HIGH-RESOLUTION SEQUENCE STRATIGRAPHIC ARCHITECTURE OF A MID-CONTINENT MISSISSIPPIAN OUTCROP IN JANE, MISSOURI

The Mid-continent Mississippian Limestone represents a geologically complex system of depositional environments, diagenetic history, and tectonic history that consists of a thick (up to 500 ft) section of carbonates deposited in a shallow, tropical, epeiric seaway 5-30° north and south of the equator. The Jane, Missouri outcrop was deposited on the southern margin of a broad, shallow carbonate platform known as the Burlington Shelf.

Understanding how primary depositional facies fit into a sequence stratigraphic framework will increase predictability of facies trends. The high-resolution sequence stratigraphic architecture study at the Jane outcrop provides a basin specific analog for identification of facies in the subsurface. The study includes analyses of facies vertically and horizontally to identify depositional environments, geometry of the depositional environments, and the vertical facies stacking pattern set within a sequence stratigraphic framework on the third, fourth and fifth order scale.

Along with detailed descriptions at the outcrop, samples were collected for thin section analysis. Thin section analysis aids in the differentiation of facies, a crucial step for determining vertical stacking packages within the sequence stratigraphic framework. Gigapan EPIC Pro software was used to generate a high-resolution photograph of the outcrop, which, when coupled with detailed facies analysis, allows for the determination of 2-D facies geometry and continuity. A field scintillometer was then used to measure spectral gamma ray response for two vertical sections of the outcrop to correlate to subsurface log signatures. Variations in the intensity of gamma ray response can distinguish the six depositional facies defined in outcrop and thin section, as well as a hierarchy of shoaling-upward packages that range from a few meters thick to tens of meters thick. Detailed analysis of the sedimentary architecture should allow for better understanding of equivalent units in the subsurface.

A high-resolution sequence stratigraphic architecture study that incorporates primary facies, depositional environments, and gamma ray response within a larger scale 2-D geometry for an outcrop can be used as a basin specific analog to identify facies trends in the subsurface.