CROOKED CREEK IMPACT STRUCTURE
by: Charles O’Dale
- Type: Complex
- Age Ma: ~348 – 323a – MISSISSIPPIAN
- Diameter: ~7 km
- Location: N 37° 50’ W 091° 23’
- Shock Metamorphism: shatter cones, PDF in quartz
a Geologic estimated age: Miller et al., in 2006 and 2007.
Dietz and Lambert (1980) reported shock features in quartz granules in Lamotte Sandstone float from the central uplift area of the Crooked Creek structure. They stated, “All grains reveal a strong undulose extinction and are highly fractured—the fractures often radiating from contact points. Some grains are broken and collapsed into former voids presenting a breccia texture. Definite decorated planar elements [decorated planar deformation features (PDFs)] in quartz are locally present, but only among those which are in point-point contact. The quartz grains with planar elements are unfractured possibly due to the low porosity of the immediate environment.”
Shatter cones at Crooked Creek are known to occur only in the central basin and are apparently restricted to Potosi Dolomite.
The Crooked Creek structure is a localized occurrence of intensely disturbed early Paleozoic strata situated on the western flank of the Ozark dome at a location about 80 km (50 mi) WNW of the St. Francois Mountains (Middendorf, 2003). The west-trending, down-to-the-north Palmer fault terminates on the east end of the structure. The south-southeast-trending, down-to-the-east Cuba fault may or may not extend to and terminate on the north end of the structure. Normal regional dip for strata in the area is about 2.8 m/km (15 ft/mi)(Hendrix, 1954).
The Crooked Creek structure is in line with seven other localized structural disturbances that occur from southern Illinois to eastern Kansas (Snyder and Gerdemann, 1965). From east to west the disturbances are Hicks dome, Avon, Furnace Creek, Crooked Creek, Hazelgreen, Decaturville, Weaubleau, and Rose dome. This line of structures defines what has been called the “38th parallel lineament” because it closely approximates the 38th parallel line of latitude (Heyl, 1972).
R. E. Beauford, FERROUS MINERALS AND IMPACTITE MINERALIZATION AT MISSOURI’S CROOKED CREEK AND DECATURVILLE IMPACT CRATERS. Arkansas Center for Space and Planetary Sciences, MUSE 202, University of Arkansas, Fayetteville, AR, 72701, USA.
Dietz, R. S. & Lambert, P. Shock Metamorphism at Crooked Creek Cryptoexplosion Structure, Mo Meteoritics, Vol. 15, p.281 1980
Miller, J.F., Evans, K.R., Ethington, R.L., Repetski, J.E., Sandberg, C.A., and Thompson, T.L., 2007, Critical stratigraphic data from reworked conodonts in impact breccias across Missouris Ozark dome: 2007 Geological Society of America South-Central and North-Central Joint Section Meeting, Abstracts with Programs, v. 39(3), p. 62.