14 Geology of the Southeastern Atlantic Continental Margin: A Poster Session with Cores, Rock Samples and Coffee (Posters)

Thursday, 31 March 2016
8:00 AM - 5:30 PM
Exhibit Hall

FORAMINIFERAL AND LITHOLOGIC CHARACTERISTICS OF COASTAL ENVIRONMENTS AT BOGUE INLET, NORTH CAROLINA

Paper number: 14-5
Program: Theme Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

Foraminifera are commonly used as a basis for paleoenvironmental interpretations. The objective of this study is to use foraminiferal data from clastic coastal subenvironments such as shoreface, inlet channel, ebb tide delta, and inner shelf, and investigate whether these environments may be distinguished micropaleontologically. In 2012, ca. 200 vibracores were collected off the coast of Bogue Banks and in Bogue Inlet, NC to assess possible sand resources. Geophyical data were used to determine which cores provided a Holocene sedimentary record. Four cores were chosen, two from an ebb tide delta and two from an inlet channel. Cores were logged using a method that is independent from composition and samples were taken from the Holocene section. The samples were washed over 710m and 63m sieves. The 63m-710m portion of each sample was dried and put through a sodium polytungstate, heavy liquid floatation process to concentrate the foraminifera.

 Three inlet channel samples, mixed bioclastic and siliciclastic in composition, averaged 39% gravel, 60% sand, and ~1% mud. Two ebb tide delta samples averaged 25% gravel, 74% sand, and ~1% mud. Foraminiferal assemblages of the inlet channel samples contained ~36% fossil (likely Miocene) foraminifera. Modern foraminifera were dominated by Elphidium excavatum (~ 28%), Quinqueloculina lamarckiana (~9%), and Quinqueloculina seminula (~4%). Diversity values (Fisher’s alpha) for the three inlet throat samples were 5, 7, and 4. The ebb tide delta samples contained ~98% modern foraminifera. The dominant species were Quinqueloculina lamarckiana (~32%), Ammonia parkinsoniana (~8%), and Elphidium mexicanum (~7%). Fisher’s alpha values were 12 and 9. These preliminary data indicate that ebb tide delta and inlet channel environments, although characterized by similar lithologies, can be distinguished by their foraminiferal assemblages.

Geological Society of America Abstracts with Programs. Vol. 48, No. 3

doi: 10.1130/abs/2016SE-273552

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