HR: 0800h
AN: U21B-0818    [Abstracts]
TI: Discrete and Continuous Gravity Studies of the Arbuckle-Simpson Aquifer, South-Central Oklahoma
AU: * Scheirer, D
EM: dscheirer@usgs.gov
AF: US Geological Survey, MS 989 345 Middlefield Rd., Menlo Park, CA 94025
AU: Hosford Scheirer, A
EM: allegra@usgs.gov
AF: US Geological Survey, MS 989 345 Middlefield Rd., Menlo Park, CA 94025
AU: Herr, R
EM: HerrR@navo.navy.mil
AF: Naval Oceanographic Office Navigation and Geodesy Applications Branch, Code N521 / Building 1205, Stennis Space Center, MS 39522
AB: We present the results of a high-resolution gravity study using traditional and novel observational methods focused on the Arbuckle-Simpson Aquifer (ASA), a major ground-water system in Oklahoma that is experiencing demand from distant regions. We have partnered with the National Park Service to conduct gravity surveys of prominent faults near the Chickasaw National Recreation Area. These structures, created during late Paleozoic orogenies, may serve as conduits for ground-water flow to the springs and wells that are important natural resources of this park. Gravity data were collected in two modes: traditional observations at discrete stations and a new approach utilizing continuous data from a marine gravity meter deployed on a moving land vehicle. With the discrete data, we clearly define the extensions of the major Sulphur, South Sulphur, and Mill Creek fault zones beneath younger, unfaulted rocks that form the surface geology of the park. Gravity anomalies range from 1 mGal to 15 mGal and arise from the juxtaposition of Paleozoic carbonate and clastic rocks across the faults. With the continuous gravity data, we increase the number of gravity observations by two or more orders of magnitude, although the precision of the continuous gravity varies with the quality of the navigation (Eotvos correction) and the measurement of vertical motion of the vehicle. To explore the limits of this continuous gravity technique, we performed numerous tests operating the vehicle at different speeds and using multiple GPS sensors that range in capability from recreational to survey quality. These tests demonstrate the tradeoff between the along-track data resolution and the precision of the gravity anomaly.
DE: 0920 Gravity methods (1219)
DE: 1219 Gravity anomalies and Earth structure (0920, 7205, 7240)
SC: Union [U]
MN: Fall Meeting 2005