The influence of plate boundary motion on planform in viscously stratified mantle convection models

2011 ◽  
Vol 116 (B12) ◽  
Author(s):  
J. P. Lowman ◽  
S. D. King ◽  
S. J. Trim
Keyword(s):  
Mantle Convection ◽  
Plate Boundary ◽  
Boundary Motion

scholarly journals Recency of Faulting and Subsurface Architecture of the San Diego Bay Pull-Apart Basin, California, USA

2021 ◽  
Vol 9 ◽  
Author(s):  
Drake M. Singleton ◽  
Jillian M. Maloney ◽  
Daniel S. Brothers ◽  
Shannon Klotsko ◽  
Neal W. Driscoll ◽  
...  
Keyword(s):  
San Diego ◽  
Plate Boundary ◽  
Fault Analysis ◽  
Normal Faults ◽  
Boundary Motion ◽  
The North ◽  
Pull Apart Basin ◽  
San Diego Bay ◽  
Slip Partitioning ◽  
The Rose

In Southern California, plate boundary motion between the North American and Pacific plates is distributed across several sub-parallel fault systems. The offshore faults of the California Continental Borderland (CCB) are thought to accommodate ∼10–15% of the total plate boundary motion, but the exact distribution of slip and the mechanics of slip partitioning remain uncertain. The Newport-Inglewood-Rose Canyon fault is the easternmost fault within the CCB whose southern segment splays out into a complex network of faults beneath San Diego Bay. A pull-apart basin model between the Rose Canyon and the offshore Descanso fault has been used to explain prominent fault orientations and subsidence beneath San Diego Bay; however, this model does not account for faults in the southern portion of the bay or faulting east of the bay. To investigate the characteristics of faulting and stratigraphic architecture beneath San Diego Bay, we combined a suite of reprocessed legacy airgun multi-channel seismic profiles and high-resolution Chirp data, with age and lithology controls from geotechnical boreholes and shallow sub-surface vibracores. This combined dataset is used to create gridded horizon surfaces, fault maps, and perform a kinematic fault analysis. The structure beneath San Diego Bay is dominated by down-to-the-east motion on normal faults that can be separated into two distinct groups. The strikes of these two fault groups can be explained with a double pull-apart basin model for San Diego Bay. In our conceptual model, the western portion of San Diego Bay is controlled by a right-step between the Rose Canyon and Descanso faults, which matches both observations and predictions from laboratory models. The eastern portion of San Diego Bay appears to be controlled by an inferred step-over between the Rose Canyon and San Miguel-Vallecitos faults and displays distinct fault strike orientations, which kinematic analysis indicates should have a significant component of strike-slip partitioning that is not detectable in the seismic data. The potential of a Rose Canyon-San Miguel-Vallecitos fault connection would effectively cut the stepover distance in half and have important implications for the seismic hazard of the San Diego-Tijuana metropolitan area (population ∼3 million people).

Effects of strain weakening in self-consistent models of mantle convection with plate-like behavior and continental drift

2020 ◽  
Author(s):  
Tobias Rolf ◽  
Maëlis Arnould
Keyword(s):  
Mantle Convection ◽  
Previous History ◽  
Plate Boundary ◽  
Continental Drift ◽  
Rheological Parameters ◽  
Plate Boundaries ◽  
The Earth ◽  
Cumulative Strain ◽  
First Results ◽  
Long Time

<p>It is now well-established that the Earth’s mantle and lithosphere form an integrated, dynamically self-regulating system. Numerical convection models that self-consistently generate plate-like behavior are a powerful tool to investigate this system, but have only recently reached a level at which they can be linked to the geodynamics of the Earth. Strongly temperature-dependent and viscoplastic rheology is known to be a key ingredient for these models to be successful. Such rheologies, however, are typically time-independent and lack a memory on the previous history of deformation. Yet, it is known that the Earth’s geodynamic evolution is somewhat guided by structures of pre-existing weakness, which was initiated a potentially long time before.</p><p>As a step forward we implement a simple form of rheological memory in the mantle convection code <em>StagYY</em>: strain weakening [<em>Fuchs & Becker, 2019,</em> <em>Role of strain-dependent weakening memory on the style of mantle convection and plate boundary stability</em>, <em>Geophys. J. Int., 218, 601-618</em>]. We present calculations in 2D cases with and without continents, and also selected 3D cases. By varying the governing parameters for plate-like behavior as well as the rates of rheological damage and healing, we examine how strain weakening modifies the generation of plate-like behavior and its time dependence as well as the drift of continents.</p><p>First results indicate the importance of the balance of weakening (via the critical strain) and thermal healing. The averaged cumulative strain (effectively the degree of lithospheric weakening) is lower when healing is more effective, so that plastic failure of the lithospheric and the formation of new plate boundaries is complicated, as expected. In initial models with strong, long-living continents, accumulated strain is very small within the continents and seems insufficient to induce substantial weakening, even if the memory on previous deformation is infinite (i.e. no healing with continents). Further models with weaker continents and different rheological parameters will be presented.</p>

scholarly journals Geodynamic diagnostics, scientific visualisation and StagLab 3.0

2018 ◽  
Author(s):  
Fabio Crameri
Keyword(s):  
Software Package ◽  
Mantle Convection ◽  
Plate Tectonics ◽  
State Of The Art ◽  
Plate Boundary ◽  
Plate Bending ◽  
Scientific Software ◽  
Mantle Dynamics ◽  
Geodynamic Models ◽  
Visual Error

Abstract. Today's Geodynamic models can, often do, and sometimes have to become very complex. Their underlying, increasingly elaborate numerical codes produce a growing amount of raw data. Post-processing such data becomes therefore more and more challenging and time consuming. In addition, visualising processed data and results has, in times of coloured figures and a wealth of half-scientific software, become one of the weakest pillars of science, widely mistreated and ignored. Efficient and automated Geodynamic diagnostics and sensible, scientific visualisation, preventing common pitfalls, is thus more important than ever. Here, a collection of numerous diagnostics for plate tectonics and mantle dynamics is provided and a case for truly scientific visualisation is made. Amongst other diagnostics are a most accurate and robust plate-boundary identification, slab-polarity recognition, plate-bending derivation, surface-topography component splitting and mantle-plume detection. Thanks to powerful image processing tools and other elaborate algorithms, these and many other insightful diagnostics are conveniently derived from only a subset of the most basic parameter fields. A brand-new set of scientifically proof, perceptually uniform colour maps including "devon", "davos", "oslo" and "broc" is introduced and made freely available. These novel colour maps bring a significant advantage over misleading, non-scientific colour maps like "rainbow"', which is shown to introduce a visual error to the underlying data of up to 7.5 %. Finally, StagLab (http://www.fabiocrameri.ch/software) is introduced, a software package that incorporates the whole suite of automated Geodynamic diagnostics and, on top of that, applies state-of-the-art, scientific visualisation to produce publication-ready figures and movies, all in a blink of an eye, all fully reproducible. StagLab, a simple, flexible, efficient and reliable tool, made freely available to everyone, is written in MatLab and adjustable for use with Geodynamic mantle-convection codes.

scholarly journals Geodynamic diagnostics, scientific visualisation and StagLab 3.0

2018 ◽  
Vol 11 (6) ◽  
pp. 2541-2562 ◽  
Author(s):  
Fabio Crameri
Keyword(s):  
Mantle Convection ◽  
Plate Tectonics ◽  
State Of The Art ◽  
Plate Boundary ◽  
Scientific Quality ◽  
Plate Bending ◽  
Scientific Software ◽  
Mantle Dynamics ◽  
Geodynamic Models ◽  
Visual Error

Abstract. Today's geodynamic models can, often do and sometimes have to become very complex. Their underlying, increasingly elaborate numerical codes produce a growing amount of raw data. Post-processing such data is therefore becoming more and more important, but also more challenging and time-consuming. In addition, visualising processed data and results has, in times of coloured figures and a wealth of half-scientific software, become one of the weakest pillars of science, widely mistreated and ignored. Efficient and automated geodynamic diagnostics and sensible scientific visualisation preventing common pitfalls is thus more important than ever. Here, a collection of numerous diagnostics for plate tectonics and mantle dynamics is provided and a case for truly scientific visualisation is made. Amongst other diagnostics are a most accurate and robust plate-boundary identification, slab-polarity recognition, plate-bending derivation, surface-topography component splitting and mantle-plume detection. Thanks to powerful image processing tools and other elaborate algorithms, these and many other insightful diagnostics are conveniently derived from only a subset of the most basic parameter fields. A brand new set of scientific quality, perceptually uniform colour maps including devon, davos, oslo and broc is introduced and made freely available (http://www.fabiocrameri.ch/colourmaps, last access: 25 June 2018). These novel colour maps bring a significant advantage over misleading, non-scientific colour maps like rainbow, which is shown to introduce a visual error to the underlying data of up to 7.5 %. Finally, StagLab (http://www.fabiocrameri.ch/StagLab, last access: 25 June 2018) is introduced, a software package that incorporates the whole suite of automated geodynamic diagnostics and, on top of that, applies state-of-the-art scientific visualisation to produce publication-ready figures and movies, all in the blink of an eye and all fully reproducible. StagLab, a simple, flexible, efficient and reliable tool made freely available to everyone, is written in MATLAB and adjustable for use with geodynamic mantle convection codes.

scholarly journals The dependence of planetary tectonics on mantle thermal state: applications to early Earth evolution

2018 ◽  
Vol 376 (2132) ◽  
pp. 20170409 ◽  
Author(s):  
Bradford J. Foley
Keyword(s):  
Grain Size ◽  
Mantle Convection ◽  
Plate Tectonics ◽  
Thermal State ◽  
Plate Boundary ◽  
Thermal Conditions ◽  
Size Reduction ◽  
Early Earth ◽  
Plate Boundaries ◽  
Boundary Formation

For plate tectonics to operate on a planet, mantle convective forces must be capable of forming weak, localized shear zones in the lithosphere that act as plate boundaries. Otherwise, a planet's mantle will convect in a stagnant lid regime, where subduction and plate motions are absent. Thus, when and how plate tectonics initiated on the Earth is intrinsically tied to the ability of mantle convection to form plate boundaries; however, the physics behind this process are still uncertain. Most mantle convection models have employed a simple pseudoplastic model of the lithosphere, where the lithosphere ‘fails’ and develops a mobile lid when stresses in the lithosphere reach the prescribed yield stress. With pseudoplasticity high mantle temperatures and high rates of internal heating, conditions relevant for the early Earth, impede plate boundary formation by decreasing lithospheric stresses, and hence favour a stagnant lid for the early Earth. However, when a model for shear zone formation based on grain size reduction is used, early Earth thermal conditions do not favour a stagnant lid. While lithosphere stress drops with increasing mantle temperature or heat production rate, the deformational work, which drives grain size reduction, increases. Thus, the ability of convection to form weak plate boundaries is not impeded by early Earth thermal conditions. However, mantle thermal state does change the style of subduction and lithosphere mobility; high mantle temperatures lead to a more sluggish, drip-like style of subduction. This ‘sluggish lid’ convection may be able to explain many of the key observations of early Earth crust formation processes preserved in the geologic record. Moreover, this work highlights the importance of understanding the microphysics of plate boundary formation for assessing early Earth tectonics, as different plate boundary formation mechanisms are influenced by mantle thermal state in fundamentally different ways.This article is part of a discussion meeting issue ‘Earth dynamics and the development of plate tectonics’.

PLANETARY SELF-ORGANIZATION

2020 ◽  
Vol 42 (3) ◽  
pp. 271-282
Author(s):  
OLEG IVANOV
Keyword(s):  
Dynamical System ◽  
Heat Source ◽  
Mantle Convection ◽  
Plate Tectonics ◽  
Rotation Speed ◽  
Self Organization ◽  
Heat Sources ◽  
Kinematic Parameters ◽  
The Earth ◽  
New Type

The general characteristics of planetary systems are described. Well-known heat sources of evolution are considered. A new type of heat source, variations of kinematic parameters in a dynamical system, is proposed. The inconsistency of the perovskite-post-perovskite heat model is proved. Calculations of inertia moments relative to the D boundary on the Earth are given. The 9 times difference allows us to claim that the sliding of the upper layers at the Earth's rotation speed variations emit heat by viscous friction.This heat is the basis of mantle convection and lithospheric plate tectonics.

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