Geological characteristics and formation age of Hundiyinhanwula broken volcano in Central-South Daxinganling Mountains
According to the survey result of the triple mapping method of"volcanic lithologic lithofacies-vol-canic structure-rock stratigraphy",a central type volcanic eruption mechanism is identified in the Hundiyin-hanwula area of the Central-South Daxinganling Mountains.The volcanic eruption products are composed of acidic volcanic clastic rocks,volcanic clastic sedimentary rocks from Xinmin Formation in the outer ring zone,and neutral lava and volcanic clastic rocks from Tamulangou Formation in the inner ring zone.The stratum orientation is inclined inward with the development of circular and radial fractures.The identified lithofacies types mainly include explosive facies,overflow facies,volcanic eruption sedimentary facies,sedi-mentary facies,volcanic eruption collapse facies,and volcanic channel facies.The main active period is from(163.7±1.7)Ma to(162.8±0.9)Ma,belonging to the late Middle Jurassic.The Diyinhanwula volcanic eruption can be divided into two volcanic eruption cycles,Xinmin period and Tamulangou period.The vol-canic eruption cycle of Xinmin period is divided into 8 rhythms based on the periodicity of eruption facies,o-verflow facies,volcanic eruption sedimentary facies or sedimentary facies.The volcanic eruption cycle of Tamulangou period is divided into 2 rhythms based on the changes in andesite texture and structure.After a-nalysis,the formation of Diyinhanwula volcanic eruption can be roughly divided into five stages,(1)strong eruption stage of acidic magma,(2)the explosive activity weakens,and the explosive phase and overflow al-ternate in stages,forming a large amount of volcanic eruption sediment during the intermittent period,(3)during the quiet overflow period,neutral andesite is formed,(4)the underground magma chamber is empty,the volcanic crater collapses,forming circular and radial fractures,and the volcanic eruption and collapse phase rocks form at the crater,(5)andesite intrudes along volcanic channels and occupies them.
Central-South Daxinganling Mountainsbreken volcanolithofaciesvolcanic evolutionzircon U-Pb age
NETL
NSTL
万方数据
