How do we turn rocks and sediments into new knowledge about the Arctic’s history?

Much Arctic research begins in the field: on a research cruise, beside a glacier, along a coastline or in the mountains. Researchers return with sediment cores, rock samples and loose material that may contain clues about past climate, ice movement, erosion and environmental change. 

But samples do not tell their stories on their own. They first need to be described, prepared and analyzed.

In this guest blog, the UiT Geological Laboratories team explains how they support researchers’ efforts to unravel the mysteries of the Arctic’s past.

Our team’s mission is to connect fieldwork with analysis and interpretation. 

This is particularly valuable in the Arctic, where fieldwork is often demanding, expensive and limited by short field seasons and changing weather. A sample from a remote location may be difficult—or impossible—to replace. Careful handling, documentation and storage are therefore essential.

The Geological Laboratories combine practical facilities for sample preparation with instruments that allow researchers to study material in detail, from entire sediment cores to microscopic structures in individual mineral grains.

In this blog, we will explain what instruments are available – and how researchers can use them to uncover the recent and distant past.

SEDIMENT CORES 

Sediment cores are among the most informative materials studied in the laboratory. Layer by layer, they can preserve evidence of what has happened in an area over hundreds or thousands of years. Changes in grain size, color, density and chemical composition can point to past glacier activity, runoff, ocean currents or mass-movement events.

Sediment cores can also contain evidence of past landslides, debris flows, floods and other events that have shaped Arctic landscapes and coastal environments. Studying these records can improve understanding of how often such events occur and under which conditions.

·      Before a sediment core is split and sampled, it can be examined using a Multi Sensor Core Logger. This instrument measures physical properties along the length of the core at high resolution. The measurements provide a detailed overview of variations between sediment layers and help researchers identify the most interesting intervals for further study.

·      The laboratory’s X-ray instrument makes it possible to look inside a sediment core without destroying it. X-ray images can show fine layering, stones and other coarse fragments, deformation and differences in density. This can help researchers spot evidence of landslides, ice-rafted debris or rapid changes in sediment deposition.

·      An XRF scanner is used to produce detailed, continuous records of changes in elemental composition through a sediment core. These measurements can help identify changes in sediment sources, the influence of material from land, or variations in marine conditions.

·      The laboratories also include an Isotope Ratio Mass Spectrometer. This instrument measures the relative abundance of different isotopes in a sample. Isotope data can be used to investigate sources and pathways of carbon, nitrogen and other elements, and to study environmental processes over time. For the iC3 Polar Research Hub, this is particularly useful, as the hub’s team is exploring the links between the cryosphere, carbon and climate.

·      A Gas Chromatograph separates the different compounds in a sample so that researchers can study its chemical composition. This can be useful for investigating organic material in sediments and other environmental samples, including how it has been transported, altered and stored in Arctic environments.

·      With a Scanning Electron Microscope, researchers can study samples at an even smaller scale. The microscope produces highly detailed images of surfaces and structures that cannot be seen with a standard light microscope. It can be used to examine minerals, grain shapes, traces of transport and abrasion, weathering, and chemical changes in the material.

Picture: the Multi Sensor Core Logger. Credit: Kai Mortensen.

THIN SECTIONS

Our laboratories also have equipment for cutting, crushing, grinding, drying, sieving, weighing and polishing geological samples. This may sound like basic work, but it strongly affects the quality of the analyses that follow.

·      One important activity is the production of thin sections from hard rocks. A thin section is a very thin slice of rock, mounted on a glass slide and ground down to around 0.03 millimeters. At this thickness, light can pass through the sample, allowing it to be studied under a microscope. Thin sections make it possible to see which minerals a rock contains, how mineral grains are arranged, and whether the rock has fractures, deformations or signs of chemical alteration. This information can help researchers to understand how a rock formed and how it has changed over time, to investigate the links between bedrock, erosion, ice and marine sediments.

Picture: thin section. Credit: Kai Mortensen.

COMBINING METHODS

The key value of the Geological Laboratories lies in the combination of methods. 

Thin sections and microscopy provide information about hard rocks, while the Multi Sensor Core Logger, X-ray imaging, XRF scanning, Isotope Ratio Mass Spectrometer, gas chromatography and the Scanning Electron Microscope offer different perspectives on sediment cores, minerals and environmental samples.

We also help researcher to establish and maintain good routines for sampling, analysis, documentation and storage. 

This makes it easier to compare data across field sites and research cruises—and ensures that valuable samples can be reused to address new research questions in the future.

Click here to learn more about the Geological Laboratories at UiT.

The laboratories are a shared resource for the Department of Geosciences’ research groups, including the Ore Geology Research Group and the Geohazard Research Group, as well as the iC3 Polar Research Hub and the Into the Blue (i2B) project. 

Additional laboratories available to iC3 researchers include the Polar MAGIC lab, the Foraminifera Culturing Lab, and – coming soon – the PlasmaLab.