Origin of Pennsylvanian Underclay and Related Seat Rocks

Huddle, John Warfield; Patterson, Sam H.

doi:10.1130/0016-7606(1961)72[1643:oopuar]2.0.co;2

Cited by 64 publications

(26 citation statements)

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“…Thus, he concluded that the two are unrelated, and that underclay is a fossil soil that formed prior to peat accumulation. In support of this idea, Wanless (1931) found that underclay has the characteristics of a poorly drained soil, and Huddle and Patterson (1961) suggested that in situ leaching of substratum may have occurred at any time before peat accumulation, during peat accumulation, or during coalification.…”

Section: Introductionmentioning

confidence: 66%

“…The small reversal in the mixed-layering trend adjacent to the coal (samples 1-3, 3-1,4-1, and 5-1, Table 1), if it is not simply experimental error, may represent a local increase in K § derived from vegetal matter in the adjacent coal. Such a K + increase also was suggested by Huddle and Patterson (1961) based on the refractory properties of underclay, and by McMillan (1956) based on underclay chemistry.…”

Section: Discussionmentioning

confidence: 85%

“…Such a gradient is shown in Figure 8 Relationship between the percentage of CaO and oxidation of pyrite in the core during storage. Huddle and Patterson (1961), however, reported underclay pHs as low as 3.9. Indeed, all the mineralogical trends observed in the underclay are consistent with an origin by acid leaching of sediment that initially contained illite, (or I/S of low expandability), chlorite, and calcite.…”

Section: Discussionmentioning

confidence: 99%

“…Like other seat rocks, it is generally non-bedded, light colored, contains plant roots (Stigmaria) and randomly oriented slickensides, and may be calcitic near its base (Huddle and Patterson, 1961). A sharp contact exists between underclay and the overlying coal, but the lower contact commonly is gradational (Gresley, 1887).…”

Section: Introductionmentioning

confidence: 99%

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Origin of an Underclay as Revealed by Vertical Variations in Mineralogy and Chemistry

Rimmer

Eberl²

1982

Clays and clay miner.

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Abstract--Regular vertical variations in mineralogy and chemistry indicate that underclay beneath the Herrin (No. 6) coal in southwestern Illinois has undergone in situ alteration. Alteration resulted from the downward movement of hydrogen ions, as indicated by the progressive leaching of acid-sensitive minerals adjacent to the coal. Mineralogical trends observed in the underclay with increasing depth below the coal include: (1) a decrease in the expandability of mixed-layer illite/smectite (I/S); (2) an increase in the amount of ordered US with respect to randomly interstratified US; (3) an increase in the amount of discrete illite with respect to expandable clays; and (4) an increase in chlorite and calcite. Ordered I/S is the dominant mixed-layer clay where calcite is present, but randomly interstratified US dominates where calcite is absent. The pH of the underclay also increases with depth. These trends are consistent with an origin by acid leaching of a preexisting mineral assemblage that included illite, chlorite, and calcite. Other acid-alteration trends may be expected for different precursor minerals and for different leaching intensities and durations.

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Section: Introductionmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Origin of an Underclay as Revealed by Vertical Variations in Mineralogy and Chemistry

Rimmer

Eberl²

1982

Clays and clay miner.

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show abstract

“…Strahan (1920), having defined the term, did not include all rocks with the necessary characteristics *• as ganisters, but implied that only those siliceous sandstones formed as palaeosols are true ganisters. Subsequently several workers (Searle, 1940;Huddle & Patterson, 1961;Hemingway, 1968;Retallack, T ' 1976Retallack, T ' , 1977 concluded that ganisters form by silica enrichment during pedogenesis, and the term has _j attained genetic significance. Recent studies of the Sheffield Blue Ganister have shown this horizon also has a pedogenic origin • (e.g.…”

Section: (Plate 1)mentioning

confidence: 99%