Study on Carboniferous Volcanic Facies of Niuquanhu-Mabei Region

The main lithology of carboniferous system volcanic rock reservoirs in the niuquanhu-mabei area includes basic-alkaline-calc-alkaline series rocks.Including lava and pyroclastic rock,38 kinds of specific rocks.Basaltand volcanic breccia are main types.Volcanic lithofacies can be divided into 5 categories and 10subfacies.In profile,effusive facies are main mode except explosive facies.Volcanic lithofacies include 2 modes:explosivefacies-effusive facies-sedimentary facies,effusive facies-sedimentary facies.The process is from weak to strong to weak.The craters' distribution are controled by fault,distributing as beads-strings along the dominating fracture.The trend is south-east.And the main type of eruption is fracture type,the second one is center type.