A revised approach to discriminating sediment transport histories in glacigenic sediments in a temperate alpine environment: A case study from Fox Glacier, New Zealand

摘要

Clast shape measurements have developed into a standard method for reconstructing the transport histories of sediments in glacial environments. The majority of studies use the 'RA-C _(40)' covariance approach, with some researchers routinely including clasts of varying lithologies within their samples. The corollary is that variable lithological properties may control clast form and roundness, rather than debris-transport mechanisms. Despite this, the role of lithology on clast shape in glacial environments has rarely been analysed. Furthermore, some studies have reported difficulties in using the RA-C _(40) co-variance plot in discriminating clasts that have undergone subglacial transport, and clasts that have been modified by fluvial activity. Results from a glacierized valley in a temperate alpine setting indicate that detailed analysis of clast shape where samples are of uniform lithology, although time consuming, is a useful tool in the investigation of deposits in glaciated environments.