Calibrated cryo-cell UV-LA-ICPMS elemental concentrations from the NGRIP ice core reveal abrupt, sub-Annual variability in dust across the GI-21.2 interstadial period

Abstract

Several abrupt shifts from periods of extreme cold (Greenland stadials, GS) to relatively warmer conditions (Greenland interstadials, GI) called Dansgaard-Oeschger events are recorded in the Greenland ice cores. Using cryo-cell UV-laser-Ablation inductively coupled-plasma mass spectrometry (UV-LA-ICPMS), we analysed a 2.85ĝ€m NGRIP ice core section (2691.50-2688.65ĝ€m depth, age interval 84.86-85.09ĝ€kaĝ€b2k, thus covering ĝ1/4 ĝ€230 years) across the transitions of GI-21.2, a short-lived interstadial prior to interstadial GI-21.1. GI-21.2 is a ĝ1/4 ĝ€100-year long period with d 18O values 3-4ĝ€‰ higher than the following ĝ1/4 ĝ€200 years of stadial conditions (GS-21.2), which precede the major GI-21.1 warming. We report concentrations of major elements indicative of dust and/or sea salt (Na, Fe, Al, Ca, Mg) at a spatial resolution of ĝ1/4 ĝ€200ĝ€μm, while maintaining detection limits in the low-ppb range, thereby achieving sub-Annual time resolution even in deep NGRIP ice. We present an improved external calibration and quantification procedure using a set of five ice standards made from aqueous (international) standard solutions. Our results show that element concentrations decrease drastically (more than 10-fold) at the warming onset of GI-21.2 at the scale of a single year, followed by relatively low concentrations characterizing the interstadial part before gradually reaching again typical stadial values.