Base-surge deposits

commonly considered as a special kind of pyroclastics

are aqueous pyroclastics that are produced by explosive magma-water interaction.Volcanic explosion provides rich material resources for base-surge.Base-surge deposits are characterized by accretionary lapilli and large-scale dunelike structures

therefore they can be easily differentiated from other volcanoclastic rocks.The clastic texture of base-surge deposits is dominated by volcanic pisolite and gravel mostly in half-round shape

followed by round shape

and some in subangular shape.Since base-surge deposits have some characters of pyroclastic debrits and sedimentary rocks

they serve as excellent oil and gas reservoirs.In addition

study on its genesis is helpful for preventing and forecasting disaster.