Mississippian sediments

Kaufman J Cander H.S., Daniels L.D. and Meyers W.J. (1988) Calcite cement stratigraphy and cementation history of the Burlington-Keokuk Formation (Mississippian), Illinois and Missouri. J. Sediment. Petrol. 58, 312-326. 

Niemann J.C., and Read J.F. (1988) Regional cementation from unconformity-recharged aquifer and burial fluids, Mississippian Newman Limestone, Kentucky. J. Sediment. Petrol. 58, 688-705. 

Mineralised breccia pipes occur in Palaeozoic sedimentary rocks of the Colorado Plateau in northern Arizona (Weinrich, 1985). These pipes are usually circular or oval at suboutcrop, have horizontal dimensions that are typically a few tens of metres and vertical dimensions that may extend to 1000 m. They appear to have developed over solution-collapse structures resulting from karstic weathering of Lower Mississippian carbonate sediments between the Upper Mississippian and Triassic. The mineralisation, comprising pitchblende and sulphides of Fe, Cu, Mo, Pb and Zn, is found beneath a massive pyrite cap, several hundreds of metres below surface. Some of the ore bodies are, or have been, mined for uranium. Gangue minerals include calcite and dolomite. 

Frank, T.D. Lohmann, K.C. (1995) Early cementation during marine-meteoric fluid mixing Mississippian Lake Valley Formation, New Mexico. J. sediment. Petrol., A65, 263-273. 

At its simplest, an onlap trap may be a blanket sand that pinches out up-dip (Fig. 8D). It is sealed by impermeable rocks beneath and by an onlapping shale (generally the source rock, as well as the cap). Many unconformities are old land surfaces, however, and sands may be deposited in old topographic lows. Alternating hard and soft sediments may have been weathered and eroded to form scarps, dip slopes, and strike valleys. Fluvial or shallow marine sands may have been deposited along the old valleys and sealed by marine muds. Stratigraphic traps of this type are known as the Mississippian Pennsylvanian imconformity of Oklahoma. Alternatively, the unconformity may have been a planar land surface that was locally incised by alluvial valleys. These may have been sand filled and drowned by... 

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