Micromorphological and preliminary X-ray observations on a basal till from Lunteren, The Netherlands

Abstract

Undisturbed box samples have been taken from a Saalian till complex and associated shear zone in the Central Netherlands. Microscopic studies of vertical thin sections of so-called mammoth-size (7 x 14 cm) and microdensitometer readings taken from X-ray images reveal amongst others (1) a closely spaced textural banding, (2) the presence of two types of unconsolidated pebbles, i.e. mud pebbles and till pebbles, (3) different types of plasmic fabric, i.e. skel-lattisepic fabric for most of the till matrix and till pebbles and a strong unistrial fabnc associated with shear zones. The present observations are in accordance with earlier macroscopic field and laboratory studies, indicating till formation under conditions of continuous subglacial shearing, by which much local material is reworked as well.