CLEAVES, ARTHUR W., II, Oklahoma State University, Stillwater, OK

ABSTRACT: Depositional Systems, Provenance, and Sequence Stratigraphy, Carter and "Millerella" Sandstones of Northeast Mississippi

The subsurface "Millerella" and Carter sandstones (middle Chesterian) of the Black Warrior basin represent the highest units

of the thick Muldon clastics deltaic facies tract. Lowstand marine conditions during Carter deposition allowed for extensive southeastwardly progradation of five distinct deltaic lobe complexes onto the stable northern shelf of the basin. With each of these lobes, both an "A" (upper) and a "B" (lower) reservoir unit can be identified. The "B" sandstone produces from delta-front sheet sands, channel-mouth bars, and possible bar fingers of river-dominated deltas. The more prolific "A" subdivision contains reservoirs in upper delta-plain point bars, crevasse splays, and distributary channel fills. The most easterly of the lobes, preserved in the Bean's Ferry field of Itawamba County, comprises an amalgamated valley-fill facies that removed a maximum of 250 ft (76 m) of lower Bangor platf rm carbonates. In contrast, the "Millerella" sandstone is a series of unconnected pods that formed as marine-reworked sand bodies during a eustatic rise in sea level.

Petrographic evidence from the "Millerella-Carter" interval indicates that all three of these quartzarenite units had a cratonic source area. The average detrital sand grain composition for four cores taken in Monroe County is 94.7% monocrystalline quartz, 2.9% polycrystalline quartz, 1.6% albite feldspar, 0.1% low-rank metamorphic rock fragments, 0.5% chert, and 0.2% muscovite. These data indicate that neither the Ozark uplift with its potassium-feldspar-rich terrain nor the Ouachita orogen with its abundant supply of low-rank metamorphic rock fragments and muscovite could have acted as the principal source area for the Carter and "Millerella" sandstones. More likely, the sedimentary-igneous terrains along the northern margin of the Illinois basin served this function. A major eustat c lowstand brought this mineralogically mature sediment across the Illinois basin through incised valleys to the northern shelf of the Black Warrior basin.

AAPG Search and Discovery Article #90989©1993 GCAGS and Gulf Coast SEPM 43rd Annual Meeting, Shreveport, Louisiana, October 20-22, 1993.