Cretaceous (Albian–Aptian) conifer wood from Northern Hemisphere high latitudes: Forest composition and palaeoclimate

Early Cretaceous vegetation and climate change at high latitude: Palynological evidence from Isachsen Formation, Arctic Canada

“…The age of Mesozoic strata in Sverdrup Basin are based primarily on ammonites, bivalves, dinoflagellate cysts and foraminifera (Table 1) but paleoclimate studies using pollen and other climate indicators in the Early Cretaceous of the Canadian Arctic are limited (Table 1; Hopkins, 1971Hopkins, , 1974Wall, 1983;Embry, 1985a;Harland et al, 2007;Selmeier and Grosser, 2011;Galloway et al, 2012Galloway et al, , 2013Schröder-Adams et al, 2014).…”

“…Taxodiacean conifers are interpreted to have been hygrophilous plants that thrived in warm to temperate wet lowland environments (Vakhrameev, 1991;Pelzer et al, 1992;Dejax et al, 2007). Plant macrofossils with affinities to Cupressaceae (Cupressinoxylon) are reported from Aptian-Albian strata of Axel Heiberg and Ellesmere islands in the Sverdrup Basin where mean annual temperature is inferred to have been between 3 and 10 °C (Harland et al, 2007). In modern environments Cupressaceae pollen is generally well dispersed and occurs with frequencies of 10-40% in late Holocene lacustrine and marine sediments where parent plants are dominant vegetation components (Gavin et al, 2005;Galloway et al, 2007Galloway et al, , 2009Galloway et al, , 2010.…”

“…Bisaccate pollen is commonly inferred to have originated from Pinaceae parent plants with a mesoxerophilous ecology growing in upland and relatively arid or well-drained environments (Barr n et al, 2006;Dejax et al, 2007). Macrofossil evidence from the Early Cretaceous of the Canadian Arctic suggests that Pinaceae were common in high latitude forests, with constituents that may have 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 been similar to modern Pinus, Picea, Larix, and Pseudotsuga (Harland et al, 2007). A component of the bisaccate pollen may therefore have been produced by parent plants with broad ecologies similar to extant Pinus and Picea.…”

“…Nearest living relative analysis of coniferous wood from the Canadian Arctic suggests that by the Aptian to Albian, climate was cooltemperate (between 3 and 10 °C mean annual temperature; Harland et al, 2007) Figure 10). We interpret the age of these rocks to be Hauterivian based on ages of bounding strata.…”

“…Price and Mutterlose (2004), Price and Nunn (2010), and Price and Bassey (2013) use oxygen and carbon isotope data from Valanginian 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 few studies suggest that a diversity of coniferous trees occurred in Early Cretaceous high northern latitude forest communities despite long dark winters and summers with continuous sunlight. Polar forests potentially promoted climate feedback effects at regional to global scales through albedo, land surface heat budget, hydrological and carbon cycles (Foley et al, 1994;DeConto et al, 2000;Beringer et al, 2005) and are therefore important to include in global climate modelling (Harland et al, 2007). Constraining the long-term vegetation and climate history of polar regions, especially during extreme warm but variable periods such as the Early Cretaceous, offers a possible analogue for a much warmer future Earth.…”