Sedimentary evolution of the early Paleogene deep-water Gulf of Biscay (proto-Atlantic): Climatic and tectonic controls

Implications of reduced turbidity current and landslide activity for the Initial Eocene Thermal Maximum – evidence from two distal, deep-water sites

“…There is evidence for steady, independent movement of the Iberian Plate from ∼55 Ma, however. Deformation was probably felt in the Pyrenean region initially but the effect at Zumaia was delayed until ∼53.5 Ma (Winkler and Gawenda, 1999;Gawenda and Winkler, 2000) which corresponds to the later progradation of a deep sea fan (Cummings and Hodgson, 2011). Thus, this deformation also postdates our studied intervals.…”

“…The pre-IETM interval was dominated at both sites by hemipelagic deposition interrupted by periodic turbidity currents -many of which were likely landslide-triggered. Warm and seasonally wet conditions are interpreted for the studied areas during this time (Gawenda and Winkler, 2000); but were dramatically altered to hot and arid at the onset-IETM, as indicated by terrestrial evaporite deposits (Schmitz and Pujalte, 2003). The IETM featured enhanced terrestrial erosion rates, but reduced hydrodynamic energy of freshwater outflow to the oceans in NE Spain (Schmitz et al, 2001).…”

“…The interval selected (54.0 to 56.3 Ma) at Zumaia avoids a faulted interval where stratigraphic repetition or omission may occur and terminates prior to a transition to a submarine fan setting, in which erosional bed amalgamation is common (Cummings and Hodgson, 2011). A coarse resolution study of turbidite frequency has previously been performed at Zumaia (Winkler and Gawenda, 1999;Gawenda and Winkler, 2000); however, it did not specifically focus on the IETM, nor were individual recurrence intervals calculated.…”