Synchronous Palynological Changes in Early Pleistocene Sediments Off New Jersey and Iberia, and a Possible Paleoceanographic Explanation

Abstract

Palynomorphs record the establishment of modern conditions in the subtropical North Atlantic during the early Pleistocene. Prior to ~1.4 Ma, muds on both the New Jersey shelf and the Iberia Abyssal Plain contained relatively few terrestrial palynomorphs, and had a dinocyst flora rich in Operculodinium israelianum and other dinocyst taxa recording warmer surface waters than at present (e.g., Tectatodinium pellitum, Lingulodinium machaerophorum, and Polysphaeridium zoharyi). Over a span of 250 ka, this palynological assemblage was succeeded by one rich in pollen and with a dinocyst flora similar to the "modern" flora, i.e. rich in Operculodinium centrocarpum, Bitectatodinium tepikiense, Spiniferites spp. (predominantly S. ramosus), and Brigantedinium spp. (predominantly B. simplex).

Late Eocene to middle Miocene (33 to 13 million years ago) vegetation and climate development on the North American Atlantic Coastal Plain (IODP Expedition 313, Site M0027)

“…These winds also currently push the Gulf Stream offshore, allowing polar surface currents to penetrate between the Gulf Stream and northeastern North America as far south as Cape Hatteras (Csanady and Hamilton, 1988). Although the modern North Atlantic Slope Water mass appears to have originated only ∼ 1.4 Ma (McCarthy et al, 2000), a low salinity (but warmer) precursor to this water mass appears to have been created by abundant fluvial runoff since the Gulf Stream originated, separating northeastern North America from the warm, saline subtropical gyre, and thus resulting in greater seasonality than in the oceanic realm. The time of the origin of the Gulf Stream remains hotly debated, but there is evidence of strong current activity on the Blake Plateau as early as the late Paleocene-early Eocene (Pinet et al, 1981) and it was an intense western boundary current by the latest Miocene, when it experienced its greatest intensification based on deep erosion of the Blake Plateau (Kaneps, 1979).…”

The effect of meter-scale lateral oxygen gradients at the sediment-water interface on selected organic matter based alteration, productivity and temperature proxies

“…In order to determine whether this degradation is selective, we incorporate them into indices with related refractory compounds, such as pristane and phytane, cholestanol, and dinostanone and dinosterone, respectively (after Nishimura and Koyama, 1977;McCaffrey et al, 1991;Mouradian et al, 2007). Another proxy for illustrating changes in export production is the ratio between gonyaulacoid and peridinioid organic-walled dinoflagellate resting cysts (e.g., Harland, 1973;McCarthy et al, 2000). However, the gonyaulacoid species are more resistant to aerobic degradation than the peridinioid species, which are sensitive to oxygen exposure (e.g., Zonneveld et al, 1997Zonneveld et al, , 2001Combourieu-Nebout et al, 1998;Versteegh and Zonneveld, 2002).…”

“…However, it is known from laboratory (e.g., Dale, 1976;Hopkins and McCarthy, 2002) and field experiments (e.g., as well as sediments (e.g., Zonneveld et al, 1997;McCarthy et al, 2000) that P-cysts are more quickly oxidized relative to the G-cysts. In both the OMZ transect and the below-OMZ-seep, the G/P ratio increases by 75 % and 66 %, respectively (Fig.…”

Distribution of dinoflagellate cysts in the Canadian Arctic marine region

“…In shelfal regions, the G : P ratio can be used to characterise the dominant trophic mode and the level of primary productivity, as long as the redox potential of the bottom water is quite uniform (McCarthy et al, 2000). The NOW polynya, Ellesmere and Baffin shelves and CAA channels are all marked by low G : P values (0-0.1), indicating predominance of heterotrophic productivity (Fig.…”