Sessions relevant to MARGINS Science
at the 2007 AGU Fall Meeting

The extensive list of sessions in AGU's Fall Meeting program can be daunting, so each year the MARGINS
Office assembles a list of sessions that we think may be of special interest to the MARGINS community. The
concise summaries included with our subjective choices are edited excerpts from the original AGU session
abstracts (www.agu.org/meetings/fm07). The sessions with * are directly addressing MARGINS themes.

AGU Code Key: Section: Day of Week (1-5): Session Time (1X-2X: 8:00 and 10:20; 3X-4X: 13:40 and 16:00).
E.g., OS12A = Ocean Sciences, Monday, Session 2A (10:20). Please refer to the AGU meeting program to verify
session times and locations.

Education and Human Resources

*ED14: Transforming Research Science to Create Inquiry-Based Undergraduate Classroom Experiences: Examples from the NSF-MARGINS Program and Other Initiatives
Conveners: D. Reed, J.G. Ryan and C. Manduca
This session will highlight efforts being made to transform undergraduate education through the repurposing of the datasets and scientific results of major research initiatives for use in classroom settings. Presentations will highlight efforts that take advantage of the fruits of major Federally-funded research initiatives, including but not limited to the NSF-MARGINS Program, Ridge 2000 and IODP, to invigorate coursework and classroom activities and facilitate focused research and research-like experiences for undergraduate students. This session is co-sponsored by NSF-MARGINS and Council on Undergraduate Research (CUR).

Ocean Sciences

OS09: Mountains to Ocean Deep: Tracking Material Fluxes and Processes During Climatic Change with New and Better Proxies
Convener: C. Siebert and B. Georg

Recent technical advances have resulted in new and improved proxies for quantifying the chemical and biological processes and fluxes that govern mass transfer from the continents to the oceans. We need to better understand how these processes respond to, and provide feedbacks and drivers for, long term climatic change. The application of proxies is rapidly expanding and this session is intended to give geochemists the chance to present and discuss their new discoveries as well as providing an overview of the latest developments in the field. We invite contributions that utilize geochemical proxies to (1) constrain key fluxes such as the macro and micro nutrients contributed by rivers, groundwater and the atmosphere, (2) elucidate the relevant controlling processes and (3) understand the link to climate change. The scope will range from micro-scale reactions in porewaters to global scale modeling of feedbacks. Constraining continental sources and fluxes is an important part of the session goals. This includes weathering processes, the relative importance of different lithologies, the roles of dust and aerosols versus rivers and versus groundwater and how together these different facets of the Earth system link to climate. Understanding transport processes including the interaction between different pathways is also an important goal of the session. Finally, we need a better understanding of the drawdown and recycling of oceanic sinks and how these might respond to global change. Although some focus of the session will be on new proxies such as non-traditional stable isotopes, contributions on other tracers, such as biomarkers, as well as multi-proxy approaches are welcome. Indeed, detailed comparisons between these approaches are seen as essential to the further development of the field.

Seismology

S03: New Perspectives into the Seismotectonics of the Andaman, Sumatra, and Java Subduction Systems
Conveners: H. DeShon and S. Bilek

The occurrence of the 2004 and 2005 great Sumatra earthquakes and the 2006 Java tsunami earthquake highlight the significant seismic hazard associated with subduction offshore Indonesia. These three earthquakes exhibited a large degree of variability in their rupture patterns, associated tsunami, aftershock locations and mechanisms, and frequency range of associated seismic energy. This session aims to improve understanding of the seismotectonics of the Andaman, Sumatra, and Java subduction systems in order to provide further insight into the range of seismogenic zone processes affecting earthquake generation. We invite contributions from a range of disciplines including passive and active source seismology, marine geophysics, geology, and geodesy that address seismotectonic issues in this region.

S15: Insights From Combined Laboratory and Theoretical Investigations of Earthquake Rupture and Aseismic Fault Slip
Conveners: Y. Fialko, N. Lapusta and A. Rosakis

Slip on faults involves a range of complex and potentially interdependent phenomena. Fault resistance to sliding can be influenced by a number of mechanisms, including rate and state effects, flash heating, pore pressure evolution, dissimilar material properties, local non-planarity of slip interfaces, and others. Earthquake dynamics involves different rupture patterns, interaction with fault geometry and, potentially, branching and supershear propagation. In the interseismic period, observations show a rich array of behaviors, from aseismic slip transients to episodic tremors. Laboratory experiments provide crucial insights for our understanding of these phenomena, either directly or though a combination of experimental observations and theoretical modeling. Laboratory experiments can also be used to validate numerical models. Papers are invited on all aspects of relevant laboratory experiments, modeling of experimental results, and incorporation of these results into theories or numerical simulations of seismic and aseismic fault behavior.

Tectonophysics

*T05: Inner Workings of Centam and IBM Subduction Factories
Conveners: J. Gill and S. Holbrook

This session's goals are to report and compare geophysical and geochemical discoveries related to subduction processes in the Central American and Izu-Bonin-Mariana arcs. The “Factory” in this session includes the incoming plate, the slab to the transition zone, the mantle wedge, and outputs to the crust and atmosphere from the forearc to rear arc, Contributions are especially welcome that draw from Workshops during 2007 about these topics, or explicitly relate geophysical and geochemical discoveries, or compare the two arcs. Syntheses of long-term projects are welcome even if some of the results have been presented before.

T08: Tectonic Erosion, Sediment Accretion and Mass Recycling in Subduction Zones
Conveners: P. Vannucchi, P. Clift and J. Phipps Morgan

The flux of continental material into subduction zones is known to have a large effect on arc magmatic chemistry, as well as on the tectonics and vertical motions of convergent margins. Recent estimates of mass recycling place the rate of mass subduction at around 3 cubic km/year, a level that is high enough to be important in the generation and maintenance of the continental crust. Of this total only around a half comprises trench sediment, with the rest made up by eroded forearc crust. What controls the rate of mass subduction is still debated but is important in understanding subduction petrogenesis and seismogenesis. Detailed geophyscial data from eroding arcs remains relatively scarce. We solicit contributions from geophysicists, geochemists and geologists working on the cycling of material through subduction zones in order to build a multidisciplinary session where the different datasets can be reconciled in a coherent model of margin evolution. Studies spanning long and shorter geological timescales are encouraged, as are those involving direct sampling or remote imaging of the subduction channel and the tectonic erosion process.

T10: Mantle Exhumation at Rifted Continental Margins: Magmatic and Tectonic Processes
Conveners: R. Fletcher, G. Manatschal, O. Müntener and A. Goodliffe

Seismic studies and drilling have shown that ultramafic rocks are exposed in the transition zone between continental and oceanic crust at some rifted continental margins. However, the tectonic and magmatic processes responsible for mantle exhumation remain enigmatic. This session will bring together scientists involved in imaging, sampling and modelling the thinned continental crust, transition zone and early oceanic crust at ‘non-volcanic’ margins, both modern and ancient.

Key questions which we aim to address include: - Why do some ‘non-volcanic’ margins exhibit mantle exhumation whilst others do not? - What is the origin and petrological history of the exhumed mantle? Can we distinguish between subcontinental and asthenospheric mantle? Can we identify and explain fertile, depleted, refertilized and infiltrated mantle? What are the implications of this on our understanding of the role of inherited mantle heterogeneity and continental break-up processes? - What is the nature and source of magnetic anomalies in the transition zone? Is there evidence for gabbroic bodies in the transition zone? How deep and pervasive is serpentinisation of peridotite in the transition zone? - How do the structural, geochemical and volcanic characteristics of the transition zone at ‘non-volcanic’ margins compare with those of ultra-slow seafloor spreading? Can mantle exhumation at ‘non-volcanic’ margins be explained by melt suppression as a result of very slow spreading rates or anomalously cool lithosphere during early seafloor spreading? - What does the sedimentary record tell us about uplift and subsidence during continental break-up? - How does continental break-up occur without the assistance of magma?

Contributors are invited to present seismic, petrological, sedimentological or structural observations and/or formation process models relating to magmatism and tectonics at ‘non-volcanic’ margins.

T11: Faults in the Ocean Crust: Perspectives From Geology And Geophysics
Conveners: N. Hayman and D. Bohnenstiehl

Faults in the oceanic crust play many roles: accommodating magmatic and tectonic strains at spreading centers, facilitating fluid flow along the ridge crest and outer-rise, and allowing the relative motions of plates along transform boundaries. Different approaches to studying ocean crustal faults include bathymetric analysis, earthquake and reflection seismology, ocean drilling, and geologic studies from submersible investigations. These diverse investigative techniques yield information at a range of temporal and spatial scales, which are challenging to integrate into a comprehensive model of oceanic fault development. Consequently, many processes and interactions involving seismicity, hydrogeology, and fault evolution remain poorly understood in oceanic settings. This session is intended to bridge disciplines to focus on open problems in ocean crustal faulting.

T13: From the Trench to the Arc: Subduction Along South America
Conveners: N. Kukowski, N. Bangs and A. Tassara

The western rim of South America has been shaped through subduction of oceanic plates since the Paleozoic; however, the existing structures of the Andes, currently Earth's largest subduction orogen, developed almost entirely during the Cenozoic. During the past decade, several large multinational and multidisciplinary initiatives have focused on the Andes to investigate subduction erosion and subduction accretion along the margin tip, formation of the Altiplano-Puna plateau, which is Earth's second largest continental plateau, arc volcanism, relationships between climate variability, erosion and tectonics, seismogenic processes along the subduction interface and associated seismic and volcanic hazards. These efforts have made significant progress, but many open questions remain about the Andean margin regarding e.g., the timing of uplift, the thermal evolution of the orogen, the interaction of climate and tectonics, and more. To review our current knowledge on the subduction processes along the South American forearc and to develop an overview of the Andean margin structures and processes, we invite contributions from all fields of geophysics and geology, including both marine and terrestrial components. We especially encourage contributions about interdisciplinary studies that combine multiple aspects of Andean evolution.

T14: Bringing Together Observations and Models at Rifted Margins and Extensional Basins
Conveners: J. Van Wijk, G. Péron-Pinvidic and D. Shillington

Recently developed numerical models are capable of simulating a wide range of factors thought to be important in controlling the evolution of extensional terranes, including variations in stretching with depth, magmatism, prerift structural heterogeneities, and rheological layering. As these models become more sophisticated, it is essential to compare model predictions with observations. Geological, petrological and geophysical datasets from extensional basins and rifted margins provide critical information on the structure of the crust and lithospheric mantle, volume of magmatism, stratigraphic and subsidence history, petrology of magmatic and mantle rocks, etc. Clearly, a close integration of numerical and analogue modeling with rift attributes from observational data can result in a greater understanding of the factors most important in controlling the evolution of continental basins and rifted margins. Additionally, numerical and analogue models can highlight rift characteristics that are as of yet still poorly constrained by existing data and thus guide future data acquisition. We invite presentations that seek to investigate rifting and the transition to seafloor spreading with diverse observations (e.g., geophysical, petrological and geological datasets) and modeling.

T18: Observations, Interpretations, and Implications of Slow Slip, Non-Volcanic Tremor, and Associated Phenomena
Conveners: J. Rubinstein, S. Ide, H. Hirose and J. Townend

Aseismic fault slip, non-volcanic tremor, and other low-frequency seismic phenomena have been observed in a variety of tectonic environments, most notably subduction zones but also within the strike-slip San Andreas Fault zone and beneath the island of Hawaii. In the Cascadia and southwest Japan subduction zones, in particular, the spatiotemporal coincidence of tremor and slow slip suggests a strong relation between these phenomena, but our understanding of the underlying physical processes is incomplete and other locations exhibit either slow slip or seismic tremor but not both. In addition to addressing the long-standing scientific goal of understanding fault mechanical processes, including the generation of megathrust earthquakes in subduction zones, recent observations have significant policy implications based on the suggestion that seismicity and seismic hazard may increase following slow slip activity.

This session seeks presentations that shed light on the mechanics of slow slip, non-volcanic tremor, and associated phenomena, as well as the hazard implications posed by these processes. In particular, we seek contributions that explore this burgeoning field of research using new techniques, new observations, and innovative modeling. We also welcome studies that address regional variations in the occurrence and characteristics of these phenomena.

*T30: Progress in Subduction Modeling
Conveners: S. Buiter, S. Goes and P. van Keken

Subduction zones display a wide range of slab morphologies, upper plate deformation regimes, plate and trench motions and mantle flow patterns. Models of varying degrees of complexity have been used to understand natural subduction regimes and their variability in space and time. Recent progress in models of subduction zone processes includes the incorporation of slab petrology and phase changes, the evaluation of effects of three-dimensionality, and an improving capability to model the evolution of the slab and trench in a dynamically self-consistent way. The aim of this session is to showcase the latest results of numerical and analogue models of subduction and initiate discussion of their current achievements and challenges. We also welcome studies that describe how observations (e.g., seismic and gravity) and laboratory measurements can be used to constrain which processes are most important in natural subduction and what parameter values, particularly for rheology, are applicable to the Earth. Topics that may be considered include, but are not restricted to: the strength of slabs, the role of pressure- and temperature-dependent rheologies (plasticity, grain-size weakening), the depth extent of slabs, the effect of phase transitions, and the role of the overriding plate.

T36: Megathrust Slip and Forearc Structure
Conveners: R. Briggs, C. Goldfinger and R. Witter

Megathrusts accommodate most of the convergence between colliding plates along subduction zones. This interdisciplinary session invites studies that address the connection between seismogenic behavior of the megathrust and forearc structure. Topics of interest may include, but are not limited to, the temporal and spatial relationship between megathrust slip (coseismic, postseismic, and aseismic) and upper plate structure; internal deformation of the overriding plate during the seismic cycle; controls on along-strike and down-dip variations in seismogenic behavior; and models that explicitly tie the earthquake cycle to evolution of the forearc. We hope to attract submissions spanning geology, marine geophysics, geodesy, seismology, and geophysical and analog modeling, and we welcome discussion of how our current understanding of megathrust slip affects seismic hazard models.

Volcanology, Geochemistry and Petrology

V03: Subduction Volcanism at Continental Margins
Conveners: A. Peslier, J. Varekamp and L. Siebert

This session focuses on volcanism at the edge of continents, as exemplified (but not exclusively) by the Mexican volcanic belt. Mass flow in subduction environments from the mantle to the surface is influenced by differentiation processes, crustal contamination, degassing, magma ascent rates and eruption type. Presentations are invited on volcanic products ranging from volcanic rocks, melt inclusions in crystals, and gases to xenoliths that provide insight into the origin, evolution and transport processes of such continental arc magmas. Fundamental topics to be addressed include the role of subduction volcanism in the formation of the continents, estimates on the amount of crustal contamination in a volcanic suite, the composition of the mantle wedge at continental margins, the volatile budget in specific subduction zones, and the application of the stratigraphic and petrologic history of a volcano to better predict future eruptions. We invite contributions thematically linked and/or inspired by the lasting and fundamental work of James F. Luhr.

*V10: From the Arc to the Back-Arc: Linking Geochemical and Geophysical Observations with Geodynamic Models of the Mantle Wedge
Conveners: P. Hall and S. Escrig

Back-arc basins (BABs) are complex tectonic environments in which oceanic crust is created at a spreading center (back-arc spreading center, BASC) in close proximity to a subduction zone. This juxtaposition results in strong spatial gradients in both geochemical and geophysical observables, providing a unique window on geodynamic and petrogenetic processes in the upper mantle. This session seeks to highlight progress in our understanding of mantle flow and melting in the mantle wedge by considering differences between arcs and BASCs, as well as between BASCs and normal mid-ocean ridges. Questions of interest include: What is the nature of the slab-derived component that contributes to arc and BASC magmatism (e.g., hydrous fluids, melts)? What is the distribution of this component within the wedge, and by what mechanism is it transported? What constraints do seismic attenuation and velocity studies provide regarding the presence of water, melt and fine-scale structure in the mantle wedge beneath BABs? How does plate kinematics (e.g., subduction angle, subduction rate, arc-back-arc separation, back-arc spreading rate) affect mantle flow and melting in arcs and BASCs? Contributions from geochemistry, petrology, seismology, geophysics, geodynamics and mineral physics are encouraged, as are contributions from researchers working in relevant Ridge and Margins focus sites (e.g., Lau Basin, Izu-Bonin-Mariana).

V24: Magmatic Processes in Arcs and Metallogeny
Conveners: R. Weinberg and A. Tomkins

This session will focus on the interaction of physical and chemical processes during magmatic evolution in island and continental arcs, and how these affect the genesis of ore deposits related to felsic magmas. The session aims to address formation of the massive metal and sulfur anomalies that characterize these deposits by taking a broad view of the magmatic system, including processes in the magma sources and the deeper part of the system. We welcome contributions from igneous petrologists, economic geologists, numerical modelers, geochemists and geophysicists describing any aspect of these magmatic systems. Studies based on field, experiments or theoretical approaches are invited.

V30: Fluid-Rock Interaction in the Crust and the Upper Mantle
Conveners: T. Müller and A. Wohlers

The presence of fluids in the crust and the upper mantle has fundamental consequences for many petrologic processes, such as the genesis of magmatic rocks, mineral reactions, rates and mechanisms of nucleation and growth of minerals, mineral solubility, isotope transport, mass transfer and partial melting. We invite contributions in the field of metamorphic and igneous petrology which address the questions and problems of fluid-rock interactions in different geological settings, and on different scales, in order to advance our understanding of the fundamental processes controlling fluid-rock interactions in earth's crust and mantle. Field, experimental and theoretical studies ranging from shallow crustal regimes to subduction zones and the upper mantle are welcome.

V35: Seafloor Hydrothermal Systems Related to Volcanic Arcs
Conveners: D. Butterfield and W. Bach

Hydrothermal venting at back-arc spreading centers and at submerged island-arc volcanoes display both similarities and differences when compared to systems found on mid-ocean ridges, with differences attributed to a range of factors including the composition of the substrate (basalt, andesite, rhyolite, dacite), contributions of magmatic volatiles to the hydrothermal system, and the depth and structure of the substrate. For example, recent studies in the southwest Pacific (Lau Basin, Manus Basin, Kermadec and Mariana Arcs) are providing evidence for volatile input (based on both alteration assemblages and vent fluid compositions). This session seeks contributions on any topic related to submarine volcanic arc hydrothermal systems.

Other Sessions of Interest

B19: Cold Seeps at Continental Margins: Past and Present
Convener: J. Sample and H. Schwartz

Study of the Earth's Deep Interior

DI02: Volatiles and Melts in the Earth's Interior
Conveners: R. Dasgupta, C. Aubaud, G. Leahy and J. Dixon

Geodesy

G12: Plate Motion and how it is Taken up in Deforming Zones
Conveners: D. Argus and J. Freymueller

G16: Postseismic Deformation: Measurements, Mechanisms and Consequences
Conveners: E. Fielding, A. Freed and I. Johanson

Hydrology

H10: Flow and Transport in Heterogeneous Media: New Experimental and Modeling Approaches
Conveners: M. Dentz, A. Englert and T. Le Borgne

Near Surface Geophysics

NS: Fault Imaging and Seismic Hazard Assessment
Conveners: M. Craig and S. Kruse

Ocean Sciences

OS02: Coastal Models and Data: Simulation, Synthesis and Integration
Conveners: C. Hearn, O. Petersen and K. Yates

Seismology

S13: Earthquake Early Warning: Design and Application Around the World
Conveners: R. Allen, P. Gasparini and O. Kamigaichi

S17: New Insights About Seismogenesis from Dense Geophysical Observations
Conveners: Y. Iio, T. Sagiya, T. Iwasaki, T. Okada and C. Thurber

Tectonophysics

T06: Tectonic, Magmatic and Surface Processes in Arc-Continent Collisions
Conveners: P. Clift and A. Draut

T20: Surface Processes, Crustal Rheology, or Regional Geology: What Controls the Structural Architecture of Convergent Continental Orogens?
Conveners: E. Cowgill, A. Forte, R. Thiede and M. Murphy

T26: Continental Collision - The Lithospheric Scale
Conveners: W. Chen, S. Chung, R. Nowack and B. Hunag

T29: Caribbean Subduction Zones - Past and Present
Conveners: U. Martens and A. García-Casco

T38: From Subduction to Collision
Conveners: F. Taming Wu, L. Teng and D. Brown

Volcanology, Geochemistry and Petrology

V11: Recycling of Deep Continental Lithosphere: Consequences for the Mantle and Crust
Conveners: R. Rudnick, S. Gao, A. Lenardic and R. Zhu

V12: Spreading Ridge Interactions with Hotspots, Subduction Zones, and Transforms
Conveners: J. Chadwick, M. Perfit and R. Keller

V26: Mud Volcanoes and Their Eruption Dynamics
Conveners: A. Mazzini, S. Planke, G. Akhmanov and C. Berndt