Polygenetic History of Paleosols In Middle-Upper Pennsylvanian Cyclothems of the Illinois Basin, U.S.A.: Part II. Integrating Geomorphology, Climate, and Glacioeustasy

Abstract

Distinct lateral and stratigraphic trends in paleosol morphology and clay mineralogy, in conjunction with the stable-isotope composition of sub-millimeter-scale spherulitic siderite (sphaerosiderite) and flint-clay kaolinite in middle-upper Pennsylvanian cyclic coal-bearing strata of the Illinois basin (IB) presented herein provide proxy records of middle-late Pennsylvanian equatorial terrestrial environments. Collectively, these data provide a better understanding of the polygenetic history of ancient soils preserved in cyclic strata and indicate that low-latitude Pennsylvanian IB soil profiles were influenced by a combination of autogenic and allogenic controls.Lateral variations in paleosol morphology from the interior of the basin to the northern margin indicate that soil development was dominantly influenced by autogenic controls, such as differences in local paleohydrology (i.e., groundwater fluctuations) and subsidence rates across the basin. Conversely, allogenic controls (i.e., glacioeustasy and climate) are interpreted to be principally responsible for the preservation of features in gleyed Protosols, gleyed Vertisols, and gleyed calcic Vertisols that occur in the interior of the IB. These paleosols are characterized by a polygenetic development history that includes (1) an initial period of soil formation in well-drained environments with seasonal wetting and drying of the profile, followed by (2) a subsequent period of waterlogging and development of reducing conditions. Paleosols that lack evidence for extensive periods of waterlogging are restricted, with the exception of two examples, to the northern margin of the basin, and they become abundant in the stratigraphic record near the middle-upper Pennsylvanian boundary (uppermost Desmoinesian). The stratigraphic distribution of these paleosols, in conjunction with a decrease in the relative abundance of kaolinite in the , 2 mm size fraction of IB paleosols near the Desmoinesian-Missourian (D-M) boundary, is interpreted to reflect a shift in the overall low-latitude regional climate to drier conditions. The stable-isotope compositions of sphaerosiderite and flint-clay kaolinite in middle-upper Pennsylvanian strata of the IB provide an additional proxy record of past equatorial terrestrial environments and are used to constrain the magnitude of paleoclimate change across the D-M (, Moscovian-Kasimovian) boundary. Sphaerosiderite d 18 O V-PDB and d 13 C V-PDB values range from 23.6% to 20.5% and 212.8% to 23.2%, respectively. In particular, sphaerosiderite d 18 O values from the B horizons of paleosols display an approximate 21.5% shift across the D-M boundary. This stratigraphically short isotopic shift occurs across the D-M boundary, on the order of one cyclothem (, 400 kyr), and is followed by a subsequent shift on the order of one cyclothem, back to more positive siderite d 18 O values. The average d 18 O V-SMOW and dD V-SMOW values of kaolinite isolated from the , 0.2 mm size fraction of a latest Desmoinesian flint-clay breccia are +21.0% and 246.5...

Architecture, paleosols and cyclicity of the Middle- Late Pennsylvanian proximal fluvial system (Nyřany Member, Pilsen Basin, Czech Republic)

“…Akin to the Pennsylvanian record in the Illinois Basin (Rosenau et al 2013), paleosols documented herein differ from modern Vertisols in their lack of smectite and subordinate presence of interstratified illite-rich illite/smectite in < 2 μm fraction. This could be the result of low-temperature illitization of smectite to I/S in the pedogenic environment during fluctuating redox conditions as a result of seasonal wetting and drying cycles (e.g., Watts 1980, Robinson & Wright 1987, Deconinck et al 1988, Huggett & Cuadros 2003, Rosenau et al 2013.…”

“…In modern Vertisols, the development of wedge-shaped aggregate structure and slickensides typically results from shrink-swell processes associated with expandable 2:1 phyllosilicates (e.g., smectite) in climates that experience seasonal precipitation and/or episodic changes in water-table position (Yaalon & Kalmar 1978, Driese et al 2005. Akin to the Pennsylvanian record in the Illinois Basin (Rosenau et al 2013), paleosols documented herein differ from modern Vertisols in their lack of smectite and subordinate presence of interstratified illite-rich illite/smectite in < 2 μm fraction. This could be the result of low-temperature illitization of smectite to I/S in the pedogenic environment during fluctuating redox conditions as a result of seasonal wetting and drying cycles (e.g., Watts 1980, Robinson & Wright 1987, Deconinck et al 1988, Huggett & Cuadros 2003, Rosenau et al 2013.…”

Plant Fossils from the Pennsylvanian–Permian Transition in Western Pangea, Abo Pass, New Mexico

“…Such seasonally dry environmental conditions also are reflected in the generally common occurrence of floral elements such as conifers, callipterids, and exotic elements, such as Charliea, Plagiozamites, or even Podozamites, in western Pangean floras earlier than their common occurrence in floras of coal basins in central Pangea (the U.S. Midcontinent through Europe). For example, compare the stratigraphic ranges of many of these plants as reported in Kerp and Fichter (1985), Blake et al (2002), Barthel (2009) (Rosenau et al, 2013), which were closely synchronized with changes in both sea level and tropical climate (Cecil et al, , 2014.…”

On the fundamental difference between coal rank and coal type

“…Climatic fluctuations, sea-level fluctuations, changes in siliciclastic sediment flux, and the formation of peat and limestone, were not independent variables (Cecil and Dulong, 2003). Rather, they all reflect ties to one another and to high-latitude ice dynamics, which itself may have been dependent on orbital forcing factors and atmospheric CO 2 levels (e.g., Birgenheier et al, 2010;Cecil and Dulong, 2003;Heckel, 2008;Horton and Poulsen, 2009;Montañez and Poulsen, 2013;Peyser and Poulsen, 2008;Poulsen et al, 2007;Rosenau et al, 2013;Royer et al, 2004;Rygel et al, 2008;Wanless and Shepard, 1936), or even unknown astronomic factors. 3 Certain aspects of tectonics also may have strong linkages to prevailing climate, which has been shown to play an important role in erosion rates, rates of uplift, and rates of basinal subsidence (e.g., Harris and Mix, 2002;Hay, 1996;Montgomery et al, 2001;Whipple, 2009).…”

“…The coals themselves contain evidence of variations in level of decay, water table, etc. throughout the seam, indicating that peat accumulation was not simply driven by transgression and progressive inland paludification (DeMaris, 2000;Gastaldo et al, 1993;Rosenau et al, 2013). Much remains to be learned concerning the effect of orbital cycles on tropical paleoclimate and peat accumulation and the role of Milankovitch orbital cycles in controlling sea level and paleoclimate.…”