A paleomagnetic approach toward refining Holocene radiocarbon‐based chronologies: Paleoceanographic records from the north Iceland (MD99‐2269) and east Greenland (MD99‐2322) margins

Abstract

[1] We report the intercalibration of paleomagnetic secular variation (PSV) and radiocarbon dates of two expanded postglacial sediment cores from geographically proximal, but oceanographically and sedimentologically contrasting settings. The objective is to improve relative correlation and chronology over what can be achieved with either method alone. Core MD99-2269 was taken from the Húnaflóaáll Trough on the north Iceland shelf. Core MD99-2322 was collected from the Kangerlussuaq Trough on the east Greenland margin. Both cores are well dated, with 27 and 20 accelerator mass spectrometry 14 C dates for cores 2269 and 2322, respectively. Paleomagnetic measurements made on u channel samples document a strong, stable, singlecomponent magnetization. The temporal similarities of paleomagnetic inclination and declination records are shown using each core's independent calibrated radiocarbon age model. Comparison of the PSV records reveals that the relative correlation between the two cores could be further improved. Starting in the depth domain, tie points initially based on calibrated 14 C dates are either adjusted or added to maximize PSV correlations. Radiocarbon dates from both cores are then combined on a common depth scale resulting from the PSV correlation. Support for the correlation comes from the consistent interweaving of dates, correct alignment of the Saksunarvatn tephra, and the improved correlation of paleoceanographic proxy data (percent carbonate). These results demonstrate that PSV correlation used in conjunction with 14 C dates can improve relative correlation and also regional chronologies by allowing dates from various stratigraphic sequences to be combined into a single, higher dating density, age-to-depth model.

A robust, multisite Holocene history of drift ice off northern Iceland: implications for North Atlantic climate

“…Our findings build on the results of quantitative XRD of the < 2 mm sediment fraction from core MD99-2269 (Table 1, Figure 2) , which has one of the best-dated Holocene records in the North Atlantic (Stoner et al, 2007). However, we agree with Alley (2003) that several cores from a region are required to fully substantiate a proxy record.…”

“…Figure 3B shows the median quartz wt.% distribution -this record is similar (r = 0.84) to the high-resolution 30 yr/sample quartz wt.% data from MD99-2269 (Figures 2 and 4A) . The fact that our multicore record captures most of the lower frequency variations in MD99-2269 ( Figure 4A) justifies the analysis of this core to provide a very high-resolution archive of Holocene environmental variability (eg, Andrews et al, 2003;Moros et al, 2006;Stoner et al, 2007) for an area affected by variations in the advection of Atlantic versus Arctic/Polar water masses (eg, Dickson et al, 1988). The time series of median quartz wt.% data is 'robust' in the sense that the estimate is not influenced by extreme values (Velleman and Hoaglin, 1981).…”

Timber Logging in Central Siberia is the Main Source for Recent Arctic Driftwood

“…However, in contrast to the NIS cores, where IP 25 and quartz wt% were well correlated (r 2 = 0.74 and 0.66 for MD99-2269 and JR51-GC35, respectively [Cabedo-Sanz et al, 2016]), their relationship is weaker for 2322 (r 2 = 0.44), likely indicating a change in provenance in one, or both, of the drift ice proxies. It is worth noting that the carbonate records in 2322 and MD99-2269 are virtually identical (Stoner et al, 2007). In contrast to the quartz and IP 25 data, the Fe grain inputs from SA42 and 43 decreased slightly over the last 1400 cal.…”

“…It has a relatively high average sedimentation rate of 1 m/kyr for the upper 7 kyr to more than 5 m/kyr below this, and an excellent age model based on 20 calibrated radiocarbon dates and paleomagnetic data (Stoner et al, 2007;Jennings et al, 2011). Shipboard observations in 1991 and 1993 along the Geikie Plateau and in Kangerlussuaq Fjord indicated individual icebergs with supraglacial, englacial, or basal debris, which was especially evident for icebergs calved within the area of basalt outcrop, and aerial photographs showed that many of the glaciers on the Geikie Plateau had supraglacial sediment loads.…”

“…Core 2322 is a very well-dated Holocene core that we analyzed to 11 cal ka B.P. (Stoner et al, 2007;Jennings et al, 2011), whereas 2263 is a box core that extends back to ca. 2 cal ka B.P., also with excellent age control (Andrews et al, 2009a).…”