Composite grains in heavy-mineral concentrates and their significance in the differentiation of surface deposits at the confluence of the Maas (Meuse) and Roer (Rur) rivers.

Abstract

The varying content of composite grains in heavy-mineral concentrates was used for the differentiation of surface sediments in a geomorphologically and pedologically complicate landscape at the confluence of the Maas (Meuse) and the Roer (Rur). West of the Maas valley, these deposits contain quantities of minor importance (<10%), while to the east surface sediments with percentages ranging from 4 to 59 occur. In this latter area a decrease in an easterly direction is suggested from the data. The characteristic high composite content is also found in sediments from the present flood plain of the Maas as well as in an old fluvial deposit of this river (Caberg terrace). It is suggested that the flood plain of the Maas is the source of the surface deposits being found to the east, and that similar deposits west of the Maas valley come from another source area. Finally the possible use of composites as provenance indicators is discussed briefly.