Geochemical Characteristics And Significance Of Mud Volcano Extrusive Suonahu Area In Qiangtang Basin

Mud volcano is an important window to reveal the internal activities of the earth and the deep tectonic movement of the crust,and it can provide a variety of valuable important geological information.Mud volcano in Suonahu area,Qiangtang Basin is rarely reported.In this paper,geochemical research of mud volcanic cluster in Suonahu area has been consrutcted,and the research significance of mud volcano has been discussed as well.The study area consists of 13 mud volcano,according to morphological character,mud volcano is divided into 4 categories,shield mud volcano,basin like mud volcano,pool like mud volcano,shield basin composite mud volcano;in accordance with the eruption time it can be divided into ancient mud volcano and modern mud volcano.The distribution of modern mud volcano and ancient mud volcano posess the characteristics of belting from east to west;There’s a big difference in the composition of mud,dolomite is widespread in ancient mud volcano,but hasn’t been found in the modern mud volcano;illite and smectite mixed layer mineral content is high in modern mud volcano,but there’s no illite and smectite mixed layer in clay mineral in ancient mud volcano.Through the study of geochemistry,groundwater in mud volcano area is mainly NaHCO₃ type water,which belongs to oilfield water;hydrogen and oxygen isotope of groundwater in mud volcano area are similar to that of oilfield water;extrusive mud of modern mud volcano is rich in methane,methane is resulted from thermal genesis.Through the discussion of the genesis of the mud volcano,it is believed that the mud volcanic gases are most likely derived from the source rocks of the Permian the Rejuechaka group.The mud source is most likely to be the mud shale of the Rejuechaka group.The fault is the passage of the gas from the deep strata,and the Paleogene conglomerate provides the most favorable reservoir space for the high-pressure gas.The permafrost layer is the most favorable gas cover.The most likely cover of high pressure gas.The high-pressure gas is destroyed by the neotectonic movement in the later stage,and the earth surface erupts to form mud volcanoes.