|2011 GSA Annual Meeting in Minneapolis (9–12 October 2011)|
|Paper No. 150-1|
|Presentation Time: 8:00 AM-8:20 AM|
EUSTATIC HISTORY, SEQUENCE ARCHITECTURE, AND LITHOFACIES SUCCESSIONS ALONG THE NJ TRANSECT: A PROGRESS REPORT
MOUNTAIN, Gregory S., Earth and Planetary Sciences, Rutgers University, Wright Labs, 610 Taylor Rd, Piscataway, NJ 08854, email@example.com and PROUST, Jean-Noel, UPR Cnrs 4661, CNRS/Universite de Rennes, Géosciences Rennes, Campus de Beaulieu, 35042 Rennes cedex, France|
IODP Expedition 313 drilled & logged 3 sites in 35 m of water 45-65 km off New Jersey in May-July 2009. These data constitute a long-awaited 'missing link' in a transect of sites from the coastal plain to the continental slope begun in 1993 to 1) calibrate the imprint of baselevel changes on sequence architecture & lithofacies successions, & 2) extract global sea-level history during times of known glaciation. Exp313 sites were located at the rollovers of Oligocene to mid-Miocene clinoforms where this record would be most clearly expressed & was feasible to drill. The tasks of evaluating sequence stratigraphic models, comparing the age of inferred sea-level falls to the δ18O glacio-eustatic proxy, & estimating the corresponding amplitudes, rates & mechanisms of sea-level change await the completion of several underway studies; here we provide a progress report.
1311 m of very good to excellent quality cores were collected with 80% recovery. The deepest was 757 mbsf; the oldest was upper Eocene. Each hole was located to intersect top-, fore- &/or toeset strata of several clinoforms linked by a grid of high-resolution 2D seismic profiles. Slim-line logs in each hole gathered spectral gamma ray, resistivity, magnetic susceptibility, sonic & acoustic televiewer measurements.
Seismic-log-core correlations, strengthened by MultiSensorCoreLogger measurements, enable us to locate samples in the seismic framework with depth uncertainties of only a few meters. Thus we're able to ground-truth lithofacies at a variety of settings in several depositional sequences. Topsets were well sorted silts & sands deposited in offshore to wave- & river-dominated shoreface settings. Toeset silts & silty clays were deposited below storm wave base & typically interbedded with poorly sorted debrites & turbidites deposited at times of clinoform degradation. Geochronologies based on Sr-isotopic ages, biostratigraphy, limited magnetic reversals & pollen markers show accumulation rates of 50-150 m/my with hiatuses across sequence boundaries from 0 to ~2 Ma. No conclusive evidence has been found of a sea-level fall below a clinoform rollover, but shoreface deposits along clinoform foresets paired with deep-water facies in topsets of the same sequence imply changes in relative sea level on the order of 60 m.
IODP Exp313 Scientific Party, coauthors
2011 GSA Annual Meeting in Minneapolis (9–12 October 2011)
General Information for this Meeting
|Session No. 150|
Applications of Bio-, Chemo-, and Lithostratigraphy to Sequence Stratigraphy
Minneapolis Convention Center: Room 200H-J
8:00 AM-12:00 PM, Tuesday, 11 October 2011
Geological Society of America Abstracts with Programs, Vol. 43, No. 5, p. 374
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