Dr Grace Shephard

Overseas Collaborator

See below for EarthByte content related to Grace.

The lost Tethyan seaways: A deep-Earth and deep-time perspective on eastern Tethyan tectonics

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Every 8 weeks we turn our attention to a Remarkable Region that deserves a spot in the scientific limelight. Following from the first entry which showcased the Eastern Mediterranean, we move further east, and back in time, to the realm of the Tethys. The southern and southeastern region of Eurasia represents one of the most tectonically complex areas in … Read more…

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

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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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Journal of Geodynamics – Geological, tomographic, kinematic and geodynamic constraints on the dynamics of sinking slabs

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Butterworth, N. P., Talsma, A. S., Müller, R. D., Seton, M., Bunge, H. P., Schuberth, B. S. A., … & Heine, C. (2014). Geological, tomographic, kinematic and geodynamic constraints on the dynamics of sinking slabs. Journal of Geodynamics, 73, 1-13. doi: 10.1016/j.jog.2013.10.006. Geological, tomographic, kinematic and geodynamic constraints on the dynamics of sinking slabs Supplementary material

Grace Shephard submits her PhD thesis

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Congratulations to Grace Shephard who submitted her PhD thesis this month! Well done! Grace will be taking up a post-doctoral position in Norway at the University of Oslo’s Centre for Earth Evolution and Dynamics (CEED) and will continue to work on plate motion modelling and numerical simulations of mantle flow.

Earth Science Reviews – The tectonic evolution of the Arctic since Pangaea breakup: Integrating constraints from surface geology and geophysics with mantle structure

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Shephard, G. E., Müller, R. D., & Seton, M. (2013). The tectonic evolution of the Arctic since Pangea breakup: Integrating constraints from surface geology and geophysics with mantle structure. Earth-Science Reviews, 124, 148-183. doi:10.1.1016/j.earscirev.2013.05.012. The tectonic evolution of the Arctic since Pangea breakup: Integrating constraints from surface geology and geophysics with mantle structure

The tectonic evolution of the Arctic since Pangea breakup: Integrating constraints from surface geology and geophysics with mantle structure

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Shephard Arctic IconCitation
Shephard, G. E., Müller, R. D., & Seton, M. (2013). The tectonic evolution of the Arctic since Pangea breakup: Integrating constraints from surface geology and geophysics with mantle structure. Earth-Science Reviews, 124, 148-183. doi:10.1016/j.earscirev.2013.05.012

Summary
The tectonic evolution of the circum-Arctic, including the northern Pacific, Siberian and North American margins, since the Jurassic has been punctuated by the opening and closing of ocean basins, the accretion of autochthonous and allochthonous terranes and associated deformation. This complexity is expressed in the uncertainty of plate tectonic models of the region, with the time-dependent configurations and kinematic history remaining poorly understood. … Read more…

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Global continental and ocean basin reconstructions since 200 Ma

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Plate reconstruction 200Ma-1Global plate motion models provide a spatial and temporal framework for geological data and have been effective tools for exploring processes occurring at the earth’s surface. However, published models either have insufficient temporal coverage or fail to treat tectonic plates in a self-consistent manner. They usually consider the motions of selected features attached to tectonic plates, such as continents, but generally do not explicitly account for the continuous evolution of plate boundaries through time. … Read more…

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Earth-Science Reviews – Global continental and ocean basin reconstructions since 200 Ma

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Seton, M., Müller, R. D., Zahirovic, S., Gaina, C., Torsvik, T., Shephard, G., … & Chandler, M. (2012). Global continental and ocean basin reconstructions since 200Ma. Earth-Science Reviews, 113(3), 212-270. doi:10.1016/j.earscirev.2012.03.002. Download the paper – pdf

Testing absolute plate reference frames and the implications for the generation of geodynamic mantle heterogeneity structure

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Shephard 2012 agegrids vels 140-1Absolute reference frames are a means of describing the motion of plates on the surface of the Earth over time, relative to a fixed point or frame. Multiple models of absolute plate motion have been proposed for the Cretaceous-Tertiary period, however, estimating the robustness and limitations of each model remains a significant limitation for refining both regional and global models of plate motion as well as fully integrated and time dependent geodynamic models. Here, we use a novel approach to compare five models of absolute plate motion in terms of their consequences for forward modelled deep mantle structure since at least 140 Ma. … Read more…

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Dynamic topography and anomalously negative residual depth of the Argentine Basin

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Shephard 2012 Argentine Basin-1A substantial portion of Earth’s topography is known to be caused by the viscous coupling of mantle flow to the lithosphere but the relative contributions of shallow asthenospheric flow versus deeper flow remains controversial. The Argentine Basin, located offshore of the Atlantic margin of southern South America, is one of the most anomalously deep ocean regions as it is significantly deeper than its age would suggest. … Read more…

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Grace Shephard invited to the 62nd Lindau Nobel Laureate Meeting

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Congratulations to Grace Shephard for being selected to participate in the 62nd Lindau Nobel Laureate Meeting, which is dedicated to Physics this year. Only the 592 most qualified Young Researchers can be given the opportunity to enrich and share the unique atmosphere of the Lindau Nobel Laureate Meetings. Congratulations Grace! Lindau Nobel Laureate Meetings website

Gondwana Research Letters – Dynamic topography and anomalously negative residual depth of the Argentine Basin

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Shephard, G. E., Liu, L., Müller, R. D., & Gurnis, M. (2012). Dynamic topography and anomalously negative residual depth of the Argentine Basin.Gondwana Research, 22(2), 658-663. doi:10.1016/j.gr.2011.12.005. Download the paper – pdf

Earth and Planetary Science Letters – Testing absolute plate reference frames and the implications for the generation of geodynamic mantle heterogeneity structure

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Shephard, G. E., Bunge, H. P., Schuberth, B. S., Müller, R. D., Talsma, A. S., Moder, C., & Landgrebe, T. C. W. (2012). Testing absolute plate reference frames and the implications for the generation of geodynamic mantle heterogeneity structure. Earth and Planetary Science Letters, 317, 204-217. doi:10.1016/j.epsl.2011.11.027. Download the paper – pdf

EarthByte to attend GSA Fragile Earth conference 2011

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EarthByte group members Dietmar Müller, Christian Heine, Nicolas Flament, Aedon Talsma, Logan Yeo and Grace Shephard are attending the GSA Fragile Earth conference in Munich, Germany from 4-7 September, 2011. Click here for details about the GSA conference

Pyrites of the Caribbean win soccer comp

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Great news! The Pyrites of the Caribbean won the Sydney Uni Social Lunchtime mixed soccer comp!!! The semi-final was 6-5 with the Pyrites beating the undefeated team “The Pretenders”, and the final game score was 1-1 and went to golden goal. Nathan scored the winning goal with one minute to spare! Woo! Well done to … Read more…

Integration of plate kinematic reconstructions in geodynamic models of mantle convection

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Project Summary
Despite more than 30 years of plate tectonics research, we still do not know exactly what drives the plates or controls the time-dependence of mantle convection. Plate motions are linked to processes in the deeper Earth interior by complex, enigmatic cause-and-effect relationships. While mantle convection is generally accepted as the underlying cause of plate motions, the geometry of mantle flow and its relation to plate motions remains poorly understood. As plate tectonics is the Earth Science paradigm, breakthroughs in this field affect understanding of all branches of Earth Science including formation and distribution of natural resources, long-term climate change and natural hazards. … Read more…

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