STRATIGRAPHY OF THE
MIDCONTINENT RIFT SYSTEM IN IOWA
 |
UNIT E |
The basal unit of the Upper Red Clastic Group, Unit E (depth 2106 to 3153 m; 7020 to 10,510 ft), is a thick, sandstone-dominated unit that is characterized by the highest percentage of lithic fragments (click here for QFL information), with a mean of Q=67 F=20 L=13, in the Eischeid well (Ludvigson and others, 1990). The unit was subdivided into two descriptive intervals, E 2 (upper) and E 1. Interval E 2 is dominated by red to brown, generally very fine- to fine-grained sandstones with red to brown (some mottled grayish green) interbedded siltstones and shales (Witzke, 1990). Core 1 sampled 10 feet of this interval and displayed horizontal bedding and two facies, one well stratified with low angle cross stratification and red mudstone intraclasts, the second a massive, nonstratified sequence with smaller mud clasts (Ludvigson and others, 1990). Interval E 1 contains more shale than E 2 and is composed of four relatively thin, fining-upward sequences, each grading from a basal very fine to fine grained sandstone, upward to a red to dark brown shale and siltstone (Witzke, 1990).
click for depositional model for Unit E
return to Midcontinent Rift System Stratigraphy
