Formation of quartz silt during humid tropical weathering of dune sands
Abstract
Quartz dune-sand grains in northeast Australia break down in situ under humid tropical weathering conditions to form substantial amounts of silt. Fragmentation appears to occur primarily due to silica solution along microfractures and dislocation structures in grains which have experienced tectonic deformation prior to deposition. The surface textures of quartz grains viewed with the SEM exhibit a close dependency on crystallographic properties. In the B and C horizons of some weathered late Pleistocene dunes silt forms up to 10% of the bulk sediment. Local remobilisation of such deposits by wind allows selective removal of the silt which is later deposited as a thin surficial sheet in more sheltered areas downwind. These observations provide further evidence that weathering processes provide a major mechanism of silt formation and are an important factor to be considered in relation to the origin of loess and siltstones.
- Publication:
-
Sedimentary Geology
- Pub Date:
- April 1983
- DOI:
- 10.1016/0037-0738(83)90050-7
- Bibcode:
- 1983SedG...34..267P