Dolomite Cement Stratigraphy of the Reelfoot Rift and the Relationship of These Cements to Dolomite Cements Found in Southeast Missouri

The formation of the southeast Missouri Mississippi Valley-type Pb, Zn, Cu ore districts have been a subject of controversy. Using petrology and geochemistry, earlier studies have attempted to reveal fluid flow, composition, and origin of the ore forming fluids. In this study, the potential role of the Reelfoot rift (New Madrid seismic zone) as a source and/or conduit for ore forming fluids is addressed. By observing cuttings and cores from four oil test wells within the Reelfoot rift using cathodluminescence, four cement types were described: 1) A multiple generation cement type similar to that observed associated with mineralization in southeastern Missouri (type I). 2) A simple two generation cement type (type II). 3) A layered non-luminescent to dully luminescent cement type (type III). 4) A brightly luminescent cement type (type IV). Each cement type was observed at different stratigraphic horizons within the study area. The paragenetic sequence of the observed cements indicates that type III was deposited first followed by type IV and finally type II. Since type I cement was not observed in the same samples as the other cements, its paragenetic relationship to the other cements cannot be determined. The undiscernible paragenetic sequence coupled with the variable stratigraphic occurrence of the cement types makes it difficult to determine the role of the Reelfoot rift as an absolute source and /or conduit for mineralizing fluids without further geochemical investigations