Origin and evolution of the deep thermochemical structure beneath Eurasia

Flament_Figure5Citation

Flament, N. et al. Origin and evolution of the deep thermochemical structure beneath Eurasia. Nat. Commun. 7, 14164 doi: 10.1038/ncomms14164 (2016).

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 before 150 million years ago before migrating ~1,500 km westward at an average rate of 1 cm per year, 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. 

This article is freely accessible using the following link http://rdcu.be/oDqg Read more…

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GPlates 2.0 Released

2016_11_MedMeet-Group.jpgGPlates 2.0 was released last week, with lots of new features including plate deformation, volume rendering, much improved project and session management, a plate topology building tool and an interactive tool to determine best-fit rotation poles using the method of Hellinger, and much more. Check out the full list of improvements here. … Read more…

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Global plate boundary evolution and kinematics since the late Paleozoic

Matthews++_SummaryFigCitation

Matthews, K.J., Maloney, K.T., Zahirovic, S., Williams, S.E., Seton, M., and Müller, R.D. (2016). Global plate boundary evolution and kinematics since the late Paleozoic, Global and Planetary Change, 146, 226-250. DOI: 10.1016/j.gloplacha.2016.10.002

Abstract

Many aspects of deep-time Earth System models, including mantle convection, paleoclimatology, paleobiogeography and the deep Earth carbon cycle, require high-resolution plate models that include the evolution of the mosaic of plate boundaries through time. We present the first continuous late Paleozoic to present-day global plate model with evolving plate boundaries, building on and extending two previously published models for the late Paleozoic (410–250 Ma) and Mesozoic-Cenozoic (230–0 Ma). We ensure continuity during the 250–230 Ma transition period between the two models, update the absolute reference frame of the Mesozoic-Cenozoic model and add a new Paleozoic reconstruction for the Baltica-derived Alexander Terrane, now accreted to western North America. This 410–0 Ma open access model provides a framework for deep-time whole Earth modelling and acts as a base for future extensions and refinement.

This model is available with a default mantle reference frame, a hybrid reference frame using moving hotspots and a true polar wander corrected paleomagnetic reference frame (see paper for details) as well as with a paleomagnetic reference frame. For times before 83 Ma, the Pacific is shifted to maintain relative motions with the circum-Pangea continents – largely due to the fact that no paleomagnetic reference frames exist that extend to the birth age of the Pacific Plate. The paleomagnetic reference frame is based on data from Torsvik, T. H., Van der Voo, R., Preeden, U., Mac Niocaill, C., Steinberger, B., Doubrovine, P. V., van Hinsbergen, D. J., Domeier, M., Gaina, C., and Tohver, E., 2012, Phanerozoic polar wander, palaeogeography and dynamics: Earth-Science Reviews, v. 114, no. 3, p. 325-368, DOI: 10.1016/j.earscirev.2012.06.007.

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GPlates 2.0 software and data sets

GPlates 1.5 PromoGPlates is a free desktop software for the interactive visualisation of plate-tectonics. The compilation and documentation of GPlates 2.0 data was primarily funded by AuScope National Collaborative Research Infrastructure (NCRIS).

GPlates is developed by an international team of scientists and professional software developers at the EarthByte Project (part of AuScope) at the University of Sydney, the Division of Geological and Planetary Sciences (GPS) at CalTech, the Geodynamics team at the Geological Survey of Norway (NGU) and the Centre for Earth Evolution and Dynamics (CEED) at the University of Oslo.  … Read more…

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SoftwareX – Badlands: A parallel basin and landscape dynamics model

Abstract: Over more than three decades, a number of numerical landscape evolution models (LEMs) have been developed to study the combined effects of climate, sea-level, tectonics and sediments on Earth surface dynamics. Most of them are written in efficient programming languages, but often cannot be used on parallel architectures. Here, I present a LEM which … Read more…

Setting up environment for DCO Demo Analysis

Mac Environment 1.1) Install Anaconda Navigate to the continuum website and download the python 2.7 Mac version of Anaconda, if not already installed. In terminal, where the downloaded anaconda source code is stored, type: bash Anaconda2-4.1.1-MacOSX-x86_64.sh Select yes to all of the prompts. Edit your .bash_profile to include the anaconda bin path in the PATH … Read more…

Ocean Basin Evolution and Global-Scale Plate Reorganization Events Since Pangea Breakup

Author List: Dietmar Müller, Maria Seton, Sabin Zahirovic, Simon Williams, Kara Matthews, Nicky Wright, Grace Shephard, Kayla Maloney, Nicholas Barnett-Moore, Maral Hosseinpour, Dan Bower and John Cannon. Citation: Müller, R.D., Seton, M., Zahirovic, S., Williams, S.E., Matthews, K.J., Wright, N.M., Shephard, G.E., Maloney, K.T., Barnett-Moore, N., Hosseinpour, M., Bower, D.J., & Cannon, J. (2016). Ocean Basin Evolution and … Read more…

Workflow explained: The interaction of subduction zone volcanism with carbonate platforms and continents

Objectives Our two objectives of analysis were to (a) quantify the km-long length areas of interaction of subduction zone volcanism with carbonate platforms and (b) characterise the subduction volcanism as either continental or intra-oceanic depending on the proximity of the subduction zones to continent-ocean boundaries. In regards to the first objective, we are interested in cases where subduction-related … Read more…

Workflow explained: Measuring global subduction zone lengths with pyGPlates

For our first analysis, we developed a simple work flow to quantify subduction zone lengths from 0 to 400 Ma, using the Matthews et al. (2016) plate kinematic model. The bash workflow consists of python scripts, GMT tools and AWK scripts organised into bash sub-routine functions. The most integral parts of the workflow are the python scripts … Read more…

PALEOMAP PaleoAtlas for GPlates

PaleoAtlas_imageThe PALEOMAP PaleoAtlas for GPlates consists of 91 paleogeographic maps spanning the Phanerozoic and late Neoproterozoic. The PaleoAtlas can be directly loaded into GPlates as a Time Dependent Raster file. The paleogeographic maps in the PaleoAtlas illustrate the ancient configuration of the ocean basins and continents, as well as important topographic and bathymetric features such as mountains, lowlands, shallow sea, continental shelves, and deep oceans. This tutorial also describes how the maps in the PaleoAtlas were made, documents the sources of information used to make the paleogeographic maps, and provides instructions how to plot user-defined paleodata on the paleogeographic maps using the program PaleoDataPlotter. Read more…

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Computers & Geosciences – Badlands: An open-source, flexible and parallel framework to study landscape dynamics

Salles, T., and Hardiman, L. (2016). Badlands: An open-source, flexible and parallel framework to study landscape dynamics. Computers & Geosciences 91 77–89. DOI: 10.1016/j.cageo.2016.03.011 Badlands: An open-source, flexible and parallel framework to study landscape dynamics

Computers & Geosciences – Badlands: An open-source, flexible and parallel framework to study landscape dynamics

Author List: Tristan Salles, Luke Hardiman Citation: Salles, T., and Hardiman, L. (2016). Badlands: An open-source, flexible and parallel framework to study landscape dynamics. Computers & Geosciences 91 77–89. DOI: 10.1016/j.cageo.2016.03.011 Abstract: In this paper, we propose a minimal numerical model which governing equations describe the following processes: erosion, sedimentation, diffusion and flexure. The model respects conservation … Read more…

pygplates beta revision 12 released

GPlates Vector Logo

GPlates Vector LogoThe first beta release of pygplates (the GPlates Python library) is now available for download.

pygplates enables access to GPlates functionality via the Python programming language. This may be of particular use to researchers requiring more flexibility than is provided by the GPlates user interface.

The following pygplates functionality is available:-

  • Load and save feature data (GPML, Shapefile, etc)
  • Create/modify/query feature data
  • Traverse/modify/query plate rotation hierarchy
  • Partition into plates and assign plate properties
  • Reconstruct geometries, flowlines, motion paths
  • Resolve topological plates and query their boundary sections (ridges/subductions)
  • Calculate velocities
  • Distance between geometries (region-of-interest queries)
  • Geometry queries (length, point-in-polygon, area, centroid, tessellate, interpolate, join, partition)

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Data Processing and Plotting Using 
Generic Mapping Tools (GMT) Course

GMT Course Image 2016

GMT Course Image 2016Course Overview
This course is designed to introduce students to different types of spatial data, data processing and interpolation functions and data plotting using GMT (Generic Mapping Tools). GMT is a set of public domain tools that will be used in conjunction with UNIX general processing tools (awk, grep) and basic shell programming. The examples presented in the course will focus on marine geophysical data, however many of the principles are applicable to other scientific data.

The learning outcomes for the course include:  … Read more…

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Ocean basin evolution and global-scale plate reorganization events since Pangea breakup

Seafloor ages from Müller et al.

Seafloor ages from Müller et al.Citation
Müller R.D., Seton, M., Zahirovic, S., Williams, S.E., Matthews, K.J., Wright, N.M., Shephard, G.E., Maloney, K.T., Barnett-Moore, N., Hosseinpour, M., Bower, D.J., Cannon, J., 2016. Ocean basin evolution and global-scale plate reorganization events since Pangea breakup, Annual Review of Earth and Planetary Sciences, Vol 44, 107-138. DOI: 10.1146/annurev-earth-060115-012211.

Abstract
We present a revised global plate motion model with continuously closing plate boundaries ranging from the Triassic at 230 Ma to the present day, assess differences between alternative absolute plate motion models, and review global tectonic events. Relatively high mean absolute plate motion rates around 9–10 cm yr-1 between 140 and 120 Ma may be related to transient plate motion accelerations driven by the successive emplacement of a sequence of large igneous provinces during that time. … Read more…

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Prospectivity of Western Australian iron ore from geophysical data using a reject option classifier

Prospectivity of Western Australian iron ore from geophysical data using a reject option classifier - figure

Prospectivity of Western Australian iron ore from geophysical data using a reject option classifier - figureCitation
Merdith, A. S., Landgrebe, T. C., & Müller, R. D. (2015). Prospectivity of Western Australian iron ore from geophysical data using a reject option classifier. Ore Geology Reviews. http://dx.doi.org/10.1016/j.oregeorev.2015.03.014

Abstract
There has recently been a rapid growth in the amount and quality of digital geological and geophysical data for the majority of the Australian continent. Coupled with an increase in computational power and the rising impor- tance of computational methods, there are new possibilities for a large scale, low expenditure digital exploration of mineral deposits. Here we use a multivariate analysis of geophysical datasets to develop a methodology that utilises machine learning algorithms to build and train two-class classifiers for provincial-scale, greenfield min- eral exploration. … Read more…

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Seafloor lithology of the ocean basins

Lithology globe Aus Ant view

Lithology globe Aus Ant viewCitation
Dutkiewicz, A., Müller, R. D., O’Callaghan, S., & Jónasson, H. (2015). Census of seafloor sediments in the world’s ocean. Geology, G36883-1. doi: 10.1130/G36883.1.

Abstract
Knowing the patterns of distribution of sediments in the global ocean is critical for understanding biogeochemical cycles and how deep-sea deposits respond to environmental change at the sea surface. We present the first digital map of seafloor lithologies based on descriptions of nearly 14,500 samples from original cruise reports, interpolated using a support vector machine algorithm. We show that sediment distribution is more complex, with significant deviations from earlier hand-drawn maps, and that major lithologies occur in drastically different proportions globally. … Read more…

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Influence of subduction history on South American topography

Case 4 paleotopography 16MaCitation
Flament, N., Gurnis, M., Müller, R. D., Bower, D. J., & Husson, L. (2015). Influence of subduction history on South American topography. Earth and Planetary Science Letters, 430, 9-18. doi: 10.1016/j.epsl.2015.08.006.

Abstract
The Cenozoic evolution of South American topography is marked by episodes of large-scale uplift and subsidence not readily explained by lithospheric deformation. The drying up of the inland Pebas system, the drainage reversal of the Amazon river, the uplift of the Sierras Pampeanas and the uplift of Patagonia have all been linked to the evolution of mantle flow since the Miocene in separate studies. Here we investigate the evolution of long-wavelength South American topography as a function of subduction history in a time-dependent global geodynamic model. This model is shown to be consistent with these inferred changes, as well as with the migration of the Chaco foreland basin depocentre, that we partly attribute to the inboard migration of subduction resulting from Andean mountain building. … Read more…

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Basin and Landscape Dynamics (Badlands)

Badlands image

Basin and Landscape Dynamics (Badlands) is a parallel TIN-based landscape evolution model, built to simulate topography development at various space and time scales. The model is capable of simulating hillslope processes, fluvial incision (erosion/transport/deposition), spatially and temporally varying geodynamic (3D displacements) and climatic forces which can be used to simulate changes in base level, as … Read more…

Geochemistry, Geophysics, Geosystems – Semi-automatic fracture zone tracking

Wessel, P., Matthews, K. J., Müller, R. D., Mazzoni, A., Whittaker, J. M., Myhill, R., & Chandler, M. T. (2015). Semi-automatic fracture zone tracking. Geochemistry, Geophysics, Geosystems. doi: 10.1002/2015GC005853. Semi-automatic fracture zone tracking This paper includes an update to the global seafloor tectonic fabric data set by Matthews et al. (JGR, 2011).  Based on the vertical gravity … Read more…

Nature Geoscience – Long-term interaction between mid-ocean ridges and mantle plumes

Whittaker, J. M., Afonso, J. C., Masterton, S., Müller, R. D., Wessel, P., Williams, S. E., & Seton, M. (2015). Long-term interaction between mid-ocean ridges and mantle plumes. Nature Geoscience, 8(6), 479-483. doi: http://dx.doi.org/10.1038/ngeo2437. Summary Plate tectonic motions are commonly considered to be driven by slab pull at subduction zones and ridge push at mid-ocean … Read more…

Long-term interaction between mid-ocean ridges and mantle plumes

Whittaker et al 2015 MORs plumes LIPSCitation
Whittaker, J. M., Afonso, J. C., Masterton, S., Müller, R. D., Wessel, P., Williams, S. E., & Seton, M. (2015). Long-term interaction between mid-ocean ridges and mantle plumes. Nature Geoscience, 8(6), 479-483.

Summary
Plate tectonic motions are commonly considered to be driven by slab pull at subduction zones and ridge push at mid-ocean ridges, with motion punctuated by plumes of hot material rising from the lower mantle. Within this model, the geometry and location of mid-ocean ridges are considered to be independent of lower-mantle dynamics, such as deeply sourced plumes that produce voluminous lava eruptions-termed large igneous provinces. Here we use a global plate model to reconstruct the locations of large igneous provinces relative to plumes and mid-ocean ridges at the time they formed. … Read more…

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Evaluating global paleoshoreline models for the Cretaceous and Cenozoic

Early CretaceousCitation
Heine, C., Yeo, L. G., & Müller, R. D. (2015). Evaluating global paleoshoreline models for the Cretaceous and Cenozoic. Australian Journal of Earth Sciences, (ahead-of-print), 1-13., doi: 10.1080/08120099.2015.1018321.

Summary
Paleoshoreline maps represent the distribution of land and sea through geologic time. These compilations provide excellent proxies for evaluating the contributions non-tectonic vertical crustal motions, such as mantle convection-driven dynamic topography, to the flooding histories of continental platforms. Until now, such data have not been available as a globally coherent compilation. Here, we present and evaluate a set of Cretaceous and Cenozoic global shoreline data extracted from two independent published global paleogeographic atlases. … Read more…

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Tectonic speed limits from plate kinematic reconstructions

Plate velocities summary figureCitation
Zahirovic, S., Müller, R. D., Seton, M., & Flament, N. (2015). Tectonic speed limits from plate kinematic reconstructions. Earth and Planetary Science Letters, 418, 40-52. doi:10.1016/j.epsl.2015.02.037.

Summary
The motion of plates and continents on the planet’s surface are a manifestation of long-term mantle convection and plate tectonics. Present-day plate velocities provide a snapshot of this ongoing process, and have been used to infer controlling factors on the speeds of plates and continents. However, present-day velocities do not capture plate behaviour over geologically representative periods of time. To address this shortcoming, we use a plate tectonic reconstruction approach to extract time-dependent plate velocities and geometries from which root mean square (RMS) velocities are computed, resulting in a median RMS plate speed of ~4 cm/yr over 200 Myr.  … Read more…

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A tectonic model reconciling evidence for the collisions between India, Eurasia and intra-oceanic arcs of the central-eastern Tethys

Gibbons etal AgeGrid Vels MagPicks v3 0175Citation
Gibbons, A., Zahirovic, S., Muller, R.D., Whittaker, J., and Yatheesh, V. 2015. A tectonic model reconciling evidence for the collisions between India, Eurasia and intra-oceanic arcs of the central-eastern Tethys. Gondwana Research FOCUS, doi: 10.1016/j.gr.2015.01.001.

Summary
Despite several decades of investigations, inferences on the timing and nature of collisions along the Mesozoic–Cenozoic Eurasian margin remain controversial. We assimilate geological and geophysical evidence into a plate tectonic model for the India–Eurasia collision that includes continuously– … Read more…

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GPlates 1.5 software and data sets

GPlates 1.5 Promo

GPlates 1.5 PromoGPlates is a free desktop software for the interactive visualisation of plate-tectonics. The compilation and documentation of GPlates 1.5 data was primarily funded by AuScope National Collaborative Research Infrastructure (NCRIS).

GPlates is developed by an international team of scientists and professional software developers at the EarthByte Project (part of AuScope) at the University of Sydney, the Division of Geological and Planetary Sciences (GPS) at CalTech, the Geodynamics team at the Geological Survey of Norway (NGU) and the Centre for Earth Evolution and Dynamics (CEED) at the University of Oslo.  … Read more…

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Age, spreading rates and spreading asymmetry of the world’s ocean crust

agegrid_ageerror_2008 rategrid_asymgrid_2008We present four companion digital models of the age, age uncertainty, spreading rates and spreading asymmetries of the world’s ocean basins as geographic and Mercator grids with 2 minute resolution. The grids include data from all the major ocean basins as well as detailed reconstructions of back-arc basins.

The age, spreading rate and asymmetry at each grid node is determined by linear interpolation between adjacent seafloor isochrons in the direction of spreading. Ages for ocean floor between the oldest identified magnetic anomalies and continental crust are interpolated by geological estimates of the ages of passive continental margin segments. … Read more…

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Supplementary resources for “Absolute plate motions since 130 Ma constrained by subduction zone kinematics”

Williams et al 2015 figure 3Citation
Williams, S., Flament, N., Müller, R. D., & Butterworth, N. (2015). Absolute plate motions since 130 Ma constrained by subduction zone kinematics. Earth and Planetary Science Letters, 418, 66-77. doi:10.1016/j.epsl.2015.02.026.

Summary
The supplementary data set comprise plate reconstructions from 130 Ma to present-day, designed to be used within the open-source reconstruction software GPlates.

There are eight sets of reconstructions. In each case, the relative plate motion (RPM) model is unchanged; the differences lie in the absolute plate motion (APM) model. This is expressed in the rotation file as the finite poles of rotation that describe motion of Africa relative to the Earth’s spin-axis. These files were the basis of the results presented in the EPSL paper.  … Read more…

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Supplementary resources for "Absolute plate motions since 130 Ma constrained by subduction zone kinematics"

Williams et al 2015 figure 3Citation
Williams, S., Flament, N., Müller, R. D., & Butterworth, N. (2015). Absolute plate motions since 130 Ma constrained by subduction zone kinematics. Earth and Planetary Science Letters, 418, 66-77. doi:10.1016/j.epsl.2015.02.026.

Summary
The supplementary data set comprise plate reconstructions from 130 Ma to present-day, designed to be used within the open-source reconstruction software GPlates.

There are eight sets of reconstructions. In each case, the relative plate motion (RPM) model is unchanged; the differences lie in the absolute plate motion (APM) model. This is expressed in the rotation file as the finite poles of rotation that describe motion of Africa relative to the Earth’s spin-axis. These files were the basis of the results presented in the EPSL paper.  … Read more…

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