Large amounts of volcanic debris-avalanche deposits, which take the shape of hummocks, are distributed around the peripheries of the Laoheishan volcano and Huoshaoshan volcano in Wudalianchi World Geopark. In earlier ...Large amounts of volcanic debris-avalanche deposits, which take the shape of hummocks, are distributed around the peripheries of the Laoheishan volcano and Huoshaoshan volcano in Wudalianchi World Geopark. In earlier times, they were called "satellite volcanoes", namely, freestanding volcanoes. This paper points out that these deposits actually came from the collapse of the cones of these two volcanoes. When the lava flow spilled out at the base of the slope of the cones, the slope broke up and collapsed under the action of gravity. Later, ravines were formed on the slope. Caved slope clastics, accompanying lava flow, accumulated at the rims of the volcano cones. Although some accumulations may form very large cones, they are not volcanoes, but deposits of volcanic debris avalanches.展开更多
Wudalianchi（五大连池） volcanoes are famous Quaternary ones with fairly good volcanic landscape in Northeast China.The volcanic rocks are phonotephrite,tephri-phonolite,trachyandesite,and basaltic trachyandesite with...Wudalianchi（五大连池） volcanoes are famous Quaternary ones with fairly good volcanic landscape in Northeast China.The volcanic rocks are phonotephrite,tephri-phonolite,trachyandesite,and basaltic trachyandesite with SiO2 contents of 47.3 wt.%-54.2 wt.%.The characteristic of high K2O content in Wudalianchi volcanic rocks suggests that they probably share a common potassic magma source.The magma evolutions of Wudalianchi volcanic rocks are similar,while the new eruption prod-ucts of Laoheishan（老黑山） and Huoshaoshan（火烧山） volcanoes are slightly more evolved than the old eruption materials,i.e.,the magma of the new eruptions in 1719-1721 from the above two volcanoes is the evolved magma in underground chamber.The main phenocrysts of Wudalianchi volcanic rocks are olivines,clinopyroxenes,and some characteristic K-rich leucites.The various-shaped melt inclu-sions are found in olivine phenocrysts from new eruption products of Laoheishan and Huoshaoshan volcanoes.By electron microprobe（EMP） analyzing,the contents of SiO2 and total alkali show a wide range,suggesting that the pre-eruptive magma was probably more complicated,or the melt inclusions were rather unhomogeneous.On the basis of EMP results,it is believed that the sulfur degassing rate from this new eruption was much higher than that of the millennium eruption of Tianchi（天池） volcano,while the chlorine degassing rate was a magnitude lower than that of Tianchi volcano.展开更多
文摘Large amounts of volcanic debris-avalanche deposits, which take the shape of hummocks, are distributed around the peripheries of the Laoheishan volcano and Huoshaoshan volcano in Wudalianchi World Geopark. In earlier times, they were called "satellite volcanoes", namely, freestanding volcanoes. This paper points out that these deposits actually came from the collapse of the cones of these two volcanoes. When the lava flow spilled out at the base of the slope of the cones, the slope broke up and collapsed under the action of gravity. Later, ravines were formed on the slope. Caved slope clastics, accompanying lava flow, accumulated at the rims of the volcano cones. Although some accumulations may form very large cones, they are not volcanoes, but deposits of volcanic debris avalanches.
基金supported by the National Eleventh Five-Year Plan, Short Term Prediction of Strong Earthquake and a Study on Hazard Relief (No. 2006BAC01B040104), of Chinathe Joint Earthquake Science Foundation of China Earthquake Administration (No. 106052)the State Key Laboratory for Mineral Deposits Research, Nanjing University (No. 12-06-05)
文摘Wudalianchi（五大连池） volcanoes are famous Quaternary ones with fairly good volcanic landscape in Northeast China.The volcanic rocks are phonotephrite,tephri-phonolite,trachyandesite,and basaltic trachyandesite with SiO2 contents of 47.3 wt.%-54.2 wt.%.The characteristic of high K2O content in Wudalianchi volcanic rocks suggests that they probably share a common potassic magma source.The magma evolutions of Wudalianchi volcanic rocks are similar,while the new eruption prod-ucts of Laoheishan（老黑山） and Huoshaoshan（火烧山） volcanoes are slightly more evolved than the old eruption materials,i.e.,the magma of the new eruptions in 1719-1721 from the above two volcanoes is the evolved magma in underground chamber.The main phenocrysts of Wudalianchi volcanic rocks are olivines,clinopyroxenes,and some characteristic K-rich leucites.The various-shaped melt inclu-sions are found in olivine phenocrysts from new eruption products of Laoheishan and Huoshaoshan volcanoes.By electron microprobe（EMP） analyzing,the contents of SiO2 and total alkali show a wide range,suggesting that the pre-eruptive magma was probably more complicated,or the melt inclusions were rather unhomogeneous.On the basis of EMP results,it is believed that the sulfur degassing rate from this new eruption was much higher than that of the millennium eruption of Tianchi（天池） volcano,while the chlorine degassing rate was a magnitude lower than that of Tianchi volcano.
