HIGH-ORDER CYCLES PRESERVED IN THE QUEEN HILL SHALE MEMBER, LECOMPTON FORMATION (SHAWNEE GROUP, VIRGILIAN STAGE, UPPER PENNSYLVANIAN) OF NORTHWEST MISSOURI

Evidence of small-scale glacio-eustatic sea-level fluctuations (transgressive-regressive cycles) in the Queen Hill Shale are seen as interbedded gray and black shales. The Queen Hill Shale Member lies above the Big Springs Limestone Member (transgressive limestone) and below the Beil Limestone Member (regressive limestone), and normally displays a lower black fissile shale facies overlain by an upper light gray to medium gray shale facies. At a location in southeastern Holt County, Missouri, (two miles west of the town of Nodaway) the Queen Hill displays this “normal” facies, but 25 meters to the west it consists of four medium to dark gray shales (each approximately 2 cm thick) interbedded with six light gray shales (each approximately 4 cm thick), overlain by a light gray shale (about 60 cm thick), just below the Beil Limestone. These vertical facies changes seem to occur over a topographic high in the underlying Big Springs Limestone. I interpret these facies changes to represent meter scale fluctuation in sea level during the high-stand phase of the major Queen Hill cyclothem. The darker shales were probably deposited during higher sea level stands with more anoxic bottom conditions, with the lighter gray shales being deposited during lower sea level stands and more oxic bottom conditions. Overall, the Queen Hill was deposited during a major sea level high-stand, but in the relatively shallow northern shelf region of the Midcontinent Basin, it exhibits a complex architecture recording several probable minor sea level fluctuations.