Ash-fusion characteristics of the Lower Kittanning seam (western Pennsylvania) can be related to environment of deposition. Non-slagging coals (coals with ashes that have ash-fusion temperatures [AFTs] in excess of 2,600°F) are associated with freshwater environments that occur toward the margins of the basin. Slagging coals (coals with ashes that melt at temperatures less than 2,200°F) occur in the central part of the basin, in areas overlain by shales that have been interpreted to have formed in a brackish environment. Trend-surface analysis indicates that whereas strong basinal trends do exist, locally variability can modify regional trends. High ash-fusion coals are associated with high clay (primarily kaolinite) contents, whereas low-fusion coals are associated with high pyrite and marcasite (and to a lesser extent, siderite) contents. Bivariate analysis of these data shows highly significant negative correlations between AFT and Fe 2 O 3 , pyrite, and siderite. Positive correlations exist between AFT and SiO 2 , Al 2 O 3 , TiO 2 , MgO, and K 2 O. Illite and kaolinite also correlate positively with AFT. An understanding of the oxide and mineral composition of the ash and the depositional environment of the peat can therefore be useful in the prediction of ash-fusion characteristics.

Simulated weathering experiments on coals and shales demonstrate that the critical factors responsible for the generation of acid mine drainage (AMD) are the amounts of total sulfur, total carbonate, and the surface area of the pyrite. Total sulfur and carbonate carbon contents differ markedly among paleoenvironments whose distribution has been mapped for the Alleghenian strata of western Pennsylvania. Freshwater ( Estheria- bearing) shales have a mean total sulfur content of 0.15 percent and a mean carbonate carbon content of 0.54 percent. Brackish ( Lingula- bearing) shales have a mean total sulfur content of 2.40 percent and a mean carbonate carbon content of 0.14 percent. Marine ( Chonetes- bearing) shales have a mean total sulfur content of 0.95 percent and a mean carbonate carbon content of 0.63 percent In the simulated weathering experiments, the amount of acidity, sulfate, and total iron exhibit a well-defined positive linear relation with total sulfur in samples whose carbonate carbon content is ≦0.01 percent. Where carbonate carbon contents are >0.01 percent, the amount of acidity, sulfate, and total iron is considerably less, and the linear relation no longer exists. Anomalously high amounts of acidity, sulfate, and total iron were encountered in both samples devoid of and containing carbonate and were associated with samples containing a high relative percentage of framboidal pyrite and/or pyrite having a high specific surface area. Because determination of the percentage of framboidal pyrite is subjective, direct measurement of pyrite surface area is preferred.

Clay mineral analyses of underclays directly below the Upper Elkhorn Coals (eastern Kentucky) and the Lower Kittanning Coal (western Pennsylvania) demonstrate systematic lateral and vertical variations that include changes in the kaolinite-illite ratio, mica loss ratio, weathering ratio, apparent thickness of mica, and distribution of chlorite. Clay mineral analyses of associated, unweathered shales indicate that approximately 30 percent of the regional variation in Lower Kittanning underclay mineralogy is inherited from the parent material. The remaining variation is attributed to in situ pedogenesis. Petrographic analysis of thin sections from a fluvial sandstone subjacent to the Upper Elkhorn underclay suggests that position of the ground-water table controlled pedogenesis. Two distinct alteration zones separated by a diffuse, subhorizontal boundary are present in the sandstone: an upper zone characterized by kaolinization of feldspars, dissolution of chlorite and detrital dolomite, and absence of siderite; and a lower zone characterized by ferron dolomite replacement of both detrital feldspar and detrital dolomite, and authigenic pore fillings of chlorite and siderite. These systematic changes in sandstone and underclay mineralogy are consistent with a pedogenic model in which the process of podzolization was controlled by position of the ground-water table and topography. In this model, the main phase of organic material accumulation occurred above the underclay after water-table levels intersected the land surface as a result of compaction, subsidence, or marine transgression. Regional gravity and structure data in western Pennsylvania further suggest that syntectonic movements were the fundamental controls on regional topography and ground-water levels, and thus, pedogenesis.