The research and mapping of volcanic associations: An example from the volcanic rocks in the Comai-Boindoi zone,Xizang

The present paper is base on the field geological investigation of the volcanic rocks within the extent of the 1:250 000 Boindoi and Comai Sheets in Xizang according to the combination of lithostratigraphy-volcanic facies -volcanic structures,referenced to the new results from volcanology at home and abroad since 1990's of last century,and the recent experience from the large-scale geological mapping during the 1:50 000 regional geological survey. The study begins from a single volcano to volcanic associations. The resultant palaeovolcanic geological maps are well-defined in volcanic structures,and may reflect the features of volcanic activities during various stages (cycles) and evolution and distribution of volcanic facies,and reasonably reconstruct the volcanic stratigraphic sequences.