Author/Authors :
Tripati، نويسنده , , Aradhna K. and Eagle، نويسنده , , Robert A. and Morton، نويسنده , , Andrew and Dowdeswell، نويسنده , , Julian A. and Atkinson، نويسنده , , Katie L. and Bahé، نويسنده , , Yannick and Dawber، نويسنده , , Caroline F. and Khadun، نويسنده , , Emma and Shaw، نويسنده , , Ruth M.H. and Shorttle، نويسنده , , Oliver and Thanabalasundaram، نويسنده , , Lavaniya، نويسنده ,
Abstract :
The widely accepted age estimate for the onset of glaciation in the Northern Hemisphere ranges between 2 and 15 million years ago (Ma). However, recent studies indicate the date for glacial onset may be significantly older. We report the presence of ice-rafted debris (IRD) in ∼ 44 to 30 Ma sediments from the Greenland Sea, evidence for glaciation in the North Atlantic during the Middle Eocene to Early Oligocene. Detailed sedimentological evidence indicates that glaciers extended to sea level in the region, allowing icebergs to be produced. IRD may have been sourced from tidewater glaciers, small ice caps, and/or a continental ice sheet.
Keywords :
Polar climate , greenhouse–icehouse transition , paleoclimate , Northern Hemisphere glaciation , ice-rafted debris , Eocene–Oligocene transition
