward propagation of supra-salt faults resulted from differential ice-sheet loading. That effect on the salt wall stopped once ice grew over the whole structure, at which time the wall subsided because of ice loading. The salt wall and faults were reactivated again once the ice front retreated so that the ice loaded only one side of the structure.
The Loop Current and its associated eddy-shedding in the Gulf of Mexico are mediating the oceanic... more The Loop Current and its associated eddy-shedding in the Gulf of Mexico are mediating the oceanic heat and salt flux from the Caribbean into the Atlantic Ocean via Yucatan Strait. Changes in Yucatan Strait surface and intermediate through flow over geological timescales in relation to sea level, through flow velocity, and atmospheric circulation are not well constrained to date. The main objective of the geological sediment sampling program was to establish spatially and temporally high-resolving reconstructions of the Late Pleistocene surface, subsurface and intermediate water variability, in relation to the Loop Current variations and related eddy shedding, Antarctic Intermediate Water migrations, and changes in the Atlantic Meridional Overturning Circulation. The multi-channel seismic program was designed to establish a sequence stratigraphic framework for current controlled sediment formations which reflect the onset and intensification of the Gulfstream as well as Mid-Pleistoce...
The Loop Current and its associated eddy-shedding in the Gulf of Mexico are mediating the oceanic... more The Loop Current and its associated eddy-shedding in the Gulf of Mexico are mediating the oceanic heat and salt flux from the Caribbean into the Atlantic Ocean via Yucatan Strait. Changes in Yucatan Strait surface and intermediate through flow over geological timescales in relation to sea level, through flow velocity, and atmospheric circulation are not well constrained to date. The main objective of the geological sediment sampling program was to establish spatially and temporally high-resolving reconstructions of the Late Pleistocene surface, subsurface and intermediate water variability, in relation to the Loop Current variations and related eddy shedding, Antarctic Intermediate Water migrations, and changes in the Atlantic Meridional Overturning Circulation. The multi-channel seismic program was designed to establish a sequence stratigraphic framework for current controlled sediment formations which reflect the onset and intensification of the Gulfstream as well as Mid-Pleistoce...
A spectacular feature of the Arabian-Nubian Shield (ANS) is the abundance of well-exposed and ext... more A spectacular feature of the Arabian-Nubian Shield (ANS) is the abundance of well-exposed and extensive Neoproterozoic dike swarms of variable compositions. Most of these dikes are late to post-orogenic with respect to the East African Orogen (EAO) and are unmetamorphosed. We dated a composite dike with latite margins and a rhyolite core (607 ± 6 Ma, U-Pb), a biotite rhyolite dike (600 ± 4 Ma, 40 Ar/ 39 Ar age of biotite), an andesite dike (594 ± 3, 40 Ar/ 39 Ar age of amphibole) and a dolerite dike (~579 Ma, 40 Ar/ 39 Ar whole rock total gas age). We propose that the first three dikes represent one generation that was emplaced at different episodes extending between 607 and 590 Ma. Time and composition equivalent dikes are common in the northern ANS. The dikes crosscut late collisional granitoids and geochemically display a subduction-related character as evidenced by a negative Nb-Ta anomaly. These dikes are absent in the alkali feldspar A-type Humrat Syenogranite dated at 586 ± 5 Ma in Jordan and equivalent rocks in the northern ANS, which are crosscut only by the (~579 Ma) dolerite dikes. The within-plate character of the dolerite dikes is supported by the absence of the Nb-Ta anomaly and high field strength element geochemistry. We propose that the dolerite dikes are a generation, distinct from the~607-590 Ma dikes, that reflects a change in tectonic regime and represents the last magmatic activity of the Neoproterozoic in the northern ANS. The ages of the dikes dated in this study agree with the published age range of the transitional stage from late orogenic calc-alkaline to extensional alkaline tectono-magmatic setting for the ANS. We propose that the magmatic activity was terminated~50 m.y. before the age of the Cambrian un-conformity at~530 Ma. Correlation with ages of dikes and magmatic rocks in the northern ANS favors this supposition. The dike geochemistry and geochronology are compatible with a tectonic model that involves mantle lithosphere delamination from below the northern ANS after a significant crust-mantle thickening caused by the EAO, followed by thermal relaxation, subsidence and gradual denudation until the age of the un-conformity at~530 Ma.
To evaluate the effect of the industrial activities on the sediment quality, we investigated long... more To evaluate the effect of the industrial activities on the sediment quality, we investigated long-term records of physical and chemical properties of bottom-surface sediments from a complex industrial site along the Jordanian coast of the Gulf of Aqaba. Sediment samples were collected from 10 m depth once a year from six different stations (S1-S6) and analyzed for grain size, loss on ignition (LOI), organic carbon (OC), hydrogen sulfide (H 2 S), total nitrogen (TN), total phosphorus (TP), and heavy metal contents. Temporal variations show a constant/decreasing trend for H 2 S, OC, and LOI, whereas an increasing trend for TN and TP was observed. Heavy metal concentrations reveal almost constant trends over time for Cd, Cu, and Zn and a decreasing trend for Cr and Pb. Statistical analysis indicates that the differences between the different sampling stations were insignificant for almost all variables. However, some differences were observed, as the highest values were recorded in S3 and the lowest values in S1. The textural proprieties show no significant variation among sites. As a result, the sediment quality at the industrial site is comparable with that in other sites along the northern Gulf of Aqaba. Sediments at the industrial site appear to have attained steady-state equilibrium where basic environmental parameters are insignificantly modified from the baseline values of the area. The decreasing trend observed over time indicates a significant improvement in the environmental quality attributed to the stringent implementation of environmental regulation in Aqaba (e.g., zero discharge policy).
The precise seismic sub-structural interpretation of Turkwal field in the Central Potwar region h... more The precise seismic sub-structural interpretation of Turkwal field in the Central Potwar region has been carried out. The research work was confined to the large fore-thrust which serves as an anticlinal structural trap through ten 2D seismic lines. Precise seismic sub-structural model of Eocene Chorgali Limestone with precise orientation of thrust and oblique slip faults shows presence of a huge fracture, which made the Eocene Chorgali Limestone a good reservoir. The abrupt surface changes in dip azimuth for Chorgali Limestone verifies the structural trends and also verifies the presence of structural traps in the Turkwal field. The logs of three wells (Turkwal deep X-2, Turkwal-01 and Fimkassar-01) were analyzed for the petrophysical studies, well synthetic results and generation of Amplitude Versus Offset (AVO) model for the area. AVO model of Turkwal deep X-2 shows abrupt changes in amplitude which depicts the presence of hydrocarbon content. Well correlation technique was used to define the overall stratigraphic setting and the thickness of the reservoir formation in two wells of Turkwal-01 and Turkwal deep X-2. Chorgali Limestone in Turkwal-01 is an upward thrusted anticlinal structure and because of close position of the both wells around the faulted anticlinal structure its thickness less differs compare with Turkwal deep X-2. The overall results confirm that the Turkwal field is amongst several similar thrusts bound oil bearing structure in the Potwar basin.
Based on integration of seismic reflection and well data analysis this study examines two major c... more Based on integration of seismic reflection and well data analysis this study examines two major contourite systems that developed during the late Creta-ceous in the southern Baltic Sea. The evolution of these Chalk Sea con-tourite systems between the Kattegat and the southern Baltic Sea started when Turonian to Campanian inversion tectonics overprinted the rather flat sea floor of the epeiric Chalk Sea. The Tornquist Zone and adjacent smaller blocks were uplifted and formed elongated obstacles that influenced the bottom currents. As a consequence of the inversion, the sea floor west of the Tornquist Zone tilted towards the northeast , creating an asymmetrical sub-basin with a steep marginal slope in the northeast and a gentle dipping slope in the southwest. A southeast directed contour current emerged in the Coniacian or Santonian along the southwestern basin margin, creating contourite channels and drifts. The previously studied contourite system offshore Stevns Klint is part of this system. A second, deeper and northwest directed counter-flow emerged along and parallel to the Tornquist Zone in the later Campanian, but was strongest in the Maastrichtian. This bottom current moderated the evolution of a drift-moat system adjacent to the elevated Tornquist Zone. The near surface Alnarp Valley in Scania represents the Danian palaeo-moat that linked the Pomeranian Bay with the Kattegat. The previously studied contourite system in the Kattegat represents the northwestern prolongation of this system. This study links previous observations from the Kattegat and offshore Stevns Klint to the here inferred two currents, a more shallow, southeast directed and a deeper, northwest directed flow.
Groundwater vulnerability maps were created for the Corridor wellfield (~300 km 2) in the eastern... more Groundwater vulnerability maps were created for the Corridor wellfield (~300 km 2) in the eastern Jordan using the DRASTIC and modified DRASTIC groundwater vulnerability assessment models. The study area is considered as one of the most important well fields therein providing partially three governorates with the needed drinking water. Detailed geological and hydrogeological parameters as well as the land-use map of the area were obtained from various sources to utilize both models. ArcGIS software was used for calculations and maps preparation. As a result, the generic DRASTIC vulnerability index ranges between 109 and 168. Thus, two vulnerability classes were observed, moderate (9.9%) and high (90.1%) vulnerability classes. On the other hand, the modified DRASTIC model (risk map) is taking into account the land-use map classes in the study area. The output risk map reveals two main classes, the moderate and high-risk areas. The moderate risk areas occupy 9.3% of the total volume of the study area while the high-risk areas are 90.7%. Due to the high depth to groundwater within the area (between 90 m and 390 m), the depth to groundwater intervals was modified in the model to become more comfortable with the situation in Jor-dan. The high percentage of the high vulnerable areas against pollutants reflects the need to do more investigation for the studied area.
This paper presents new findings that contribute to the understanding of the deformational style ... more This paper presents new findings that contribute to the understanding of the deformational style of the Wadi Shueib Structure (WSS) and the Amman-Halabat Structure (AHS) and their relationship with the regional tectonic regime of the Dead Sea Transform Fault (DSTF). Our research utilized Landsat-8 OLI imagery for the automatic extraction of lineaments, and our lineament mapping was facilitated by processing and digital image enhancement using principal component analysis (PCA). Our data revealed a relatively higher density of lineaments along the extension of the major faults of the WSS and AHS. However, a relatively lower density of lineaments was shown in areas covered by recent deposits. Two major lineament trends were observed (NNE-SSW and NW-SE) in addition to a minor one (NE-SW), and most of these lineaments are parallel to the orientation of the WSS and AHS. We offer the supposition that the DSTF has merged into the major faults of the WSS and AHS. We further suppose that these faults were reactivated as a restraining bend composed of active strike-slip fault branches that developed due to the NNW-SSE-trending Dead Sea transpressional stress field. Depending on the relationship between the direction of the WSF and AHF strands and the regional tectonic displacement along the DSTF, thrust components are present on faults with horsetail geometry, and these movements are accompanied by folding and uplifting. Thus, the major faults of the WSS and AHS represent a contractional horsetail geometry with associated folding and thrusting deformation.
In this study we investigate the Late Cretaceous to recent tectonic evolution of the southwestern... more In this study we investigate the Late Cretaceous to recent tectonic evolution of the southwestern Baltic Sea based on a dense grid of seismic reflection profiles. This area covers the Baltic Sea sector of the salt influenced North German Basin and its transition to the salt free Baltic Shield across the Tornquist Zone. The Upper Cretaceous to recent structural evolution is discussed by means of individual seismic sections and derived high-resolution time-structure maps of the main horizons, i.e., the Upper Cretaceous, Tertiary and Pleistocene. The Upper Creta-ceous and Tertiary layers reveal numerous significant faults throughout the study area. Several of these faults propagate upwards across the unconsolidated Pleistocene sediments and occasionally penetrate the surface. The salt influenced North German Basin reveals three major fault trends: NW-SE, N-S and NNE-SSW. Several of these faults are located directly above basement (sub-salt) faults and salt pillows. The majority of these faults are trending N-S to NNE-SSW and parallel the direction of the Glückstadt Graben faults. In the salt free Tornquist Zone, we identify two major shallow fault trends, which are NW-SE and NE-SW. The majority of these faults are located above basement faults, following the direction of the Tornquist Zone. We conclude that generally basement tectonics controls activation and trends of shallow faults. If salt is present, the ductile salt layer causes a lateral shift between the sub-and supra-salt faults. Major plate reorganisation related to the Africa-Iberia-Europe convergence and the subsequent Alpine Orogeny caused reactivation of pre-existing faults and vertical salt movement in the Late Cretaceous. The change of stress orientation from NE-SW to a NW-SE during Neogene caused another phase of fault and salt tectonic reactivation. We explain that the ice-sheet loading and/or present day stress field may have acted in combination, causing the recent tectonics and upward extension of the faults.
The research program aimed on the in-depth understanding the volcano-tectonic evolution of the Az... more The research program aimed on the in-depth understanding the volcano-tectonic evolution of the Azores plateau and associated geo-hazards such as submarine landslides and volcanic surges. Oceanic plateaus like the Azores plateau are large areas of anomalously thick crust forming large bathymetric swells in the ocean basins and their petrological formation and subsequent sedimentological evolution is only poorly understood. The reason for the magmatic and volcanic activity that built the igneous part of the Azores Plateau is intensely debated. As in other places of the world deep, hot mantle plumes are believed to cause the magmatism due to their high excess temperature. According to an alternative model volcanism is explained by excess melting of the mantle due to an elevated volatile content. In addition, the structural evolution of the plateau and the relationship between rifting and volcanism particularly in the Azores is a matter of active scientific debate. It is suggested that an oblique spreading axis jumped incrementally from the East Azores Fracture Zone towards the north-east. The Terceira rift axis represents the present stage and the recent plate boundary between the Eurasian and African plates. In addition, recurrence rate, trigger mechanisms, volumes, and transport processes of large scale mass wasting events are amongst the scientific questions targeted. Multi-beam and seismic data will provide the crucial site-survey data for ROV sampling during a future research cruise. The micro- and nano-plastic concentration within the surface water will be measured by geochemical analyses of water sampled during the cruise.
In this study we investigate faulting above a salt wall in the Glückstadt Graben / North German B... more In this study we investigate faulting above a salt wall in the Glückstadt Graben / North German Basin. Two supra-salt faults are mapped from coast to coast over a distance of 6–9 km based on offshore and onshore seismic data. These faults form a ca. 2 km wide crestal collapse graben and pierce the seafloor. Salt wall evolution started in the early Late Triassic to Early Jurassic due to regional extension and resulting sub-salt faulting. The salt wall was eroded following exposure to costal and sub-aerial erosion by the regional Mid-Late Jurassic to Early Cretaceous uplift. Late Cretaceous to Early Paleogene compressional tectonics reactivated the vertical salt movement and shortened the salt wall, creating a salt-cored anticline with the crestal collapse graben above. The supra-salt faults were reactivated between the Late Eocene and Middle Miocene when the principal horizontal stress orientation changed from a NE-SW to a NW-SE, the present-day orientation. Stratigraphic data indicate that these faults moved mainly in the Cenozoic. Several observations strongly suggest that the faults continued developing during the Pleistocene until today: (i) the Pleistocene Unconformity is concave upwards and cut by faults; (ii) growth strata within the marine Holocene deposits above the graben imply recent tectonic movements; (iii) onshore high-resolution P-wave vibroseis data of the south-eastern Eckernförde Bay suggest about 10 m of faulted Holocene strata; and (iv) marine seismic data show the faults piercing the seafloor. We suggest that the recent salt tectonics and upward propagation of supra-salt faults resulted from differential ice-sheet loading. That effect on the salt wall stopped once ice grew over the whole structure, at which time the wall subsided because of ice loading. The salt wall and faults were reactivated again once the ice front retreated so that the ice loaded only one side of the structure.
The Loop Current and its associated eddy-shedding in the Gulf of Mexico are mediating the oceanic... more The Loop Current and its associated eddy-shedding in the Gulf of Mexico are mediating the oceanic heat and salt flux from the Caribbean into the Atlantic Ocean via Yucatan Strait. Changes in Yucatan Strait surface and intermediate through flow over geological timescales in relation to sea level, through flow velocity, and atmospheric circulation are not well constrained to date. The main objective of the geological sediment sampling program was to establish spatially and temporally high-resolving reconstructions of the Late Pleistocene surface, subsurface and intermediate water variability, in relation to the Loop Current variations and related eddy shedding, Antarctic Intermediate Water migrations, and changes in the Atlantic Meridional Overturning Circulation. The multi-channel seismic program was designed to establish a sequence stratigraphic framework for current controlled sediment formations which reflect the onset and intensification of the Gulfstream as well as Mid-Pleistoce...
Jörg Lang (1), Muayyad Al Hseinat (2), Christian Brandes (1), Andrea Hampel (1), Christian Hübsch... more Jörg Lang (1), Muayyad Al Hseinat (2), Christian Brandes (1), Andrea Hampel (1), Christian Hübscher (2), and Jutta Winsemann (1)
(1) Leibniz Universität Hannover, Institut für Geologie, Hannover, Germany (lang@geowi.uni-hannover.de), (2) Universität Hamburg, Institut für Geophysik, Hamburg, Germany
A correlation between salt structures, glacigenic features and faulting of Pleistocene deposits above salt structures has been recognized in many places of the formerly glaciated areas in northern central Europe and attributed to ice-sheet loading. Conceptual models predict that the load applied by an ice sheet will favour ice-marginal salt rise and obstruct salt rise beneath the ice sheet (e.g., Liszkowski, 1993). To test these models, we simulated the response of salt structures to ice-sheet loading using a 2D finite-element model (ABAQUS). The subsurface geometries used in our models are based on regional geological cross-sections and 2D seismic profiles of salt structures in the Central European Basin System. The model layers represent (i) sedimentary rocks of elastoplastic rheology, (ii) a viscoelastic salt structure and (iii) elastoplastic basement rocks. At the model surface a temporarily and spatially variable pressure simulates ice-sheet loading. All our simulations show a response of salt structures to ice-sheet loading, which strongly depends on the location of the ice margin relative to the salt structure. Salt structures rise in front of the ice margin (up to 4 m), if load is applied to the salt source layer. Beneath an ice sheet salt structures are pushed down (up to 36 m). Much of the subglacial downwards displacement is compensated by a reversal of the movement during ice retreat. The resulting surface displacements are therefore rather low and depend on the spatial and temporal configuration of the ice load (Lang et al., 2014). Permanent deformation is restricted to the model layers above the salt structure, which either have a low yield stress to represent the unconsolidated infill of secondary rim-synclines or are dissected by steeply dipping crestal graben faults. Ice-induced salt movements will reactivate faults above the crests of salt structures, although the resulting displacements will be low due to the repeated reversals of the sense of movement. The surface displacement due to ice-load induced salt movement will impact the pattern of glacigenic deformation, erosion and deposition. Ice-marginal uplift will provide favourable conditions for push-moraine formation, while subglacial subsidence of salt structures will enhance erosion and contribute to tunnel-valley incision.
References Lang, J., Hampel, A., Brandes, C., Winsemann, J. (2014) Response of salt structures to ice-sheet loading: implications for ice-marginal and subglacial processes. Quaternary Science Reviews 101, 217-233. Liszkowski, J. (1993) The effects of Pleistocene ice-sheet loading-deloading cycles on the bedrock structure of Poland. Folia Quaternaria 64, 7-23.
M. Al Hseinat*1, C. Hübscher1, J. Lang2, I. Ott1, U. Polom3, C. Brandes2, A. Hampel2, J. Winseman... more M. Al Hseinat*1, C. Hübscher1, J. Lang2, I. Ott1, U. Polom3, C. Brandes2, A. Hampel2, J. Winsemann2 (1) University of Hamburg, Institute of Geophysics, Hamburg, Germany (2) Leibniz Universität Hannover, Institut für Geologie, Hannover, Germany (3) Leibniz Institute for Applied Geophysics, Hannover, Germany
Marine high-resolution multi-channel seismic data from the Eckernförde Bay in the SW Baltic Sea show two major NNW-SSE striking faults above a salt diapir that evolved above eastern Glückstadt Graben faults. These normal faults are parallel and dip in opposing directions towards the core of an anticline, forming a crestal collapse graben above the crest of the salt anticline. Fault displacement proves that the crestal graben evolved mainly in the Cenozoic. The faults partly pierce the surface and are consequently active. The glacial erosional unconformity between the major faults is concave upwards and dissected by faults, implying that the Quaternary thin-skinned extension in the crestal graben pursued. A High-resolution P-wave seismic data reveal asymmetric and irregular normal and reverse faults atypical of thin-skinned extensional subsidence. Numerical modelling suggests that the recent tectonic overprinting of Pleistocene sediments results from differential loading by advancing ice-sheets, which squeezes salt into the salt diapir and causes diapir rise. During complete ice coverage the entire diapir is pushed down but rises again during ice retreat. The resulting absolute vertical displacement is low due to the repeated reversals of the sense of movement. Beside the deformation of Pleistocene sediments we attribute the reactivation of the crestal graben faults to ice-load induced salt movements. Ice-marginal uplift provides favourable conditions for the observed push-moraine formation, while subglacial subsidence of salt structures will enhance erosion and contribute of tunnel-valley incision as in the village of Surendorf. We explain the generation of the major collapse-faults in the upper crust as a consequence of ice-load induced salt tectonics that occurred by reactivating of basement fault. Thus, the rise of the diapir and the supra-salt collapse-faults were reactivated during the Pleistocene ice advances.
ABSTRACT Advancing ice sheets have a strong impact on the earth’s topography. For example, they l... more ABSTRACT Advancing ice sheets have a strong impact on the earth’s topography. For example, they leave behind an erosional unconformity, bulldozer the underlying strata and form tunnel valleys, primarily by subglacial melt-water erosion and secondarily by direct glacial erosion. The conceptual models of the reactivation of faults within the upper crust, due to the ice sheets’ load, are also established. However, this phenomenon is also rather under-explored. Here, we propose a causal link between ice-load induced tectonics, the generation of near-vertical faults in the upper crust above an inherited deep-rooted fault and the evolution of tunnel valleys. The Kossau tunnel valley in the southeastern Bay of Kiel has been surveyed by means of high-resolution multi-channel seismic and echosounder data. It strikes almost south to north and can be mapped over a distance of ca. 50 km. It is 1200 to 8000 m wide with a valley of up to 200 m deep. Quaternary deposits fill the valley and cover the adjacent glaciogenic unconformity. A near-vertical fault system with an apparent dip angle of >80°, which reaches from the top Zechstein upwards into the Quaternary, underlies the valley. The fault partially pierces the seafloor and growth is observed within the uppermost Quaternary strata only. Consequently, the fault evolved in the Late Quaternary. The fault is associated with an anticline that is between 700 and 3000 m wide and about 20 to 40 m high. The fault–anticline assemblage neither resembles any typical extensional, compressional or strike-slip deformation pattern, nor is it related to salt tectonics. Based on the observed position and deformation pattern of the fault–anticline assemblage, we suggest that these structures formed as a consequence of the differential ice-load induced tectonics above an inherited deep-rooted sub-salt fault related to the Glückstadt Graben. Lateral variations in the ice-load during the ice sheet’s advance caused differential subsidence, thus rejuvenating the deep-rooted fault. As a result, the inherited fault propagated upwards across the Zechstein and post-Permian overburden and further grew during the ice sheet’s retreat. The developing fault and anticline system under the ice sheet created a weakness zone that facilitated erosion by pressurized glacial and subglacial melt-water, as well as by the glaciers themselves. Near-vertical faults cutting through the post-Permian are abundant in the southwestern Baltic realm, which implies that the ice-load induced tectonic activity described above was not an isolated incident.
Abstract In this study we investigate the Late Cretaceous to recent tectonic evolution of the sou... more Abstract In this study we investigate the Late Cretaceous to recent tectonic evolution of the southwestern Baltic Sea based on a dense grid of seismic reflection profiles. This area covers the Baltic Sea sector of the salt influenced North German Basin and its transition to the salt free Baltic Shield across the Tornquist Zone. The Upper Cretaceous to recent structural evolution is discussed by means of individual seismic sections and derived high-resolution time-structure maps of the main horizons, i.e., the Upper Cretaceous, Tertiary and Pleistocene. The Upper Cretaceous and Tertiary layers reveal numerous significant faults throughout the study area. Several of these faults propagate upwards across the unconsolidated Pleistocene sediments and occasionally penetrate the surface. The salt influenced North German Basin reveals three major fault trends: NW-SE, N-S and NNE-SSW. Several of these faults are located directly above basement (sub-salt) faults and salt pillows. The majority of these faults are trending N-S to NNE-SSW and parallel the direction of the Gluckstadt Graben faults. In the salt free Tornquist Zone, we identify two major shallow fault trends, which are NW-SE and NE-SW. The majority of these faults are located above basement faults, following the direction of the Tornquist Zone. We conclude that generally basement tectonics controls activation and trends of shallow faults. If salt is present, the ductile salt layer causes a lateral shift between the sub- and supra-salt faults. Major plate reorganisation related to the Africa-Iberia-Europe convergence and the subsequent Alpine Orogeny caused reactivation of pre-existing faults and vertical salt movement in the Late Cretaceous. The change of stress orientation from NE-SW to a NW-SE during Neogene caused another phase of fault and salt tectonic reactivation. We explain that the ice-sheet loading and/or present-day stress field may have acted in combination, causing the recent tectonics and upward extension of the faults.
Based on integration of seismic reflection and well data analysis this study examines two major c... more Based on integration of seismic reflection and well data analysis this study examines two major contourite systems that developed during the late Creta-ceous in the southern Baltic Sea. The evolution of these Chalk Sea con-tourite systems between the Kattegat and the southern Baltic Sea started when Turonian to Campanian inversion tectonics overprinted the rather flat sea floor of the epeiric Chalk Sea. The Tornquist Zone and adjacent smaller blocks were uplifted and formed elongated obstacles that influenced the bottom currents. As a consequence of the inversion, the sea floor west of the Tornquist Zone tilted towards the northeast , creating an asymmetrical sub-basin with a steep marginal slope in the northeast and a gentle dipping slope in the southwest. A southeast directed contour current emerged in the Coniacian or Santonian along the southwestern basin margin, creating contourite channels and drifts. The previously studied contourite system offshore Stevns Klint is part of this system. A second, deeper and northwest directed counter-flow emerged along and parallel to the Tornquist Zone in the later Campanian, but was strongest in the Maastrichtian. This bottom current moderated the evolution of a drift-moat system adjacent to the elevated Tornquist Zone. The near surface Alnarp Valley in Scania represents the Danian palaeo-moat that linked the Pomeranian Bay with the Kattegat. The previously studied contourite system in the Kattegat represents the northwestern prolongation of this system. This study links previous observations from the Kattegat and offshore Stevns Klint to the here inferred two currents, a more shallow, southeast directed and a deeper, northwest directed flow.
In this study we investigate faulting above a salt wall in the Glückstadt Graben / North German B... more In this study we investigate faulting above a salt wall in the Glückstadt Graben / North German Basin. Two supra-salt faults are mapped from coast to coast over a distance of 6–9 km based on offshore and onshore seismic data. These faults form a ca. 2 km wide crestal collapse graben and pierce the seafloor. Salt wall evolution started in the early Late Triassic to Early Jurassic due to regional extension and resulting sub-salt faulting. The salt wall was eroded following exposure to costal and sub-aerial erosion by the regional Mid-Late Jurassic to Early Cretaceous uplift. Late Cretaceous to Early Paleogene compressional tectonics reactivated the vertical salt movement and shortened the salt wall, creating a salt-cored anticline with the crestal collapse graben above. The supra-salt faults were reactivated between the Late Eocene and Middle Miocene when the principal horizontal stress orientation changed from a NE-SW to a NW-SE, the present-day orientation. Stratigraphic data indicate that these faults moved mainly in the Cenozoic. Several observations strongly suggest that the faults continued developing during the Pleistocene until today: (i) the Pleistocene Unconformity is concave upwards and cut by faults; (ii) growth strata within the marine Holocene deposits above the graben imply recent tectonic movements; (iii) onshore high-resolution P-wave vibroseis data of the south-eastern Eckernförde Bay suggest about 10 m of faulted Holocene strata; and (iv) marine seismic data show the faults piercing the seafloor. We suggest that the recent salt tectonics and upward propagation of supra-salt faults resulted from differential ice-sheet loading. That effect on the salt wall stopped once ice grew over the whole structure, at which time the wall subsided because of ice loading. The salt wall and faults were reactivated again once the ice front retreated so that the ice loaded only one side of the structure.
The Loop Current and its associated eddy-shedding in the Gulf of Mexico are mediating the oceanic... more The Loop Current and its associated eddy-shedding in the Gulf of Mexico are mediating the oceanic heat and salt flux from the Caribbean into the Atlantic Ocean via Yucatan Strait. Changes in Yucatan Strait surface and intermediate through flow over geological timescales in relation to sea level, through flow velocity, and atmospheric circulation are not well constrained to date. The main objective of the geological sediment sampling program was to establish spatially and temporally high-resolving reconstructions of the Late Pleistocene surface, subsurface and intermediate water variability, in relation to the Loop Current variations and related eddy shedding, Antarctic Intermediate Water migrations, and changes in the Atlantic Meridional Overturning Circulation. The multi-channel seismic program was designed to establish a sequence stratigraphic framework for current controlled sediment formations which reflect the onset and intensification of the Gulfstream as well as Mid-Pleistoce...
The Loop Current and its associated eddy-shedding in the Gulf of Mexico are mediating the oceanic... more The Loop Current and its associated eddy-shedding in the Gulf of Mexico are mediating the oceanic heat and salt flux from the Caribbean into the Atlantic Ocean via Yucatan Strait. Changes in Yucatan Strait surface and intermediate through flow over geological timescales in relation to sea level, through flow velocity, and atmospheric circulation are not well constrained to date. The main objective of the geological sediment sampling program was to establish spatially and temporally high-resolving reconstructions of the Late Pleistocene surface, subsurface and intermediate water variability, in relation to the Loop Current variations and related eddy shedding, Antarctic Intermediate Water migrations, and changes in the Atlantic Meridional Overturning Circulation. The multi-channel seismic program was designed to establish a sequence stratigraphic framework for current controlled sediment formations which reflect the onset and intensification of the Gulfstream as well as Mid-Pleistoce...
A spectacular feature of the Arabian-Nubian Shield (ANS) is the abundance of well-exposed and ext... more A spectacular feature of the Arabian-Nubian Shield (ANS) is the abundance of well-exposed and extensive Neoproterozoic dike swarms of variable compositions. Most of these dikes are late to post-orogenic with respect to the East African Orogen (EAO) and are unmetamorphosed. We dated a composite dike with latite margins and a rhyolite core (607 ± 6 Ma, U-Pb), a biotite rhyolite dike (600 ± 4 Ma, 40 Ar/ 39 Ar age of biotite), an andesite dike (594 ± 3, 40 Ar/ 39 Ar age of amphibole) and a dolerite dike (~579 Ma, 40 Ar/ 39 Ar whole rock total gas age). We propose that the first three dikes represent one generation that was emplaced at different episodes extending between 607 and 590 Ma. Time and composition equivalent dikes are common in the northern ANS. The dikes crosscut late collisional granitoids and geochemically display a subduction-related character as evidenced by a negative Nb-Ta anomaly. These dikes are absent in the alkali feldspar A-type Humrat Syenogranite dated at 586 ± 5 Ma in Jordan and equivalent rocks in the northern ANS, which are crosscut only by the (~579 Ma) dolerite dikes. The within-plate character of the dolerite dikes is supported by the absence of the Nb-Ta anomaly and high field strength element geochemistry. We propose that the dolerite dikes are a generation, distinct from the~607-590 Ma dikes, that reflects a change in tectonic regime and represents the last magmatic activity of the Neoproterozoic in the northern ANS. The ages of the dikes dated in this study agree with the published age range of the transitional stage from late orogenic calc-alkaline to extensional alkaline tectono-magmatic setting for the ANS. We propose that the magmatic activity was terminated~50 m.y. before the age of the Cambrian un-conformity at~530 Ma. Correlation with ages of dikes and magmatic rocks in the northern ANS favors this supposition. The dike geochemistry and geochronology are compatible with a tectonic model that involves mantle lithosphere delamination from below the northern ANS after a significant crust-mantle thickening caused by the EAO, followed by thermal relaxation, subsidence and gradual denudation until the age of the un-conformity at~530 Ma.
To evaluate the effect of the industrial activities on the sediment quality, we investigated long... more To evaluate the effect of the industrial activities on the sediment quality, we investigated long-term records of physical and chemical properties of bottom-surface sediments from a complex industrial site along the Jordanian coast of the Gulf of Aqaba. Sediment samples were collected from 10 m depth once a year from six different stations (S1-S6) and analyzed for grain size, loss on ignition (LOI), organic carbon (OC), hydrogen sulfide (H 2 S), total nitrogen (TN), total phosphorus (TP), and heavy metal contents. Temporal variations show a constant/decreasing trend for H 2 S, OC, and LOI, whereas an increasing trend for TN and TP was observed. Heavy metal concentrations reveal almost constant trends over time for Cd, Cu, and Zn and a decreasing trend for Cr and Pb. Statistical analysis indicates that the differences between the different sampling stations were insignificant for almost all variables. However, some differences were observed, as the highest values were recorded in S3 and the lowest values in S1. The textural proprieties show no significant variation among sites. As a result, the sediment quality at the industrial site is comparable with that in other sites along the northern Gulf of Aqaba. Sediments at the industrial site appear to have attained steady-state equilibrium where basic environmental parameters are insignificantly modified from the baseline values of the area. The decreasing trend observed over time indicates a significant improvement in the environmental quality attributed to the stringent implementation of environmental regulation in Aqaba (e.g., zero discharge policy).
The precise seismic sub-structural interpretation of Turkwal field in the Central Potwar region h... more The precise seismic sub-structural interpretation of Turkwal field in the Central Potwar region has been carried out. The research work was confined to the large fore-thrust which serves as an anticlinal structural trap through ten 2D seismic lines. Precise seismic sub-structural model of Eocene Chorgali Limestone with precise orientation of thrust and oblique slip faults shows presence of a huge fracture, which made the Eocene Chorgali Limestone a good reservoir. The abrupt surface changes in dip azimuth for Chorgali Limestone verifies the structural trends and also verifies the presence of structural traps in the Turkwal field. The logs of three wells (Turkwal deep X-2, Turkwal-01 and Fimkassar-01) were analyzed for the petrophysical studies, well synthetic results and generation of Amplitude Versus Offset (AVO) model for the area. AVO model of Turkwal deep X-2 shows abrupt changes in amplitude which depicts the presence of hydrocarbon content. Well correlation technique was used to define the overall stratigraphic setting and the thickness of the reservoir formation in two wells of Turkwal-01 and Turkwal deep X-2. Chorgali Limestone in Turkwal-01 is an upward thrusted anticlinal structure and because of close position of the both wells around the faulted anticlinal structure its thickness less differs compare with Turkwal deep X-2. The overall results confirm that the Turkwal field is amongst several similar thrusts bound oil bearing structure in the Potwar basin.
Based on integration of seismic reflection and well data analysis this study examines two major c... more Based on integration of seismic reflection and well data analysis this study examines two major contourite systems that developed during the late Creta-ceous in the southern Baltic Sea. The evolution of these Chalk Sea con-tourite systems between the Kattegat and the southern Baltic Sea started when Turonian to Campanian inversion tectonics overprinted the rather flat sea floor of the epeiric Chalk Sea. The Tornquist Zone and adjacent smaller blocks were uplifted and formed elongated obstacles that influenced the bottom currents. As a consequence of the inversion, the sea floor west of the Tornquist Zone tilted towards the northeast , creating an asymmetrical sub-basin with a steep marginal slope in the northeast and a gentle dipping slope in the southwest. A southeast directed contour current emerged in the Coniacian or Santonian along the southwestern basin margin, creating contourite channels and drifts. The previously studied contourite system offshore Stevns Klint is part of this system. A second, deeper and northwest directed counter-flow emerged along and parallel to the Tornquist Zone in the later Campanian, but was strongest in the Maastrichtian. This bottom current moderated the evolution of a drift-moat system adjacent to the elevated Tornquist Zone. The near surface Alnarp Valley in Scania represents the Danian palaeo-moat that linked the Pomeranian Bay with the Kattegat. The previously studied contourite system in the Kattegat represents the northwestern prolongation of this system. This study links previous observations from the Kattegat and offshore Stevns Klint to the here inferred two currents, a more shallow, southeast directed and a deeper, northwest directed flow.
Groundwater vulnerability maps were created for the Corridor wellfield (~300 km 2) in the eastern... more Groundwater vulnerability maps were created for the Corridor wellfield (~300 km 2) in the eastern Jordan using the DRASTIC and modified DRASTIC groundwater vulnerability assessment models. The study area is considered as one of the most important well fields therein providing partially three governorates with the needed drinking water. Detailed geological and hydrogeological parameters as well as the land-use map of the area were obtained from various sources to utilize both models. ArcGIS software was used for calculations and maps preparation. As a result, the generic DRASTIC vulnerability index ranges between 109 and 168. Thus, two vulnerability classes were observed, moderate (9.9%) and high (90.1%) vulnerability classes. On the other hand, the modified DRASTIC model (risk map) is taking into account the land-use map classes in the study area. The output risk map reveals two main classes, the moderate and high-risk areas. The moderate risk areas occupy 9.3% of the total volume of the study area while the high-risk areas are 90.7%. Due to the high depth to groundwater within the area (between 90 m and 390 m), the depth to groundwater intervals was modified in the model to become more comfortable with the situation in Jor-dan. The high percentage of the high vulnerable areas against pollutants reflects the need to do more investigation for the studied area.
This paper presents new findings that contribute to the understanding of the deformational style ... more This paper presents new findings that contribute to the understanding of the deformational style of the Wadi Shueib Structure (WSS) and the Amman-Halabat Structure (AHS) and their relationship with the regional tectonic regime of the Dead Sea Transform Fault (DSTF). Our research utilized Landsat-8 OLI imagery for the automatic extraction of lineaments, and our lineament mapping was facilitated by processing and digital image enhancement using principal component analysis (PCA). Our data revealed a relatively higher density of lineaments along the extension of the major faults of the WSS and AHS. However, a relatively lower density of lineaments was shown in areas covered by recent deposits. Two major lineament trends were observed (NNE-SSW and NW-SE) in addition to a minor one (NE-SW), and most of these lineaments are parallel to the orientation of the WSS and AHS. We offer the supposition that the DSTF has merged into the major faults of the WSS and AHS. We further suppose that these faults were reactivated as a restraining bend composed of active strike-slip fault branches that developed due to the NNW-SSE-trending Dead Sea transpressional stress field. Depending on the relationship between the direction of the WSF and AHF strands and the regional tectonic displacement along the DSTF, thrust components are present on faults with horsetail geometry, and these movements are accompanied by folding and uplifting. Thus, the major faults of the WSS and AHS represent a contractional horsetail geometry with associated folding and thrusting deformation.
In this study we investigate the Late Cretaceous to recent tectonic evolution of the southwestern... more In this study we investigate the Late Cretaceous to recent tectonic evolution of the southwestern Baltic Sea based on a dense grid of seismic reflection profiles. This area covers the Baltic Sea sector of the salt influenced North German Basin and its transition to the salt free Baltic Shield across the Tornquist Zone. The Upper Cretaceous to recent structural evolution is discussed by means of individual seismic sections and derived high-resolution time-structure maps of the main horizons, i.e., the Upper Cretaceous, Tertiary and Pleistocene. The Upper Creta-ceous and Tertiary layers reveal numerous significant faults throughout the study area. Several of these faults propagate upwards across the unconsolidated Pleistocene sediments and occasionally penetrate the surface. The salt influenced North German Basin reveals three major fault trends: NW-SE, N-S and NNE-SSW. Several of these faults are located directly above basement (sub-salt) faults and salt pillows. The majority of these faults are trending N-S to NNE-SSW and parallel the direction of the Glückstadt Graben faults. In the salt free Tornquist Zone, we identify two major shallow fault trends, which are NW-SE and NE-SW. The majority of these faults are located above basement faults, following the direction of the Tornquist Zone. We conclude that generally basement tectonics controls activation and trends of shallow faults. If salt is present, the ductile salt layer causes a lateral shift between the sub-and supra-salt faults. Major plate reorganisation related to the Africa-Iberia-Europe convergence and the subsequent Alpine Orogeny caused reactivation of pre-existing faults and vertical salt movement in the Late Cretaceous. The change of stress orientation from NE-SW to a NW-SE during Neogene caused another phase of fault and salt tectonic reactivation. We explain that the ice-sheet loading and/or present day stress field may have acted in combination, causing the recent tectonics and upward extension of the faults.
The research program aimed on the in-depth understanding the volcano-tectonic evolution of the Az... more The research program aimed on the in-depth understanding the volcano-tectonic evolution of the Azores plateau and associated geo-hazards such as submarine landslides and volcanic surges. Oceanic plateaus like the Azores plateau are large areas of anomalously thick crust forming large bathymetric swells in the ocean basins and their petrological formation and subsequent sedimentological evolution is only poorly understood. The reason for the magmatic and volcanic activity that built the igneous part of the Azores Plateau is intensely debated. As in other places of the world deep, hot mantle plumes are believed to cause the magmatism due to their high excess temperature. According to an alternative model volcanism is explained by excess melting of the mantle due to an elevated volatile content. In addition, the structural evolution of the plateau and the relationship between rifting and volcanism particularly in the Azores is a matter of active scientific debate. It is suggested that an oblique spreading axis jumped incrementally from the East Azores Fracture Zone towards the north-east. The Terceira rift axis represents the present stage and the recent plate boundary between the Eurasian and African plates. In addition, recurrence rate, trigger mechanisms, volumes, and transport processes of large scale mass wasting events are amongst the scientific questions targeted. Multi-beam and seismic data will provide the crucial site-survey data for ROV sampling during a future research cruise. The micro- and nano-plastic concentration within the surface water will be measured by geochemical analyses of water sampled during the cruise.
In this study we investigate faulting above a salt wall in the Glückstadt Graben / North German B... more In this study we investigate faulting above a salt wall in the Glückstadt Graben / North German Basin. Two supra-salt faults are mapped from coast to coast over a distance of 6–9 km based on offshore and onshore seismic data. These faults form a ca. 2 km wide crestal collapse graben and pierce the seafloor. Salt wall evolution started in the early Late Triassic to Early Jurassic due to regional extension and resulting sub-salt faulting. The salt wall was eroded following exposure to costal and sub-aerial erosion by the regional Mid-Late Jurassic to Early Cretaceous uplift. Late Cretaceous to Early Paleogene compressional tectonics reactivated the vertical salt movement and shortened the salt wall, creating a salt-cored anticline with the crestal collapse graben above. The supra-salt faults were reactivated between the Late Eocene and Middle Miocene when the principal horizontal stress orientation changed from a NE-SW to a NW-SE, the present-day orientation. Stratigraphic data indicate that these faults moved mainly in the Cenozoic. Several observations strongly suggest that the faults continued developing during the Pleistocene until today: (i) the Pleistocene Unconformity is concave upwards and cut by faults; (ii) growth strata within the marine Holocene deposits above the graben imply recent tectonic movements; (iii) onshore high-resolution P-wave vibroseis data of the south-eastern Eckernförde Bay suggest about 10 m of faulted Holocene strata; and (iv) marine seismic data show the faults piercing the seafloor. We suggest that the recent salt tectonics and upward propagation of supra-salt faults resulted from differential ice-sheet loading. That effect on the salt wall stopped once ice grew over the whole structure, at which time the wall subsided because of ice loading. The salt wall and faults were reactivated again once the ice front retreated so that the ice loaded only one side of the structure.
The Loop Current and its associated eddy-shedding in the Gulf of Mexico are mediating the oceanic... more The Loop Current and its associated eddy-shedding in the Gulf of Mexico are mediating the oceanic heat and salt flux from the Caribbean into the Atlantic Ocean via Yucatan Strait. Changes in Yucatan Strait surface and intermediate through flow over geological timescales in relation to sea level, through flow velocity, and atmospheric circulation are not well constrained to date. The main objective of the geological sediment sampling program was to establish spatially and temporally high-resolving reconstructions of the Late Pleistocene surface, subsurface and intermediate water variability, in relation to the Loop Current variations and related eddy shedding, Antarctic Intermediate Water migrations, and changes in the Atlantic Meridional Overturning Circulation. The multi-channel seismic program was designed to establish a sequence stratigraphic framework for current controlled sediment formations which reflect the onset and intensification of the Gulfstream as well as Mid-Pleistoce...
Jörg Lang (1), Muayyad Al Hseinat (2), Christian Brandes (1), Andrea Hampel (1), Christian Hübsch... more Jörg Lang (1), Muayyad Al Hseinat (2), Christian Brandes (1), Andrea Hampel (1), Christian Hübscher (2), and Jutta Winsemann (1)
(1) Leibniz Universität Hannover, Institut für Geologie, Hannover, Germany (lang@geowi.uni-hannover.de), (2) Universität Hamburg, Institut für Geophysik, Hamburg, Germany
A correlation between salt structures, glacigenic features and faulting of Pleistocene deposits above salt structures has been recognized in many places of the formerly glaciated areas in northern central Europe and attributed to ice-sheet loading. Conceptual models predict that the load applied by an ice sheet will favour ice-marginal salt rise and obstruct salt rise beneath the ice sheet (e.g., Liszkowski, 1993). To test these models, we simulated the response of salt structures to ice-sheet loading using a 2D finite-element model (ABAQUS). The subsurface geometries used in our models are based on regional geological cross-sections and 2D seismic profiles of salt structures in the Central European Basin System. The model layers represent (i) sedimentary rocks of elastoplastic rheology, (ii) a viscoelastic salt structure and (iii) elastoplastic basement rocks. At the model surface a temporarily and spatially variable pressure simulates ice-sheet loading. All our simulations show a response of salt structures to ice-sheet loading, which strongly depends on the location of the ice margin relative to the salt structure. Salt structures rise in front of the ice margin (up to 4 m), if load is applied to the salt source layer. Beneath an ice sheet salt structures are pushed down (up to 36 m). Much of the subglacial downwards displacement is compensated by a reversal of the movement during ice retreat. The resulting surface displacements are therefore rather low and depend on the spatial and temporal configuration of the ice load (Lang et al., 2014). Permanent deformation is restricted to the model layers above the salt structure, which either have a low yield stress to represent the unconsolidated infill of secondary rim-synclines or are dissected by steeply dipping crestal graben faults. Ice-induced salt movements will reactivate faults above the crests of salt structures, although the resulting displacements will be low due to the repeated reversals of the sense of movement. The surface displacement due to ice-load induced salt movement will impact the pattern of glacigenic deformation, erosion and deposition. Ice-marginal uplift will provide favourable conditions for push-moraine formation, while subglacial subsidence of salt structures will enhance erosion and contribute to tunnel-valley incision.
References Lang, J., Hampel, A., Brandes, C., Winsemann, J. (2014) Response of salt structures to ice-sheet loading: implications for ice-marginal and subglacial processes. Quaternary Science Reviews 101, 217-233. Liszkowski, J. (1993) The effects of Pleistocene ice-sheet loading-deloading cycles on the bedrock structure of Poland. Folia Quaternaria 64, 7-23.
M. Al Hseinat*1, C. Hübscher1, J. Lang2, I. Ott1, U. Polom3, C. Brandes2, A. Hampel2, J. Winseman... more M. Al Hseinat*1, C. Hübscher1, J. Lang2, I. Ott1, U. Polom3, C. Brandes2, A. Hampel2, J. Winsemann2 (1) University of Hamburg, Institute of Geophysics, Hamburg, Germany (2) Leibniz Universität Hannover, Institut für Geologie, Hannover, Germany (3) Leibniz Institute for Applied Geophysics, Hannover, Germany
Marine high-resolution multi-channel seismic data from the Eckernförde Bay in the SW Baltic Sea show two major NNW-SSE striking faults above a salt diapir that evolved above eastern Glückstadt Graben faults. These normal faults are parallel and dip in opposing directions towards the core of an anticline, forming a crestal collapse graben above the crest of the salt anticline. Fault displacement proves that the crestal graben evolved mainly in the Cenozoic. The faults partly pierce the surface and are consequently active. The glacial erosional unconformity between the major faults is concave upwards and dissected by faults, implying that the Quaternary thin-skinned extension in the crestal graben pursued. A High-resolution P-wave seismic data reveal asymmetric and irregular normal and reverse faults atypical of thin-skinned extensional subsidence. Numerical modelling suggests that the recent tectonic overprinting of Pleistocene sediments results from differential loading by advancing ice-sheets, which squeezes salt into the salt diapir and causes diapir rise. During complete ice coverage the entire diapir is pushed down but rises again during ice retreat. The resulting absolute vertical displacement is low due to the repeated reversals of the sense of movement. Beside the deformation of Pleistocene sediments we attribute the reactivation of the crestal graben faults to ice-load induced salt movements. Ice-marginal uplift provides favourable conditions for the observed push-moraine formation, while subglacial subsidence of salt structures will enhance erosion and contribute of tunnel-valley incision as in the village of Surendorf. We explain the generation of the major collapse-faults in the upper crust as a consequence of ice-load induced salt tectonics that occurred by reactivating of basement fault. Thus, the rise of the diapir and the supra-salt collapse-faults were reactivated during the Pleistocene ice advances.
A systematic study of Base Quaternary mapping and shallow faults in the Northeast German Basin an... more A systematic study of Base Quaternary mapping and shallow faults in the Northeast German Basin and the transition zone to the Baltic shield has not been carried out yet. The availability of large (ca. 20.000 km), high-resolution, multi-channel seismic and hydroacoustic data from the southwestern Baltic Sea provides the unique chance to study the Quaternary geological evolution therein. The comparison of the Quaternary fault map with deep-rooted (basement) faults published in a large number of studies will give a first idea about the driving forces, e.g., plate tectonics, salt tectonics or ice-load induced tectonics. All seismic data were uploaded to the IHS ''KINGDOM'' interpretation system for depositional and structural interpretation. We primarily identified the Base Quaternary and Seafloor horizons in all seismic sections. Several faults cut the Base Quaternary surface and some of these faults are partially pierce the Seafloor horizon. A more detailed view of the parametric echosounder data elucidates that the Holocene reflections are in some cases faulted and cut by the underneath Quaternary faults. In KINGDOM we created a time-structure map that shows the present-day vertical depth (in two way travel time) to the Base Quaternary surface. In this case, time-structure map is used to identify the locations and trends of different fault systems that are affected the Base Quaternary horizons. This map illustrates that most of the faults are trending NW-SE and other faults NE-SW and NNE-SSW. Hence, we observe a vertical coincidence between the location of the Quaternary faults (this study) and the location of the deep-rooted (basement) faults (literature). We hypothesis basement faults were reactivated during the Pleistocene by advancing and retreating
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https://www.tib.eu/en/search/id/awi%3Adoi~10.2312%252Fcr_m113_1/
(1) Leibniz Universität Hannover, Institut für Geologie, Hannover, Germany (lang@geowi.uni-hannover.de), (2) Universität Hamburg, Institut für Geophysik, Hamburg, Germany
A correlation between salt structures, glacigenic features and faulting of Pleistocene deposits above salt structures has been recognized in many places of the formerly glaciated areas in northern central Europe and attributed to ice-sheet loading. Conceptual models predict that the load applied by an ice sheet will favour ice-marginal salt rise and obstruct salt rise beneath the ice sheet (e.g., Liszkowski, 1993). To test these models, we simulated the response of salt structures to ice-sheet loading using a 2D finite-element model (ABAQUS). The subsurface geometries used in our models are based on regional geological cross-sections and 2D seismic profiles of salt structures in the Central European Basin System. The model layers represent (i) sedimentary rocks of elastoplastic rheology, (ii) a viscoelastic salt structure and (iii) elastoplastic basement rocks. At the model surface a temporarily and spatially variable pressure simulates ice-sheet loading. All our simulations show a response of salt structures to ice-sheet loading, which strongly depends on the location of the ice margin relative to the salt structure. Salt structures rise in front of the ice margin (up to 4 m), if load is applied to the salt source layer. Beneath an ice sheet salt structures are pushed down (up to 36 m). Much of the subglacial downwards displacement is compensated by a reversal of the movement during ice retreat. The resulting surface displacements are therefore rather low and depend on the spatial and temporal configuration of the ice load (Lang et al., 2014). Permanent deformation is restricted to the model layers above the salt structure, which either have a low yield stress to represent the unconsolidated infill of secondary rim-synclines or are dissected by steeply dipping crestal graben faults. Ice-induced salt movements will reactivate faults above the crests of salt structures, although the resulting displacements will be low due to the repeated reversals of the sense of movement. The surface displacement due to ice-load induced salt movement will impact the pattern of glacigenic deformation, erosion and deposition. Ice-marginal uplift will provide favourable conditions for push-moraine formation, while subglacial subsidence of salt structures will enhance erosion and contribute to tunnel-valley incision.
References
Lang, J., Hampel, A., Brandes, C., Winsemann, J. (2014) Response of salt structures to ice-sheet loading: implications for ice-marginal and subglacial processes. Quaternary Science Reviews 101, 217-233.
Liszkowski, J. (1993) The effects of Pleistocene ice-sheet loading-deloading cycles on the bedrock structure of Poland. Folia Quaternaria 64, 7-23.
(1) University of Hamburg, Institute of Geophysics, Hamburg, Germany
(2) Leibniz Universität Hannover, Institut für Geologie, Hannover, Germany
(3) Leibniz Institute for Applied Geophysics, Hannover, Germany
Marine high-resolution multi-channel seismic data from the Eckernförde Bay in the SW Baltic Sea show two major NNW-SSE striking faults above a salt diapir that evolved above eastern Glückstadt Graben faults. These normal faults are parallel and dip in opposing directions towards the core of an anticline, forming a crestal collapse graben above the crest of the salt anticline. Fault displacement proves that the crestal graben evolved mainly in the Cenozoic. The faults partly pierce the surface and are consequently active. The glacial erosional unconformity between the major faults is concave upwards and dissected by faults, implying that the Quaternary thin-skinned extension in the crestal graben pursued. A High-resolution P-wave seismic data reveal asymmetric and irregular normal and reverse faults atypical of thin-skinned extensional subsidence. Numerical modelling suggests that the recent tectonic overprinting of Pleistocene sediments results from differential loading by advancing ice-sheets, which squeezes salt into the salt diapir and causes diapir rise. During complete ice coverage the entire diapir is pushed down but rises again during ice retreat. The resulting absolute vertical displacement is low due to the repeated reversals of the sense of movement. Beside the deformation of Pleistocene sediments we attribute the reactivation of the crestal graben faults to ice-load induced salt movements. Ice-marginal uplift provides favourable conditions for the observed push-moraine formation, while subglacial subsidence of salt structures will enhance erosion and contribute of tunnel-valley incision as in the village of Surendorf. We explain the generation of the major collapse-faults in the upper crust as a consequence of ice-load induced salt tectonics that occurred by reactivating of basement fault. Thus, the rise of the diapir and the supra-salt collapse-faults were reactivated during the Pleistocene ice advances.
https://www.tib.eu/en/search/id/awi%3Adoi~10.2312%252Fcr_m113_1/
(1) Leibniz Universität Hannover, Institut für Geologie, Hannover, Germany (lang@geowi.uni-hannover.de), (2) Universität Hamburg, Institut für Geophysik, Hamburg, Germany
A correlation between salt structures, glacigenic features and faulting of Pleistocene deposits above salt structures has been recognized in many places of the formerly glaciated areas in northern central Europe and attributed to ice-sheet loading. Conceptual models predict that the load applied by an ice sheet will favour ice-marginal salt rise and obstruct salt rise beneath the ice sheet (e.g., Liszkowski, 1993). To test these models, we simulated the response of salt structures to ice-sheet loading using a 2D finite-element model (ABAQUS). The subsurface geometries used in our models are based on regional geological cross-sections and 2D seismic profiles of salt structures in the Central European Basin System. The model layers represent (i) sedimentary rocks of elastoplastic rheology, (ii) a viscoelastic salt structure and (iii) elastoplastic basement rocks. At the model surface a temporarily and spatially variable pressure simulates ice-sheet loading. All our simulations show a response of salt structures to ice-sheet loading, which strongly depends on the location of the ice margin relative to the salt structure. Salt structures rise in front of the ice margin (up to 4 m), if load is applied to the salt source layer. Beneath an ice sheet salt structures are pushed down (up to 36 m). Much of the subglacial downwards displacement is compensated by a reversal of the movement during ice retreat. The resulting surface displacements are therefore rather low and depend on the spatial and temporal configuration of the ice load (Lang et al., 2014). Permanent deformation is restricted to the model layers above the salt structure, which either have a low yield stress to represent the unconsolidated infill of secondary rim-synclines or are dissected by steeply dipping crestal graben faults. Ice-induced salt movements will reactivate faults above the crests of salt structures, although the resulting displacements will be low due to the repeated reversals of the sense of movement. The surface displacement due to ice-load induced salt movement will impact the pattern of glacigenic deformation, erosion and deposition. Ice-marginal uplift will provide favourable conditions for push-moraine formation, while subglacial subsidence of salt structures will enhance erosion and contribute to tunnel-valley incision.
References
Lang, J., Hampel, A., Brandes, C., Winsemann, J. (2014) Response of salt structures to ice-sheet loading: implications for ice-marginal and subglacial processes. Quaternary Science Reviews 101, 217-233.
Liszkowski, J. (1993) The effects of Pleistocene ice-sheet loading-deloading cycles on the bedrock structure of Poland. Folia Quaternaria 64, 7-23.
(1) University of Hamburg, Institute of Geophysics, Hamburg, Germany
(2) Leibniz Universität Hannover, Institut für Geologie, Hannover, Germany
(3) Leibniz Institute for Applied Geophysics, Hannover, Germany
Marine high-resolution multi-channel seismic data from the Eckernförde Bay in the SW Baltic Sea show two major NNW-SSE striking faults above a salt diapir that evolved above eastern Glückstadt Graben faults. These normal faults are parallel and dip in opposing directions towards the core of an anticline, forming a crestal collapse graben above the crest of the salt anticline. Fault displacement proves that the crestal graben evolved mainly in the Cenozoic. The faults partly pierce the surface and are consequently active. The glacial erosional unconformity between the major faults is concave upwards and dissected by faults, implying that the Quaternary thin-skinned extension in the crestal graben pursued. A High-resolution P-wave seismic data reveal asymmetric and irregular normal and reverse faults atypical of thin-skinned extensional subsidence. Numerical modelling suggests that the recent tectonic overprinting of Pleistocene sediments results from differential loading by advancing ice-sheets, which squeezes salt into the salt diapir and causes diapir rise. During complete ice coverage the entire diapir is pushed down but rises again during ice retreat. The resulting absolute vertical displacement is low due to the repeated reversals of the sense of movement. Beside the deformation of Pleistocene sediments we attribute the reactivation of the crestal graben faults to ice-load induced salt movements. Ice-marginal uplift provides favourable conditions for the observed push-moraine formation, while subglacial subsidence of salt structures will enhance erosion and contribute of tunnel-valley incision as in the village of Surendorf. We explain the generation of the major collapse-faults in the upper crust as a consequence of ice-load induced salt tectonics that occurred by reactivating of basement fault. Thus, the rise of the diapir and the supra-salt collapse-faults were reactivated during the Pleistocene ice advances.