@article{SippelMeessenCacaceetal.2017, author = {Sippel, Judith and Meessen, Christian and Cacace, Mauro and Mechie, James and Fishwick, Stewart and Heine, Christian and Scheck-Wenderoth, Magdalena and Strecker, Manfred}, title = {The Kenya rift revisited}, series = {Solid earth}, volume = {8}, journal = {Solid earth}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1869-9510}, doi = {10.5194/se-8-45-2017}, pages = {45 -- 81}, year = {2017}, abstract = {We present three-dimensional (3-D) models that describe the present-day thermal and rheological state of the lithosphere of the greater Kenya rift region aiming at a better understanding of the rift evolution, with a particular focus on plume-lithosphere interactions. The key methodology applied is the 3-D integration of diverse geological and geophysical observations using gravity modelling. Accordingly, the resulting lithospheric-scale 3-D density model is consistent with (i) reviewed descriptions of lithological variations in the sedimentary and volcanic cover, (ii) known trends in crust and mantle seismic velocities as revealed by seismic and seismological data and (iii) the observed gravity field. This data-based model is the first to image a 3-D density configuration of the crystalline crust for the entire region of Kenya and northern Tanzania. An upper and a basal crustal layer are differentiated, each composed of several domains of different average densities. We interpret these domains to trace back to the Precambrian terrane amalgamation associated with the East African Orogeny and to magmatic processes during Mesozoic and Cenozoic rifting phases. In combination with seismic velocities, the densities of these crustal domains indicate compositional differences. The derived lithological trends have been used to parameterise steady-state thermal and rheological models. These models indicate that crustal and mantle temperatures decrease from the Kenya rift in the west to eastern Kenya, while the integrated strength of the lithosphere increases. Thereby, the detailed strength configuration appears strongly controlled by the complex inherited crustal structure, which may have been decisive for the onset, localisation and propagation of rifting.}, language = {en} } @article{FreymarkBottCacaceetal.2019, author = {Freymark, Jessica and Bott, Judith and Cacace, Mauro and Ziegler, Moritz 0. and Scheck-Wenderoth, Magdalena}, title = {Influence of the Main Border Faults on the 3D Hydraulic Field of the Central Upper Rhine Graben}, series = {Geofluids}, journal = {Geofluids}, publisher = {Wiley-Hindawi}, address = {London}, issn = {1468-8115}, doi = {10.1155/2019/7520714}, pages = {21}, year = {2019}, abstract = {The Upper Rhine Graben (URG) is an active rift with a high geothermal potential. Despite being a well-studied area, the three-dimensional interaction of the main controlling factors of the thermal and hydraulic regime is still not fully understood. Therefore, we have used a data-based 3D structural model of the lithological configuration of the central URG for some conceptual numerical experiments of 3D coupled simulations of fluid and heat transport. To assess the influence of the main faults bordering the graben on the hydraulic and the deep thermal field, we carried out a sensitivity analysis on fault width and permeability. Depending on the assigned width and permeability of the main border faults, fluid velocity and temperatures are affected only in the direct proximity of the respective border faults. Hence, the hydraulic characteristics of these major faults do not significantly influence the graben-wide groundwater flow patterns. Instead, the different scenarios tested provide a consistent image of the main characteristics of fluid and heat transport as they have in common: (1) a topography-driven basin-wide fluid flow perpendicular to the rift axis from the graben shoulders to the rift center, (2) a N/NE-directed flow parallel to the rift axis in the center of the rift and, (3) a pronounced upflow of hot fluids along the rift central axis, where the streams from both sides of the rift merge. This upflow axis is predicted to occur predominantly in the center of the URG (northern and southern model area) and shifted towards the eastern boundary fault (central model area).}, language = {en} } @article{SpoonerScheckWenderothCacaceetal.2020, author = {Spooner, Cameron and Scheck-Wenderoth, Magdalena and Cacace, Mauro and G{\"o}tze, Hans-J{\"u}rgen and Luijendijk, Elco}, title = {The 3D thermal field across the Alpine orogen and its forelands and the relation to seismicity}, series = {Global and planetary change}, volume = {193}, journal = {Global and planetary change}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0921-8181}, doi = {10.1016/j.gloplacha.2020.103288}, pages = {14}, year = {2020}, abstract = {Temperature exerts a first order control on rock strength, principally via thermally activated creep deformation and on the distribution at depth of the brittle-ductile transition zone. The latter can be regarded as the lower bound to the seismogenic zone, thereby controlling the spatial distribution of seismicity within a lithospheric plate. As such, models of the crustal thermal field are important to understand the localisation of seismicity. Here we relate results from 3D simulations of the steady state thermal field of the Alpine orogen and its forelands to the distribution of seismicity in this seismically active area of Central Europe. The model takes into account how the crustal heterogeneity of the region effects thermal properties and is validated with a dataset of wellbore temperatures. We find that the Adriatic crust appears more mafic, through its radiogenic heat values (1.30E-06 W/m3) and maximum temperature of seismicity (600 degrees C), than the European crust (1.3-2.6E-06 W/m3 and 450 degrees C). We also show that at depths of < 10 km the thermal field is largely controlled by sedimentary blanketing or topographic effects, whilst the deeper temperature field is primarily controlled by the LAB topology and the distribution and parameterization of radiogenic heat sources within the upper crust.}, language = {en} } @article{DegenSpoonerScheckWenderothetal.2021, author = {Degen, Denise and Spooner, Cameron and Scheck-Wenderoth, Magdalena and Cacace, Mauro}, title = {How biased are our models?}, series = {Geoscientific model development : an interactive open access journal of the European Geosciences Union}, volume = {14}, journal = {Geoscientific model development : an interactive open access journal of the European Geosciences Union}, number = {11}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1991-959X}, doi = {10.5194/gmd-14-7133-2021}, pages = {7133 -- 7153}, year = {2021}, abstract = {Geophysical process simulations play a crucial role in the understanding of the subsurface. This understanding is required to provide, for instance, clean energy sources such as geothermal energy. However, the calibration and validation of the physical models heavily rely on state measurements such as temperature. In this work, we demonstrate that focusing analyses purely on measurements introduces a high bias. This is illustrated through global sensitivity studies. The extensive exploration of the parameter space becomes feasible through the construction of suitable surrogate models via the reduced basis method, where the bias is found to result from very unequal data distribution. We propose schemes to compensate for parts of this bias. However, the bias cannot be entirely compensated. Therefore, we demonstrate the consequences of this bias with the example of a model calibration.}, language = {en} } @article{RodriguezPicedaScheckWenderothBottetal.2022, author = {Rodriguez Piceda, Constanza and Scheck-Wenderoth, Magdalena and Bott, Judith and Gomez Dacal, Maria Laura and Cacace, Mauro and Pons, Michael and Prezzi, Claudia and Strecker, Manfred}, title = {Controls of the Lithospheric Thermal Field of an Ocean-Continent Subduction Zone}, series = {Lithosphere / Geological Society of America}, volume = {2022}, journal = {Lithosphere / Geological Society of America}, number = {1}, publisher = {GeoScienceWorld}, address = {McLean}, issn = {1941-8264}, doi = {10.2113/2022/2237272}, pages = {26}, year = {2022}, abstract = {In an ocean-continent subduction zone, the assessment of the lithospheric thermal state is essential to determine the controls of the deformation within the upper plate and the dip angle of the subducting lithosphere. In this study, we evaluate the degree of influence of both the configuration of the upper plate (i.e., thickness and composition of the rock units) and variations of the subduction angle on the lithospheric thermal field of the southern Central Andes (29 degrees-39 degrees S). Here, the subduction angle increases from subhorizontal (5 degrees) north of 33 degrees S to steep (similar to 30 degrees) in the south. We derived the 3D temperature and heat flow distribution of the lithosphere in the southern Central Andes considering conversion of S wave tomography to temperatures together with steady-state conductive thermal modeling. We found that the orogen is overall warmer than the forearc and the foreland and that the lithosphere of the northern part of the foreland appears colder than its southern counterpart. Sedimentary blanketing and the thickness of the radiogenic crust exert the main control on the shallow thermal field (<50km depth). Specific conditions are present where the oceanic slab is relatively shallow (<85 km depth) and the radiogenic crust is thin. This configuration results in relatively colder temperatures compared to regions where the radiogenic crust is thick and the slab is steep. At depths >50km, the temperatures of the overriding plate are mainly controlled by the mantle heat input and the subduction angle. The thermal field of the upper plate likely preserves the flat subduction angle and influences the spatial distribution of shortening.}, language = {en} } @article{SpoonerScheckWenderothCacaceetal.2022, author = {Spooner, Cameron and Scheck-Wenderoth, Magdalena and Cacace, Mauro and Anikiev, Denis}, title = {How Alpine seismicity relates to lithospheric strength}, series = {International journal of earth sciences}, volume = {111}, journal = {International journal of earth sciences}, number = {4}, publisher = {Springer}, address = {Berlin ; Heidelberg}, issn = {1437-3254}, doi = {10.1007/s00531-022-02174-5}, pages = {1201 -- 1221}, year = {2022}, abstract = {Despite the amount of research focussed on the Alpine orogen, different hypotheses still exist regarding varying spatial seismicity distribution patterns throughout the region. Previous measurement-constrained regional 3D models of lithospheric density distribution and thermal field facilitate the generation of a data-based rheological model of the region. In this study, we compute the long-term lithospheric strength and compare its spatial variation to observed seismicity patterns. We demonstrate how strength maxima within the crust (similar to 1 GPa) and upper mantle (> 2 GPa) occur at temperatures characteristic of the onset of crystal plasticity in those rocks (crust: 200-400 degrees C; mantle: similar to 600 degrees C), with almost all seismicity occurring in these regions. Correlation in the northern and southern forelands between crustal and lithospheric strengths and seismicity show different patterns of event distribution, reflecting their different tectonic settings. Seismicity in the plate boundary setting of the southern foreland corresponds to the integrated lithospheric strength, occurring mainly in the weaker domains surrounding the strong Adriatic plate. In the intraplate setting of the northern foreland, seismicity correlates to modelled crustal strength, and it mainly occurs in the weaker and warmer crust beneath the Upper Rhine Graben. We, therefore, suggest that seismicity in the upper crust is linked to weak crustal domains, which are more prone to localise deformation promoting failure and, depending on the local properties of the fault, earthquakes at relatively lower levels of accumulated stress than their neighbouring stronger counterparts. Upper mantle seismicity at depths greater than modelled brittle conditions, can be either explained by embrittlement of the mantle due to grain-size sensitive deformation within domains of active or recent slab cooling, or by dissipative weakening mechanisms, such as thermal runaway from shear heating and/or dehydration reactions within an overly ductile mantle. Results generated in this study are available for open access use to further discussions on the region.}, language = {en} } @article{RodriguezPicedaScheckWenderothCacaceetal.2022, author = {Rodriguez Piceda, Constanza and Scheck-Wenderoth, Magdalena and Cacace, Mauro and Bott, Judith and Strecker, Manfred}, title = {Long-Term Lithospheric Strength and Upper-Plate Seismicity in the Southern Central Andes, 29 degrees-39 degrees S}, series = {Geochemistry, geophysics, geosystems}, volume = {23}, journal = {Geochemistry, geophysics, geosystems}, number = {3}, publisher = {American Geophysical Union}, address = {Washington}, issn = {1525-2027}, doi = {10.1029/2021GC010171}, pages = {22}, year = {2022}, abstract = {We examined the relationship between the mechanical strength of the lithosphere and the distribution of seismicity within the overriding continental plate of the southern Central Andes (SCA, 29 degrees-39 degrees S), where the oceanic Nazca Plate changes its subduction angle between 33 degrees S and 35 degrees S, from subhorizontal in the north (<5 degrees) to steep in the south (similar to 30 degrees). We computed the long-term lithospheric strength based on an existing 3D model describing variations in thickness, density, and temperature of the main geological units forming the lithosphere of the SCA and adjacent forearc and foreland regions. The comparison between our results and seismicity within the overriding plate (upper-plate seismicity) shows that most of the events occur within the modeled brittle domain of the lithosphere. The depth where the deformation mode switches from brittle frictional to thermally activated ductile creep provides a conservative lower bound to the seismogenic zone in the overriding plate of the study area. We also found that the majority of upper-plate earthquakes occurs within the realm of first-order contrasts in integrated strength (12.7-13.3 log Pam in the Andean orogen vs. 13.5-13.9 log Pam in the forearc and the foreland). Specific conditions characterize the mechanically strong northern foreland of the Andes, where seismicity is likely explained by the effects of slab steepening.}, language = {en} }