Palaeoclimatic constraints for palaeozoic Palaeolatitudes of Laurentia and Euramerica

Abstract

Palaeozoic lithic palaeoclimatic data were plotted at the series or stage level for Laurentia (North America) andEuramerica. Their distribution was used to infer the extent of humid and arid climatic belts across the continent for specified time intervals. Climatic data are potentially useful for constraining palaeolatitudes for times when zonal atmospheric circulation remains the dominant pattern. Arid lithic indicators (evaporites, carbonate oolite) and humid indicators (coal, bauxite) were constrained to provide the best fit of these data into a simple zonal climatic pattern delineating subtropical arid belts and equatorial and/or temperate humid belts, respectively. An attempt was made to minimize occurrences of arid indicators in interpreted equatorial regions to maximize a zonal fit. Climatic belts can be arranged in a temporally consistent zonal climatic scheme for much of the Palaeozoic, but monsoonal and orographic effects apparently disrupted the general zonal pattern during portions of the Late Palaeozoic. The interpreted climatic patterns suggest progressive southward movement of Laurentia during the Cambrian through Early Devonian followed by general northward drift of Euramerica during the Middle Devonian through Permian. Lithic palaeoclimatic data provide an independent means to test palaeolatitudes interpreted from palaeomagnetic data. There is general agreement between palaeoclimatic and palaeomagnetic interpretations, but some discrepancies, particularly for the Devonian and Early Carboniferous, warrant further attention.

Precessional and half-precessional climate forcing of Mid-Devonian monsoon-like dynamics

“…Ever since Barrell's interpretation (1916), paleoclimatic indicators confirmed this view (e.g., Woodrow et al, 1973;Heckel and Witzke, 1979;Woodrow, 1985;Witzke and Heckel, 1988;Sageman et al, 2003;Cressler, 2006;Cressler et al, 2010), and a consensus on the seasonal wet-and-dry climate model for the Devonian of the Euramerican coastal plains exists. The paleolatitude combined with the proximity of large continental areas (as well Euramerica as Gondwana) play an important role in determining the potential for an intense monsoonal circulation over Euramerica (Witzke, 1990). Given the significant influence of astronomical forcing on modern monsoonal systems, it is highly probable that also during the Devonian period, Milanković cycles influenced the climatic factors controlling the detrital inputs to the Rhenohercynian basin (i.e., wind and precipitation) and/or of carbonate productivity, both affecting the MS signal (Riquier et al, 2010).…”

Desmoinesian coal beds of the Eastern Interior and surrounding basins: The largest tropical peat mires in Earth history

“…The Desmoinesian coals of the Eastem Interior Basin accumulated at tropical latitudes (Witzke, 1990;Heckel, 1994Heckel, , 1995 and appear to have consisted of widespread topogenous to soligenous mires or mii-e complexes, relatively undivided by extrabasinal secondary and tertiary drainages. If a 10:1 peat-to-coal compaction ratio is assumed, the only modem peats with comparable thicknesses to these Desmoinesian paleomires are the ombrogenous mires of Indonesia.…”

“…0° (Witzke, 1990) Marathon Ouachita Figure 18. Paleogeography of Desmoinesian peatlands in eastern and middle United States (modified from information in Heckel, 1980;Thomas, 1989;Johnson et al, 1988;Donaldson and Eble, 1991).…”

“…Peats may not have been completely coeval. Westphalian (MorrowanEarly Desmoinesian) paleoequator from Witzke (1990). Desmoinesian-Virgilian paleoequator from Heckel (1995).…”

The Machaeridian Lepidocoleus Sarlei Clarke, 1896, from the Rochester Shale (Silurian) of New York State

“…The siliciclastic muds derived from the erosion of tectonic highlands to the south-east in New York State were deposited in the northern, apparently blind, end of the Appalachian Foreland Basin whose axis trended approximately north-east±south-west. These sediments accumulated in a shallow subtropical muddy sea approximately 15±20 degrees south of the palaeoequator (Ziegler et al 1977;Witzke 1990). Brett (1983a, b) concluded that the local facies strike in western New York and Ontario was approximately east±west, paralleling the modern Niagara escarpment outcrop belt.…”