DGS Reports of Investigations

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Browsing DGS Reports of Investigations by Author "Benson, R.N."

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    Geologic And Hydrologic Studies Of The Oligocene - Pleistocene Section Near Lewes, Delaware
    (Newark, DE: Delaware Geological Survey, University of Delaware, 1990-10) Andres, A.S.; Benson, R.N.; Ramsey, K.W.; Talley, J.H.
    Borehole Oh25-02, located about 3 miles southwest of Lewes, Delaware, ends at a total depth of 1,337 ft in a mid-Oligocene glauconitic silt unit. It penetrated 317 ft of glauconitic sands and silts between the base of the Calvert Formation at a depth of 1,020 ft and total depth. A hiatus at 1,218 ft separates an outer neritic lower Miocene interval (Globorotalia kugleri Zone) above it from a deep upper bathyal mid-Oligocene (G. opima opima Zone) section below; the lower section is characterized by abundant large uvigerinid benthic foraminiferal species representing the transition from Uvigerina tumeyensis to Tiptonina nodifera. Similar uvigerinid assemblages identify the mid-Oligocene unit in boreholes near Bridgeville and Milford, Delaware; Cape May, New Jersey; and Ocean City, Maryland. Updip from these boreholes, the Calvert Formation, of latest Oligocene-middle Miocene age in Delaware, unconformably overlies middle Eocene glauconitic sands of the Piney Point Formation. The juxtaposition of the downdip mid-Oligocene rocks against the updip middle Eocene rocks can best be explained by a fault between the two regions.
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    Hydrocarbon Resource Potential Of The Baltimore Canyon Trough
    (Newark, DE: Delaware Geological Survey, University of Delaware, 1979-01) Benson, R.N.
    It is now possible to evaluate some of the earlier assessments and offer tentative conclusions about the hydrocarbon resource potential of the Baltimore Canyon trough, a major northeast-southwest trending sedimentary basin off the Mid-Atlantic coast of the United States. For this purpose the Delaware Geological Survey has examined more than 2,500 miles (4,022 km) of seismic reflection profiles, the results of some offshore magnetic and gravity surveys, the results of the COST B-2 well, and the nonproprietary results through 1978 of exploratory drilling by the petroleum industry on federal leases.
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    Internal Stratigraphic Correlation Of The Subsurface Potomac Formation, New Castle County, Delaware, And Adjacent Areas In Maryland And New Jersey
    (Newark, DE: Delaware Geological Survey, University of Delaware, 2006) Benson, R.N.; McLaughlin, P.P.
    This report presents a new time-stratigraphic framework for the subsurface Potomac Formation of New Castle County, Delaware, part of adjacent Cecil County, Maryland, and nearby tie-in boreholes in New Jersey. The framework is based on a geophysical well-log correlation datum that approximates the contact between Upper and Lower Cretaceous sediments. This datum is constrained by age determinations based on published and unpublished results of studies of fossil pollen and spores in samples of sediment cores from boreholes in the study area. Geophysical log correlation lines established above and below the datum approximate additional chronostratigraphic surfaces. The time-stratigraphic units thus defined are not correlated parallel to the basement unconformity, as in previous practice, but instead onlap it in an updip direction. In future studies, the sedimentary facies of the Potomac Formation within each time-stratigraphic layer may be mapped and analyzed as genetically related contemporaneous units. This new stratigraphic framework will allow better delineation of the degree of lateral connection between potential aquifer sands, thus enhancing understanding of aquifer architecture.
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    Stratigraphy And Correlation Of The Oligocene To Pleistocene Section At Bethany Beach, Delaware
    (Newark, DE: Delaware Geological Survey, University of Delaware, 2008) McLaughlin, P.P.; Miller, K.G.; Browning, J.V.; Ramsey, K.W.; Benson, R.N.; Tomlinson, J.L.; Sugarman, P.J.
    The Bethany Beach borehole (Qj32-27) provides a nearly continuous record of the Oligocene to Pleistocene formations of eastern Sussex County, Delaware. This 1470-ft-deep, continuously cored hole penetrated Oligocene, Miocene, and Pleistocene stratigraphic units that contain important water-bearing intervals. The resulting detailed data on lithology, ages, and environments make this site an important reference section for the subsurface geology of the region.