Paleoclimate controls on stratigraphic repetition of chemical and siliciclastic rocks

Palaeoenvironmental significance of palustrine carbonates and calcretes in the geological record

“…There must be suffi cient rainfall to carr y the carbo nate-rich solutions either in the surface or in groWl d waters (De Wet et aI., 1998). Very arid or very humid climates do not favour carbonate deposition in lakes (Cecil, 1990), whereas semi-arid to sub-humid cli mates with marked seasonality are more appropriate (platt and Wright, 1991;Sanz et aI., 1995;Gierlowski Kordesch, 1998). Palustrine carbonates are sensitive to variations in humidity.…”

Palaeoecology of Macroneuropteris scheuchzeri, and its implications for resolving the paradox of ‘xeromorphic’ plants in Pennsylvanian wetlands

“…Prior to, and during the early phases, of its range (beginning in the Atokan; early to mid-Moscovian), the tropics were dominantly subjected to humid-to-perhumid climates, meaning that they were relatively wet year-round, even during the more seasonal portions of glacial-interglacial cycles, when peat was not forming (Cecil et al, 2003;Cleal and Thomas, 2005;Cleal et al, 2009). These conditions often led to the development of oligotrophic, domed phases during accumulation of some peat deposits and intense leaching of sulfate, iron, and carbonate from the terrestrial landscape (Cecil et al, 1985;Cecil, 1990;Eble et al, 2001;Greb et al, 2002). M. scheuchzeri was rare at this time.…”

“…Major compositional and structural changes took place in wetland tropical landscapes across the Desmoinesian-Missourian boundary (Middleto-Late Pennsylvanian: Falcon-Lang et al, 2011a). Considerable evidence (e.g., Phillips and Peppers, 1984;Schutter and Heckel, 1985;Cecil, 1990;Winston, 1990;DiMichele et al, 2001;Fielding et al, 2008aFielding et al, , 2008bHeckel, 2008;Rygel et al, 2009;Bishop et al, 2010) suggests a shift in the climate cycle to increased overall dryness (greater seasonal dryness during both the drier intervals and wetter intervals of glaciogenic cycles) at this time, a change reflecting a period of intensified global warming and ice melting in the south polar regions. Beginning at the time of this major climatic shift, the distributional pattern of this species documents continued ecological confinement to the wettest, swampy environments of the Late Pennsylvanian, particularly those associated with some clastic influx.…”

“…These collections occur either directly above or below coal beds, generally in gradational contact with them. As coals are interpreted as having formed under humid climates, or in the case of some of the older (Atokan) coals, under perhumid conditions (Cecil et al, 1985(Cecil et al, , 2003Cecil, 1990), clastic beds in direct gradational contact are interpreted to have formed in widespread wetlands transitional to, or from, those in which peat formed. (2) The remainder of the collections represents a diversity of deposits formed under more strongly seasonal climatic regimes in which peat did not form, and where better-drained landscapes were widespread within basinal lowlands.…”

On the fundamental difference between coal rank and coal type

“…However, in representing a much longer time interval of nearly 20 million years, the Pennsylvanian "coal age" encompassed far greater ranges of variability in climate state and environmental fluctuation than has the Quaternary age (Bishop et al, 2010;Cecil, 1990;Eros et al, 2012;Fielding et al, 2008a,b;Montañez and Poulsen, 2013), including periods of nearly ice-free poles as well as intervals of intense glaciation. The physical and biological dynamics of this time were superimposed on the complex low-latitude landscape where a vast amount of Pennsylvanian peat formed (e.g., Cecil et al, 2003a;Cleal et al, 2009;Gastaldo et al, 1993;Greb et al, 1999Greb et al, , 2003Greb et al, , 2008Staub, 2002).…”