The pioneering seafloor mapping and visualization by Marie Tharp played a key role in the acceptance of the plate tectonic theory. Her physiographic maps, published with B. Heezen, covered the Earth’s oceans and revealed with astonishing accuracy the submarine landscape. She exposed the topography of a seafloor that turned out not to be flat, displaying instead features such as seamounts and volcanic chains, trenches, mid-ocean ridges, and transform faults. Marie Tharp co-authored the first papers describing the major fracture zones in the Central Atlantic (Chain, Romanche, Vema), and her work directly contributed to the recognition of the role of mid-ocean ridges in plate tectonics and oceanic accretion.

To honour Marie Tharp’s profound and lasting contribution to plate tectonics and marine goesciences, this session seeks contributions addressing plate tectonics in the oceans, based primarily on information from seafloor mapping, including regular or high resolution bathymetry, seafloor imagery (sonar or optical) at all scales, geophysical imaging of the seafloor, in addition to satellite altimetry, and in situ observations (robots or submersibles). Results of seafloor sampling, seismic imaging, seismicity studies or in-situ monitoring are also very welcome. Contributions may address the role of faults, seafloor volcanism, magmatism, and hydrothermal circulations, in the construction and evolution of the ocean crust and lithosphere from mid-ocean ridges and transform faults, to mid-plate domains and subductions. We seek contributions at all scales, from regional studies to a global scope, as that pioneered by Marie Tharp.

Tectonic models represent hypothesised approximations of past geological events that best fit and explain a pre-defined collection of data points. Incorporation of geological observations with an understanding and consideration of geodynamic concepts, geological processes, and physical properties of geological materials ensures that empirical models are consistent with physics and mechanics, and that numerical models are consistent with field observations and petrological constraints. Integrating these constraints and concepts within a plate kinematic framework that considers the size, distribution and past and present motions of tectonic plates ensures that models are consistent with global plate tectonics. Incorporating this information with interpretations of the distribution of subducted slabs and plumes in the upper and lower mantle allows for construction of tectonic models that consider the global tectonic-mantle system. We welcome state-of-the-art, multi-disciplinary, and multi-scale studies that combine geological and geophysical constraints from the bedrock record with interpretations of deep mantle structure and/or plate kinematic datasets to investigate geodynamic events of past and present. These may include, but are not limited to studies of rifting and ocean spreading, subduction, orogeny and terrane accretion, and dynamic topography. We expect this session to include a diverse range of multi-disciplinary studies united by a common goal of understanding the geological evolution of our planet’s tectonic-mantle system.

Structure and dynamics of the lithosphere-asthenosphere system is one of the key questions for understanding geological processes. Constraining the styles, mechanisms and fabrics evolution in the crust and the upper mantle come from both direct and indirect observations with the use of variety of methods. Seismological studies focusing on anisotropy have successfully improved our knowledge of deformation patterns, acting both at present as well as in the past. When combined with tomographic models, velocity anisotropy can shed light on the geometry, structure, and dynamics of deformation in the lithosphere and the asthenosphere. Sophisticated geodynamic modelling and laboratory experiments enhance our understanding of flow patterns in the upper mantle and their effects on vertical motions of the crust and the lithosphere. Combining with inferences from seismic anisotropy, these methods have the potential to reveal mechanisms that create deformation-induced features such as shape preferred orientation (SPO) and lattice-preferred orientation (LPO), which created in the past or during the last deforming processes. Structural and kinematic characterization of deformation events by geometric and kinematic analyses infer the direction and magnitude of the tectonic forces involved in driving deformation within crust and upper mantle. Additionally, both physical analogue and numerical modelling foster our understanding of complex 3D-plate interaction on various timescales, controlled through the degree of plate coupling and the rheology of the lithosphere.
However, additional work is required to better integrate various experimental and modelling techniques, and to link them with multi-scale observations. The session aims at bringing together inferences from different disciplines that focus on structure and deformation of the lithosphere and the sub-lithospheric upper mantle as well as on the dynamics and nature of the lithosphere-asthenosphere system. The main goal is to demonstrate the potential of different methods, and to share ideas of how we can collaboratively study lithosphere structure, and how the present-day fabrics of the lithosphere relates to the contemporary deformation processes and ongoing dynamics within the asthenospheric mantle. Contributions from studies employing seismic anisotropy observation, geodynamical modelling (analogue and numerical), structural geology, and mineral and rock physics are welcome.

Invited Speakers:
Eric Debayle (Laboratoire de Geologie de Lyon-Terre, Planètes, Environnement, CNRS, France)
Christof Völksen (Bayerische Akademie der Wissenschaften, Germany)

The Arctic realm hosts vast extended continental shelves bordering old land masses, one of the largest submarine Large Igneous Provinces (LIPs) -the Alpha-Mendeleev Ridge - of Mesozoic age, and the slowest mid-ocean spreading ridge (the Gakkel Ridge) on the globe. Extreme variations in the evolution of landscapes and geology reflect the tug-of-war between the formation of new oceans, like the North Atlantic, and the destruction of older oceans: the South Anyui, Angayucham and North Pacific, which were accompanied by rifting, collision, uplift and subsidence. The causal relationships between the deep-mantle and surface processes in the Circum-Arcic region remain unclear. Geoscientific information on the relationship between the onshore geology and offshore ridges and basins in combination with variations in the mantle is the key for any deeper understanding of the entire Arctic Ocean.
This session provides a forum for discussions of a variety of problems linked to the Circum-Arctic geodynamics and aims to bring together a diversity of sub-disciplines including plate tectonics, mantle tomography, seismology, geodynamic modelling, igneous and structural geology, geophysical imaging, sedimentology, and geochemistry. Particularly encouraged are papers that address lithospheric-mantle interactions in the North Atlantic, the Arctic and North Pacific regions, mantle dynamics and vertical and horizontal motion of crustal blocks and consequences for paleogeography. As geologic and tectonic models are inherently tied with changes in the oceanographic and climatic development of the Arctic, we also invite studies that focus on the interplay between these processes and across timescales. Lastly, we would like to invite contributions from studies concerning the implications of how the Arctic’s geography and geology are portrayed by modern data and issues related to jurisdiction and sovereign rights with particular focus on the UN Convention on the Law of the Sea.

Geoscientists have long assumed that variations in the Earth’s topography are primarily due to variations within the lithosphere (density, thickness, flexural rigidity), and are compensated isostatically within the asthenosphere. But geodynamic considerations predict that mantle convection should cause long wavelength deflections of the Earth’s surface, with length scales > 500 km and vertical amplitudes as large as 1 to 2 km. The largest deflections seem to be associated with subduction zones and plumes. These long-wavelength deflects are called “dynamic topography” given that they are caused by dynamic pressures associated with convection.

Over the last decade, there has been increasing interest in resolving the long-term evolution of dynamic topography. Methods include global dynamic models; kinematic reconstruction of plate motions and plate boundaries; geomorphic and stratigraphic studies of basins, coastal terraces, and rivers; paleotopography studies using paleotemperature or precipitation isotopes, erosion studies using thermochronology; landform studies; and stratigraphic analysis at continental scales to map hiatus area. Geodynamic methods have expanded now to include adjoint inversion methods, which allow a more optimal integration between observations and theory. The simultaneous growth of observations and theoretical capabilities provides us with unprecedented opportunity to test the underlying assumptions of dynamic Earth models. This transdisciplinary session brings together observational and theoretical scientists to discuss the scope and format of established and nascent convection related observables, and welcomes contributions that highlight the noisy nature of observables while exploring methods to handle the impact of uncertainty in the geodynamic data assimilation framework.

Since the Neoproterozoic breakup of the supercontinent Rodinia, continental fragments episodically rifted from their original location and systematically drifted towards more northerly positions, culminating in the Late Palaeozoic amalgamation of the supercontinent Pangaea. In this session we focus on the processes responsible for the transportation of terranes from Gondwana to the northern continental masses (Baltica, Laurentia, and later Laurussia) before, during and after the collision between Laurussia and Gondwana and the amalgamation of Pangaea. We welcome multi-disciplinary (tectonics, geodynamics, basin analysis, palaeomagnetism, palaeogeography, plate reconstruction, etc.) contributions dealing with i) the geodynamic evolution (rift-drift-accretion) of terranes such as Ganderia, Avalonia, Carolinia, Meguma, Armorica, Moesia, North China, South China, etc., ii) the fate of intervening oceans (Iapetus, Rheic, Palaeotethys, Neotethys, etc.) and iii) the geodynamic drivers of their respective evolutions.
Contribution to IGCP project No. 648: Supercontinent Cycles and Global Geodynamics.

Processes responsible for formation and development of the early Earth (> 2500Ma) are not
well understood and strongly debated, reflecting in part the poorly preserved, altered, and
incomplete nature of the geological record from this time.
In this session we encourage the presentation of new approaches and models for the development of Earth's early crust and mantle and their methods of interaction. We encourage contributions from the study of the preserved rock archive as well as geodynamic models of crustal and mantle dynamics so as to better understand the genesis and evolution of continental crust and the stabilization of cratons.
We invite abstracts from a large range of disciplines including geodynamics, geology, geochemistry, and petrology but also studies of early atmosphere, biosphere and early life relevant to this period of Earth history.