Cobb Mountain Subchron recorded at IODP Site U1306 (Eirik Drift, off SE Greenland)

Abstract

The Cobb Mountain Subchron (CMS) is recorded over ∼5 m of core at ∼180 metres composite depth in the sediment sequence recovered at IODP Site U1306, in an interval where sedimentation rates are estimated at ∼15 cm kyr−1. The relatively high-resolution record of the CMS was acquired from u-channel samples from multiple core sections from four holes drilled at the site. Large-scale swings in magnetization directions at the onset of the subchron lead to virtual geomagnetic poles (VGPs) looping over the Indian Ocean, followed by a looping transit northward through the central Pacific Ocean, a ∼10 kyr (∼1.7 m) interval of VGPs at high northern latitudes particularly in the North Atlantic and NW Pacific Oceans, followed by an abrupt normal to reverse transition as VGPs track southward through Africa. Although the VGP paths are intricate and complex, they can be compared with other CMS VGP paths from Pacific and Atlantic sites, including ODP Sites 983 and 984. The age model for Site U1306 places the CMS in the 1178–1215 ka interval (∼37 kyr duration) which bridges marine isotope stages 35–36.