215 results on '"Flament, Nicolas"'
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2. Assembly of the basal mantle structure beneath Africa
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Flament, Nicolas, Bodur, Ömer F., Williams, Simon E., and Merdith, Andrew S.
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- 2022
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3. Factors Contributing to Slab Locations and Geometries in Reconstructions of Past Mantle Flow.
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Weber, Joshua and Flament, Nicolas
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LITHOSPHERE ,EARTH'S mantle ,SLABS (Structural geology) ,SUBDUCTION ,EARTHQUAKES - Abstract
Individual sinking slabs present markedly different geometries between 410 and 660 km depths, from vertical slabs penetrating the lower mantle to slabs stagnating above the lower mantle. The proposed factors determining these contrasted geometries include mantle viscosity and the magnitude and evolution of trench retreat. Here, we assess the success of paleo‐geographically driven global mantle flow models in matching slabs in tomographic models between 400 km and 1,000 km depth. We quantify the spatial match between predicted present‐day mantle temperature anomalies and vote maps of tomographic models. We investigate the sensitivity of the spatial match to input parameters of the mantle flow model: imposed tectonic reconstruction, model start age, and viscosity contrast between the upper and lower mantle. We evaluate the visual match between model slabs and tomographic vote maps for three circum‐Pacific regions with contrasted slab dip angles between 400 km and 1,000 km depth. Predicted model slabs better match slabs inferred from tomography when there is an increase in viscosity at 660 km depth. The temporal evolution of the models and the global match at present day suggest that the subduction history could be refined in the global tectonic reconstructions that we considered. For example, we suggest that the subduction to the east of Japan should be offset by approximately 100 km to the west at ∼80 Ma to match the anchoring of a continuous slab into the lower mantle suggested by tomography. Plain Language Summary: Oceanic lithosphere is recycled as sinking slabs into Earth's mantle, and the analysis of global earthquake data compiled in tomographic models has revealed that the dip angle of slabs varies between regions. In this manuscript, we analyze the geometry of mantle slabs predicted by forward models of past global mantle flow that follow imposed surface tectonic motions. We present some of the first quantifications of the spatial match between the present‐day mantle temperature predicted by reconstructions of past global mantle flow and that imaged by global tomographic models. Few studies have quantified this match and clearly exposed it spatially. We quantify the match between the upper mantle slabs predicted by these models and those inferred from a series of tomographic models. We show that the models successfully reproduce the steeply dipping Mariana slab and stagnating Western Pacific slab under Japan and the intermediate geometry of the Farallon and Nazca slabs under South America. We find that trench retreat is the main driver of the geometry of these slabs. Our results suggest that the geometry of slabs can be used to refine global tectonic reconstructions and to calibrate the viscosity contrast between the upper and lower mantle in global mantle flow models. Key Points: We quantitatively compare slab locations in mantle flow and tomographic modelsTrench retreat and mantle viscosity influence the location of sinking slabsOur comparison indicates where global tectonic reconstructions could be improved [ABSTRACT FROM AUTHOR]
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- 2024
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4. Reconstructing seafloor age distributions in lost ocean basins
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Williams, Simon, Wright, Nicky M., Cannon, John, Flament, Nicolas, and Müller, R. Dietmar
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- 2021
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5. On the impact of true polar wander on heat flux patterns at the core–mantle boundary.
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Frasson, Thomas, Labrosse, Stéphane, Nataf, Henri-Claude, Coltice, Nicolas, and Flament, Nicolas
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HEAT flux ,POLAR wandering ,CORE-mantle boundary ,SEISMOLOGY ,PRINCIPAL components analysis ,MAGNETIC dipoles ,ROTATION of the earth ,SEISMIC tomography - Abstract
The heat flux across the core–mantle boundary (CMB) is a fundamental variable for Earth evolution and internal dynamics. Seismic tomography provides access to seismic heterogeneities in the lower mantle, which can be related to present-day thermal heterogeneities. Alternatively, mantle convection models can be used to either infer past CMB heat flux or to produce statistically realistic CMB heat flux patterns in self-consistent models. Mantle dynamics modifies the inertia tensor of the Earth, which implies a rotation of the Earth with respect to its spin axis, a phenomenon called true polar wander (TPW). This rotation must be taken into account to link the dynamics of the mantle to the dynamics of the core. In this study, we explore the impact of TPW on the CMB heat flux over long timescales (∼1 Gyr) using two recently published mantle convection models: one model driven by a plate reconstruction and a second that self-consistently produces a plate-like behaviour. We compute the geoid in both models to correct for TPW. In the plate-driven model, we compute a total geoid and a geoid in which lateral variations of viscosity and density are suppressed above 350 km depth. An alternative to TPW correction is used for the plate-driven model by simply repositioning the model in the original paleomagnetic reference frame of the plate reconstruction. The average TPW rates range between 0.4 and 1.8° Myr -1 , but peaks up to 10° Myr -1 are observed. We find that in the plate-driven mantle convection model used in this study, the maximum inertia axis produced by the model does not show a long-term consistency with the position of the magnetic dipole inferred from paleomagnetism. TPW plays an important role in redistributing the CMB heat flux, notably at short timescales (≤10 Myr). Those rapid variations modify the latitudinal distribution of the CMB heat flux, which is known to affect the stability of the magnetic dipole in geodynamo simulations. A principal component analysis (PCA) is computed to obtain the dominant CMB heat flux pattern in the different cases. These heat flux patterns are representative of the mantle convection cases studied here and can be used as boundary conditions for geodynamo models. [ABSTRACT FROM AUTHOR]
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- 2024
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6. The GPlates Portal: Cloud-Based Interactive 3D Visualization of Global Geophysical and Geological Data in a Web Browser.
- Author
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Müller, R Dietmar, Qin, Xiaodong, Sandwell, David T, Dutkiewicz, Adriana, Williams, Simon E, Flament, Nicolas, Maus, Stefan, and Seton, Maria
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Geology ,Computer Graphics ,Internet ,Software ,Web Browser ,General Science & Technology - Abstract
The pace of scientific discovery is being transformed by the availability of 'big data' and open access, open source software tools. These innovations open up new avenues for how scientists communicate and share data and ideas with each other and with the general public. Here, we describe our efforts to bring to life our studies of the Earth system, both at present day and through deep geological time. The GPlates Portal (portal.gplates.org) is a gateway to a series of virtual globes based on the Cesium Javascript library. The portal allows fast interactive visualization of global geophysical and geological data sets, draped over digital terrain models. The globes use WebGL for hardware-accelerated graphics and are cross-platform and cross-browser compatible with complete camera control. The globes include a visualization of a high-resolution global digital elevation model and the vertical gradient of the global gravity field, highlighting small-scale seafloor fabric such as abyssal hills, fracture zones and seamounts in unprecedented detail. The portal also features globes portraying seafloor geology and a global data set of marine magnetic anomaly identifications. The portal is specifically designed to visualize models of the Earth through geological time. These space-time globes include tectonic reconstructions of the Earth's gravity and magnetic fields, and several models of long-wavelength surface dynamic topography through time, including the interactive plotting of vertical motion histories at selected locations. The globes put the on-the-fly visualization of massive data sets at the fingertips of end-users to stimulate teaching and learning and novel avenues of inquiry.
- Published
- 2016
7. The evolution of basal mantle structure in response to supercontinent aggregation and dispersal
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Cao, Xianzhi, Flament, Nicolas, Bodur, Ömer F., and Müller, R. Dietmar
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- 2021
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8. Cenozoic Uplift of south Western Australia as constrained by river profiles
- Author
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Barnett-Moore, Nicholas, Flament, Nicolas, Heine, Chistian, Butterworth, Nathaniel, and Müller, R. Dietmar
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Physics - Geophysics - Abstract
The relative tectonic quiescence of the Australian continent during the Cenozoic makes it an excellent natural laboratory to study recent large-scale variations in surface topography, and processes that influence changes in its elevation. Embedded within this topography is a fluvial network that is sensitive to variations in horizontal and vertical motions. The notion that a river acts as a 'tape recorder' for vertical perturbations suggests that changes in spatial and temporal characteristics of surface uplift can be deduced through the analysis of longitudinal river profiles. We analyse 20 longitudinal river profiles around the Australian continent. Concave upward profiles in northeast Australia indicate an absence of recent surface uplift. In contrast, the major knickzones within longitudinal profiles of rivers in southwest Australia suggest recent surface uplift. Given the lack of recent large-scale tectonic activity in that region, this uplift requires an explanation. Applying an inverse algorithm to river profiles of south Western Australia reveals that this surface uplift started in the Eocene and culminated in the mid-late Neogene. The surface uplift rates deduced from this river profile analysis generally agree with independent geological observations including preserved shallow-marine sediment outcrops across the Eucla Basin and south Western Australia. We show that the interplay between global sea level and long-wavelength dynamic topography associated with south Western Australia's plate motion path over the remnants of an ancient Pacific slab is a plausible mechanism driving this surface uplift., Comment: 33 pages including 7 figures. Published in Tectonophysics, please see final manuscript there
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- 2013
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9. Global kinematics of tectonic plates and subduction zones since the late Paleozoic Era
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Young, Alexander, Flament, Nicolas, Maloney, Kayla, Williams, Simon, Matthews, Kara, Zahirovic, Sabin, and Müller, R. Dietmar
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- 2019
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10. Author Correction: Assembly of the basal mantle structure beneath Africa
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Flament, Nicolas, Bodur, Ömer F., Williams, Simon E., and Merdith, Andrew S.
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- 2022
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11. A tectonic-rules-based mantle reference frame since 1 billion years ago – implications for supercontinent cycles and plate–mantle system evolution
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Müller, R. Dietmar, primary, Flament, Nicolas, additional, Cannon, John, additional, Tetley, Michael G., additional, Williams, Simon E., additional, Cao, Xianzhi, additional, Bodur, Ömer F., additional, Zahirovic, Sabin, additional, and Merdith, Andrew, additional
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- 2022
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12. A rapid burst in hotspot motion through the interaction of tectonics and deep mantle flow
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Hassan, Rakib, Mller, R. Dietmar, Gurnis, Michael, Williams, Simon E., and Flament, Nicolas
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Volcanic hotspots -- Observations ,Tectonics (Geology) -- Observations ,Earth -- Mantle ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Abstract
Author(s): Rakib Hassan (corresponding author) [1]; R. Dietmar Mller [1]; Michael Gurnis [2]; Simon E. Williams [1]; Nicolas Flament [1] Volcanic hotspot tracks featuring linear progressions in the age of [...]
- Published
- 2016
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13. Mapping global kimberlite potential from reconstructions of mantle flow over the past billion years
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Grabreck, Anton, primary, Flament, Nicolas, additional, and Bodur, Ömer F., additional
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- 2022
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14. Global kimberlite prospectivity from reconstructions of mantle flow over the past billion years
- Author
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Grabreck Anton, Flament, Nicolas, and Bodur, ��mer
- Subjects
mantle convection ,LLSVPs ,diamond ,kimberlites ,tectonics ,geodynamics ,exploration - Abstract
This online supplement contains the following data and scripts. Data sets Tectonic Reconstruction The directory “Reconstruction” contains the reconstruction considered in the study, as well as craton outlines (“shapes_cratons_Merdith_et_al.gpml” and “shapes_cratons_Artemieva.gpml”). There are two “.gproj” files to make it straightforward to open the reconstruction with GPlates, either with net rotation removed (“M21NNR.gproj”) or not (“M21.gproj”). The rotation files are called by the script “Compute_EDFs_of_distances_between_kimberlites_and_high_prospectivity_areas.ipynb”. Kimberlite eruption locations The directory “Kimberlite_eruption_locations” contains the kimberlite eruptions considered in the study formatted for GPlates: “T18_centroids_since_640Ma_within_10Myr.gpml”. This file is called by the script “Compute_EDFs_of_distances_between_kimberlites_and_high_prospectivity_areas.ipynb”. Cluster maps The directory “Cluster_maps” contains time-dependent cluster maps for mantle flow models C1-C6, each in a sub-directory as well as present-day cluster maps for the six considered tomographic models. Prospectivity maps The directory “Prospectivity_maps” contains time-dependent maps of the distance to model high-prospectivity areas for mantle flow models C1-C6 and for tomographic models. These maps are nested in subdirectory mapping the considered tectonic reconstruction and craton shapes. Scripts Two python3 scripts are provided in the Jupyter Notebook format. Script to compute the distance between reconstructed kimberlite eruption locations and model high-prospectivity areas “Compute_EDFs_of_distances_between_kimberlites_and_high_prospectivity_areas.ipynb” is a script to compute the distances between kimberlite eruption locations and the nearest model high-prospectivity area. The script plots sample Empirical Distributions Functions (EDFs) for each considered case, and exports results to a “.csv” file. Dependencies: GMT6 Python packages: pygplates numpy os pandas matplotlib Python scripts (included in main directory): call_system_command.py Script to plot Figure 10 The script “Plot-Figure10.ipynb” can be used to reproduce Figure 10, providing the four required data frames have been produced using “Compute_EDFs_of_distances_between_kimberlites_and_high_prospectivity_areas.ipynb”. Dependencies: Python packages: numpy pandas matplotlib
- Published
- 2021
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15. Assembly of the basal mantle structure beneath Africa (online supplement)
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Flament, Nicolas, Bodur, Omer F, Williams, Simon E, and Merdith, Andrew S
- Subjects
volcanism ,supercontinents ,mantle convection ,LLSVPs ,tectonics ,basal mantle structures - Abstract
Please see the updated version athttps://doi.org/10.5281/zenodo.5717595. This online supplement contains the following data and scripts. Data sets Tectonic Reconstructions The directory “Reconstructions” contains the four reconstructions considered in the study, each in a sub-directory (“M16”, “Y19”, “M21” and “M21NNR”). Each sub-directory contains a “.gproj” file to make it straightforward to open the reconstruction with GPlates. The rotation files are called by the script “Compute-and-plot-match-to-volcanic-products.ipynb”. Volcanic products The directory “Volcanic_products” contains the four databases of volcanic products considered in the study. Because plate IDs have been assigned by tectonic reconstruction, there are four sub-directories (“M16”, “Y19”, “M21” and “M21NNR”), each containing four sub-directories (“D16”, “EY17”, “J18”, “T18”). Each of these sub-directories contains: • The centroids of the relevant database of volcanic products with plate IDs for a given tectonic reconstruction, in GPlates Markup Language (“.gpml”) format; for example: “D16_centroids_M21_plateIDs.gpml” • The same centroids as selected within 10 Myr of each considered age, in the sub-directory “Selected_within_10Myr”; for example: “D16_centroids_M21_plateIDs_since_640Ma_within_10Myr.gpml” • The same centroids reconstructed at the time of eruption and shown at present-day, in the sub-directory “Reconstructed_locations_since_320Ma_at_present-day_with_ages”; for example: “D16_centroids_M21_plateIDs_reconstructed_locations_since_320Ma_at_present-day_with_ages.gpml”. Files in sub-directories “Selected_within_10Myr” are called by the script “Compute-and-plot-match-to-volcanic-products.ipynb”. Cluster maps The directory “Cluster_maps” contains time-dependent cluster maps for mantle flow models C1-C22, each in a sub-directory that also contains a list of available times (e.g. “C1.tlist”), as well as present-day cluster maps for the seven considered tomographic models. Paraview visualisation for the preferred mantle flow model case The directory “Paraview_visualisation_Case7” contains files required to visualise the evolution of mantle structure since one billion year ago predicted by Case 7. The resolution has been decreased so that the visualisation can be carried out on a single processor. To open the visualisation, load the state file “Case7_decimated_ParaView.pvsm” in ParaView (make sure to select the option “Search files under specified directory” and select the directory containing the visualisation). Scripts Three python scripts are provided in the Jupyter Notebook format. These scripts were originally developed for python2, however it should be straightforward to use them with python3. Script to compute the match to volcanic products and fractional area The script “Compute-and-plot-match-to-volcanic-products.ipynb” makes it possible to compute median distances and related statistical quantities described in the study, as well as the fractional area covered by basal mantle structures. The script also plots sample Empirical Distributions Functions (EDFs) as well as random EDFs for each considered case. Dependencies: - GMT6 - Python packages: o pygplates o numpy o os o math o pandas o matplotlib - Python scripts (included in main directory): o sphere_tools.py o call_system_command.py o kuiper.py (from: https://github.com/aarchiba/kuiper/blob/master/kuiper.py) - Lists of models (included in main directory): o main_cases_320Ma.dat o all_cases_320Ma.dat o all_cases_640Ma.dat Script to compute the match to volcanic products and fractional area The script “Compute-match-to-tomographic-models.ipynb” makes it possible to compute the match (accuracy, see study) between mantle flow models and tomographic models in cluster space. Dependencies: - Python packages: o numpy o sys o os o stripy o pygplates o pandas o netcdf from scipy.io - gpml file (included in main directory): o citcoms_mesh_caps_129_129_no_duplicates.gpmlz Script to plot a summary of the results The script “Plot_results_summary.ipynb” makes it possible to plot key results for mantle flow models and tomographic models on a single figure. Dependencies: - Python packages: o numpy o pandas o matplotlib
- Published
- 2021
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16. Spreading continents kick-started plate tectonics
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Rey, Patrice F., Coltice, Nicolas, and Flament, Nicolas
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Continents -- Natural history ,Plate tectonics -- Natural history ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Abstract
Stresses acting on cold, thick and negatively buoyant oceanic lithosphere are thought to be crucial to the initiation of subduction and the operation of plate tectonics (1,2), which characterizes the present-day geodynamics of the Earth. Because the Earth's interior was hotter in the Archaean eon, the oceanic crust may have been thicker, thereby making the oceanic lithosphere more buoyant than at present (3), and whether subduction and plate tectonics occurred during this time is ambiguous, both in the geological record and in geodynamic models (4). Here we show that because the oceanic crust was thick and buoyant (5), early continents may have produced intra-lithospheric gravitational stresses large enough to drive their gravitational spreading, to initiate subduction at their margins and to trigger episodes of subduction. Our model predicts the co-occurrence of deep to progressively shallower mafic volcanics and arc magmatism within continents in a self-consistent geodynamic framework, explaining the enigmatic multimodal volcanism and tectonic record of Archaean cratons (6). Moreover, our model predicts a petrological stratification and tectonic structure of the sub-continental lithospheric mantle, two predictions that are consistent with xenolith (5) and seismic studies, respectively, and consistent with the existence of a mid-lithospheric seismic discontinuity (7). The slow gravitational collapse of early continents could have kick-started transient episodes of plate tectonics until, as the Earth's interior cooled and oceanic lithosphere became heavier, plate tectonics became self-sustaining., Present-day plate tectonics is primarily driven by the negative buoyancy of cold subducting plates. Petrological and geochemical proxies of subduction preserved in early continents point to subduction-like processes already operating [...]
- Published
- 2014
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17. Plate tectonics and mantle controls on plume dynamics
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Arnould, Maëlis, Coltice, Nicolas, Flament, Nicolas, Mallard, Claire, Arnould, Maëlis, Coltice, Nicolas, Flament, Nicolas, and Mallard, Claire
- Abstract
Mantle plumes provide valuable information about whole-mantle convection: they originate at the core-mantle boundary, cross Earth's mantle and interact with the lithosphere. For instance, it has been proposed that the mobility/stability of plumes depends on plume intrinsic properties, on how slabs interact with the basal boundary layer, on mantle flow, or on their proximity to mid-ocean ridges. Here, we use 3D-spherical models of mantle convection generating self-consistent plate-like behaviour to investigate the mechanisms linking tectonics and mantle convection to plume dynamics. Our models produce fully-dynamic mantle plumes that rise vertically with deflection <10°and present excess temperatures, rising speeds, buoyancy and heat fluxes comparable to observations. In the absence of plate tectonics, plumes are stable and their lifetime exceeds hundreds of million years. With plate tectonics, plumes are more mobile, and we identify four physical mechanisms controlling their stability. 1/ Fixed plumes are located at saddle points of basal mantle flow. 2/ Plumes moving at speeds between 0.5-1 cm yr−1 are slowly entrained by passive mantle flow. 3/ Fast plume motions between 2-5 cm yr−1 lasting several tens of million years are caused by slab push. 4/ Plumes occasionally drift at speeds >5 cm yr−1 over <10 Myr through plume merging. We do not observe systematic anchoring of plumes to mid-oceanic ridges. Independent of the presence of a dense basal layer, plate-like regimes decrease the lifetime of plumes compared to stagnant-lid models. Plume age, temperature excess or buoyancy flux are not diagnostic of plume lateral speed. The fraction of plumes moving by less than 0.5 cm yr−1 is >25%, which suggests that fixed hotspot reference frames can be defined from carefully selected hotspot tracks.
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- 2020
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18. Coupled evolution of plate tectonics and basal mantle structure
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Cao, Xianzhi, Flament, Nicolas, Müller, R. Dietmar, Cao, Xianzhi, Flament, Nicolas, and Müller, R. Dietmar
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The relationships between plate motions and basal mantle structure remain poorly understood, with some models implying that the basal mantle structure has remained stable over time, while others suggest that it could be shaped by the aggregation and dispersal of supercontinents. Here we investigate the evolution of mantle flow driven by end-member plate tectonic models over 1 Gyr. We implement a tectonic scenario in which supercontinent reassembly occurs by introversion, and consider three distinct references frames that result in different net lithospheric rotation. Our flow models predict a dominant degree-2 mantle structure most of the time. We analyze the relationship between imposed tectonic velocities and deep mantle flow, and find that at spherical harmonic degree 2, the maxima of lower mantle radial flow and temperature follow the motion path of the maxima of surface divergence. It may take 160–240 Myr for lower mantle structure to reflect plate motion changes when the lower mantle is reorganized by slabs sinking onto basal thermochemical structures, and/or when slabs stagnate in the transition zone before sinking to the lower mantle. Basal thermochemical structures move at less than 0.6°/Myr in our models, with a temporal average of 0.16°/Myr when there is no net lithospheric rotation, and between 0.20 and 0.23°/Myr when net lithospheric rotation exists and is induced in the lower mantle. Our results suggest that basal thermochemical structures are not stationary, but rather linked to global plate motions and plate boundary reconfigurations, reflecting the dynamic nature of the coevolving plate- mantle system.
- Published
- 2020
19. The influence of mantle flow on intracontinental basins: Three examples from Australia
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Young, Alexander, Flament, Nicolas, Hall, Lisa, Merdith, Andrew, Young, Alexander, Flament, Nicolas, Hall, Lisa, and Merdith, Andrew
- Abstract
© 2020 International Association of Sedimentologists and European Association of Geoscientists and Engineers and John Wiley & Sons Ltd During the Paleozoic, sedimentary basins developed within Gondwana without evolving to diverging plate boundaries. Such intracontinental basins present long subsidence histories with multiple phases of accelerated subsidence that are not always easily explained by far-field tectonic forces, and may be driven by processes other than rifting and thermal subsidence. Here we investigate the subsidence of Paleozoic Australian intracontinental basins by comparing one-dimensional backstripped tectonic subsidence histories from the western Australian Canning and Southern Carnarvon Basins and the central Australian Cooper Basin to forward subsidence models for pure shear lithospheric thinning. We make the hypothesis that differences between observed and model subsidence may be explained by mantle-flow driven topography, in addition to tectonic forces. To test this hypothesis, we compute dynamic topography from the first geodynamic models of mantle flow spanning the entire Phanerozoic Eon, and we analyse the relationship between dynamic topography and anomalous basin subsidence to dynamic topography and mantle flow. Although reconstructions of mantle flow in deep geological times are uncertain, our results suggest that long-wavelength dynamic topography could explain aspects of the complex tectonic histories intracontinental basins. In the presented reconstruction of mantle flow, topographic rebound following the sinking of a Cambrian aged slab resulted in a minor phase of dynamic uplift in the Cooper Basin in middle Permian times. Throughout Carboniferous-Triassic times Australia was positioned above a mantle upwelling driven by a hot structure at the base of the mantle. Structural uplift in the Canning and Southern Carnarvon basins during the Triassic-Jurassic interval was augmented by dynamic uplift produced by that large-scale upwelling, a
- Published
- 2020
20. Drainage and Sedimentary Responses to Dynamic Topography
- Author
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Ding, Xuesong, primary, Salles, Tristan, additional, Flament, Nicolas, additional, Mallard, Claire, additional, and Rey, Patrice F., additional
- Published
- 2019
- Full Text
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21. Constraining absolute plate motions since the Triassic - Plate reconstruction files 220-0 Ma
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Tetley, Michael G., Williams, Simon, Gurnis, Michael, Flament, Nicolas, and Müller, Dietmar R.
- Abstract
Paleogeographic plate tectonic reconstruction of the Earth from 220-0 Ma. Requires the open-source GPlates software for visualization. GPlates can be downloaded for free from: https://www.gplates.org. A full set of tutorials on how to use GPlates can be found at: https://sites.google.com/site/gplatestutorials, with the manual/user documentation available for download from: https://www.gplates.org/docs.html. Source publicationavailable here:https://doi.org/10.1029/2019JB017442
- Published
- 2019
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22. The interplay of dynamic topography and eustasy on continental flooding in the late Paleozoic
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Cao, Wenchao, Flament, Nicolas, Zahirovic, Sabin, Williams, Simon E, Muller, R. Dietmar, Cao, Wenchao, Flament, Nicolas, Zahirovic, Sabin, Williams, Simon E, and Muller, R. Dietmar
- Abstract
Global sea level change can be inferred from sequence stratigraphic and continental flooding data. These methods reconstruct sea level from peri-cratonic and cratonic basins that are assumed to be tectonically stable and sometimes called reference districts, and from spatio-temporal correlations across basins. However, it has been understood that long-wavelength (typically hundreds of km) and low-amplitude (km) vertical displacements of the Earth's surface due to mantle flow, namely dynamic topography, can occur in the absence of crustal deformation. Dynamic topography can drive marine inundation or regional emergence of continents and must be taken into consideration for eustasy estimates. Our analysis indicates that the long-term trend in global-scale maximum flooding over the late Paleozoic generally correlates with global sea level curves. The first-order flooding history of North America correlates with some estimates of eustasy. The Paleozoic inundation of South America does not follow long-term sea level variations. The flooding lows during the Early Carboniferous and high during the Late Carboniferous are at odds with estimates of eustasy and can be explained by dynamic uplift and subsidence, respectively. Our dynamic topography models indicate that the Yangtze Platform of South China experienced significant dynamic subsidence during the transition from Permian to Triassic largely due to proto-Pacific subduction and its northward motion to collide with North China. The reference districts - Western New York, Oklahoma and Kansas, and West Texas in North America - were to some degree affected by dynamic uplift and subsidence associated with long-lived Panthalassa subduction zones, closure of the Rheic Ocean and large-scale upwelling above the African deep-mantle structure during late Paleozoic times. This indicates that some published global sea level curves may include non-eustatic signals such as dynamic uplift or subsidence. The interpretation of stratigrap
- Published
- 2019
23. The deep roots of Earth’s surface
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Flament, Nicolas and Flament, Nicolas
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The structure of the lithosphere is key to reconciling the dynamic topography predicted by mantle convection models with residual topography derived from observations, suggest analyses of both models and data.
- Published
- 2019
24. Drainage and Sedimentary Responses to Dynamic Topography
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Ding, Xuesong, Salles, Tristan, Flament, Nicolas, Mallard, Claire, Rey, Patrice F, Ding, Xuesong, Salles, Tristan, Flament, Nicolas, Mallard, Claire, and Rey, Patrice F
- Abstract
Dynamic topography due to mantle flow contributes to shaping Earth's evolving landscapes by affecting sediment routing, which has rarely been explored in source-to-sink contexts. Here we design a generic model to investigate the impact of dynamic topography on both landscape evolution and stratigraphic formations. An imposed wave of dynamic topography propagates laterally under a fixed continent, exerting transient surface uplift and subsidence. We find that a migrating dynamic topography can induce significant drainage reorganizations and affect sediment routing from source to sink. Variations in sediment supply driven by the lateral migrating dynamic topography contribute to the formation of diachronous unconformities along the margin. The predicted sediment flux histories are then put into perspective with the Cretaceous sedimentary records along the Southern African margins. Finally, we demonstrate that correlating offshore depositional hiatuses and unconformities has the potential to constrain the spatiotemporal evolution of past dynamic topography events.
- Published
- 2019
25. Constraining Absolute Plate Motions Since the Triassic
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Tetley, Michael, Williams, Simon E, Gurnis, Michael, Flament, Nicolas, Muller, R. Dietmar, Tetley, Michael, Williams, Simon E, Gurnis, Michael, Flament, Nicolas, and Muller, R. Dietmar
- Abstract
The absolute motion of tectonic plates since Pangea can be derived from observations of hotspot trails, paleomagnetism, or seismic tomography. However, fitting observations is typically carried out in isolation without consideration for the fit to unused data or whether the resulting plate motions are geodynamically plausible. Through the joint evaluation of global hotspot track observations (for times <80 >Ma), first‐order estimates of net lithospheric rotation (NLR), and parameter estimation for paleo-trench migration (TM), we present a suite of geodynamically consistent, data‐optimized global absolute reference frames from 220 Ma to the present. Each absolute plate motion (APM) model was evaluated against six published APM models, together incorporating the full range of primary data constraints. Model performance for published and new models was quantified through a standard statistical analyses using three key diagnostic global metrics: root‐mean square plate velocities, NLR characteristics, and TM behavior. Additionally, models were assessed for consistency with published global paleomagnetic data and for ages motion, track geometry, and time dependence. Optimized APM models demonstrated significantly improved global fit with geological and geophysical observations while performing consistently with geodynamic constraints. Critically, APM models derived by limiting average rates of NLR to ~0.05°/Myr and absolute TM velocities to ~27‐mm/year fit geological observations including hotspot tracks. This suggests that this range of NLR and TM estimates may be appropriate for Earth over the last 220 Myr, providing a key step toward the practical integration of numerical geodynamics into plate tectonic reconstructions.
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- 2019
26. Present-dayd dynamic topography and lower-mantle structure from palaeogeographically constrained mantle flow models
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Flament, Nicolas and Flament, Nicolas
- Abstract
Earth's large-scale topography and lower-mantle structure are linked to past tectonic motions and mantle flow, making it possible to gain insights in the properties of the solid Earth from time-dependent global convection models driven by tectonic reconstructions. Recent work suggests that the amplitude of residual topography, obtained by subtracting models of isostatic topography from total topography, may be up to ~1000 m at spherical harmonic degree two (wavelength ~13 300 km) and > 200 m at spherical harmonic degree 12 (wavelength ~3000 km). The amplitude of dynamic topography and the structure of the lower mantle predicted by time-dependent forward mantle flow models both depend on the physical assumption and on model parameters. Here, I investigate the consequence of using the Boussinesq, extended Boussinesq or truncated anelastic liquid approximation (TALA) in time-dependent flow models for predicting present-day mantle structure and dynamic topography; I characterize the sensitivity of the spectral distribution of dynamic topography amplitude to the boundary conditions and model set-up for the computation of dynamic topography; and I investigate the sensitivity of model results to parameters including the depth- and temperature dependence of viscosity, the model initial age and the density of the basal layer. Extended Boussinesq and TALA models are preferred to Boussinesq models that overpredict the volume of lower-mantle slabs and the amplitude of long-wavelength dynamic topography. The correlation between dynamic and residual topography models for spherical harmonic degrees 1-3 generally ranges between 0.4 and 0.5. The flow models better predict the geographical location of large low shear velocity provinces than that of lower-mantle slabs, which cover smaller areas in map view. I show that preserving shallow lateral viscosity variations in the computation of dynamic topography increases the amplitude of dynamic topography for wavelengths > 6000 km. Parame
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- 2019
27. Palaeolatitudinal distribution of lithologic indicators of climate in a palaeogeographic framework
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Cao, Wenchao, Williams, Simon E, Flament, Nicolas, Zahirovic, Sabin, Scotese, Christopher, Muller, R. Dietmar, Cao, Wenchao, Williams, Simon E, Flament, Nicolas, Zahirovic, Sabin, Scotese, Christopher, and Muller, R. Dietmar
- Abstract
Whether the latitudinal distribution of climate-sensitive lithologies is stable through greenhouse and icehouse regimes remains unclear. Previous studies suggest that the palaeolatitudinal distribution of palaeoclimate indicators, including coals, evaporites, reefs and carbonates, has remained broadly similar since the Permian period, leading to the conclusion that atmospheric and oceanic circulation control their distribution rather than the latitudinal temperature gradient. Here we revisit a global-scale compilation of lithologic indicators of climate, including coals, evaporites and glacial deposits, back to the Devonian period. We test the sensitivity of their latitudinal distributions to the uneven distribution of continental areas through time and to global tectonic models, correct the latitudinal distributions of lithologies for sampling- and continental area-bias, and use statistical methods to fit these distributions with probability density functions and estimate their high-density latitudinal ranges with 50% and 95% confidence intervals. The results suggest that the palaeolatitudinal distributions of lithologies have changed through deep geological time, notably a pronounced poleward shift in the distribution of coals at the beginning of the Permian. The distribution of evaporites indicates a clearly bimodal distribution over the past ~400 Ma, except for Early Devonian, Early Carboniferous, the earliest Permian and Middle and Late Jurassic times. We discuss how the patterns indicated by these lithologies change through time in response to plate motion, orography, evolution and greenhouse/icehouse conditions. This study highlights that combining tectonic reconstructions with a comprehensive lithologic database and novel data analysis approaches provide insights into the nature and causes of shifting climatic zones through deep time.
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- 2019
28. Quantitative stratigraphic analysis in a source-to-sink numerical framework
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Ding, Xuesong, primary, Salles, Tristan, additional, Flament, Nicolas, additional, and Rey, Patrice, additional
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- 2019
- Full Text
- View/download PDF
29. Erratum: Present-dayd dynamic topography and lower mantle structure from paleogeographically-constrained mantle flow models
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Flament, Nicolas, primary
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- 2019
- Full Text
- View/download PDF
30. Paleolatitudinal distribution of lithologic indicators of climate in a paleogeographic framework
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Cao, Wenchao, Williams, Simon, Flament, Nicolas, Zahirovic, Sabin, Scotese, Christopher, and Müller, Dietmar
- Subjects
Physical Sciences and Mathematics ,Earth Sciences ,Geology ,FOS: Earth and related environmental sciences - Abstract
Whether the latitudinal distribution of climate-sensitive lithologies are stable through greenhouse and icehouse regimes remains unclear. Previous studies suggest that the paleolatitudinal distribution of paleoclimate indicators, including coals, evaporites, reefs and carbonates, have remained broadly similar since Permian times, leading to the conclusion that atmospheric and oceanic circulation control their distribution rather than the latitudinal temperature gradient. Here we revisit a global-scale compilation of lithologic indicators of climate, including coals, evaporites and glacial deposits, back to the Devonian period. We test the sensitivity of their latitudinal distributions to the uneven distribution of continental areas through time and to global tectonic models, correct the latitudinal distributions of lithologies for sampling- and continental area-bias, and use statistical methods to fit these distributions with probability density functions and estimate their high-density latitudinal ranges with 50% and 95% confidence intervals. The results suggest that the paleolatitudinal distributions of lithologies have changed through deep geological time, notably a pronounced poleward shift in the distribution of coals at the beginning of the Permian. The distribution of evaporites indicate a clearly bimodal distribution over the past ~400 Ma, except for Early Devonian, Early Carboniferous (Serpukhovian), the earliest Permian (Asselian-Sakmarian) and Middle and Late Jurassic times. We discuss how the patterns indicated from these lithologies change through time in response to plate motion, orography, evolution, and greenhouse/icehouse conditions. This study highlights that plate reconstructions, combined with a comprehensive lithologic database, and novel data analysis provide insights on the shifting climatic zones through deep time.
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- 2017
31. Present-day dynamic topography and lower-mantle structure from palaeogeographically constrained mantle flow models
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Flament, Nicolas, primary
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- 2018
- Full Text
- View/download PDF
32. The dynamic topography of eastern China since the latest Jurassic Period
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Cao, Xianzhi, Flament, Nicolas, Muller, R. Dietmar, Li, Sanzhong, Cao, Xianzhi, Flament, Nicolas, Muller, R. Dietmar, and Li, Sanzhong
- Abstract
Some changes in the topography of eastern China since Late Jurassic times cannot be well explained by lithospheric deformation. Here we analyze global mantle flow models to investigate how mantle‐driven long‐wavelength topography may have contributed to shaping the surface topography of eastern China. Paleodrainage directions suggest that a southward tilted topography once existed in eastern North China in the latest Jurassic Period, which is different from that at present day (southeastward tilting). Our model dynamic topography reveals a southward tilting topography between 160 and 150 Ma, followed by southeastward tilting and rapid subsidence, which is compatible with paleodrainage directions and tectonic subsidence of the Ordos Basin. The Cretaceous anomalous subsidence of the Songliao and North Yellow Sea basins, as well as the Cenozoic anomalous subsidence of the East China Sea Shelf Basin can also be explained by dynamic topography. An apatite fission track study in the Taihang Mountains reveals four stages of evolution: Late Jurassic fast unroofing, Cretaceous slow unroofing, early Cenozoic fast unroofing and late Cenozoic slow unroofing. We propose that mantle flow influenced this surface unroofing because the model predicts Late Jurassic dynamic uplift, Cretaceous dynamic subsidence, early Cenozoic dynamic uplift and late Cenozoic dynamic subsidence. Apatite fission track data from northern South China are also in reasonable agreement with predicted dynamic topography between 80 and 30 Ma. The spatial and temporal agreement between geological observations and model dynamic topography indicates that mantle flow has had a significant influence in shaping the surface topography of eastern China.
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- 2018
33. Unpacking the history of how Earth feeds life, and life changes Earth
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Dosseto, Anthony, Young, Alexander, Flament, Nicolas, Dosseto, Anthony, Young, Alexander, and Flament, Nicolas
- Abstract
Although often separated as two unique subjects in science, geology and biology have been intricately intertwined since life on Earth first evolved billions of years ago.
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- 2018
34. On the scales of dynamic topography in whole-mantle convection models
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Arnould, Maelis R, Coltice, Nicolas, Flament, Nicolas, Seigneur, V, Muller, R. Dietmar, Arnould, Maelis R, Coltice, Nicolas, Flament, Nicolas, Seigneur, V, and Muller, R. Dietmar
- Abstract
Mantle convection shapes Earth's surface by generating dynamic topography. Observational constraints and regional convection models suggest that surface topography could be sensitive to mantle flow for wavelengths as short as 1,000 and 250 km, respectively. At these spatial scales, surface processes including sedimentation and relative sea‐level change occur on million‐year timescales. However, time‐dependent global mantle flow models do not predict small‐scale dynamic topography yet. Here we present 2‐D spherical annulus numerical models of mantle convection with large radial and lateral viscosity contrasts. We first identify the range of Rayleigh number, internal heat production rate and yield stress for which models generate plate‐like behavior, surface heat flow, surface velocities, and topography distribution comparable to Earth's. These models produce both whole‐mantle convection and small‐scale convection in the upper mantle, which results in small‐scale (km) to large‐scale (>104 km) dynamic topography, with a spectral power for intermediate scales (500 to 104 km) comparable to estimates of present‐day residual topography. Timescales of convection and the associated dynamic topography vary from five to several hundreds of millions of years. For a Rayleigh number of 107, we investigate how lithosphere yield stress variations (10-50 MPa) and the presence of deep thermochemical heterogeneities favor small‐scale (200-500 km) and intermediate‐scale (500-104 km) dynamic topography by controlling the formation of small‐scale convection and the number and distribution of subduction zones, respectively. The interplay between mantle convection and lithosphere dynamics generates a complex spatial and temporal pattern of dynamic topography consistent with constraints for Earth.
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- 2018
35. Geodynamic reconstruction of an accreted Cretaceous back-arc basin in the Northern Andes
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Braz, Carmen, Seton, Maria, Flament, Nicolas, Muller, R. Dietmar, Braz, Carmen, Seton, Maria, Flament, Nicolas, and Muller, R. Dietmar
- Abstract
A complex history of subduction, back-arc basin formation, terrane accretion and transpressional shearing characterizes the evolution of the Caribbean and northern South American margin since Jurassic times. Quantitative plate tectonic reconstructions of the area do not include Jurassic-Cretaceous back-arc terranes of which there are both geological and geophysical observations. We developed a revised plate tectonic reconstruction based on geological observations and seismic tomography models to constrain the Jurassic-Cretaceous subduction history of eastern Panthalassa, along the western margin of the Caribbean region. This reconstruction considers the opening of a Northern Andean back-arc basin at 145 Ma, the Quebradagrande back-arc, closing at 120 Ma and followed by terrane accretion and northward translation along the South American margin starting at 100 Ma. This kinematic reconstruction is tested against two previously published tectonic reconstructions via coupling with global numerical mantle convection models using CitcomS. A comparison of modelled versus tomographically imaged mantle structure reveals that subduction outboard of the South American margin, lacking in previous tectonic models, is required to reproduce mid-mantle positive seismic anomalies imaged in P- and S-wave seismic tomography beneath South America, 500-2000 km in depth. Furthermore, we show that this subduction zone is likely produced by a back-arc basin that developed along the northern Andes during the Cretaceous via trench roll-back from 145 Ma and was closed at 100 Ma. The contemporaneous opening of the Quebradagrande back-arc basin with the Rocas Verdes back-arc basin in the southern Andes is consistent with a model that invokes return flow of mantle material behind a retreating slab and may explain why extension along the Peruvian and Chilean sections of the Andean margin did not experience full crustal break-up and back-arc opening during the late Jurassic-early Cretaceous Period
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- 2018
36. Dynamic topography of passive continental margins and their hinterlands since the Cretaceous
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Muller, R. Dietmar, Hassan, Rakib, Gurnis, Michael, Flament, Nicolas, Williams, Simon E, Muller, R. Dietmar, Hassan, Rakib, Gurnis, Michael, Flament, Nicolas, and Williams, Simon E
- Abstract
Even though it is well accepted that the Earth's surface topography has been affected by mantle-convection induced dynamic topography, its magnitude and time-dependence remain controversial. The dynamic influence to topographic change along continental margins is particularly difficult to unravel, because their stratigraphic record is dominated by tectonic subsidence caused by rifting. We follow a three-fold approach to estimate dynamic topographic change along passive margins based on a set of seven global mantle convection models. We first demonstrate that a geodynamic forward model that includes adiabatic and viscous heating in addition to internal heating from radiogenic sources, and a mantle viscosity profile with a gradual increase in viscosity below the mantle transition zone, provides a greatly improved match to the spectral range of residual topography end-members as compared with previous models at very long wavelengths (spherical degrees 2-3). We then combine global sea level estimates with predicted surface dynamic topography to evaluate the match between predicted continental flooding patterns and published paleo-coastlines by comparing predicted versus geologically reconstructed land fractions and spatial overlaps of flooded regions for individual continents since 140 Ma. Modelled versus geologically reconstructed land fractions match within 10% for most models, and the spatial overlaps of inundated regions are mostly between 85% and 100% for the Cenozoic, dropping to about 75-100% in the Cretaceous. Regions that have been strongly affected by mantle plumes are generally not captured well in our models, as plumes are suppressed in most of them, and our models with dynamically evolving plumes do not replicate the location and timing of observed plume products. We categorise the evolution of modelled dynamic topography in both continental interiors and along passive margins using cluster analysis to investigate how clusters of similar dynamic topography
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- 2018
37. Global tectonic reconstructions with continuously deforming and evolving rigid plates
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Gurnis, Michael, Yang, Ting, Cannon, John, Turner, Mark, Williams, Simon E, Flament, Nicolas, Muller, R. Dietmar, Gurnis, Michael, Yang, Ting, Cannon, John, Turner, Mark, Williams, Simon E, Flament, Nicolas, and Muller, R. Dietmar
- Abstract
Traditional plate reconstruction methodologies do not allow for plate deformation to be considered. Here we present software to construct and visualize global tectonic reconstructions with deforming plates within the context of rigid plates. Both deforming and rigid plates are defined by continuously evolving polygons. The deforming regions are tessellated with triangular meshes such that either strain rate or cumulative strain can be followed. The finite strain history, crustal thickness and stretching factor of points within the deformation zones are tracked as Lagrangian points. Integrating these tools within the interactive platform GPlates enables specialized users to build and refine deforming plate models and integrate them with other models in time and space. We demonstrate the integrated platform with regional reconstructions of Cenozoic western North America, the Mesozoic South American Atlantic margin, and Cenozoic southeast Asia, embedded within global reconstructions, using different data and reconstruction strategies.
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- 2018
38. Global kinematics of tectonic plates and subduction zones since the late Paleozoic Era
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Young, Alexander, Flament, Nicolas, Maloney, Kayla, Williams, Simon E, Matthews, Kara J, Zahirovic, Sabin, Muller, R. Dietmar, Young, Alexander, Flament, Nicolas, Maloney, Kayla, Williams, Simon E, Matthews, Kara J, Zahirovic, Sabin, and Muller, R. Dietmar
- Abstract
Detailed global plate motion models that provide a continuous description of plate boundaries through time are an effective tool for exploring processes both at and below the Earth's surface. A new generation of numerical models of mantle dynamics pre- and post-Pangea timeframes requires global kinematic descriptions with full plate reconstructions extending into the Paleozoic (410 Ma). Current plate models that cover Paleozoic times are characterised by large plate speeds and trench migration rates because they assume that lowermost mantle structures are rigid and fixed through time. When used as a surface boundary constraint in geodynamic models, these plate reconstructions do not accurately reproduce the present-day structure of the lowermost mantle. Building upon previous work, we present a global plate motion model with continuously closing plate boundaries ranging from the early Devonian at 410 Ma to present day. We analyse the model in terms of surface kinematics and predicted lower mantle structure. The magnitude of global plate speeds has been greatly reduced in our reconstruction by modifying the evolution of the synthetic Panthalassa oceanic plates, implementing a Paleozoic reference frame independent of any geodynamic assumptions, and implementing revised models for the Paleozoic evolution of North and South China and the closure of the Rheic Ocean. Paleozoic (410-250 Ma) RMS plate speeds are on average ∼8 cm/yr, which is comparable to Mesozoic-Cenozoic rates of ∼6 cm/yr on average. Paleozoic global median values of trench migration trend from higher speeds (∼2.5 cm/yr) in the late Devonian to rates closer to 0 cm/yr at the end of the Permian (∼250 Ma), and during the Mesozoic-Cenozoic (250-0 Ma) generally cluster tightly around ∼1.1 cm/yr. Plate motions are best constrained over the past 130 Myr and calculations of global trench convergence rates over this period indicate median rates range between 3.2 cm/yr and 12.4 cm/yr with a present day median rate
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- 2018
39. On the scales of dynamic topography in whole-mantle convection models - preprint version
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ARNOULD, Maëlis, Coltice, Nicolas, Flament, Nicolas, Seigneur, Valentin, and Müller, Dietmar
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bepress|Physical Sciences and Mathematics ,Physics::Fluid Dynamics ,bepress|Physical Sciences and Mathematics|Earth Sciences|Geophysics and Seismology ,EarthArXiv|Physical Sciences and Mathematics|Earth Sciences|Geophysics and Seismology ,Earth Sciences ,Physical Sciences and Mathematics ,bepress|Physical Sciences and Mathematics|Earth Sciences ,EarthArXiv|Physical Sciences and Mathematics|Earth Sciences ,Geophysics and Seismology ,Physics::Atmospheric and Oceanic Physics ,EarthArXiv|Physical Sciences and Mathematics ,Physics::Geophysics - Abstract
Mantle convection shapes Earths surface by generating dynamic topography. Observational constraints and regional convection models suggest that surface topography could be sensitive to mantle flow for wavelengths as short as 1,000 km and 250 km, respectively. At these spatial scales, surface processes including sedimentation and relative sea-level change occur on million year timescales. However, time dependent global mantle flow models do not predict small-scale dynamic topography yet. Here, we present 2D-spherical annulus numerical models of mantle convection with large radial and lateral viscosity contrasts. We first identify the range of Rayleigh number, internal heat production rate and yield stress for which models generate plate-like behaviour, surface heat flow, surface velocities and topography distribution comparable to Earths. These models produce both whole mantle convection and small-scale convection in the upper mantle, which results in small- (< 500 km) to large-scale (> 10^4 km) dynamic topography, with a spectral power for intermediate scales (500 to 10^4 km) comparableto estimates of present-day residual topography. Timescales of convection and the associated dynamic topography vary from five to several hundreds of millions of years. For a Rayleigh number of 10^7, we investigate how lithosphereyield stress variations (10-50 MPa) and the presence of deep thermochemical heterogeneities favour small-scale (200-500 km) and intermediate scale (500-10^4 km) dynamic topography by controlling the formation of small scale convection and the number and distribution of subduction zones, respectively. The interplay between mantle convection and lithosphere dynamics generates a complex spatial and temporal pattern of dynamic topography consistent with constraints for Earth.
- Published
- 2017
- Full Text
- View/download PDF
40. Improving global paleogeography since the late Paleozoic using paleobiology
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Cao, Wenchao, primary, Zahirovic, Sabin, additional, Flament, Nicolas, additional, Williams, Simon, additional, Golonka, Jan, additional, and Müller, R. Dietmar, additional
- Published
- 2017
- Full Text
- View/download PDF
41. The role of deep Earth dynamics in driving the flooding and emergence of New Guinea since the Jurassic
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Harrington, Lauren, Zahirovic, Sabin, Flament, Nicolas, Muller, R. Dietmar, Harrington, Lauren, Zahirovic, Sabin, Flament, Nicolas, and Muller, R. Dietmar
- Abstract
The paleogeography of New Guinea indicates fluctuating periods of flooding and emergence since the Jurassic, which are inconsistent with estimates of global sea level change since the Eocene. The role of deep Earth dynamics in explaining these discrepancies has not been explored, despite the strongly time-dependent geodynamic setting within which New Guinea has evolved. We aim to investigate the role of subduction-driven mantle flow in controlling long-wavelength dynamic topography and its manifestation in the regional sedimentary record, within a tectonically complex region leading to orogeny. We couple regionally refined global plate reconstructions with forward geodynamic models to compare trends of dynamic topography with estimates of eustasy and regional paleogeography. Qualitative corroboration of modelled mantle structure with equivalent tomographic profiles allows us to ground-truth the models. We show that predicted dynamic topography correlates with the paleogeographic record of New Guinea from the Jurassic to the present. We find that subduction at the East Gondwana margin locally enhanced the high eustatic sea levels from the Early Cretaceous (∼145 Ma) to generate long-term regional flooding. During the Miocene, however, dynamic subsidence associated with subduction of the Maramuni Arc played a fundamental role in causing long-term inundation of New Guinea during a period of global sea level fall.
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- 2017
42. Dynamic topography and eustasy controlled the paleogeographic evolution of northern Africa since the mid-Cretaceous
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Barnett-Moore, N, Hassan, Rakib, Muller, R. Dietmar, Williams, Simon E, Flament, Nicolas, Barnett-Moore, N, Hassan, Rakib, Muller, R. Dietmar, Williams, Simon E, and Flament, Nicolas
- Abstract
Northern Africa underwent widespread inundation during the Late Cretaceous. Changes in eustasy do not explain the absence of this inundation across the remainder of Africa, and the timing and location of documented tectonic deformation do not explain the large-scale paleogeographic evolution. We investigate the combined effects of vertical surface displacements predicted by a series of mantle flow models and eustasy on northern African paleoenvironmental change. We compare changes in base level computed as the difference between eustasy and long-wavelength dynamic topography arising from sources of buoyancy deeper than 350 km to the evolution of paleoshorelines derived from two interpolated global data sets since the mid-Cretaceous. We also compare the predicted mantle temperature field of these mantle flow models at present-day to several seismic tomography models. This approach reveals that dynamic subsidence, related to Africa's northward motion away from the buoyant regions overlying the African large low shear velocity province, amplified sea level rise, resulting in maximum inundation of northern Africa during the Cenomanian and Turonian. By the Cenozoic, decreased magnitudes of dynamic subsidence, reflecting the reduced drawdown effects of slab material beneath northern Africa associated with the impact of the Africa-Eurasia collision, combined with a comparatively pronounced progressive sea level fall resulted in ongoing region-wide regression along coastal regions. The temporal match between our preferred model and the paleoshoreline data sets suggests that the paleogeographic evolution of this region since the Late Cretaceous has mainly been influenced by the interplay between eustasy and long-wavelength dynamic topography arising from large-scale, subduction-driven, lower mantle convection.
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- 2017
43. Improving global paleogeography since the late Paleozoic using paleobiology
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Cao, Wenchao, Zahirovic, Sabin, Flament, Nicolas, Williams, Simon E, Golonka, Jan, Muller, R. Dietmar, Cao, Wenchao, Zahirovic, Sabin, Flament, Nicolas, Williams, Simon E, Golonka, Jan, and Muller, R. Dietmar
- Abstract
Paleogeographic reconstructions are important to understand Earth's tectonic evolution, past eustatic and regional sea level change, paleoclimate and ocean circulation, deep Earth resources and to constrain and interpret the dynamic topography predicted by mantle convection models. Global paleogeographic maps have been compiled and published, but they are generally presented as static maps with varying map projections, different time intervals represented by the maps and different plate motion models that underlie the paleogeographic reconstructions. This makes it difficult to convert the maps into a digital form and link them to alternative digital plate tectonic reconstructions. To address this limitation, we develop a workflow to restore global paleogeographic maps to their present-day coordinates and enable them to be linked to a different tectonic reconstruction. We use marine fossil collections from the Paleobiology Database to identify inconsistencies between their indicative paleoenvironments and published paleogeographic maps, and revise the locations of inferred paleo-coastlines that represent the estimated maximum transgression surfaces by resolving these inconsistencies. As a result, the consistency ratio between the paleogeography and the paleoenvironments indicated by the marine fossil collections is increased from an average of 75 % to nearly full consistency (100 %). The paleogeography in the main regions of North America, South America, Europe and Africa is significantly revised, especially in the Late Carboniferous, Middle Permian, Triassic, Jurassic, Late Cretaceous and most of the Cenozoic. The global flooded continental areas since the Early Devonian calculated from the revised paleogeography in this study are generally consistent with results derived from other paleoenvironment and paleo-lithofacies data and with the strontium isotope record in marine carbonates. We also estimate the terrestrial areal change over time associated with transferri
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- 2017
44. Correspondence: Reply to 'Numerical modelling of the PERM anomaly and the Emeishan large igneous province'
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Flament, Nicolas, Williams, Simon E, Muller, R. Dietmar, Gurnis, Michael, Bower, Dan J, Flament, Nicolas, Williams, Simon E, Muller, R. Dietmar, Gurnis, Michael, and Bower, Dan J
- Abstract
Tectonic plates and plate boundaries migrate substantially through time and mantle plumes are generally accepted to be mobile within the convecting mantle, but it has been proposed that large low shear velocity provinces (LLSVPs) could have been fixed and rigid for as much as 540 million years (Myr) The hypotheses of fixed and rigid LLSVPs cannot be easily tested in the absence of constraints on the past location of lowermost mantle structures. We evaluated the hypothesis of lower mantle thermochemical structure fixity with numerical experiments. As in earlier studies, we argue11 that the location of lower mantle thermochemical structures has changed through time.
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- 2017
45. Influence of mantle flow on the drainage of eastern Australia since the Jurassic Period
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Salles, Tristan, Flament, Nicolas, Muller, R. Dietmar, Salles, Tristan, Flament, Nicolas, and Muller, R. Dietmar
- Abstract
Recent studies of the past eastern Australian landscape from present-day longitudinal river profiles and from mantle flow models suggest that the interaction of plate motion with mantle convection accounts for the two phases of large-scale uplift of the region since 120 Ma. We coupled the dynamic topography predicted from one of these mantle flow models to a surface process model to study the evolution of the eastern Australian landscape since the Jurassic Period. We varied the rainfall regime, erodibility, sea level variations, dynamic topography magnitude, and elastic thickness across a series of experiments. The approach accounts for erosion and sedimentation and simulates catchment dynamics. Despite the relative simplicity of our model, the results provide insights on the fundamental links between dynamic topography and continental-scale drainage evolution. Based on temporal and spatial changes in longitudinal river profiles as well as erosion and deposition maps, we show that the motion of the Australian plate over the convecting mantle has resulted in significant reorganization of the eastern Australian drainage. The model predicts that the Murray river drained eastward between 150 and ∼120 Ma, and switched to westward draining due to the tilting of the Australian plate from ∼120 Ma. First order comparisons of eight modeled river profiles and of the catchment shape of modeled Murray-Darling Basin are in agreement with present-day observations. The predicted denudation of the eastern highlands is compatible with thermochronology data and sedimentation rates along the southern Australian margin are consistent with cumulative sediment thickness.
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- 2017
46. The deep Earth origin of the Iceland plume and its effects on regional surface uplift and subsidence
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Barnett-Moore, N, Hassan, Rakib, Flament, Nicolas, Muller, R. Dietmar, Barnett-Moore, N, Hassan, Rakib, Flament, Nicolas, and Muller, R. Dietmar
- Abstract
The present-day seismic structure of the mantle under the North Atlantic Ocean indicates that the Iceland hotspot represents the surface expression of a deep mantle plume, which is thought to have erupted in the North Atlantic domain during the Palaeocene. The spatial and temporal evolution of the plume since its eruption is still highly debated, and little is known about its deep mantle history. Here, we use palaeogeographically constrained global mantle flow models to investigate the evolution of deep Earth flow beneath the North Atlantic since the Jurassic. The models show that over the last ∼ 100 Myr a remarkably stable pattern of convergent flow has prevailed in the lowermost mantle near the tip of the African Large Low-Shear Velocity Province (LLSVP), making it an ideal plume nucleation site. We extract model dynamic topography representative of a plume beneath the North Atlantic region since eruption at ∼ 60 Ma to present day and compare its evolution to available offshore geological and geophysical observations across the region. This comparison confirms that a widespread episode of Palaeocene transient uplift followed by early Eocene anomalous subsidence can be explained by the mantle-driven effects of a plume head ∼ 2500 km in diameter, arriving beneath central eastern Greenland during the Palaeocene. The location of the model plume eruption beneath eastern Greenland is compatible with several previous models. The predicted dynamic topography is within a few hundred metres of Palaeocene anomalous subsidence derived from well data. This is to be expected given the current limitations involved in modelling the evolution of Earth's mantle flow in 3-D, particularly its interactions with the base of a heterogeneous lithosphere as well as short-wavelength advective upper mantle flow, not captured in the presented global models.
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- 2017
47. Origin and evolution of the deep thermochemical structure beneath Eurasia
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Flament, Nicolas, Williams, Simon E, Muller, R, Gurnis, Michael, Bower, Dan J, Flament, Nicolas, Williams, Simon E, Muller, R, Gurnis, Michael, and Bower, Dan J
- Abstract
A unique structure in the Earth's lowermost mantle, the Perm Anomaly, was recently identified beneath Eurasia. It seismologically resembles the large low-shear velocity provinces (LLSVPs) under Africa and the Pacific, but is much smaller. This challenges the current understanding of the evolution of the plate-mantle system in which plumes rise from the edges of the two LLSVPs, spatially fixed in time. New models of mantle flow over the last 230 million years reproduce the present-day structure of the lower mantle, and show a Perm-like anomaly. The anomaly formed in isolation within a closed subduction network ¿22,000 km in circumference prior to 150 million years ago before migrating ¿1,500 km westward at an average rate of 1 cm year -1, indicating a greater mobility of deep mantle structures than previously recognized. We hypothesize that the mobile Perm Anomaly could be linked to the Emeishan volcanics, in contrast to the previously proposed Siberian Traps.
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- 2017
48. The deep Earth origin of the Iceland plume and its effects on regional surface uplift and subsidence
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Barnett-Moore, Nicholas, primary, Hassan, Rakib, additional, Flament, Nicolas, additional, and Müller, Dietmar, additional
- Published
- 2017
- Full Text
- View/download PDF
49. Provenance of plumes in global convection models
- Author
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Hassan, Rakib, Flament, Nicolas, Gurnis, Michael, Bower, Dan J., and Müller, Dietmar
- Abstract
In global convection models constrained by plume motions and subduction history over the last 230 Myr, plumes emerge preferentially from the edges of thermochemical structures that resemble present-day large low shear velocity provinces (LLSVPs) beneath Africa and the Pacific Ocean. It has been argued that large igneous provinces (LIPs) erupting since 200 Ma may originate from plumes that emerged from the edges of the LLSVPs and numerical models have been devised to validate this hypothesis. Although qualitative assessments that are broadly in agreement with this hypothesis have been derived from numerical models, a quantitative assessment has been lacking. We present a novel plume detection scheme and derive Monte Carlo-based statistical correlations of model plume eruption sites and reconstructed LIP eruption sites. We show that models with a chemically anomalous lower mantle are highly correlated to reconstructed LIP eruption sites, whereas the confidence level obtained for a model with purely thermal plumes falls just short of 95%. A network of embayments separated by steep ridges form in the deep lower mantle in models with a chemically anomalous lower mantle. Plumes become anchored to the peaks of the chemical ridges and the network of ridges acts as a floating anchor, adjusting to slab push forces through time. The network of ridges imposes a characteristic separation between conduits that can extend into the interior of the thermochemical structures. This may explain the observed clustering of reconstructed LIP eruption sites that mostly but not exclusively occur around the present-day LLSVPs.
- Published
- 2015
50. Quantitative stratigraphic analysis in a source-to-sink numerical framework.
- Author
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Xuesong Ding, Salles, Tristan, Flament, Nicolas, and Rey, Patrice
- Subjects
SEDIMENTS ,STRATIGRAPHIC geology ,SEA level - Abstract
The sedimentary architecture at continental margins reflects the interplay between the rate of change of accommodation creation (δA) and the rate of change of sediment supply (δS). As a result, stratigraphic interpretation increasingly focuses on understanding the link between deposition patterns and changes in δA/δS. Here, we use the landscape modelling framework pyBadlands to assess the respective performance of two well-established stratigraphic interpretation techniques: the trajectory analysis method and the accommodation succession method. In contrast to most Stratigraphic Forward Models (SFMs), pyBadlands provides self-consistent sediment supply to basin margins as it simulates erosion, sediment transport and deposition in a source-to-sink context. We present a landscape evolution that takes into account periodic sea level variations and passive margin thermal subsidence over 30 million years, under uniform rainfall. We implement the two aforementioned approaches to interpret the resulting depositional cycles at the continental margin. We first apply both the trajectory analysis and the accommodation succession methods to manually map key stratigraphic surfaces and define stratigraphic units from shelf-edge (or offlap break) trajectories, stratal terminations and stratal geometries. We then design a set of post-processing numerical tools to calculate shoreline and shelf-edge trajectories, the temporal evolution of changes in accommodation and sedimentation, and automatically produce stratigraphic interpretations. Comparing manual and automatic stratigraphic interpretations reveals that the results of the trajectory analysis method depend on time-dependent processes such as thermal subsidence whereas the accommodation succession method does not. In addition to reconstructing stratal stacking patterns, the tools we introduce here make it possible to quickly extract Wheeler diagrams and synthetic cores at any location within the simulated domain. Our work provides an efficient and flexible quantitative sequence stratigraphic framework to evaluate the main drivers (climate, sea level and tectonics) controlling sedimentary architectures and investigate their respective roles in sedimentary basins development. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
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