Please see below for more sessions of interest to the GeoPRISMS Community, taking place at the 2015 AGU Fall Meeting, December 14-18 in San Francisco. Note, AGU abstract submission deadline is August 5, 2015.
See http://fallmeeting.agu.org/2015/
Submit your abstract: http://fallmeeting.agu.org/2015/abstract-submissions/
T015. Cumulative deformation in the overlying plate due to subduction and related feedbacks
Session ID#: 8167
Subduction over time modifies the overriding plate by fractionation, accretion, and tectonic deformation. This can lead to processes such as tectonic shortening (orogeny), regional uplift, weakening by back-arc spreading and volcanism, basin formation, and/or destabilization of the lithosphere. In turn, the composition, strength, and morphology of the overlying plate, which may be the product of a long geological history and have significant along-strike variations, can affect current large-scale subduction dynamics such as slab dip, and ultimately broad-scale plate kinematics in two and three dimensions. Examples of geological settings that bear witness to these processes are found along the Pacific Rim, the Tethys margin, including the Mediterranean mobile belt, and northwestern North America. We seek contributions from all disciplines, including geodesy, geology, geochemistry, seismology, and geodynamics, that document the tectonic evolution of overlying plate deformation and their link to subduction processes.
Onno Oncken, GFZ-Potsdam U.
Thorsten W Becker (University of Southern California)
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T021. From the seismic cycle to geological time scales, how do subduction processes that can possibly modify the megathrust geometry and mechanical properties control the tectonic evolution and deformation of active margins, and the subduction seismic behavior?
Session ID#: 7866
A fundamental feature of overriding plates is that on 100 to 107yr time-scales, they deform both abruptly and dramatically or slowly and subtly in response to an array of distinct subduction processes, among which are earthquake cycles, subducting ridges, and erosion/accretion. Over short time-scales, the pattern of upper-plate vertical deformation is dominated by subduction seismic cycles controlled by the megathrust structure and mechanical properties. Over longer time-scales, upper-plates present various vertical deformation patterns, which can be transient, vary along-strike, reflect long lasting elastic behavior (no permanent deformation) or not (building of permanent topography). Consequently, observations of long-term vertical deformation offer clues to investigate the structure, properties and processes enveloping the interplate thrust zone and their significance regarding subduction seismic behavior. This session welcomes insights focusing on active deformation at convergent margins through observations and modeling that seek to integrate the different time-scales to comprehend the factors controlling subduction zone behavior.
Luc L Lavier, Jackson School of Geosciences, Austin
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T037. Revisiting the Tectonics, Regional Structure, and Geodynamics of Alaska and the North Pacific
Session ID#: 9027
The Pacific-North American plate boundary in Alaska is in the scientific spotlight now because of the spectacular geology and tectonic processes preserved and ongoing in the region, and the major financial investment by the National Science Foundation through EarthScope and GeoPRISMS. It is timely to review the available data and tectonic-geodynamic models, as several major new scientific efforts are now in their infancy. Certain tectonic components have a first order effect, including the impact of the subduction of the Yakutat terrane, and the role of lithospheric heterogeneity from broad scales to more localized zones of weakness, such as the Denali fault. In this diffuse plate boundary, active deformation is partitioned across a large area, including related tectonic systems in Canada and Russia. We welcome submissions using observational and modeling studies relevant to the Alaska-Aleutian subduction zone and the North Pacific region, including new work and review or integrative submissions.
Douglas H Christensen, University of Alaska Fairbanks
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T038. Rifts and Passive Margins: Tectonics, Dynamics, Processes
Session ID#: 7198
This session presents recent advances on rifts and passive margins from geological and geophysical studies that are based on seismic interpretation, field geological data, plate reconstructions, sedimentology, and modeling.
We aim to assemble presentations on basin, regional and global scale that provide new insight on rift evolution in terms of inheritance and strain localization, fault interaction and stratigraphy, partial melting and volcanism, surface stress evolution, tectonics-climate interaction, small-scale convection, driving forces, and rift-to-drift transition. Most rifts feature significant along-strike structural variations. We therefore particularly encourage abstract submission on 2D investigations with regional perspective, 3D seismic arrays, as well as 3D analogue and numerical experiments.
Special emphasis will be put on contributions that develop an integrated picture by bridging multiple spatial or temporal scales or by combining results from active rifts, failed rift arms, passive margins or obducted rifted margins.
Giacomo Corti, Instituto di Geoscienze e Georisorse
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T039. Scientific advances from subduction zone observatories
Session ID#: 7617
Subduction zones contain the Earth’s richest diversity of tectonic processes, from plate-scale over millennia to grain-scale over micro-seconds. Most span continental to oceanic environments, and interact with climatological and biological processes, which multiplies the diversity and observational challenges, but also opportunities to leverage and learn. Finally, subduction zones host many of Earth’s most extreme natural events, which coupled with increasing human populations, leads to an urgent need to understand how they work. The scientific community is exploring the potential to develop a new Subduction Zone Observatory (SZO) as a multidisciplinary facility, stretching along several circum-Pacific’s subduction zones. A SZO would provide a comprehensive suite of multidisciplinary onshore and offshore observations to understand the entire subduction zone system. We welcome contributions that show scientific advances resulting from coordinated instrumentation, sampling, and analog experimentation/modeling of a subduction zone, or present scientific ideas and findings relevant to future development of a SZO.
Anne Meltzer, Lehigh University
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T043. Subduction across scales
Session ID#: 8926
Both risk assessment and lithosphere dynamics call for a better understanding of subduction zones, particularly along and across the subduction interface.
How can we bridge the gap between observations made at rock and plate scale, or between signals lasting from seconds to million years? Are we able to image and understand physical conditions and processes at work along the subduction interface at relevant scales, such as years and meters?
Time has come to further our understanding of the nature and structure of the subduction interface and elucidate which lithologies are incorporated and how, which rheological behaviours prevail, which fluids are there and where, or what is their exact bearing on earthquake ruptures.
Building on the recent wealth of geophysical and petrological data and models gathered on the plate-slab interface, we welcome stimulating contributions from all disciplines, seeking to foster joint collaboration and bridge the gap between the various communities.
Bradley R Hacker, University of California Santa Barbara
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V002. 4D Variations in Cascade Arc Magmatic Systems: Linking Tectonics, Geochemistry, and Geodynamics
Session ID#: 9089
This session draws together researchers in tectonics, geophysics, geochronology, geochemistry, and dynamic modeling to improve our spatial and temporal understanding of the Cascades magmatic arc. Since its enigmatic inception about 40 Ma, the arc has undergone significant changes in magmatic productivity and composition. In addition, the Cascades are volcanically and tectonically segmented into regions that differ in volcanic style, flux, and composition, as well as in faulting style, degree of crustal rotation, and relative uplift. These spatio-temporal variations may reflect differences in subduction rate or angle, the nature of the lower and upper plate, and regional tectonics. Can we determine which of these relationships are causative, and can we derive a geodynamic model for the variability of volcanism and plutonism through space and time? We seek contributions from researchers with geochemical or geophysical data sets, conceptual or numerical models, and other approaches that illuminate and help address these fundamental questions.
Haiying Gao, University of Massachusetts Amherst
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V011. Geochemistry of sediments and sediment recycling and implications for crust and mantle evolution over Earth history
Session ID#: 8150
Sedimentary rocks record information on diverse topics such as environmental conditions from the distant past, the average composition of the continents, and the redox state of the oceans and atmosphere. Although much of the Earth’s sedimentary record has been removed from our view by subduction processes, a long term consequence may be that the mantle “sees” and is influenced by Earth surface conditions. We seek a broad range of contributions that deal with the record of continental evolution and the rise of oxygen, seen both in the sedimentary record and also potentially in igneous systems as a result of sediment recycling over Earth history.
Elizabeth A Bell, University of California Los Angeles
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V018. How and when do volcanic eruptions start and stop, and what controls the tempo of everything in between?
Session ID#: 8269
There is much information now accumulating about the timing of volcanic eruptions, from the millennia (or longer) for the accumulation of magma into its eruptible state through to real-time observations of contemporary eruptive activity. A key aim of volcanology is to forecast the course of future events and provide advice on the timing and processes at ongoing eruptions on timescales that are relevant to humanity and with a degree of confidence about the processes involved. We invite contributions that address all the facets of this topic. These might include (1) magmatic forensics of past eruption products that contribute to accurate assessment of timescales and processes in past events; (2) studies of modern eruptions and the controls on their durations, including prolonged, multi-episode events; and (3) how temporal information about magmatic and volcanic processes can be translated into sound and useful advice to civil authorities for managing ongoing and future events.
Paul J Wallace, University of Oregon
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V027. Quantifying Storage, Transport, and Volumes of Magmas in the Earth’s Crust
Session ID#: 9804
When, where and for how long magmas are stored within the Earth and how they contribute to the crustal chemical, physical and thermal architecture remain important challenges in geosciences. Magmatic bodies have been detected with a wide range of geophysical approaches; however, the volumes, mechanics, chemical signatures and evolution of these bodies remain poorly constrained. We seek contributions that utilise field, numerical and experimental methods to address the following key themes: (i) how do we detect magmas bodies and do we determine their states and volumes in the Earth’s crust, (ii) how can we quantify chemical, mechanical and thermal processes that operate within those volumes, (iii) what can minerals, glass/melt and volatile emissions tell us about timescale of magmatic processes constructing the architecture of the continental crust, volcanoes and atmosphere. This session aims to foster cross-disciplinary interactions and collaborations between field geologists, geochemists, petrologists, volcanologists, geophysicists, and numerical modelers.
Kate J Dobson, Ludwig Maximilian University of Munich
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V032. The Earth’s geodynamic carbon cycle: subduction, storage, migration, and outgassing
Session ID#: 8341
The carbon cycle is of fundamental importance to Earth processes over geologic time. However, the physics of deep carbonaceous reservoirs and the fluxe(s) between Earth’s interior (mantle) and exterior (crust, hydrosphere & atmosphere) remain enigmatic.
This session aims to promote the latest multidisciplinary research involving the behaviour of carbon within the subducted slab, crust, and mantle. We welcome contributions related to: (1) solubility and storage of carbon within Earth’s interior; (2) origin and migration of C-rich fluids and melts and their impact on redox processes, diamond formation, mantle metasomatism and associated (alkaline) magmatism; (3) the petrology of carbonaceous phases at extreme P-T conditions; (4) stable isotope fractionation; and (5) carbon release to the exosphere through volcanic, tectonic and other styles of degassing.
We invite contributions from volcanology, natural/experimental geochemistry/petrology, and mineral physics, as well as theoretical and computational studies. Submissions by early career scientists and graduate students are particularly encouraged.
Taryn Michelle Lopez, University of Alaska Fairbanks
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V034. The ophiolite-subduction connection: Using peridotites as analogs for subduction zone mantle
Session ID#: 8521
Supra-subduction zone ophiolites, which form in the mantle wedge of nascent subduction zones, preserve mantle lithologies that formed in response to hydrous melting. The refractory residuum of this process enhances our understanding of the geochemical flux in the mantle wedge and is critical to our understanding of the ‘subduction factory’ and resulting arc volcanism. The resulting architecture of these ophiolites demonstrates that they are petrologically and chemically distinct from igneous rocks formed at modern spreading centers in the major ocean basins. Abstracts addressing ophiolite petrogenesis with respect to subduction initiation, peridotite geochemistry, extent and nature of melt extraction, extent of fluid flux through the mantle wedge, and subsequent mantle-melt interactions are welcomed. This session aims to integrate the chemical and physical structure of the mantle wedge, address controversial origins of well-known ophiolites, and discuss the diversity in the architecture and geochemical fingerprints observed in ophiolites.
Véronique Le Roux, Woods Hole Oceanographic Inst
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V045. Where Arc Magmas Reside: Comparing the Volcanic and Plutonic Records
Session ID#: 9834
Magmatic processes are powerful agents for creating and reworking the Earth’s crust. Passage and stalling of magmas in arcs brings new material into the crust and drives interactions with wall rock, magma mixing and fractionation, leaving complex crystal histories in both volcanic and plutonic rocks. In intrusive terrains, field relationships, aureole or igneous thermobarometry, and physical modeling inform where magmas reside and get modified. Erupted magmas carry quenched time series of mineralogical and compositional imprints of their crustal traverse. We invite contributions that use continental arc igneous assemblages to understand magma accumulation and residence in the crust, investigate magma-crust interactions and crustal assimilation, and the processes of magma mobility and eruptibility. We welcome discussions on the nature of plutonic versus volcanic rocks (cumulates/fractionates versus compositional equivalents) and volcanic-plutonic volume ratios. Contributions are welcome from petrology, geochemistry, geophysics, modelling and related fields.
Emily E. Salings, Missouri State University
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MR020. The spectrum of slip behaviors of continental and subduction fault zones
Session ID#: 8995
Recent global deployment of geophysical instrumentation produced a vast quantity of data, allowing major advances in the characterization of the slip behavior of continental/subduction fault zones. Complex modes of fault slip – including tectonic tremor, tsunami earthquakes and slow earthquakes – have been observed in the transition zone at the up-dip and down-dip limits of the seismogenic zone. These behaviours complement classic views of fault slip behaviours, where fast, frictional sliding during earthquakes and slow, aseismic sliding during creep events occur along faults.
Although recent studies have proposed heterogeneities in fault structure, frictional properties and deformation mechanisms, to explain the broad spectrum of fault slip behavior, our understanding of these processes is still limited. We welcome multidisciplinary, innovative contributions addressing the mechanical/physical properties and sliding behaviours of fault zones during the seismic cycle through the integration of field, laboratory and seismological data.
Wenlu Zhu, University of Maryland College Park
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DI007. Geochemical and geophysical links between subduction zone dynamics and arc systems
Session ID#: 9788
This session aims to explore the complex processes linking subduction dynamics and arc volcanism. We focus particularly on reconciling geochemical and geophysical observables with dynamic processes. Subduction zones exhibit heterogeneity in composition and thickness of subducting sediments, slab age and morphology, faulting characteristics, and thermal structure. This heterogeneity leads to temporal and spatial variability in mantle flow, seismicity, magma composition and productivity, and rates of subduction and back-arc spreading. The physical-chemical conditions and processes in arc systems have been inferred from geophysical and geochemical observations, experimental rheologic data, and geodynamic modeling. We invite contributions from these disciplines and others that link the physical-chemical conditions at volcanic arcs and the underlying mantle wedge with the dynamic processes in subduction zones.
Cian Wilson; Lamont-Doherty Earth Observatory
Maryjo N Brounce, University of Rhode Island Narragansett Bay
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S027. Unraveling the complexities of mantle flow, crustal rotation and crustal faulting in the Cascade subduction zone system
Session ID#: 8194
Recognition of the clockwise rotation of the Cascadia forearc, arc, and backarc from paleomagnetic and GPS observations represents one of the most exciting discoveries in subduction zone dynamics. This discovery requires a new paradigm to understand how crustal faults accommodate this rotation in a framework that includes Basin and Range extension, the active magmatic arc, north-directed compression against stable Canada, and plate subduction along the megathrust. The existing USGS Quaternary Fault database is woefully incomplete and does not explain the clockwise rotation of the crust. A variety of recent studies have addressed this shortfall, including new geologic mapping, high-resolution airborne LiDAR, new potential field geophysical surveys, paleoseismic studies of identified scarps, and seismic imaging of known faults. This session seeks contributions that present recent findings and new kinematic and dynamic models to explain the role of mantle flow and crustal faulting in accommodating Cascadia rotation.
