Conference Agenda

In a trench along the central part of the Peel Boundary fault zone (PBFZ), Roer Valley Rift System (RVRS), southeastern Netherlands, evidence was found for a large faulting event that occurred around 14 ka. The event caused a fault scarp in unconsolidated sediments of ~1 meter. A colluvial wedge was formed next to the scarp. A second faulting event offsets this colluvial wedge by 0.2 - 0.1m. This event can be tentatively dated at ~13 ka. During or immediately after the second event, a large clastic dyke intruded along the fault plane. The dyke is not faulted, but its emplacement did cause some minor thrust faulting around the injection. The sudden character of the main faulting event, the brittle deformation style of loam layers, the lack of growth faulting in the colluvial wedge, the clastic dykes and the flame structures demonstrate that the main faulting event was a surface rupturing earthquake. Based on the scarp height, the estimated moment magnitude is about 6.8±0.3. Similar observations in a previous trench site suggest that the length of the surface rupture was at least 32 km, which is in agreement with the inferred magnitude. In general, glacio-isostatic movements might explain the earthquake events in the RVRS, like in northern Germany and Denmark. The Maas river crosses the PBFZ and shows several morphodynamic responses that are synchronous with the fault displacement. This forms a unique example of a transient river response to abrupt, surface-rupturing faulting and it is different to what classical models predict

Karsts have been documented in a large number of hydrocarbon reservoirs but their origin has generally been attributed to meteoric processes. In the last years, however, it has been increasingly recognized that many of them have a hypogenic origin which implies that the CO₂ and/or H₂S responsible for carbonate dissolution come from deep sources transport being favoured by upward flow of hot fluids. These cavities can be meter to few tens of meters large, therefore being below the resolution power of seismic studies; they are often associated with large dolomitized bodies and the occurrence of silicified rocks, as well as the presence of exotic minerals such as barite. Similar features are being identified in carbonate successions targeted for geothermal heat extraction. Tools are needed to predict the distribution and geometry of these karsts and, eventually to implement them in reservoir simulators.

In this contribution we report on the extensive work we have performed in caves developed in Neoproterozoic, generally tight carbonates of the Salitre Formation (Irece basin, Bahia state, Brazil). Integrating portable LiDAR modelling with structural and petrographic study we we propose a model for the development of these large-scale dissolution features.

Fluids responsible for the formation of the hypogenic caves were expelled from the base of the Braziliano orogeny and/or during subsequent exhumation and experienced long-range migration towards the foreland along regional aquifers. Once flow encountered steep features such as strike-slip or thrust faults, hot aggressive fluids started moving upward along the fault zone and/or related fracture corridors. If upward flow became prevented by the presence of an impermeable layers, fluids were compelled to flow laterally along high permeability layers. Permeability changes in the carbonates we have analysed are essentially related to changes in fracture density. The lateral flow and associated cooling of chemically aggressive fluids caused widespread speleogenesis and, roughly at the same time, deposition of silica. Geometry and dimensions of cave passages are controlled by a complex interplay between the ability of flow to bring acids to the carbonate wall and retrieve the reaction products and the reaction kinetics. The direction of passage was influenced by fracture sets, but their spacing is related to intrinsic flow processes rather than to the spacing of the fractures themselves. Our model has a general value and is applicable not only to foredeep settings but also in rifted continental margin were regional flow takes place and is often intercepted by steep faults.

This study deals with modelling the distribution of the subsurface temperature in space and the respective evolution in time in response to variations in the thermal boundary condition starting from the last glacial maximum (LGM, 26 ka BP). The aim here is to better understand (i) the feedback mechanisms between the atmosphere and solid earth components, and (ii) to which degree this coupling might be relevant for subsurface thermal modelling studies. The study area is the Central European Basin System (CEBS) in northern and Central Europe and state-of-the-art temperature reconstructions from the LGM to present have been used to model the surface thermal boundary conditions. Thereby, investigations on how such transient surface temperature conditions influence the temperature distribution with depth and over time within a heterogeneous sedimentary cover were carried out. The subsurface beneath the CEBS consists of more than 10 km thick sediments, which have been heavily restructured by salt movements during the whole Mesozoic evolution. Our 3D geological model resolves all major sedimentary and crustal domains, and we relied on the Max-Planck-Institute Earth System Model (MPI-ESM) temperature chronology. Starting from steady-state initial conditions, transient simulation runs are performed which cover the time from the LGM to present. Results are discussed in terms of temperature evolution over time and space. The focus will lie on quantifying subsurface conditions favourable to the establishment and maintenance of abnormally low temperature evolution and the related equilibration time within the sedimentary pile and which implications this might have for geothermal projects.

For the first time, we quantified the erosional pulse around the Permian-Triassic Boundary (PTB) over an entire sedimentary basin. Our GIS-based analysis relies on basin-wide homogenized seismic, sedimentary and stratigraphic data of the Petroleum Geological Atlas of the Southern Permian Basin. We calculated sediment volumes, sediment fluxes and sedimentation rates (SR) averaged over the entire basin from isopach maps of the Rotliegend, the Zechstein, the Lower, Middle and Upper Buntsandstein, the Muschelkalk and the Keuper. To separate chemical versus clastic sediments, we analyzed facies maps according to their predominant sediment composition.

The result is a 3 – 8 fold increase of clastic SR in the Lower Buntsandstein compared to the Rotliegend until the Keuper. These rates stayed elevated until the Upper Buntsandstein. We calculated clastic SR of 37 and 28 m/Myr in the Rotliegend and Zechstein, respectively, before they rose to 120 m/Myr in the Lower Buntsandstein. The Middle and Upper Buntsandstein show clastic SR in the order of 75 m/Myr, whereas they dropped to around 13 m/Myr in the Muschelkalk and Keuper. Mechanical denudation rates of the Buntsandstein is abnormally high compared to modern systems with similar climate and relief, but for the Rotliegend, Zechstein, Muschelkalk, and Keuper they are in a good agreement. Chemical SR mirror marine connectivity and the evaporitic level of the basin and cannot be treated in the sense of chemical denudation of the hinterland. Maximum chemical sedimentation took place in the Zechstein with 93 m/Myr, followed by the Upper Buntsandstein with 52 m/Myr and the Muschelkalk with 39 m/Myr. By reviewing of sedimentary, climatic, palynological, and tectonic constraints, we conclude that the detrital peak of the Buntsandstein must have been caused by the globally visible environmental perturbations at the PTB.

Abstract: The post-Variscan nonconformity formed due to the denudation of the Variscan orogen which had taken place between Devonian and early Permian. The widespread post-Variscan nonconformity in central Europe represents an important first-order bounding surface. In this study, the petrological, mineralogical, and geochemical features of the Paleozoic basement, the overlying volcanic and sedimentary rocks from the drill core GA1 on the Sprendlinger Horst, Germany are analyzed by polarizing microscope, SEM (scanning electron microscope), XRD, XRF and ICP-MS. The lithology of the basement rock is gabbroic diorite based on the mineral and major elements results. The ubiquitous fractures at the top of the gabbroic diorite indicate intense physical weathering. The overlying lava is a basaltic andesite, the physical weathering intensity is much more limited compared to the basement part. The secondary minerals are dominated by illite and a mixed-layer phase of illite and smectite in both basement and volcanic lava. From top to base, chemical weathering indices are indicating a transition from intermediate to un-weathered conditions in the gabbroic diorite and extremely to un-weathered conditions in the basaltic andesite. The τ values in both parts show an abnormal enrichment of K, Rb and Cs, which all are closely correlated. Accompanying hydrothermal minerals such as quartz, dolomite and adularia suggest an overprint by hydrothermal fluids. The overall order of element depletion in both basaltic andesite and gabbroic diorite during the weathering process is as follows: large ion lithophile elements (LILE) > rare earth elements (REE) > high field-strength elements (HFSE). Among REE, the heavy rare earth elements are less depleted than light rare earth elements. We conclude that palaeo-weathering as well as hydrothermal alteration during deep burial acted intensively along the nonconformity and that both can be well distinguished by the A-CN-K diagram combine with mineral characteristic.

The Upper Triassic Burgsandstein (Löwenstein Formation) in Franconia presents a fossil desertlike playa landscape with episodic supply of clastic material. It occurs as sheet wash and river deposits. A tight interplay of deposition and soil formation evidences longer periods of standstill with soil formation and shorter periods of fine to coarse clastic alluvial and fluvial deposition. While in shales tight bedding with unconformities veil the frequent and real change of sheet wash and soil formation, e.g., paleo-Vertisols, in clastic river deposits this deposition-soil interplay is much better detectable in form of quartz sandstone with Leptosols and Gleysols. Strong weathering close by in the dolomitic facies with deep solution cavities could find an equivalent in the siliceous facies as silicate weathering. Diagenetic garnishing are bleaching nodules, and Dia-Gley as reduction hems below the edge of water-saturated sandstone.
River deposits (fluments) show among themselves relationships of vertically alternating texture, in which a deposition uses the interflument depressions of the preceding flument deposits. As consequence, the lithological boundaries between subdivision units in the Burgsandstein are wavy.
Pleistocene sediment deformations act in both the mantle rock and the pre-Pleistocene deposits thus challenging considerations whether some of the deformations are of synsedimentary Triassic or of postsedimentary Pleistocene age.

Recent high resolution 3D seismic reflection data allowed to map Late Cenozoic Mass Transport Deposits (MTD) in great detail. These deformation structures in Miocene/Pliocene sediments are linked to the Eridanos delta system and the corresponding clinoforms. The structures have been identified in the Northern Dutch and German offshore where they can be found now in the depth range of 500-1000m bsf. Aim of this research was to identify and to characterize MTDs by scanning of state-of-the-art seismic data. The findings were used to assist in a better understanding of the spatial characteristics and internal anatomy of the features. In addition it was investigated to what extend these MTDs could constitute a drilling hazard for wells targeting deeper strata. The projects resulted in the detailed mapping of fourteen isolated mass-transport complexes with lateral dimensions ranging from 40-1300 km2. These geobodies are predominantly concentrated in the G, M, and F quadrants of the Dutch North Sea, and show a westward direction of sediment movement, in line with the direction of progradation of the Baltic river system. The internal structure of the MTDs indicates an extensional stress regime in the upper domain of the feature, while the lower domain is characterized by compressional stresses. Different options for slope failure were examined. Although, there are indications that the preconditions relate to climatic events in the changing late Cenozoic environment. Salt seems to play a role as a triggering mechanism in the southern part of the research area, since Zechstein salt diapirs were found directly beneath the headwall scarp of five out of fourteen MTDs. For the two northernmost MTDs indications for a relation with shallow gas are determined by the presence of bright spots. Based upon analysis of EBNs Geo-Drilling Event database, no significant drilling risk appears to be associated with penetrating these MTDs. Whilst the MTDs have been intersected by wells multiple times, none of the approximately 1000 drilling events in the database did correlate with the MTDs as mapped.

The Williston Basin is an intracratonic basin in Canada and the USA, located atop the structurally complex suture zone between the Archean Superior province to the east and the Archean basement of the Wyoming structural provinces to the west. The basin in general has a very homogeneous subsidence history throughout most of the Paleozoic, that can be largely explained by simple thermal subsidence.

This simple subsidence model should result in a very predictive facies distribution with more proximal facies near the basin margin and the more distal deposition near the basin center. Although this type of regional facies distribution is present during large parts of the Devonian, including the Famennian Lower Bakken Shale deposition, the Pronghorn Member of the Bakken Formation does not adhere to this model.

Results from detailed (sub-centimeter scale) lithofacies descriptions and chemostratigraphy from 26 cores from North Dakota and Saskatchewan suggests that the Pronghorn Member changes in facies, composition, and thickness along known structural lineaments, such as the Weldon-Brockton-Froid Zone and the Goose Lake Trend. The data presented here suggests that these lineaments were active during the latest Devonian and dissected the Williston Basin into multiple sub-basins during Pronghorn deposition.

This detailed facies and chemostratigraphy study provides a new careful look on the controls of late Devonian deposition in the Williston Basin, and food for thought how tectonics might influence deposition in an intracratonic basin located hundreds of miles from an orogenic front.