Project Grant 2534630

RAPID: LEVERAGING ICE CORE DUST ANALYSIS TO CONSTRAIN ATMOSPHERIC CIRCULATION -GLACIER ICE IN POLAR AND ALPINE REGIONS ACTS AS A NATURAL ENVIRONMENTAL SAMPLER, PRESERVING ATMOSPHERIC DUST AND OTHER PARTICULATES THROUGH TIME. TO LEARN ABOUT THE SOURCES OF DUST TO THE POLAR ICE SHEETS, THE PROJECT TEAM WILL USE A TECHNIQUE CALLED ISOTOPIC FINGERPRINTING. THEY WILL APPLY THIS APPROACH TO DUST SAMPLES ISOLATED FROM ICE CORES, WHICH ARE CYLINDERS DRILLED THROUGH A GLACIER OR ICE SHEET, AND WHICH REPRESENT AN IMPORTANT ARCHIVE OF EARTH?S CLIMATE SYSTEM. THEY WILL ALSO MEASURE THE GRAIN SIZE DISTRIBUTION AND CONCENTRATION OF THE DUST PARTICLES. TOGETHER WITH THE ISOTOPIC FINGERPRINTS, THESE ANALYSES WILL ALLOW THEM TO INFER THE SOURCE AND TRANSPORT PATHWAY OF THE DUST AT DIFFERENT TIMES IN THE PAST TO IMPROVE UNDERSTANDING OF PAST ATMOSPHERIC CIRCULATION. THEY WILL APPLY THIS APPROACH TO ICE CORE SAMPLES FROM SEVERAL SITES IN GREENLAND AND ANTARCTICA. DETERMINATION OF DUST SOURCE, OR PROVENANCE, THROUGH COMPOSITIONAL ANALYSIS IS A POWERFUL APPROACH FOR UNDERSTANDING EARTH SURFACE PROCESSES AND CHANGES IN THE EARTH?S CLIMATE SYSTEM. PREVIOUS WORK HAS SHOWN THAT PAIRED MEASUREMENTS OF DUST PARTICLE CONCENTRATION AND GRAIN SIZE DISTRIBUTION REPRESENT AN IMPORTANT COMPLEMENT TO GEOCHEMICAL ANALYSES, ALLOWING SIMULTANEOUS ASSESSMENT OF CHANGING SOURCE INPUTS AND TRANSPORT INTENSITY TO REMOTE ICE CORE LOCATIONS. DEVELOPMENT OF PROVENANCE AND GRAIN SIZE DATASETS ON ICE CORE DUST FROM GREENLAND AND ANTARCTICA WILL ENABLE THE PROJECT TEAM TO TEST A RANGE OF HYPOTHESES ABOUT PAST ATMOSPHERIC CIRCULATION. FOR INSTANCE, THEY WILL EVALUATE EVIDENCE FOR A POTENTIAL WEST ANTARCTIC ICE SHEET COLLAPSE DURING THE LAST INTERGLACIAL PERIOD, KNOWN AS MARINE ISOTOPE STAGE 5E, USING ICE SAMPLES FROM TAYLOR GLACIER. THEY WILL TEST A NEW HYPOTHESIS THAT SUMMERTIME WARMTH DURING THE YOUNGER DRYAS INTERVAL LED TO WIDESPREAD GLACIAL RECESSION IN THE NORTHERN HEMISPHERE, ACTIVATING HIGH-LATITUDE DUST SOURCES SUCH AS THOSE IN SOUTHERN ALASKA. THEY WILL COMPARE SAMPLES FROM THE LAST GLACIAL MAXIMUM (LGM) AND YOUNGER DRYAS IN THE GISP2 ICE CORE TO ASSESS WHETHER THE GREENLAND SUMMIT WAS IMPACTED BY THE EMERGENCE OF THESE HIGH-LATITUDE DUST SOURCES. FINALLY, THEY WILL APPLY A NOVEL METHOD TO COMBINE POTASSIUM/ARGON (K/AR) GEOCHRONOLOGY WITH STRONTIUM, NEODYMIUM, AND LEAD (SR-ND-PB) RADIOGENIC ISOTOPE ANALYSIS, DEVELOPED THROUGH A PREVIOUS GRANT, TO A SUITE OF ICE CORE SAMPLES FROM A RANGE OF SITES IN GREENLAND AND ANTARCTICA, INCLUDING INTERGLACIAL AND LGM-AGE ICE. THIS WILL ALLOW THEM TO BETTER CONSTRAIN PAST ATMOSPHERIC CIRCULATION PATTERNS AND CLARIFY INTERPRETATIONS ABOUT DUST TRANSPORT DURING THE PAST. THIS AWARD REFLECTS NSF'S STATUTORY MISSION AND HAS BEEN DEEMED WORTHY OF SUPPORT THROUGH EVALUATION USING THE FOUNDATION'S INTELLECTUAL MERIT AND BROADER IMPACTS REVIEW CRITERIA.- SUBAWARDS ARE NOT PLANNED FOR THIS AWARD.