Tectonic understanding from the micro-scale analysis of the pebble
The essence of this paper is to show how a single pebble, in fact a few grains from a pebble from the molasse can influence our understanding of a tectonically significant event as great as the India/Asia collision. The key to this study is to show that microstructural analysis and microchemical data can provide key information to the regional and even plate-scale tectonics.
The selection of the pebble from such an extensive molasse was done with the following criteria: 1) to choose a representative sample that is common within the molasse; 2) that it is a well preserved so that analyse can be undertaken in order to produce quality data; and 3) that minerals within the sample are of the right composition to allow geochronology on the preserved deformational or metamorphic events that still remain in this small exotic rock. Such a pebble was selected. It is a rounded pristine granitic pebble containing aligned white mica grains thus preserving both deformational information and possible igneous and/or metamorphic information. Minerals in the sample are suitable to be dated using 40Ar/39Ar geochronology to determine both timing and duration of events.