Shale Mississippi River

The black shales were deposited during Late Devonian and Early Mississippian time in a large epeiric (inland) sea that covered much of middle and eastern United States east of the Mississippi River. The area includes the broad, shallow Interior Platform on the west that grades eastward into the Appalachian Basin. The depth to the base of the Devonian-Mississippian black shales ranges from surface exposures on the Interior Platform to more than 2700 m along the depositional axis of the Appalachian Basin (De Witt et al., 1993). The Late Devonian sea was relatively shallow with minimal current and wave action, much like the environment in which the Alum Shale... 

Fig. 8. Shale-normalized lanthanide compositions of 0.22 (tm filtrates of the Amazon, Fly (Papua New Guinea) and Mississippi River waters. Amazon and Mississippi data from Sholkovitz (1993, 1995) Fly River data from unpublished work of Sholkovitz. G/J Avg. refers to the averaged river water composition of Goldstein and Jacobsen (1988a).

The mineralogy of the suspended matter carried by rivers is not well documented. There are numerous analyses either of the clay fraction or of sands carried by rivers, but only a few total quantitative analyses are reported in the literature. As examples, the average mineralogical composition of two large river systems, the Amazon and the Mississippi, are presented in Table 9.9. This table also includes the mean mineralogical composition of shales for comparison with river suspended sediments. The overall average of 300 samples of shales analyzed by Shaw and Weaver (1965) is 30.8% quartz, 4.5% feldspar, 60.9% clay minerals, and... 

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