Early and Middle Jurassic climate changes: implications for palaeoceanography and tectonics

TY - ABST

T1 - Early and Middle Jurassic climate changes: implications for palaeoceanography and tectonics

AU - Korte, Christoph

AU - Hesselbo, Stephen

AU - Ullmann, Clemens Vinzenz

AU - Ruhl, Micha

AU - Thibault, Nicolas Rudolph

PY - 2014

Y1 - 2014

N2 - The occurrence of ‘ice ages’ within the overall warm Jurassic Period has been the subject of much discussion and not a little controversy. Recently it has been suggested on the basis of occurrence of glendonites in circum-Arctic basins that cold episodes took place in the Jurassic (Price, 1999; Rogov and Zakharov, 2010). Here we present new high-resolution oxygen isotope datasets from marine calcitic fossils of different European basins that indicate strong temperature fluctuations during the Pliensbachian-Bajocian time span. The already reported cold Late Pliensbachian episode with at least three pronounced oxygen isotope ‘Ice Age’ cycles, and the subsequent well known Toarcian Oceanic Anoxic ‘supergreenhouse’ Event is followed by very warm seawater temperatures in the late Toarcian. Moreover, a very pronounced and effective cooling occurred during the latest Toarcian and early Aalenian (Early-Middle Jurassic Boundary Event) resulted in substantial expansion of Arctic climates to palaeolatitudes as low as 45° and in distinctly cooler seawater temperatures in lower latitude European seas. At least the extensive cooling at the Early-Middle Jurassic Boundary Event was most likely driven by substantial changes in oceanic current patterns which were initiated by a major tectonic uplift that prevented the transport of heat to Polar Regions.

AB - The occurrence of ‘ice ages’ within the overall warm Jurassic Period has been the subject of much discussion and not a little controversy. Recently it has been suggested on the basis of occurrence of glendonites in circum-Arctic basins that cold episodes took place in the Jurassic (Price, 1999; Rogov and Zakharov, 2010). Here we present new high-resolution oxygen isotope datasets from marine calcitic fossils of different European basins that indicate strong temperature fluctuations during the Pliensbachian-Bajocian time span. The already reported cold Late Pliensbachian episode with at least three pronounced oxygen isotope ‘Ice Age’ cycles, and the subsequent well known Toarcian Oceanic Anoxic ‘supergreenhouse’ Event is followed by very warm seawater temperatures in the late Toarcian. Moreover, a very pronounced and effective cooling occurred during the latest Toarcian and early Aalenian (Early-Middle Jurassic Boundary Event) resulted in substantial expansion of Arctic climates to palaeolatitudes as low as 45° and in distinctly cooler seawater temperatures in lower latitude European seas. At least the extensive cooling at the Early-Middle Jurassic Boundary Event was most likely driven by substantial changes in oceanic current patterns which were initiated by a major tectonic uplift that prevented the transport of heat to Polar Regions.

M3 - Conference abstract in journal

SN - 1607-7962

VL - 16

JO - Geophysical Research Abstracts

JF - Geophysical Research Abstracts

M1 - 15944-1

T2 - EGU General Assembly 2014

Y2 - 27 April 2014 through 3 May 2014

ER -