SEPM Annual Meeting

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Mike Blum’s research interests lie in fluvial, coastal, and shallow marine depositional systems, Quaternary climate and sea-level change, and source-to-sink routing of sediments to deepwater systems. He has been a Senior Research Scientist at ExxonMobil Upstream Research Company in Houston since 2008. Blum’s current focus is on developing exploration-scale stratigraphic research concepts and models. Prior to that, he was Harrison Professor in Geology and Geophysics at LSU, where he worked on evolution of the Mississippi Valley and Gulf of Mexico shoreline. Mike’s talk is entitled Impact of Sea-Level Change and Regional Subsidence on Coastal Evolution: Prospects for the Mississippi Delta.

The Mississippi River delta is in the midst of an environmental transformation that is of a scale unprecedented in United States history. Greater than 25% of deltaic wetlands have disappeared since 1932 and the entire region is increasingly vulnerable to storm surge.

Holocene history of the delta region is well known and reflects filling of a glacial-period incised valley followed by construction of an extensive and complex delta plain. Mean rates of deposition required to fill the valley and construct the delta plain over the past 11–12 years are ~230 million tons/year, with the remaining supply dispersed to the shelf. Prior to the 20th century, sediment was dispersed to the delta plain through crevasse and distributary channels, but continuous levees now render the delta plain transport-limited. Moreover, >40,000 dams now trap ~50% of the Mississippi’s natural sediment load: total modern loads are ~200 million tons/year, less than the time-averaged rates for the storage component alone over the entire post-glacial period. The modern delta plain is therefore also severely supply-limited.

Predictions of future submergence due to global sea-level rise and subsidence face uncertainties that are not easily resolved. However, the Gulf of Mexico tracks global sea-level rise, which is currently ~3 mm/year: extrapolating the linear acceleration of global sea-level rise from the 20th century place rates at 4 mm/year by 2100, whereas more extreme views include accelerated melting of ice sheets and estimate >6 mm/year.

Geologic and geodetic data converge on a hinge-like subsidence profile with rates of 0–1 mm/year updip to >6-8 mm/year in downdip reaches. A more conservative relative sea-level rise scenario will inundate the ~14,000 sq. km that is now <0.4 m in elevation by the year 2100, and a worst-case scenario will inundate >18,000 sq. km.

Land-building diversions of Mississippi and Atchafalaya River water and sediment are envisioned to mitigate potential submergence and achieve sustainability of delta surface area. An estimated ~18–24 billion tons of sediment will be required to fill new accommodation and sustain surface area to the year 2100, which is more than can be drawn from the Mississippi and Atchafalaya Rivers in their current supply-limited state. However, even if natural loads were restored, rates of sea-level rise are >3 times higher than at any time in the last 6,000 years, the period over which the delta plain was constructed, and significant drowning is inevitable.

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SEPM President Christopher Fielding invites you to an evening of celebration to honor the 2012 award winners of SEPM — Society for Sedimentary Geology — and the perfect place to network and visit with colleagues old and new.

The Twenhofel Medal, the highest award of SEPM given in recognition of a career of outstanding contributions to sedimentary geology, will be presented to John C. Harms. SEPM Honorary Membership, given for both scientific contributions and service to the society, will be awarded to Richard (Skip) Davis.

The other science award recipients are James V. Gardner, who will receive the Francis P. Shepard Medal in recognition of excellence in marine geology; Carleton E. Brett, the Raymond C. Moore Medal in recognition of excellence in paleontology; Norman D. Smith, the Pettijohn Medal for excellence in sedimentology; and Shahin Dashtgard, the Wilson Award for excellence in sedimentary geology by a younger geoscientist.

SEPM will honor the recipients of the Best Paper Awards for 2010 in both of its journals, Journal of Sedimentary Research and PALAIOS. SEPM will also recognize the Best Student Presentation Awards from the 2012 Annual Meeting, where cash prizes will be presented to the top student presenters from the SEPM Student Awards Poster Session scheduled for Monday.

As always SEPM will recognize the members of the 2012 Annual Meeting Organizing Committee, without whom the meeting could not take place, and SEPM Foundation Student Grant recipients. The reception will begin at 7:00 p.m., with cocktails available at cash bars and substantial hors d’oeuvres. The awards ceremony will start at 7:30 p.m.

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The Society for Sedimentary Geology (SEPM) would like to invite anyone who is interested in research group activities to attend the SEPM Research Group Meetings. Individual Research Groups will meet on Monday, 23 April. Specific locations will be announced later. Check the SEPM website for updates at www.sepm.org.

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The Society for Sedimentary Geology (SEPM) would like to invite all students to attend the combined AAPG/SEPM Student Reception sponsored by ExxonMobil. The reception is held just prior to the SEPM Research Group meetings on Monday, 23 April at the Renaissance Hotel. Students can enjoy food and drink and then go on to the SEPM Research Group topic of their choice to network and listen to the latest discussions.

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Carbonate margin, slope and basinal depositional environments, and their transitions, are highly dynamic and heterogeneous components of carbonate platform systems, are repositories for volumetrically significant amounts of sediment produced from nearly all carbonate environments, provide a stratigraphic record not necessarily preserved in platform-top or basinal strata, and serve as a complex link between the prevailing in situ sediment factories and domains dominated by resedimentation processes. Recent research has highlighted important academic and industry-applied aspects of these systems and will be presented in a special oral and poster session.