Salem Anticline
Location
From T1S, R2E, Jefferson County, to T3N, R2E, Marion County (H-5, 6; 1-6)
References
Arnold 1939, Cohee and Carter 1939, Siever 1950, Brownfield 1954, Bristol and Buschbach 1973, Whitaker and Treworgy 1990
Description
The Salem Anticline is most noteworthy for providing the structural trap for the Salem Oil Field. This giant field with multiple pay horizons has a cumulative production of about 389.5 million barrels and is the largest in the Illinois Basin.
The Salem Anticline lies east of the main branch of the Du Quoin Monocline and more or less in line with the northeast branch of the monocline (fig. 31). Projected northward, the axis of the Salem Anticline aligns with that of the Louden Anticline, which holds the second largest oil field, in terms of cumulative production, in the Illinois Basin.
The area of closure on the Salem Anticline is approximately 7 miles (11 km) north to south and 3.5 miles (5.6 km) maximum east to west. Closure on the top of the lower Chesterian Yankeetown ("Benoist") Sandstone is more than 220 feet (67 m). The east limb has an average dip of 80 to 90 feet per mile (approximately 1°), whereas the west limb dips about 220 feet per mile (approximately 2°) (Arnold 1939). Gradual elongate nosing occurs at the north and south ends of the structure.
A series of isopach maps showed that the Salem Anticline began to develop in the Chesterian Epoch but the major folding took place early in the Pennsylvanian Period (Brownfield 1954). Additional deformation occurred during and after middle Pennsylvanian sedimentation. The history of the Salem Anticline is thus similar to that of the Du Quoin Monocline and other adjacent folds.
The steep west limb of the Salem Anticline suggests that the anticline was controlled by faulting in the basement (Arnold 1939). Although the seismic profile as illustrated (fig. 32) does not reveal faulting, other proprietary seismic lines reveal faulting on the west flank of the anticline at depth. Thus, the anticline probably overlies a basement fault block that was raised and tilted eastward.
Figure(s)
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