TY - JOUR A1 - Freymark, Jessica A1 - Bott, Judith A1 - Cacace, Mauro A1 - Ziegler, Moritz 0. A1 - Scheck-Wenderoth, Magdalena T1 - Influence of the Main Border Faults on the 3D Hydraulic Field of the Central Upper Rhine Graben JF - Geofluids N2 - 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). Y1 - 2019 U6 - https://doi.org/10.1155/2019/7520714 SN - 1468-8115 SN - 1468-8123 PB - Wiley-Hindawi CY - London ER - TY - JOUR A1 - Soumaya, Abdelkader A1 - Ben Ayed, Noureddine A1 - Rajabi, Mojtaba A1 - Meghraoui, Mustapha A1 - Delvaux, Damien A1 - Kadri, Ali A1 - Ziegler, Moritz A1 - Maouche, Said A1 - Braham, Ahmed T1 - Active Faulting Geometry and Stress Pattern Near Complex Strike-Slip Systems Along the Maghreb Region BT - Constraints on Active Convergence in the Western Mediterranean JF - Tectonics N2 - The Maghreb region (from Tunisia to Gibraltar) is a key area in the western Mediterranean to study the active tectonics and stress pattern across the Africa-Eurasia convergent plate boundary. In the present study, we compile comprehensive data set of well-constrained crustal stress indicators (from single focal mechanism solutions, formal inversion of focal mechanism solutions, and young geologic fault slip data) based on our and published data analyses. Stress inversion of focal mechanisms reveals a first-order transpression-compatible stress field and a second-order spatial variation of tectonic regime across the Maghreb region, with a relatively stable S-Hmax orientation from east to west. Therefore, the present-day active contraction of the western Africa-Eurasia plate boundary is accommodated by (1) E-W strike-slip faulting with reverse component along the Eastern Tell and Saharan-Tunisian Atlas, (2) a predominantly NE trending thrust faulting with strike-slip component in the Western Tell part, and (3) a conjugate strike-slip faulting regime with normal component in the Alboran/Rif domain. This spatial variation of the present-day stress field and faulting regime is relatively in agreement with the inferred stress information from neotectonic features. According to existing and newly proposed structural models, we highlight the role of main geometrically complex shear zones in the present-day stress pattern of the Maghreb region. Then, different geometries of these major inherited strike-slip faults and its related fractures (V-shaped conjugate fractures, horsetail splays faults, and Riedel fractures) impose their component on the second- and third-order stress regimes. Neotectonic and smoothed present-day stress map (mean S-Hmax orientation) reveal that plate boundary forces acting on the Africa-Eurasia collisional plates control the long wavelength of the stress field pattern in the Maghreb. The current tectonic deformations and the upper crustal stress field in the study area are governed by the interplay of the oblique plate convergence (i.e., Africa-Eurasia), lithosphere-mantle interaction, and preexisting tectonic weakness zones. KW - Maghreb KW - strike-slip system KW - conjugate fractures KW - horsetail splays KW - active stress KW - tectonic regime Y1 - 2018 U6 - https://doi.org/10.1029/2018TC004983 SN - 0278-7407 SN - 1944-9194 VL - 37 IS - 9 SP - 3148 EP - 3173 PB - American Geophysical Union CY - Washington ER -