HR: 0830h
AN: S41C-04    [Abstracts]
TI: Analysis of Fracture Alignment and Hydrothermal Flow in Accommodation Zones That Link Facing Half-Grabens, Oregon Basalt Plateau
AU: * Osterloo, M M
EM: osterloo@lanl.gov
AF: Los Alamos National Laboratory, International, Space and Response Technologies PO Box 1663, MS D466, Los Alamos, NM 87545 United States
AU: * Osterloo, M M
EM: osterloo@lanl.gov
AF: Department of Geological Sciences Indiana University, 1001 East 10th St, Bloomington, IN 47405 United States
AU: Brumby, S P
EM:
AF: Los Alamos National Laboratory, International, Space and Response Technologies PO Box 1663, MS D466, Los Alamos, NM 87545 United States
AU: Douglas, B J
EM:
AF: Department of Geological Sciences Indiana University, 1001 East 10th St, Bloomington, IN 47405 United States
AU: Finkelstein, D B
EM:
AF: Department of Geological Sciences Indiana University, 1001 East 10th St, Bloomington, IN 47405 United States
AU: Funsten, H O
EM:
AF: Los Alamos National Laboratory, International, Space and Response Technologies PO Box 1663, MS D466, Los Alamos, NM 87545 United States
AU: Pratt, L L
EM:
AF: Department of Geological Sciences Indiana University, 1001 East 10th St, Bloomington, IN 47405 United States
AB: The Warner Valley, located in the southern Oregon portion of the Basin and Range Province, is composed of igneous units originating from the Steens Mountains volcanism. Normal faults associated with two opposing half grabens which define the valley are linked by a fractured accommodation zone. Within the valley are a series of shallow dilute to evaporatively concentrated hypersaline alkaline lakes that are being investigated as an analog to evaporative paleo-lakes on Mars. Little precipitation falls during the summer months and most of the surface water originates as runoff from snow pack in the winter and early spring. One additional recharge mechanism for the lakes is infill from fracture-controlled springs. Several of these springs are hydrothermal in nature with temperatures ranging from 18° C to 70° C. Integration of remote sensing datasets with field-based data provides a unique opportunity to combine medium to high spatial resolution imaging with ground truth measurements. This permits identification and correlation of the fault and spring locations and verification of the fracture control on the distribution of springs based on a larger data set than is available from field work alone. Landsat and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) data, as well as digital elevation models, are used in the analysis. Gradients and absolute values from digital elevation models are used to define the trends of the faults and fractures as well as the fault offsets. Many of the springs are marked by highly vegetated riparian zones that are identified via spectral and textural signatures present in these types of multispectral visible/infrared imagery. A majority of the hot springs are located within the accommodation zone of the opposing half-grabens; this highly fractured area is investigated in the datasets. Maps of vegetation variations within the valley coupled with thermal anomalies, derived from the imagery, serve to verify locations and trends of the faults, fractures, and hydrothermal springs. Results based on the remote sensing data are corroborated by field observations referenced using GPS locations, fault and fracture surface strike and dip measurements, as well as textural field observations.
DE: 8000 STRUCTURAL GEOLOGY (New field, replaces single entry 8165)
DE: 8010 Fractures and faults
DE: 8040 Remote sensing
DE: 8424 Hydrothermal systems (8135)
SC: Seismology [S]
MN: 2005 Joint Assembly