Geology and coal reserves of the Kermit and Varney area, Kentucky

Geochronological data from the Faxinal coal succession, southern Paraná Basin, Brazil: A preliminary approach combining radiometric U-Pb dating and palynostratigraphy

“…Monosaccate pollen grains, produced by gymnosperm vegetation (including Cordaitophyta), comprise Cannanoropollis diffusus (Tiwari) Dias-Fabrício 1981 The composition similarity between palynofloras in the basal portion of the upper coal seam and those in the tonstein indicates that the paleoecological conditions in which coal formed persisted during tonstein accumulation. These data support the hypothesis of rapid deposition, probably spanning days or weeks, as in recent ash falls (Huddle and Englund, 1996). Accordingly, the change in palynofloras of the coal beds that overlie the tonstein horizon in Faxinal's upper coal seam may be attributed to the chemical effects of ash-fall deposition.…”

“…Tonsteins are excellent time markers for stratigraphic and basin analysis, because they were evidently deposited during a limited time interval (Huddle and Englund, 1996). Combining biostratigraphic data from the coal seams with biostratigraphic and radiometric data from the tonsteins provides a useful tool for stratigraphic correlation and dating.…”

Effect of volcanic ash-fall on a Permian peat-forming environment, on the basis of palynology, palynofacies and paleobotany (Faxinal Coalfield, Brazil)

“…According to most literature sources, under conditions favorable to coal formation, tuffs are converted into tonsteins. Hudle & Englund (1966) reported that tonsteins are excellent time markers for stratigraphic and basin analyses, corresponding to units deposited during a limited period of time. Creech (2002) pointed out the importance of tonsteins in correlating different coal seams with those stratigraphically equivalent in adjacent coalfields, so that radiometric data supplied by tonstein layers facilitate their application as isochronous markers in coal bearing-strata.…”

Radiometric age determination of tonsteins and stratigraphic constraints for the Lower Permian coal succession in southern Paraná Basin, Brazil

“…The volcanic rocks are recorded by discrete and continuous horizons of clay beds identified as tonsteins interbedded within coal seams in Candiota and Faxinal coalfields (Formoso et al, 1999, Guerra-Sommer et al, 2006.They are excellent time markers for stratigraphic and basinal analyses, corresponding to units deposited during a limited period of time (Hudle and Englund, 1966). Consequently, radiometric data supplied by tonstein layers facilitate their application as isochronous markers.…”