EarthScope - GeoPRISMS
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An EarthScope- GeoPRISMS Science Workshop for Eastern North America (ENAM) was held at Lehigh University in Bethlehem, PA on October 27-29, 2011. Approximately 95 people were in attendance. Despite a poorly timed Nor’easter on the last day of the workshop – which ultimately led to four days of power outage in Bethlehem and interesting travel for the participants – the workshop was very successful. A consensus plan for the GeoPRISMS ENAM primary site was reached, and synergies with the EarthScope program were fully explored.
The scale, the complicated record of multiple Wilson cycles, and the along-strike geologic variations of ENAM made selecting a single focus area impractical. Consequently, the workshop identified three potential regions for GeoPRISMS focused research, and articulated the alignment with EarthScope priorities for each of those locations. Additionally, significant discussion addressed thematic and synoptic studies that are less site specific, but which also afford synergistic opportunities between GeoPRISMS and EarthScope science goals.
The three focus areas identified are:
(1) A long, NW-SE oriented swath from the Appalachian foreland in Kentucky to true oceanic crust offshore the Blake Plateau, through the city of Charleston, SC (“The “Charleston Swath”). This area presented clear opportunities for the GeoPRISMS and EarthScope communities to work together on a number of topics. In combination, onshore and offshore studies could address fundamental questions about orogeny, rifting, post-rifting, and neotectonic deformation. The swath includes a classic section through the Appalachian mountains (including the highest topography in the Appalachians), multiple accreted terranes, rifting recorded in the South Georgia basin onshore, effusive breakup magmatism beneath the Carolina trough offshore, two zones of known seismicity (Charleston and Eastern Tennessee), large landslides preserved on the slope and the extensive Blake Ridge gas hydrate province. Work in this area could connect to the funded OINK EarthScope project in the mid-continent, thereby forming a complete swath from the orogenic foreland to oceanic crust.
(2) A swath across the Canadian Appalachians to true oceanic crust offshore Nova Scotia. This area is critical to understanding magmatism as a fundamental control on the process of rifting: It contains the transition from magmatic (south) to amagmatic (north) rupture and continental breakup along eastern North America. Consequently, this study area provides the opportunity to determine the characteristics and causes of this transition (i.e., differences in lithospheric properties and rheologies, extension magnitudes). Attractive targets for the onland component are accretion of the northern Appalachian regions, strike-slip tectonism along terrane boundaries, the record of rifting in the Fundy basin, and the active seismicity of the Charlevoix region. The area has logistical advantages, including abundant offshore industry seismic-reflection data and government and academic seismic-refraction data and some onshore permanent seismic observatories. While the motivation for this study area comes primarily from magmatic-to-amagmatic transition recorded offshore, there was interest in extending the footprint of Transportable Array of USArray into New Brunswick and Nova Scotia, to provide the onshore context for an offshore OBS deployment.
(3) A mid-Atlantic focus area that stretches along strike from about Philadelphia, PA to Richmond, VA and across strike from the Appalachian Plateau to the offshore Baltimore Canyon and Carolina troughs. Onshore, this area offers numerous advantages to studying orogenesis and rifting, and is less affected by terrane accretion than the northern or southern Appalacians. As a corollary, the mid-Atlantic section of the Appalachian orogen provides opportunities to understand the transition between the southern and northern Appalachians. This area contains exposures of both Iapetan and Mesozoic rift margins, and it records a wide range of magmatism, valuable for timing constraints and geodynamic inferences. A key advantage of this area is that it is well suited for linked, interdisciplinary studies of geomorphology, Cenozoic basin development, and upper mantle structure and dynamics. Mantle imaging in this area has already begun, with a recently completed, year-long seismic deployment (TEENA).
In addition to these focus areas, there were two areas of interest from an EarthScope perspective.
First, the New England region was considered for studying orogenic and rift initiation processes. This area provides an extremely telescoped orogeny, the presence of island-arcs as accreted terranes, a major extensional basin, and the presence of an ancient hotspot track. Second, there was interest in extending the scope of the funded SESAME EarthScope project in a variety of ways, including studying the role of terrane (continental fragment) accretion, the role of Iapetan transform faulting on subsequent deformation, or the nature of incomplete rifting on the southern end of the Appalachians. In general, there was support for conducting multiple cross-strike and along-strike swaths through the Appalachian Mountains, in order to develop a time-integrated evolution of the entire mountain belt.
Finally, a model was proposed for future EarthScope community projects that could leverage academic resources and interest in ENAM including, for example, the relatively high number of four-year colleges in the region. The goal would be to enable inclusive participation of geoscientists, in particular, faculty who are experts in the regional tectonic evolution ENAM. One possibility would be to provide community resources for pursuing a variety of synoptic studies. Discussions also considered the next generation of EarthScope science projects, perhaps including extended backbone ENAM TA and PBO deployments.
The meeting attendees are thanked for their active participation and contributing to the spirit of consensus building on the GeoPRISMS implementation plan for the Eastern North American margin, and identifying opportunities for further engaging EarthScope. The graduate students, in particular, were actively engaged in the workshop process and their insights and input were formally presented and played a significant role in moving the discussion forward during the decision-making process. The speakers, break-out group leaders, and white paper authors all contributed to the success the workshop.
The conveners and selected break-out leaders plan to prepare a comprehensive workshop report for distribution by January 2012, and an updated draft of the GeoPRISMS ENAM science implementation plan by February 2012. The implementation plan will be made available for public comment prior to final release. It will serve as a guide for proposals submitted for the next NSF GeoPRISMS solicitation, July 1, 2012, and the next EarthScope solicitation deadline, July 16, 2012.
Frank Pazzaglia (Lehigh University)
Maggie Benoit (College of New Jersey)
Peter Flemings (University of Texas - Austin)
Vadim Levin (Rutgers University)
Daniel Lizarralde (WHOI)
Lori Summa (ExxonMobil)
Basil Tikoff (University of Wisconsin-Madison)
Martha Withjack (Rutgers University)
Julia Morgan, GeoPRISMS Chair (Rice University)
Ramón Arrowsmith, EarthScope Steering Committee Chair (Arizona State University)
Final ENAM Workshop Report Now Available
The final ENAM Workshop Report is now available, you can download it below: