A plate tectonic mechanism for methane hydrate release along subduction zones

Three time–space profiles have been constructed using geologic data from British Columbia between 49° N and 56° N. They illustrate variations across the Cordillera, (1) in the stratigraphic and tectonic setting of volcanism, (2) in the age and modal type of granitoids, and (3) in the distribution and types of copper and lead deposits related to volcanic and plutonic rocks. These profiles provide the basis for a plate tectonic synthesis of the Mesozoic–Cenozoic geology, illustrated by six true-scale cross sections.The preferred model has, in the Triassic, two eastward-dipping subduction zones, giving rise to the copper-rich Karmutsen and Nicola–Takla volcanics respectively. After collision of the two volcanic belts by the Early Jurassic, a single eastward-dipping subduction zone remained active until the Eocene. Magmas produced by partial melting and fractionation of subducted lithosphere occurred across the western 300 km of the Cordillera, leading to thickening of the crust, and eventually to anatectic melting to generate large batholiths now containing pendants of volcanics. Jurassic and later geologic and metallogenic events across the eastern 500 km of the Cordillera are the results of an increased heat flux through inhomogeneous crust of varying thickness, comprised of relict ocean floor, continental margin sediments, older volcanics, and ancient cratonic basement. This results in patterns of metamorphism, volcanism, and plutonism which have no simple spatial relationship to the subduction zone.

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Back to the future 3: Analysing tectonically induced tidal resonance with conceptual models

10.5194/egusphere-egu2020-596 ◽

2020 ◽

Author(s):

Hannah Davies ◽

J.A. Mattias Green ◽

Joao C. Duarte

Keyword(s):

Subduction Zones ◽

Open Ocean ◽

Global Ocean ◽

Plate Tectonic ◽

Tidal Dissipation ◽

Tidal Model ◽

Continental Plate ◽

Global Coverage ◽

Tethys Ocean ◽

North And South

Recent research of coupled tidal and tectonic modelling has found that during periods in an ocean&#8217;s Wilson cycle, (i.e. during dispersal, and subsequent convergence of oceans due to plate tectonic movement), oceans occasionally become resonant for the semi-diurnal component of the tide (M2). This results in an approximately 20-Million-year long period of enhanced tidal dissipation in the resonant ocean (assuming continental plate drift rates of ~5 cm yr-1). This resonant &#8220;Super-tide&#8221; has been simulated in numerical tidal models for both past and future tectonic scenarios, and they show that the current tides are among the most energetic found.Here we use an established tidal model to analyse the conditions required for open ocean tidal resonance. Our conceptual &#8220;Earths&#8221; consist of two or more simplified oceans, which are shaped to represent conceptual versions of oceans of the past, present, and future: triangular (Tethys ocean), circular (Pacific and Arctic oceans), rectangular (Southern and Indian oceans), and rhomboid shaped (North, and South Atlantic Ocean). Each scenario was conducted using ocean bathymetry ranging from a &#8220;bathtub&#8221; ocean (a uniformly deep flat abyssal plane from coast to coast), to a continental shelf with no abyssal bathymetry, to a &#8220;realistic&#8221; ocean with ocean shelves, ridges, and subduction zones. The global ocean land ratio and ocean volume was conserved to present-day in most conceptual scenarios however, to investigate the maximum tidal dissipation possible on Earth, some scenarios deviated from the ocean volume and global coverage. In every scenario, ocean width is progressively increased relative to the predominant ocean boundaries, simulating plate tectonic opening of each ocean.The aim of the work was to assess the frequency of the occurrence of resonance in the open ocean, and the upper limit for tidal dissipation of the semi-diurnal tide on Earth. We found that super-tides are common in the results with their dissipative strength varying from weaker than present day to five times present day.The occurrence of tidal resonances in modelled conceptual oceans further confirms the link between tectonics and tidal evolution. These super-tidal periods of markedly increased tidal dissipation alter the ocean&#8217;s energy budget, nutrient dispersal and the carrying capacity of coastal and oceanic ecosystems.

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Emergence of plate tectonic during the Archean: insights from 3D numerical modelling.

10.5194/egusphere-egu21-8809 ◽

2021 ◽

Author(s):

Andrea Piccolo ◽

Boris Kaus ◽

Richard White ◽

Nicolas Arndt ◽

Nicolas Riel

Keyword(s):

Phase Transitions ◽

Subduction Zones ◽

Plate Tectonics ◽

Large Scale ◽

Potential Temperature ◽

Secular Change ◽

Plate Boundaries ◽

Plate Tectonic ◽

Subduction Initiation ◽

The Earth

In the plate tectonic convection regime, the external lid is subdivided into discrete plates that move independently. Although it is known that the system of plates is mainly dominated by slab-pull forces, it is not yet clear how, when and why plate tectonics became the dominant geodynamic process in our planet. It could have started during the Meso-Archean (3.0-2.9 Ga). However, it is difficult to conceive a subduction driven system at the high mantle potential temperatures (Tp) that are thought to have existed around that time, because Tp controls the thickness and the strength of the compositional lithosphere making subduction unlikely. In recent years, however, a credible solution to the problem of subduction initiation during the Archean has been advanced, invoking a plume-induced subduction mechanism[1] that seems able to generate plate-tectonic like behaviour to first order. However, it has not yet been demonstrated how these tectonic processes interact with each other, and whether they are able to eventually propagate to larger scale subduction zones.The Archean Eon was characterized by a high Tp[2], which generates weaker plates, and a thick and chemically buoyant lithosphere. In these conditions, slab pull forces are inefficient, and most likely unable to be transmitted within the plate. Therefore, plume-related proto-plate tectonic cells may not have been able to interact with each other or showed a different interaction as a function of mantle potential temperature and composition of the lithosphere. Moreover, due to secular change of Tp, the dynamics may change with time. In order to understand the complex interaction between these tectonic seeds it is necessary to undertake large scale 3D numerical simulations, incorporating the most relevant phase transitions and able to handle complex constitutive rheological model.Here, we investigate the effects of the composition and Tp independently to understand the potential implications of the interaction of plume-induced subduction initiation. We employ a finite difference visco-elasto-plastic thermal petrological code using a large-scale domain (10000 x 10000 x 1000 km along x, y and z directions) and incorporating the most relevant petrological phase transitions. We prescribed two oceanic plateaus bounded by subduction zones and we let the negative buoyancy and plume-push forces evolve spontaneously. The paramount question that we aim to answer is whether these configurations allow the generation of stable plate boundaries. The models will also investigate whether the presence of continental terrain helps to generate plate-like features and whether the processes are strong enough to generate new continental terrains&#160;or assemble them .&#160;[1]&#160;&#160;&#160;&#160;&#160;&#160; T. V. Gerya, R. J. Stern, M. Baes, S. V. Sobolev, and S. A. Whattam, &#8220;Plate tectonics on the Earth triggered by plume-induced subduction initiation,&#8221; Nature, vol. 527, no. 7577, pp. 221&#8211;225, 2015.[2]&#160;&#160;&#160;&#160;&#160;&#160; C. T. Herzberg, K. C. Condie, and J. Korenaga, &#8220;Thermal history of the Earth and its petrological expression,&#8221; Earth Planet. Sci. Lett., vol. 292, no. 1&#8211;2, pp. 79&#8211;88, 2010.[3]&#160;&#160;&#160;&#160;&#160;&#160; R. M. Palin, M. Santosh, W. Cao, S.-S. Li, D. Hern&#225;ndez-Uribe, and A. Parsons, &#8220;Secular metamorphic change and the onset of plate tectonics,&#8221; Earth-Science Rev., p. 103172, 2020.

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Plate tectonic chain reaction constrained from noise in the Cretaceous Quiet Zone

10.5194/egusphere-egu2020-2777 ◽

2020 ◽

Author(s):

Derya Gürer ◽

Roi Granot ◽

Douwe J.J. van Hinsbergen

Keyword(s):

Subduction Zones ◽

Kinematic Model ◽

Plate Boundary ◽

Western Mediterranean ◽

Plate Motion ◽

Plate Boundaries ◽

Plate Tectonic ◽

Test Bed ◽

Chain Reaction ◽

Tectonic Plates

The relative motions of the tectonic plates show remarkable variation throughout Earth&#8217;s history. Major changes in relative motion between the tectonic plates are traditionally viewed as spatially and temporally isolated events linked to forces acting on plate boundaries (i.e., formation of same-dip double subduction zones, changes in the strength of the boundary), or thought to be associated with mantle dynamics. A Cretaceous global plate reorganization event has been postulated to have affected all major plates. The Cretaceous &#8216;swing&#8217; in Africa-Eurasia relative plate motion provides an ideal test-bed for assessing the temporal and spatial evolution of both relative plate motions and surrounding geological markers. Here we show a novel plate kinematic model for the closure of the Tethys Ocean by implementing intra-Cretaceous Quiet Zone time markers and combine the results with the geological constraints found along the convergent plate boundary. Our results allow to assess the order, causes and consequences of geological events and unravel a chain of tectonic events that set off with the onset of horizontally-forced double subduction ~105 Myr ago, followed by a 40 Myr long period of acceleration of the Africa relative to Eurasia that peaked at 80 Myr ago (at rates four times as high as previously predicted). This acceleration, which was likely caused by the pull of two same-dip subduction zones was followed by a sharp decrease in plate velocity, when double subduction terminated with ophiolite obduction onto the African margin. These tectonic forces acted on the eastern half of the Africa-Eurasia plate boundary, which led to counterclockwise rotation of Africa and sparked new subduction zones in the western Mediterranean region. Our analysis identifies the Cretaceous double subduction episode between Africa and Eurasia as a link in the global plate tectonic chain reaction and provides a dynamic view on plate reorganizations.

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Phanerozoic paleogeographic, plate tectonic and paleoclimatic reconstructions

The Paleontological Society Special Publications ◽

10.1017/s2475262200008236 ◽

1992 ◽

Vol 6 ◽

pp. 263-263 ◽

Cited By ~ 1

Author(s):

Christopher R. Scotese

Keyword(s):

General Circulation ◽

Subduction Zones ◽

Coastal Upwelling ◽

Hot Spot ◽

Circulation Model ◽

Time Interval ◽

Plate Boundaries ◽

Plate Tectonic ◽

Prevailing Wind Direction ◽

Event Stratigraphy

In 1913, in the concluding remarks to his two volume compendium, Principles of Stratigraphy, Amadeus Grabau wrote, “When the science of Stratigraphy has developed so that its basis is no longer purely or chiefly paleontological, and when the sciences of Lithogenisis and Orogenesis … are given their due share in the comprehensive investigation of the history of the earth, then we may hope that Paleogeography, the youthful daughter science of Stratigraphy will have attained unto that stature that will make it the crowning attraction to the student of earth history.” It has taken nearly 80 years for Grabau's vision to be realized. The fruits of the plate tectonic revolution combined with our new understanding of global eustasy and event stratigraphy, make it now possible to map the changing geography of the earth's surface with unparalleled detail and accuracy.In this poster session, we present 28 paleogeographic maps illustrating the changing configuration of mountains, land, shallow seas, and deep ocean basins during the Phanerozoic. The plate boundaries (spreading ridges, subduction zones, and transform faults) that were active during each time interval are also shown. For the Mesozoic and Cenozoic these plate boundaries are based on a synthesis of linear magnetic anomaly data and fracture zone locations compiled by PALEOMAP Project (International Lithosphere Program). The Mesozoic and Cenozoic orientation of the continents relative to the Earth's axis of rotation has been determined using a combination of paleomagnetic data and hot spot tracks. The location of Paleozoic plate boundaries, though speculative, is based evidence of past subduction and inferred sea floor spreading. The relative longitudinal positions of the continents and the width of the intervening Paleozoic oceans have been adjusted to best explain changing biogeographic and paleoclimatic patterns.The land, sea and mountain distributions portrayed on these 28 paleogeographic reconstructions have been used as input for a series of computer simulations of paleoclimate. The paleoclimatic model, which was developed by C.R. Scotese and M. I. Ross, uses the latitudinal distribution of land and sea, as well as the orientation of ancient mountain belts to predict the distr ibution of high and low pressure cells, prevailing wind direction, relative wetness/dryness, as well as zones of coastal upwelling. This model, which takes a simple parametric approach, makes predictions which are similar to the more robust General Circulation Model (GCM), but requires far less computer resources.

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Mariana-type ophiolites constrain the establishment of modern plate tectonic regime during Gondwana assembly

Nature Communications ◽

10.1038/s41467-021-24422-z ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Jinlong Yao ◽

Peter A. Cawood ◽

Guochun Zhao ◽

Yigui Han ◽

Xiaoping Xia ◽

...

Keyword(s):

Subduction Zones ◽

Oceanic Lithosphere ◽

Surface Erosion ◽

Plate Tectonic ◽

Mountain Ranges ◽

Tectonic Regime ◽

Subduction Initiation ◽

The Earth ◽

Tethys Ocean ◽

Roll Back

AbstractInitiation of Mariana-type oceanic subduction zones requires rheologically strong oceanic lithosphere, which developed through secular cooling of Earth’s mantle. Here, we report a 518 Ma Mariana-type subduction initiation ophiolite from northern Tibet, which, along with compilation of similar ophiolites through Earth history, argues for the establishment of the modern plate tectonic regime by the early Cambrian. The ophiolite was formed during the subduction initiation of the Proto-Tethys Ocean that coincided with slab roll-back along the southern and western Gondwana margins at ca. 530-520 Ma. This global tectonic re-organization and the establishment of modern plate tectonic regime was likely controlled by secular cooling of the Earth, and facilitated by enhanced lubrication of subduction zones by sediments derived from widespread surface erosion of the extensive mountain ranges formed during Gondwana assembly. This time also corresponds to extreme events recorded in climate and surface proxies that herald formation of the contemporary Earth.

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Is Venus an analogue for Proterozoic Earth?

10.5194/egusphere-egu21-12082 ◽

2021 ◽

Author(s):

Richard Ghail

Keyword(s):

Subduction Zones ◽

Plate Tectonics ◽

High Surface ◽

Global Network ◽

Evolutionary Stage ◽

Plate Tectonic ◽

Spreading Ridges ◽

Igneous Provinces ◽

Detachment Layer ◽

High Surface Temperature

Venus is our most Earth-like twin, from a geological standpoint, but lacks Earth-like plate tectonics. Its lower mean density implies a smaller core and relatively large mantle, which combined with the inhibited cooling effected by its high surface temperature, suggests that Venus today may be at an earlier evolutionary stage than Earth. Geologically, a global network of rifts and corona chains (e.g. Parga Chasma) indicate subsurface, plate tectonic-like, spreading ridges below a crustal detachment layer, but there are no obvious corresponding subduction zones. Subduction has been inferred locally at a few large corona (e.g. Artemis) but only in relation to specific plumes, not global plate tectonics. Elsewhere there is evidence for numerous large igneous provinces and perhaps an even larger Overturn Upwelling Zones (OUZO) event at Lada Terra. These features suggest a planet in transition from an Archaean-like regime dominated by instability and overturns, towards a more stable plate tectonic regime: i.e. a planet analogous to the early Proterozoic Earth.

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The inception of plate tectonics: a record of failure

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2017.0414 ◽

2018 ◽

Vol 376 (2132) ◽

pp. 20170414 ◽

Cited By ~ 13

Author(s):

Craig O'Neill ◽

Simon Turner ◽

Tracy Rushmer

Keyword(s):

Subduction Zones ◽

Plate Tectonics ◽

Initial Conditions ◽

Numerical Models ◽

Early History ◽

Early Earth ◽

Strong Nonlinearity ◽

Plate Tectonic ◽

Geological Record ◽

History Of

The development of plate tectonics from a pre-plate tectonics regime requires both the initiation of subduction and the development of nascent subduction zones into long-lived contiguous features. Subduction itself has been shown to be sensitive to system parameters such as thermal state and the specific rheology. While generally it has been shown that cold-interior high-Rayleigh-number convection (such as on the Earth today) favours plates and subduction, due to the ability of the interior stresses to couple with the lid, a given system may or may not have plate tectonics depending on its initial conditions. This has led to the idea that there is a strong history dependence to tectonic evolution—and the details of tectonic transitions, including whether they even occur, may depend on the early history of a planet. However, intrinsic convective stresses are not the only dynamic drivers of early planetary evolution. Early planetary geological evolution is dominated by volcanic processes and impacting. These have rarely been considered in thermal evolution models. Recent models exploring the details of plate tectonic initiation have explored the effect of strong thermal plumes or large impacts on surface tectonism, and found that these ‘primary drivers’ can initiate subduction, and, in some cases, over-ride the initial state of the planet. The corollary of this, of course, is that, in the absence of such ongoing drivers, existing or incipient subduction systems under early Earth conditions might fail. The only detailed planetary record we have of this development comes from Earth, and is restricted by the limited geological record of its earliest history. Many recent estimates have suggested an origin of plate tectonics at approximately 3.0 Ga, inferring a monotonically increasing transition from pre-plates, through subduction initiation, to continuous subduction and a modern plate tectonic regime around that time. However, both numerical modelling and the geological record itself suggest a strong nonlinearity in the dynamics of the transition, and it has been noted that the early history of Archaean greenstone belts and trondhjemite–tonalite–granodiorite record many instances of failed subduction. Here, we explore the history of subduction failure on the early Earth, and couple these with insights from numerical models of the geodynamic regime at the time. This article is part of a discussion meeting issue ‘Earth dynamics and the development of plate tectonics'.

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Dynamics of upper and lower mantle subduction and its effects on the amplitude and pattern of mantle convection.

10.5194/egusphere-egu21-11502 ◽

2021 ◽

Author(s):

Erik van der Wiel ◽

Cedric Thieulot ◽

Wim Spakman ◽

Douwe van Hinsbergen

Keyword(s):

Tectonic Evolution ◽

Lower Mantle ◽

Mantle Convection ◽

Subduction Zones ◽

Morphological Evolution ◽

Phase Changes ◽

Plate Motion ◽

Plate Tectonic ◽

Model Setup ◽

Modeling Strategy

Long-lived, Mesozoic-Cenozoic subduction zones such as the Pacific slab under the Americas and the Tethyan slab under Eurasia consumed thousands of kms of lithosphere of which remnants are detected in today&#8217;s mantle by seismic tomography. Major differences, however, in subduction zone evolution occurred between these systems which include strong variations in subduction rate, slab morphological evolution, and trench motion, which all appear mostly to be accommodated in the upper 1000 km of the mantle (van der Meer et al. 2018). Furthermore, sinking rates of slabs below this zone tend to be similar for different subduction systems and an order of magnitude smaller than their plate/subduction velocities. Working from the premise that the mantle rheology that accommodated these subduction systems is basically similar, although still poorly constrained, we test the hypothesis that the contrasting evolution of these subduction systems is primarily tied in with the global plate tectonic forcing of subduction.It is generally accepted that plate motion is primarily driven by slab pull with contributions from ridge push, rather than the drag of the underlying mantle. If correct, numerical subduction models should be able to obtain upper as well as lower mantle subduction velocities and sinking rates similar to those reconstructed from geological records. We are at the start of this investigation and will present the numerical model setup, modeling strategy, and preliminary results of a 2-D subduction modelling experiment. We implement a 2D-cylindrical model setup for solving the conservation of momentum, mass and energy with the open-source geodynamics code ASPECT (Kronbichler et al. 2012) using a nonlinear visco-plastic rheology and including the major phase changes. Our focus is on the possible role of the absolute motion of the subducting and overriding plates in concert with slab pull variation reconstructed from plate tectonic evolution models, while in both subduction cases the same (partly nonlinear) mantle rheological processes are required to accommodate slab morphology change and slab sinking. Kinematic modelling constraints are derived from global plate tectonic evolution models, while the tomographically inferred present-day stage provides the end-stage geometry of slabs.van der Meer, D. G., Van Hinsbergen, D. J., & Spakman, W. (2018). Atlas of the underworld: Slab remnants in the mantle, their sinking history, and a new outlook on lower mantle viscosity.&#160;Tectonophysics,&#160;723, 309-448.Kronbichler, M., Heister, T., & Bangerth, W. (2012). High accuracy mantle convection simulation through modern numerical methods.&#160;Geophysical Journal International,&#160;191(1), 12-29.

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