GEOCHEMISTRY, SEDIMENTOLOGY, AND PALEOECOLOGY OF SUBGLACIAL SEDIMENT IN THE 1966 CAMP CENTURY CORE REVEAL MULTI-MILLION-YEAR HISTORY OF NORTHWEST GREENLAND

Basal materials in ice cores contain information about paleoclimate conditions, glacial processes, and the timing of past ice-free events, all of which are critical for understanding future ice-sheet stability and potential contributions to sea-level rise. Only a few ice cores have been drilled to the bed and they recovered only limited materials for analysis. The Camp Century ice core, which was drilled in northwest Greenland from 1960-1966, recovered 3.44 meters of subglacial sediment – the longest sedimentary archive extracted from beneath the Greenland Ice Sheet. The sediment has not been thoroughly studied.

We documented, described, and then cut each frozen archived sample (n=26). We saved an archival half and then cut the working half into eight oriented sub-samples under controlled temperature and light conditions for varied physical, geochemical, isotopic, sedimentological, and biological analyses. Initial results from grain size, bulk density, ice content, pore ice pH and conductivity, and magnetic susceptibility measurements, and CT scanning suggest that the sediment core contains five stratigraphic units. From the base there is a diamicton with sub-horizontal ice lenses (Unit 1); vertically-fractured sediment-rich ice (Unit 2); and Units 3-5 represent course to fine sediments formed by fluvial transport. Plant macrofossil remains were present in all samples and most abundant in Units 3 and 4; insect remains were present in some samples (Units 1, 3, and 5). This initial dataset indicates the presence of multiple facies that represent different depositional subglacial and ice-free environments. Stable oxygen, nitrogen, and carbon isotope data as well as major and trace element data in pore ice augment physical stratigraphic observations. Future studies of ice-core basal materials that implement intentional planning of core sub-sampling, processing methodologies, and archiving strategies will optimize the collection of paleoclimate data from rare sediment archives of limited size.