Paleoclimatology

One main application of the Itrax Corescanner is paleoclimatic reconstructions based on data from sediment cores. Element information from the XRF analyses offers proxies for a wide range of parameters, including e.g. seasonal changes, oxic/anoxic conditions, amount of shell/foraminifera, grain size related effects, tephra, shallow water aragonite source, sediment grading, redox related diagenesis, biogenic silica, etc. in marine as well as limnological environment. Furthermore, it includes provenance studies, laminations counting, reconstruction of past lake conductivity, and estimations of past productivity, weathering, cyclone frequency, leaching and erosion intensities. The x-ray radiography that also is a part of the Itrax Core Scanner provides important, complementary information to the XRF.

In lakes, yearly and even seasonal changes including temperature estimates can be traced. Itrax Core Scanner is found at the major climate research institutes. Many research project, large and small, are currently running, involving high resolution scanning of core material. These projects aim at tracing changes on a seasonal or yearly scale for every year from today and back in time, sometimes thousands of years. Such projects include the Lake El´gygytgyn project, the SCOPSCO project of lake Ohrid, and many others where the Itrax XRF Corescanner is applied. Several hundreds of scientific articles containing Itrax data have been published, and more than 100 are added to the list every year. More information on some of these projects can be found under Articles in the main menu.

The Itrax XRF scanner does not only provide XRF signals from all elements found in the sample, but also the scattered radiation from the sample surface as well as the x-ray radiographic signals and the RGB signals from the optical line camera, which all can be combined into various proxies for different type of sedimentary components.The scattered radiation is a proxy for the average atomic number of the sample in each point. The x-ray radiographic image shows minute changes in density and chemical composition.

According to Croudace and Rothwell (Micro-XRF Studies of Sediment Cores, edited by I Croudace and G Rothwell, Springer 2015) over 60 different chemical proxies (elements, element ratios or scattered ratios) has been identified in the literature since the introduction of this technique. The Itrax post-processing software tools allows the operator to display profiles of such proxies directly on the optical image recorded from the scanner, like TOC or biogenic silica (see below).
You can download a list of these proxies in the Downloads section.

This photo shows a 90 millimeter long section of a sediment core. Overlaid in the center of the photo is a x-ray radiograph image of the corresponding sample section. Superimposed on the image are shown element profiles of Silica (Si, red) and Biogenic Silica proxy (Si/Ti, blue) and Detrital Carbonate proxy (Ca/Sr, green) in an alpine lake sediment sample. These element profiles serve as examples of the wide range of elements and proxies that can be registered with high precision, even at high resolution and in only 1-3 seconds per point. The element data have an analytical resolution of 200 micrometers. Please note the fine structures in this laminated samples. The radiograph image confirms the existence and position of each layer, and can also verify element migration when that occurs. The sample width is 56 millimeters, while the width of the radiographic image is 20 millimeters.

The TOC (Total Organic Content) proxy from scattered radiation in the same alpine lake sediment. All data were recorded with Itrax Corescanner. By courtesy of Professor Michael Strasser, University of Innsbruck.