Research On Volcanic Cluster Of The Quaternary Period In Nuominhe Region

The volcanic cluster of Nuominhe is located in Elunchun Autonomic county of Hulunbeier city in Inner-Mongolia Autonomic Region. It belongs to the east slope of the middle and north part of the Daxinganling. The vocanic landscape is preserved well , because it is covered by the forest of the Daxinganling and there has a sparse population. The volcanic cluster of Nuominhe includes 27 point eruptions. These volcanoes mostly spread for NE trending, some others for NNW trending, and are all controlled by the basement rift. Using the situation of volcanic weathering ,erosion and degradation, the relation of the volcanic geomorphology and the water system, the basalt and the Quaternary deposit, and the thermoluminescence isotope age of the volcanic rocks, four phases of the volcanoes activity can be divided:early stage up-Pleistocene, lately stage up-Pleistocene, early stage Holocene and lately stage Holocene. Five types of volcanic edifices can be seen here:Hawaiian,strombolian, sub-plinian,maar and compound volcano. In the early stage of up-pleistocene volcano eruptions were mainly phreatomamatic eruptions, which formed the maar eruption.Then,in the lately stage of up-pleistocene ,the basement rift had intense activity,the magma of the mantle erupted through the rift and formed many strombolian and Hawaiian eruptions. The NW trending fault of Bilahe river actived intensely in the early stage of Holocene ,so volcanic eruptions moved to the Bilahe river,and mainly formed Havaiian and compound eruption. Maanshan volcano erupted In the lately stage of Holocene. it is sub-plinian eruption.The rock types are mainly alkali olivine basalt and lydite. The basalt magma mainly come from low-part melting of rich mantle,but some experience the low crystallization-differentiation process of olivine and pyroxene ,and all of them never happen crustal contamination. They are formed in the primary stage of inner-continent rift. The confirmation of Holocene volcano is of important scientific value for researching on the activity of deep crust and the assessment of volcanic disaster .The volcanic resource is very abundant in Nuominhe region,and it has very great reality significance for the development of tour and economy.