Sediment dynamics during Heinrich event H1 inferred from grain size

Abstract

Throughout the last glacial period, massive volumes of icebergs were discharged periodically from the Hudson Strait region during so-called Heinrich (H) events depositing sediments in distinct layers across the North Atlantic as they melted. The objective of this research was to measure and describe sedimentation associated with a meltwater plume discharged during the H1 ice-rafting event (14–19 ka) by examining sediment texture. The H1 layer was sampled in 11 piston cores that cover about 4000 km of the slope between Hudson Strait and the Bay of Fundy and range in water depth from 818–2740 m. Disaggregated inorganic grain size (DIGS) distributions were determined using a Coulter Counter. Additionally, carbonate content and the coarse fraction were measured and DIGS spectra were parameterized using an inverse ?oc model and sorted using entropy analysis. Results suggest that H1 layer sediments were mainly delivered by plume, ice-rafting and turbidity currents. In general, plume deposition was only significant proximally and distal sediments were mainly delivered by ice-rafting. However, the lack of plume deposited sediments distally does not necessarily imply the absence of a plume.