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.

Continental rifting is a complex process spanning from the inception of extension to continental rupture or the formation of a failed rift. This session aims at combining new data, concepts and techniques elucidating the structure and dynamics of rifts and rifted margins. We invite submissions highlighting the time-dependent evolution of processes such as: initiation and growth of faults and ductile shear zones, tectonic and sedimentary history, magma migration, storage and volcanism, lithospheric necking and rift strength loss, influence of the pre-rift lithospheric structure, rift kinematics and plate motion, mantle flow and dynamic topography, as well as break-up and the transition to sea-floor spreading. We encourage contributions using multi-disciplinary and innovative methods from field geology, geochronology, geochemistry, petrology, seismology, geodesy, marine geophysics, plate reconstruction, or numerical or analogue modelling. Special emphasis will be given to presentations that provide an integrated picture by combining results from active rifts, passive margins, failed rift arms or by bridging the temporal and spatial scales associated with rifting.

Public information:
Dear participants of EGU session GD6.3 on rifting

We will start the discussion at 10:45 CET on Friday 8 May, and it will last until 12:30 CET, although the chat will remain active for 30 min more.

This is how we plan to carry on the session:

· Every contribution will get about 5 minutes of discussion
· The conveners will introduce the contribution (title, authors,..)
· The presenting authors will give a short summary/introduction (2-3 sentences) of their work and contact details for potential further discussion (@ authors, please prepare these in advance to ensure a smooth transition).
· Discussion with participants

If time permits, we will have a more general discussion after all contributions have been presented.

Here’s the order of the presentations:

· Tortelli et al.
· Welford & Geng
· Phillips & McCaffrey
· Pan et al.
· Glerum & Brune
· Braschi et al.
· Bauer et al.
· Pagli et al.
· La Rosa et al.
· Keir et al.
· King et al.
· Lymer et al.
· Yang & Welford
· Chenin et al.
· Forzese et al.
· Frasca et al.

The acquisition of new datasets at Continent-Ocean-Transition (COT) of rifted margins show significant variability, highlighting the diversity of parameters controlling the rift-to-drift transition during continental breakup. This session aims at gathering new observations, concepts, and techniques to investigate deformation mechanisms, dynamics of continental breakup, and generation of the first oceanic crust. We invite presentations focusing on topics from rifting up to incipient seafloor spreading, including studies discussing the structure and nature of COT, tectonic, magmatic, rheological and thermal evolution, melt initiation, sedimentary records, deformation mechanisms, and alteration processes. We encourage contributions using multidisciplinary and innovative methods including marine geosciences, seismology, sedimentology, field geology, geochemistry, thermochronology, plate reconstruction, and modelling. We welcome studies based on worldwide natural examples from active rifts, fossil and present-day rifted margins. Special emphasis will be given to presentations that integrate comparisons of tectonic and magmatic processes between continental and oceanic settings that could improve our understanding of continental breakup and mid-oceanic ridge initiation.

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.

Plate tectonic processes and associated rates of deformation can be quantified using geomorphological and sedimentary evidence in actively deformed landscapes. A variety of geomorphic markers (e.g., topography and rivers, fluvial deposits, marine terraces) and sedimentary archives (e.g., syntectonic sedimentation, stratigraphic evidence) can be used to constrain rates and dates of tectonic deformation and its processes. Any of these and their combinations, when used in key natural laboratories at adequate time spans, can provide essential clues to understand the tectonic activity and large-scale geodynamic evolution of tectonic plates, and unravel the dynamic changes and tip-points in plate boundary conditions.

We invite contributions that aim to understand the dynamics and evolution of active plate boundaries and deforming plate interiors through geomorphic and/or sedimentary evidence. We welcome all types of studies regardless of their methodology, and especially interdisciplinary efforts, that use geomorphic and sedimentary records to quantify the rates of active deformation and tectonic events, at key sites and across various spatial and temporal scales.

Public information:
Welcome everyone to “Geomorphic and sedimentary records of active tectonics” [TS12.1]!
Thank you for attending!

We, the conveners, would like to thank all contributing authors, and in particular, everyone who uploaded a Display. We really appreciate it!

The life-chat will start at 10.45 and we will continue to discuss Displays until 12.30.
Thereafter, the chat will remain open for discussion if you want.

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Schedule for the Live-Chat (Thursday 7th of May)

10:45-10:50 Introduction
10:50-10:57 Ed Rhodes
10:57-11:04 Rajeeb Lochan Mishra
11:04-11:11 Paul Zemann
11:11-11:18 Bernhard Salcher
11:18-11:25 Oswald Malcles
11:25-11:32 Tarik Kernif
11:32-11:39 Haralambos Kranis
11:39-11:46 Roland Freisleben
11:46-11:53 Hao Liang
11:53-12:00 Ping Huang
12:00-12:07 Gerben de Jager
12:07-12:14 Debora Duarte
12:14-12:21 Shao-I Kao
12:21-12:30 Final Discussion

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We would like to organize the session as follows:

- A ca. 7 min time slot will be allocated to each of the 13 contributors that have uploaded a Display This should not only allow for some discussion of the Displays but also leave 10 minutes at the end of the session for the discussion of remaining questions.

- The conveners introduce the contribution

- The presenting author shortly introduces the Display (@authors, please prepare these in advance to ensure a smooth transition and include your email address!)

- Discussion with participants starts
For questions, please use @name to address the correct person.