Records Of The Late Glacial Influx Of Ice-Rafted Detritus On The Orphan Knoll, Northwest Atlantic Ocean

Abstract

The top 110 centimeters of IRD records for GVY002 reveal 5 distinct peaks in IRD input, each between 4000-6500 lithics/gram. Three of these peaks coincide with three peaks in the Ca/Sr ratios in the upper meter indicative of dolomite rich IRD from the Canadian margin. The IRD record and Ca/Sr ratio record generated in this study, when compared to the previously generated similar records in GVY001, reveals a similar pattern but over a much longer downcore sediment interval (over the upper 4.5 meters in GVY001 versus the upper 1.8 meters in GVY002). This is due to the higher sedimentation rate in GVY001. Hendry, et al. (2019) tentatively correlated the shallowest peaks in Ca/Sr ratios with Heinrich Events H0 - H4 by correlating the Ca/Sr ratio records in GVY001 to the δ18O record of N. pachyderma (s.). An IRD peak in GVY001 corresponds to each of the Heinrich Events identified in Hendry, et al. (2019). Subsequent comparison of GVY002 IRD records with those of GVY001 suggest that Heinrich Events H0, H1, and H2 can be identified over the first meter. Both GVY002 and GVY001 display two additional IRD peaks of at least 4000 lithics/gram between H1 and H2 during intervals of very low Ca/Sr ratios.