Applications of ichnology to hydrogeology, with examples from the Cape Fear Formation (Cretaceous), South Carolina

Conference · Wed Jan 01 04:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5807952

Martin, A J ^[1]; Simones, G C ^[2]

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1. Emory Univ., Atlanta, GA (United States). Geosciences Program
2. South Carolina Water Resources Commission, Columbia, SC (United States)

Ichnology, the study of modern and ancient traces left by organisms, has provided supplemental information to geologic subdisciplines such as sedimentology and stratigraphy. The major objective of the authors paper is to emphasize the valuable information that can be conveyed by trace fossils in the investigation of hydrogeologic units. Bioturbation has a net effect of mixing different types and layers of sediments, such as introducing clays into sands and vice versa. This mixing can decrease porosity and permeability of sandy units, thus changing potential aquifers into confining units. For example, a sandy fluvial deposit will contain distinctive nonmarine trace fossils, thus defining channel sands that may serve as permeable conduits for ground-water flow. In contrast, a sandy shelf deposit will contain marine trace fossils in a sand body geometry that will be markedly different from aquifers produced in nonmarine environments. Bioturbation also causes geochemical and diagenetic changes in sediments, causing irrigation of previously anoxic sediments and precipitation of ion oxides. The Cretaceous Cape Fear Formation of the Atlantic Coastal Plain, in the subsurface of South Carolina, is presented as an example of a hydrogeologic unit that has been reinterpreted using ichnologic data. Extensive bioturbation caused mixing of clays and sands in Cape Fear sediments, which resulted in the Cape Fear becoming a regional confining system. Trace fossil assemblages indicate a brackish water environment, perhaps estuarine, for the Cape Fear, as opposed to previous interpretations of fluvial and deltaic environments. Bioturbated zones also have significantly more oxidized iron than unbioturbated zones, highlighting potential effects on ground-water quality.

• OSTI ID: 5807952
• Report Number(s): CONF-921058--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 24:7
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AQUIFERS
BIOLOGICAL MATERIALS
BIOLOGICAL WASTES
CLAYS
DEVELOPED COUNTRIES
ENVIRONMENTAL QUALITY
FOSSILS
GEOLOGY
GROUND WATER
HYDROGEN COMPOUNDS
HYDROLOGY
MATERIALS
MIXING
NORTH AMERICA
OXYGEN COMPOUNDS
PERMEABILITY
POROSITY
SAND
SEDIMENTS
SOUTH CAROLINA
USA
WASTES
WATER
WATER QUALITY