Holocene chronostratigraphy of northeastern Baffin Bay based on radiocarbon and palaeomagnetic data

Abstract

The northeastern Baffin Bay continental margin, which experiences high sediment accumulation rates, is an excellent location to study Holocene sedimentary variations. However, it is often difficult to obtain reliable chronologies of the sediment archives using traditional methods (δ18O and radiocarbon) due to specific oceanographic conditions (e.g. corrosive bottom waters). Here we propose a chronostratigraphy of three cores collected on the northwestern Greenland margin (AMD14‐204, AMD14‐210 and AMD14‐Kane2B) based on a combination of radiocarbon dating and palaeomagnetic records. Geophysical properties of discrete samples were used to verify the reliability of the palaeomagnetic records. Palaeomagnetic analyses indicate a strong and stable natural remanent magnetization carried by low coercivity ferrimagnetic minerals (magnetite) in the pseudo‐single domain grain size range. Correlation of the full palaeomagnetic vector (inclination, declination, and relative palaeointensity) was used to establish a reliable chronostratigraphical framework for two of the cores (AMD14‐204 and AMD14‐210) and to propose an original palaeomagnetic record for the previously 14C‐dated core AMD14‐Kane2B that covers most of the Holocene. Overall, this new chronostratigraphy allowed improvement of the timing of the main palaeoenvironmental changes that occurred in this area during the Holocene.

Evolution of sea‐surface conditions on the northwestern Greenland margin during the Holocene

“…The two cores used in this study (204 and Kane2B) were described in detail by Caron et al . () and Georgiadis et al . () and major sedimentological units (Fig.…”

“…Overall, the lithology of core 204 is relatively homogeneous and fine grained and is largely dominated by hemipelagic sedimentation. By contrast, core Kane2B shows a more variable sedimentation associated with higher inputs of ice‐rafted debris and reworked sediments throughout the core (Caron et al ., ; Georgiadis et al ., ). Palynological results provide additional details on environmental changes for both cores.…”

“…Thus, the relatively low reconstructed salinity values in core 204 support evidence of high meltwater discharge from the GIS prior to 7750 cal a bp , also suggested by Caron et al . ().…”

“…In the Kane Basin, immediately after the retreat of grounded ice from the core site, the high concentration of reworked palynomorphs (Fig. ) associated with a high ice‐rafted debris content support ice‐proximal conditions with high meltwater discharge from both IIS and GIS (Caron et al ., ; Georgiadis et al ., ). This strong meltwater input, linked to the retreating ice sheets, probably resulted in very harsh sea‐surface conditions with a quasi‐permanent SIC during this period (prior to 8300 cal a bp ; Ledu et al ., ), which would explain the very low concentration of dinocysts observed during this period.…”

“…() for Kane2B and from Caron et al . () for core 204; paleomagnetic stratigraphic markers from Caron et al . () and organic matter is from Giraudeau et al .…”