georefid:1999-025649SEDIS Publication Catalogue

ana.macario@awi.de

http://sedis.iodp.org/pub-catalogue/informationpointOfContact2011-06-23T00:00:00Zhttp://sedis.iodp.org/pub-catalogue/index.php?id=1999-0256491998-01-01publicationgeorefid:1999-025649Harris, Lisa C.Central Washington University, Geology Department, Ellensburg, WA, United StatesauthorWhiting, Brian M.authorGeological Society of America (GSA), Boulder, CO, United StatespublisherdocumentHardcopyIn: Anonymous, Geological Society of America, 1998 annual meeting30 (7)268ODP Leg 174A recovered a good record of late Tertiary sea-level variation along the shelf edge of the New Jersey margin. Glauconite was present in many layers of the core, often closely associated with sequence boundaries. Glauconite is generally agreed to be a reliable indicator of low sedimentation rate, but little systematic work has been done to specify the role of glauconite in a sequence-stratigraphic framework. For example, glauconite is common in transgressive systems tracts and lower highstand systems tracts; and condensed sections contain high concentrations of mature glauconite. The objective of this study is to determine the depositional setting and sequence-stratigraphic significance of glauconite-rich intervals recovered from Leg 174A cores. The most glauconite-rich and/or sequence-stratigraphically important intervals from Leg 174A cores have been identified. These intervals have been examined using both the binocular microscope and XRD to confirm the presence of glauconite. The morphology of glauconite grains, as determined by SEM, indicates the degree of evolution. The different types of glauconite (nascent, slightly evolved, evolved, and highly evolved) concentrate in specific settings, which assists in sequence-stratigraphic interpretation. For example, detrital glauconite is often associated with the lowstand fan complex; autochthonous glauconite may mark the bases of parasequences; and condensed sections contain very mature glauconite. The results of this study are being combined with seismic, biostratigraphic, and other Leg 174A data to provide an integrated study of the glauconite occurrence. As part of a broader study of the New Jersey margin, the ages of glauconites will also be determined using K-Ar dating to constrain the age and timing of sequence-boundary formation. By determining the sequence-stratigraphic significance of glauconite, this study will help constrain sequence-stratigraphic models for the Tertiary evolution of the western North Atlantic margin.completedStratigraphyAtlantic OceanbiostratigraphyCenozoiccontinental margincoresgeophysical methodsgeophysical surveysglauconiteLeg 174mica groupNew JerseyNorth AtlanticOcean Drilling Programsea-level changessedimentationsedimentation ratesseismic methodsSEM datasequence stratigraphysheet silicatessilicatessurveysTertiaryUnited Statesupper TertiaryvariationsX-ray diffraction dataEnglishgeoscientificInformation-80.000020.00000.000075.0000New JerseyNorth Atlantic