TY - JOUR A1 - Rajaonarison, Tahiry A. A1 - Stamps, D. Sarah A1 - Fishwick, Stewart A1 - Brune, Sascha A1 - Glerum, Anne A1 - Hu, Jiashun T1 - Numerical modeling of mantle flow beneath Madagascar to constrain upper mantle rheology beneath continental regions JF - Journal of geophysical research : Solid earth N2 - Over the past few decades, azimuthal seismic anisotropy measurements have been widely used proxy to study past and present-day deformation of the lithosphere and to characterize convection in the mantle. Beneath continental regions, distinguishing between shallow and deep sources of anisotropy remains difficult due to poor depth constraints of measurements and a lack of regional-scale geodynamic modeling. Here, we constrain the sources of seismic anisotropy beneath Madagascar where a complex pattern cannot be explained by a single process such as absolute plate motion, global mantle flow, or geology. We test the hypotheses that either Edge-Driven Convection (EDC) or mantle flow derived from mantle wind interactions with lithospheric topography is the dominant source of anisotropy beneath Madagascar. We, therefore, simulate two sets of mantle convection models using regional-scale 3-D computational modeling. We then calculate Lattice Preferred Orientation that develops along pathlines of the mantle flow models and use them to calculate synthetic splitting parameters. Comparison of predicted with observed seismic anisotropy shows a good fit in northern and southern Madagascar for the EDC model, but the mantle wind case only fits well in northern Madagascar. This result suggests the dominant control of the measured anisotropy may be from EDC, but the role of localized fossil anisotropy in narrow shear zones cannot be ruled out in southern Madagascar. Our results suggest that the asthenosphere beneath northern and southern Madagascar is dominated by dislocation creep. Dislocation creep rheology may be dominant in the upper asthenosphere beneath other regions of continental lithosphere. KW - seismic anisotropy KW - edge-driven convection KW - mantle flow modeling KW - lattice preferred orientations KW - lithosphere-mantle wind interactions KW - splitting parameters Y1 - 2019 U6 - https://doi.org/10.1029/2019JB018560 SN - 2169-9313 SN - 2169-9356 VL - 125 IS - 2 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Naliboff, John B. A1 - Glerum, Anne A1 - Brune, Sascha A1 - Péron-Pinvidic, G. A1 - Wrona, Thilo T1 - Development of 3-D rift heterogeneity through fault network evolution JF - Geophysical Research Letters N2 - Observations of rift and rifted margin architecture suggest that significant spatial and temporal structural heterogeneity develops during the multiphase evolution of continental rifting. Inheritance is often invoked to explain this heterogeneity, such as preexisting anisotropies in rock composition, rheology, and deformation. Here, we use high-resolution 3-D thermal-mechanical numerical models of continental extension to demonstrate that rift-parallel heterogeneity may develop solely through fault network evolution during the transition from distributed to localized deformation. In our models, the initial phase of distributed normal faulting is seeded through randomized initial strength perturbations in an otherwise laterally homogeneous lithosphere extending at a constant rate. Continued extension localizes deformation onto lithosphere-scale faults, which are laterally offset by tens of km and discontinuous along-strike. These results demonstrate that rift- and margin-parallel heterogeneity of large-scale fault patterns may in-part be a natural byproduct of fault network coalescence. KW - magma-poor KW - continental lithosphere KW - extension KW - insights KW - margins KW - architecture KW - systems KW - models KW - sea KW - reactivation Y1 - 2019 VL - 47 IS - 13 PB - John Wiley & Sons, Inc. CY - New Jersey ER - TY - GEN A1 - Naliboff, John B. A1 - Glerum, Anne A1 - Brune, Sascha A1 - Péron-Pinvidic, G. A1 - Wrona, Thilo T1 - Development of 3-D rift heterogeneity through fault network evolution T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Observations of rift and rifted margin architecture suggest that significant spatial and temporal structural heterogeneity develops during the multiphase evolution of continental rifting. Inheritance is often invoked to explain this heterogeneity, such as preexisting anisotropies in rock composition, rheology, and deformation. Here, we use high-resolution 3-D thermal-mechanical numerical models of continental extension to demonstrate that rift-parallel heterogeneity may develop solely through fault network evolution during the transition from distributed to localized deformation. In our models, the initial phase of distributed normal faulting is seeded through randomized initial strength perturbations in an otherwise laterally homogeneous lithosphere extending at a constant rate. Continued extension localizes deformation onto lithosphere-scale faults, which are laterally offset by tens of km and discontinuous along-strike. These results demonstrate that rift- and margin-parallel heterogeneity of large-scale fault patterns may in-part be a natural byproduct of fault network coalescence. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1183 KW - magma-poor KW - continental lithosphere KW - extension KW - insights KW - margins KW - architecture KW - systems KW - models KW - sea KW - reactivation Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-524661 SN - 1866-8372 IS - 13 ER - TY - JOUR A1 - Glerum, Anne A1 - Brune, Sascha A1 - Stamps, D. Sarah A1 - Strecker, Manfred T1 - Victoria continental microplate dynamics controlled by the lithospheric strength distribution of the East African Rift JF - Nature Communications N2 - The Victoria microplate between the Eastern and Western Branches of the East African Rift System is one of the largest continental microplates on Earth. In striking contrast to its neighboring plates, Victoria rotates counterclockwise with respect to Nubia. The underlying cause of this distinctive rotation has remained elusive so far. Using 3D numerical models, we investigate the role of pre-existing lithospheric heterogeneities in continental microplate rotation. We find that Victoria's rotation is primarily controlled by the distribution of rheologically stronger zones that transmit the drag of the major plates to the microplate and of the mechanically weaker mobile belts surrounding Victoria that facilitate rotation. Our models reproduce Victoria's GPS-derived counterclockwise rotation as well as key complexities of the regional tectonic stress field. These results reconcile competing ideas on the opening of the rift system by highlighting differences in orientation of the far-field divergence, local extension, and the minimum horizontal stress. One of the largest continental microplates on Earth is situated in the center of the East African Rift System, and oddly, the Victoria microplate rotates counterclockwise with respect to the neighboring African tectonic plate. Here, the authors' modelling results suggest that Victoria microplate rotation is caused by edge-driven lithospheric processes related to the specific geometry of rheologically weak and strong regions. Y1 - 2020 U6 - https://doi.org/10.1038/s41467-020-16176-x SN - 2041-1723 VL - 11 IS - 1 PB - Nature Publishing Group CY - London ER - TY - GEN A1 - Baes, Marzieh A1 - Sobolev, Stephan Vladimir A1 - Gerya, Taras V. A1 - Brune, Sascha T1 - Plume-induced subduction initiation BT - Single-slab or multi-slab subduction? T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Initiation of subduction following the impingement of a hot buoyant mantle plume is one of the few scenarios that allow breaking the lithosphere and recycling a stagnant lid without requiring any preexisting weak zones. Here, we investigate factors controlling the number and shape of retreating subducting slabs formed by plume-lithosphere interaction. Using 3-D thermomechanical models we show that the deformation regime, which defines formation of single-slab or multi-slab subduction, depends on several parameters such as age of oceanic lithosphere, thickness of the crust and large-scale lithospheric extension rate. Our model results indicate that on present-day Earth multi-slab plume-induced subduction is initiated only if the oceanic lithosphere is relatively young (<30-40 Myr, but >10 Myr), and the crust has a typical thickness of 8 km. In turn, development of single-slab subduction is facilitated by older lithosphere and pre-imposed extensional stresses. In early Earth, plume-lithosphere interaction could have led to formation of either episodic short-lived circular subduction when the oceanic lithosphere was young or to multi-slab subduction when the lithosphere was old. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1167 KW - subduction zone KW - plume KW - numerical model KW - singleslab KW - multi-slab Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-522742 SN - 1866-8372 IS - 2 ER - TY - JOUR A1 - Baes, Marzieh A1 - Sobolev, Stephan V. A1 - Gerya, Taras V. A1 - Brune, Sascha T1 - Subduction initiation by Plume-Plateau interaction BT - insights from numerical models JF - Geochemistry, geophysics, geosystems N2 - It has recently been demonstrated that the interaction of a mantle plume with sufficiently old oceanic lithosphere can initiate subduction. However, the existence of large lithospheric heterogeneities, such as a buoyant plateau, in proximity to a rising plume head may potentially hinder the formation of a new subduction zone. Here, we investigate this scenario by means of 3-D numerical thermomechanical modeling. We explore how plume-lithosphere interaction is affected by lithospheric age, relative location of plume head and plateau border, and the strength of the oceanic crust. Our numerical experiments suggest four different geodynamic regimes: (a) oceanic trench formation, (b) circular oceanic-plateau trench formation, (c) plateau trench formation, and (d) no trench formation. We show that regardless of the age and crustal strength of the oceanic lithosphere, subduction can initiate when the plume head is either below the plateau border or at a distance less than the plume radius from the plateau edge. Crustal heterogeneity facilitates subduction initiation of old oceanic lithosphere. High crustal strength hampers the formation of a new subduction zone when the plume head is located below a young lithosphere containing a thick and strong plateau. We suggest that plume-plateau interaction in the western margin of the Caribbean could have resulted in subduction initiation when the plume head impinged onto the oceanic lithosphere close to the border between plateau and oceanic crust. KW - subduction zone KW - plume KW - plateau KW - numerical modeling KW - plume-induced KW - subduction initiation (PISI) Y1 - 2020 U6 - https://doi.org/10.1029/2020GC009119 SN - 1525-2027 VL - 21 IS - 8 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Baes, Marzieh A1 - Sobolev, Stephan A1 - Gerya, Taras V. A1 - Brune, Sascha T1 - Plume-induced subduction initiation BT - single-slab or multi-slab subduction? JF - Geochemistry, geophysics, geosystems N2 - Initiation of subduction following the impingement of a hot buoyant mantle plume is one of the few scenarios that allow breaking the lithosphere and recycling a stagnant lid without requiring any preexisting weak zones. Here, we investigate factors controlling the number and shape of retreating subducting slabs formed by plume-lithosphere interaction. Using 3-D thermomechanical models we show that the deformation regime, which defines formation of single-slab or multi-slab subduction, depends on several parameters such as age of oceanic lithosphere, thickness of the crust and large-scale lithospheric extension rate. Our model results indicate that on present-day Earth multi-slab plume-induced subduction is initiated only if the oceanic lithosphere is relatively young (<30-40 Myr, but >10 Myr), and the crust has a typical thickness of 8 km. In turn, development of single-slab subduction is facilitated by older lithosphere and pre-imposed extensional stresses. In early Earth, plume-lithosphere interaction could have led to formation of either episodic short-lived circular subduction when the oceanic lithosphere was young or to multi-slab subduction when the lithosphere was old. KW - subduction zone KW - plume KW - numerical model KW - singleslab KW - multi-slab Y1 - 2020 U6 - https://doi.org/10.1029/2019GC008663 SN - 1525-2027 VL - 21 IS - 2 PB - American Geophysical Union CY - Washington ER -