R ENW Services - Geophysics & GIS

Size: px

Start display at page:

Download "R ENW Services - Geophysics & GIS"

Holly O’Neal’
5 years ago
Views:

1 Yankton Block 1 Vermillion Block 2 N Block 3 Elk Point MILES Block 4 R KILOMETERS Block 5 Figure courtesy of ENW Services - Geophysics & GIS Block 6 Test hole R is located at NW¼ NW¼ NW¼ NE¼ sec. 13, T. 90 N., R. 50 W. The highest readings are colored pink, the lowest in deep blue. Figure 1. Aeromagnetic data from a flight line along the Missouri River from Yankton, South Dakota, to Ponca State Park, Nebraska.

The overshot retrieves the core barrel Water is flowing freely through the core rod Once the flowing formation was intersected, water flowed freely through the core rod when not

2 The overshot retrieves the core barrel Water is flowing freely through the core rod Once the flowing formation was intersected, water flowed freely through the core rod when not coring. Photo is taken looking east. (December, 2002; drillers, from left to right: Dennis Iverson, Gary Jensen, Scott Jensen). Figure 2. Photograph of coring through the flowing formation.

3 D = Devonian; O = = Cambrian; p@ = Precambrian Lake clay Alluvium Brown Dolostone Gray-green Decorah 642 ft Platteville Formation 659 ft Glenwood Formation 671 ft Missouri River sand over glacial outwash 101 ft with thin layers Vuggy Dolostone Dakota Formation analysis ft analysis ft analysis ft 409 ft Bottom of casing: 411 ft Devonian carbonates D O Wise Lake Formation? ft karst development in dolostone 472 ft Gray-green St. Peter Davis Formation Wonewoc 699 ft analysis ft analysis ft analysis - 741, 742, and 745 ft 752 ft The Wonewoc flowed starting at 760 ft below land surface. T D Legend Clay and Silt Sand and Clay Sand and Gravel and Dakota Formation Cretaceous Cherty Dolostone Dunleith Formation ft Dolostone,, and Dolostone,, and "Glauconite Sand" Glauconite sand zones Bonneterre/ Eau Claire Fm 799 ft 822 ft analysis ft analysis ft, finer-grained and Shaly, some Sand and Dolostone Dolomitic Gray-green Decorah Galena Group Mt. Simon 879 ft 898 ft Chemically weathered p@ 917 ft Geochemical analysis R Dolostone Cavities > 4 inches wide Cherty Dolostone Dolomitic Dolostone,, Saprolite Metagabbro Geochemical analysis R Geochemical analysis R Metagabbro Figure 3. Graphic log of rocks intersected in test hole R

4 ?? 750 Paleozoic Rocks Absent?? Test hole; number is top of the Paleozoic surface in feet above mean sea level Test holes from this study; number is top of the Paleozoic surface in feet above mean sea level. R is the eastern drill hole ? 650 Contour line; dashed where approximate, queried where unknown; number is top of the Paleozoic surface in feet above mean sea level. Contour interval is 50 feet 650 Location map of study area N MILES KILOMETERS Figure 4. A structure contour map of the Paleozoic surface in Union County, South Dakota.

5 Test hole; number is top of the Precambrian surface in feet above mean sea level Test hole R ; number is top of the Precambrian surface in feet above mean sea level 400 Contour line; number is top of the Precambrian surface in feet above mean sea level. Contour interval is 100 feet Subcrop of Precambrian Sioux Quartzite Subcrop of Precambrian igneous and metamorphic rocks, undifferentiated Location map of study area 2N MILES KILOMETERS Figure 5. A structure contour map of the Precambrian surface in Union County, South Dakota.

6 Geophysical log was zeroed at the top of the casing which was 1 foot above ground surface. Thus, the footages shown on the log read 1 foot higher than actual depths. D = Devonian; O = = Cambrian; p@ = Precambrian Depth below land surface in feet Devonian dolostone 440 D 450 O Wise Lake Formation of the 460 Galena Group; dolostone Dunleith Formation of the Galena Group; cherty dolostone Dunleith Formation; sandstone Decorah of the Galena Group; dolomitic shale Platteville Formation Glenwood Formation 680 St. Peter ; well-sorted sandstone with thin 690 O organic-rich shale Depth below land surface in feet p@ Davis Formation; dolomitic shale with glauconite Wonewoc ; dolomite cemented at top, poorly consolidated below Bonneterre or Eau Claire Formation Bonneterre Formation; dolostone with glauconite; shale lenses common Mt. Simon Saprolite Weathered basement rock Precambrian metagabbro Single point resistivity (ohms) Natural gamma (API-GR) Figure 6. Geophysical log showing single point resistivity and natural gamma signatures of Paleozoic and Precambrian rocks in test hole R

7 cm Figure 7. An exterior mold of a brachiopod (an indeterminate cyrtinid) of probably Devonian age in dolostone.

R20-2002-01 Figure courtesy of ENW Services - Geophysics & GIS See figure 1 for location of

8 R Figure courtesy of ENW Services - Geophysics & GIS See figure 1 for location of block 6 Figure 8. The block 6 aeromagnetic anomaly located 4 miles south of Elk Point, South Dakota.

9 R R R Figure courtesy of ENW Services - Geophysics & GIS See figure 8 for location of line 5 (L5) See figure 1 for location of block 6 Figure 9. Profile along line 5 of the block 6 aeromagnetic anomaly.

10 R Figure courtesy of ENW Services - Geophysics & GIS See figure 1 for location of block 6 Figure 10. A 2½-dimensional magnetic model of the block 6 aeromagnetic anomaly.

DRILLING OF AN AEROMAGNETIC ANOMALY IN SOUTHEASTERN SOUTH DAKOTA: RESULTS FROM ANALYSIS OF PALEOZOIC AND PRECAMBRIAN CORE

DRILLING OF AN AEROMAGNETIC ANOMALY IN SOUTHEASTERN SOUTH DAKOTA: RESULTS FROM ANALYSIS OF PALEOZOIC AND PRECAMBRIAN CORE STATE OF SOUTH DAKOTA M. Michael Rounds, Governor DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES Steven M. Pirner, Secretary DIVISION OF FINANCIAL AND TECHNICAL ASSISTANCE David Templeton, Director GEOLOGICAL