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Stratigraphic and geographic controls on the distribution of major elements, minor elements, and minerals define depositional environments and provide a base line with which to compare local geochemical distributions in the detection of anomalies or trends related to gas production. Data consist of (1) cuttings from more than 30 wells in western and southern West Virginia, (2) similar analyses on samples collected from outcropping rocks of the Greenland Gap Group and Hampshire Formation in eastern West Virginia, and (3) outcropping black shales in eastern Kentucky.
Factor analyses revealed several groups of elements: a detrital association of aluminum, potassium, titanium, iron, and sodium; a carbonate association of magnesium and calcium; an association of sulfur, iron, and zinc; and an association of phosphorus and calcium. The carbonate association is observed in black shales of Kentucky; the association of calcium with phosphorus is observed in carbonate-poor clastics of West Virginia.
Within most West Virginia wells, such elements as potassium, silicon, and aluminum show gradual trends through the section, contrasting with abrupt changes in abundance exhibited by sulfur and titanium. Sulfur occurs in high percentages with black shales. In some wells, silicon has a higher abundance in black shales than in gray shales.
Trend surface analyses of data from western and southern West Virginia show that titanium peaks in easternmost wells, sulfur peaks in westernmost wells, and silicon peaks in easternmost and some westernmost wells. Observed trends agree with the accepted view of a prograding delta complex in Late Devonian time, but geographically local, time-restricted depositional processes influenced elemental percentages in subsets of wells and stratigraphic intervals. One example of such a process is possible deposition of clastics from a source west of the study area in West Virginia.
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