Expedition 374 methods

McKay, Robert; Santis, Laura De; Kulhanek, Denise K.; Browne, I. M.; Shevenell, A.; Scientists, Expedition

doi:10.14379/iodp.proc.374.102.2019

Cited by 15 publications

(2 citation statements)

References 146 publications

(1 reference statement)

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“…The framework that we devised in this study draws upon the sub-sampling approaches commonly used for ice cores, lake, and marine sediment cores, which save archival material and allocate samples for a variety of analyses (e.g., Hodson et al, 2016;Mckay et al, 2019;Priscu and SALSA Science Team, 2021;Souney et al, 2014). These large community efforts today devise sampling plans that consider current and future, as yet unknown, analytical techniques prior to core collection.…”

Section: Acquisition and Sampling Of Basal Ice Core Materialsmentioning

confidence: 99%

Scientific history, sampling approach, and physical characterization of the Camp Century sub-glacial sediment core, a rare archive from beneath the Greenland Ice Sheet

Bierman,

Christ,

Collins

et al. 2024

Preprint

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Abstract. Basal materials in ice cores contain information about paleoclimate conditions, glacial processes, and the timing of past ice-free intervals, all of which aid understanding of ice-sheet stability and its contribution to sea-level rise in a warming climate. Only a few ice cores have been drilled through ice sheets to the underlying sediment and bedrock, producing limited material for analysis. The Camp Century ice core, which the US Army drilled in northwest Greenland from 1960–1966 CE, recovered about 3.5 meters of sub-glacial sediment. Here, we document the scientific history of the Camp Century sub-glacial sediment, and present our recent core-cutting, sub-sampling, and processing methodology and results for what remains of this unique archive. In 1972, curators in the Buffalo Ice Core Laboratory cut the original core segments into 32 segments each about 10-cm long. Since then, two segments are unaccounted for, two were thawed, and two were cut as pilot samples in 2019. With the exception of the two thawed segments, the rest of the extant core remained frozen since collection. In fall 2021, we documented, described, and then cut each of the remaining frozen archived segments (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 physical, geochemical, isotopic, sedimentological, magnetic, and biological analyses. Our approach maximized sample usage for multi-proxy analysis, minimized contamination, and preserved archive material for future analyses of this legacy sample material. Grain size, bulk density, sedimentary features, magnetic susceptibility, ice content, as well as pore-ice pH and conductivity, suggest that the basal sediment contains five stratigraphic units. We interpret these stratigraphic units as representing different depositional environments in sub-glacial or ice-free conditions: from bottom to top, a diamicton with sub-horizontal ice lenses (Unit 1); vertically-fractured ice with dispersed fine-grain sediments (< 20 % in mass) (Unit 2); a normally graded bed of pebbles to very fine sand in an icy matrix (Unit 3); bedded very fine to fine sand (Unit 4); and stratified medium to coarse sand (Unit 5). Plant macrofossils are present in all samples and most abundant in Units 3 and 4; insect remains are present in some samples (Units 1, 3, and 5). Our approach provides a working template for future studies of ice-core basal sediment because it includes intentional planning of core sub-sampling, processing methodologies, and archiving strategies in order to optimize the collection of paleoclimate, glacial process, geochemical, geochronological, and sediment properties from archives of limited size. Our work benefited from a carefully curated and preserved archive, allowing for the application of techniques not available in 1966. Preserving uncontaminated core material for future analytical capabilities is an important consideration for rare archive materials such as these from Camp Century.

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Section: Acquisition and Sampling Of Basal Ice Core Materialsmentioning

confidence: 99%

Scientific history, sampling approach, and physical characterization of the Camp Century sub-glacial sediment core, a rare archive from beneath the Greenland Ice Sheet

Bierman,

Christ,

Collins

et al. 2024

Preprint

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“…Digital linescan images of the archive-half sections were collected during the expedition using a JAI linescan camera and LED lights to illuminate the core surface (McKay et al, 2019a). These section images were loaded into Igor Pro (Wavemetrics) using the Code for Ocean Drilling Data (CODD) of Wilkens et al (2017) and concatenated into composite core images used to verify tie points when constructing the CCSF depth scale.…”

Section: Core Imagesmentioning

confidence: 99%

Data report: IODP Site U1523 composite section and stratigraphic splice based on X-ray fluorescence data

Kulhanek¹,

Prunella²,

McLaughlin³

et al. 2022

Proceedings of the International Ocean Discovery Program

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A large West Antarctic Ice Sheet explains early Neogene sea-level amplitude

Marschalek

Zurli

Talarico

et al. 2021

Nature

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Early to Middle Miocene sea-level oscillations of approximately 40-60 m estimated from farfield records 1,2,3 are interpreted to reflect the loss of virtually all East Antarctic ice during peak warmth 2 . This contrasts with ice-sheet model experiments suggesting most terrestrial ice in East Antarctica was retained even during the warmest intervals of the Middle Miocene 4,5 . Data and model outputs can be reconciled if a large West Antarctic Ice Sheet (WAIS) existed and expanded across most of the outer continental shelf during the Early Miocene, accounting for maximum ice-sheet volumes. Here, we provide the earliest geological evidence proving large WAIS expansions occurred during the Early Miocene (~17.72-17.40 Ma). Geochemical and petrographic data show glacimarine sediments recovered at International Ocean Discovery Program (IODP) Site U1521 in the central Ross Sea derive from West Antarctica, requiring the presence of a WAIS covering most of the Ross Sea continental shelf. Seismic, lithological and palynological data reveal the intermittent proximity of grounded ice to Site U1521. The erosion rate calculated from this sediment package greatly exceeds the long-term mean, implying rapid erosion of West Antarctica. This interval therefore captures a key step in the genesis of a marine-based WAIS and a tipping point in Antarctic ice-sheet evolution.

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Expedition 374 methods

Cited by 15 publications

References 146 publications

Scientific history, sampling approach, and physical characterization of the Camp Century sub-glacial sediment core, a rare archive from beneath the Greenland Ice Sheet

Scientific history, sampling approach, and physical characterization of the Camp Century sub-glacial sediment core, a rare archive from beneath the Greenland Ice Sheet

Data report: IODP Site U1523 composite section and stratigraphic splice based on X-ray fluorescence data

A large West Antarctic Ice Sheet explains early Neogene sea-level amplitude

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