Size and Shape of Sedimentary grains by Automated Dynamic Image Analysis.

All type of sediment transport processes on the earth surface result in shape differences depending on the distance, duration and kind of the transport. Automated Dynamic Image Analysis (ADIA) is a new, fast and efficient tool to determine size and shape of sedimentary grains and makes it possible to process large amounts of different samples. It determines the shape of a large number of particles (typically 5,000 to 50,000 or more) in the size range between 20 to 2,500 µm. ADIA measurements are performed with a RapidVue particle analyzer (Beckman Coulter Company, Hialieah, Florida). Size and shape of particles are determined by analyzing digital images. Each image is composed of shapes that represent cross-sections of particles. The analysis yields the area and perimeter of each particle cross-section, which are turned into size-independent shape values.
The results are statistically representative and highly reproducible. Since no operator selection of images enters the measurement procedure, the risk of bias caused by subjective sample selections is avoided.
The large amount of investigated particles and the size independent shape data allow the construction of a two dimensional histogram, which can possibly be used as some kind of signature of the sediment transport process.