Towards successful cleaning of chert samples for improved 10Be and 26Al measurements

International audienceIn situ-produced cosmogenic Be-10 and Al-26 measurements are widely applied in geomorphological studies and in archaeology and paleoanthropology as a chronologic tool applicable to the past 5 Ma. While most of these measurements are made from concentrates of quartz, a ubiquitous and resistant mineral, it is of great interest to extend this method to other silicates and particularly to the amorphous silicates whose purification may not be as straightforward. This paper presents a cleaning procedure that has been applied on ten samples of various siliceous rocks (chert, granite and quartzolite). The aim is to monitor the Be-10, Al-27 and Al-26 concentration evolution as a function of cleaning steps. While this protocol appears suitable for Be-10, when measuring Al-26 careful attention should be paid to Al-27, whose concentration should be measured regularly to ensure that a constant value is achieved and most important, allowing measuring Al-26/Al-27 by AMS