Oceanography

Over the last decades there has been a rapid development of technology to recover deep see sediments. Today, over 100.000 meters of marine sediment core is recovered each year by IODP (International Ocean Discovery Program), and other scientific programs. Many techniques are available for sediment examinations, however few techniques combine non-destructive features, a wealth of important information available down to the microscopic scale, and data recovery which is quick enough not to damage the valuable sediment cores. A combination of these features has made XRF core scanning the standard tool for examination of sediment cores, often used as a first sample overview from which scientists can decide for the following steps to take when examining their samples. With onboard core scanner installations, core examinations can even be performed while the core sampling ship is still at the sampling spot, and an overview scan with centimeter steps can be performed within a few minutes. Data on the variation of different elements along the cores, when combined in the right way to so called proxies, provide much information of the origin of the different sediment sections. The list of aspects on climate related information that can be retrieved through proxies has grown much in the last few years.

Itrax-data-marine-compiledHere are shown a few data examples from Itrax Core Scanner. These data are from analysis of a section of a marine sediment core from the Arctic,and give an idea of the level of accuracy and detail of core data that can be gathered in short time . The photos were recorded with Itrax Core Scanner, and the top photo shows the sample as seen by eye.

Of the left three photos, the first one shows the sample as seen by the naked eye. The second photo from the left shows the same sample, but after digital contrast enhancement of the leftmost image. Imprints from the Magnetic Susceptibility measurement appear as circular marks on the sample surface, while Itrax optical, radiographic and XRF analyses do not touch the surface during analysis.

The third photo from the left shows again the same image, but here overlaid with a radiographic image of that same sample, placed along the center line of the image. Please note that the x-ray radiographic image reveals structures also in areas of the sample that by eye seem to be homogenous. X-ray radiography is a useful complement to XRF since it releals density as well as chemical changes and can clarify whether peaks or other shifts in the XRF signal relate to layered structures, or not.

The two larger photos to the right show a blow up of the marked 200 millimeter section of the same sample. In the left one of these, two element profiles in Red and Blue are overlaid on the photo, showing the variation of Silica (Si) concentration along the sample as determined in two consecutive scans. The Si concentration is on average roughly 10%. The rightmost photo shows the same sample section, here with two Manganese (Mn) profiles overlaid. The two Mn profiles were registred during the same two scans as for Si. Together they give an idea of the level of reproducibility for light as well as heavier elements, when scaning with one second of measuring time per point. The Mn concentration is on average roughly 0.07% (700 PPM). The beam size and step was 0.2 millimeter. The elements that were determined simultaneously in this sample scan were Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Br, Rb, Sr, Zr, Ba, La and Pb (only Si and Mn shown). These measurement were conducted with an Itrax Core scanner equipped with our top-of the-line XRF offering a count rate of up to 300.000 x-ray photon counts per second. Please click this link to open a larger sample image in a separate window

Core material with courtesy of Dr. Richard Gyllencreutz, Stockholm University. From IODP Expedition LOMROG III 2012, Lomonosov ridge, off Greenland. Sampled at 4228 meters depth.