preliminary results, helicopter electromagnetic and magnetic survey of the seco creek area, medina...
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Preliminary Results, Helicopter Electromagnetic and Magnetic Survey of the Seco Creek Area,
Medina and Uvalde Counties, Texas
Bruce D Smith, Richard Irvine, Charles D. Blome, Allan Clark, and David V Smith
Index map
Geologic studiesGeologic StudiesGeologic Studies
Four 7.5’ Four 7.5’ TopoTopo Quads Quads SecoSeco Creek AreaCreek Area
Eddie Collins (BEG) and Kyle Murray (USGS) Eddie Collins (BEG) and Kyle Murray (USGS) Digital geologic map Digital geologic map Open file report in preparationOpen file report in preparation
Chuck Chuck Blome Blome and Jason Faith (USGS) and Jason Faith (USGS) Fault and fracture mapping Fault and fracture mapping
Preliminary geologic map from Kyle and Collins HEM SURVEY
RECHARGE ZONE
RECHARGE
ZONE
CATCHMENTAREA
CATCHMENT AREA
0 5,000 10,000 15,000 20,0002,500
Meters
CONFINED
ZONE
NOT
CONFINED ZONE
Hydrology 101Hydrology 101:Hydrology 101:
Faults (fracture flow & barrier)
Lithology (aquifers and aquitards)
Karst
Seco Helicopter
2002 HEM SurveySENSOR SYSTEM 6 EM Frequencies 400 – 100,000 Hz Internal Magnetometer High Resolution GPS Laser Altimeter
Geology with flight lines
Geologic Map Showing Flight Lines
81 square miles
200 meter line spacing
Red dot – sink hole
Black USGS funding
Red EAA funding
100kHz Apparent Resistivity
25kHz Apparent Resistivity
6200Hz Apparent Resistivity
1500Hz Apparent Resistivity
400 Hz Apparent Resistivity
Depth section calculations
UBC EM1DFM
EMFLOW
Differential Depth
Line 10240
Vertical Exaggeration~x20
2000m
1 Mile
100m
TrinityGroup
Sinkhole
Del Rio ClayEdwardsGroup
nothing
SOUTH NORTH
Geophysical structurecorrelation
Mapped structurecorrelation
Sinkhole
Geology with flight lines
Geologic Map Showing Flight Lines
81 square miles
200 meter line spacing
Red dot – sink hole
Black USGS funding
Red EAA funding
Line 10500 Resistivity depth section
Vertical Exaggeration~x10
2000m
1 Mile
200m
Geophysical structure correlation
Mapped structure correlation
STRUCTURAL MAPPINGSTRUCTURAL MAPPINGSTRUCTURAL MAPPING
Many more than currently mapped Many more than currently mapped
Contact between recharge and confined zonesContact between recharge and confined zones
Contact between Contact between catchment catchment area and recharge area and recharge zone zone
KarstKarst features targeted for ground followfeatures targeted for ground follow--upup
STRATIGRAPHIC MAPPINGSTRATIGRAPHIC MAPPINGSTRATIGRAPHIC MAPPING
Upper and Lower Devils River distinguishedUpper and Lower Devils River distinguished
Del Rio marker mapped in the subsurfaceDel Rio marker mapped in the subsurface
Possible shale marker in the Glen Rose GroupPossible shale marker in the Glen Rose Group
Line 10500 location