黑龙江五大连池陆相枕状熔岩的特征及其形成机制

THE CHARACTER AND THE FORMATION OF THE WUDALIANCHI CONTINENTAL PI LLOW LAVA

五大连池火山群位于黑龙江省黑河地区德都县境内,在讷谟尔河以北的玄武岩台地上,方圆600平方公里。 五大连池火山最后一次喷发是在1720年,形成了老黑山和火烧山。以白垩纪下统的砂页岩,海西期花岗岩和更新统的旧期玄武岩为基底,由老黑山和火烧山火口四周溢出熔岩流,特别向南蜿蜒流动,形成貌似“石龙”的熔岩,人们称之为“石龙”熔岩。

It is recognized that pillow lava is of marine facies, but in fact there is continental pillow lava too. During the volcan Carem eruption in 1963, B.B. Ywanorve had observed the andesite-dacite lava flow formed pillow lave. The writer had found similar pillow lava around the Wudalianchi extinctive volcano.The pillow lava was seen on the top surface, the sides and the front of the Shih-lunite. The pillow structure takes shape in steamed bun, ball, ellipsoid, pillow, bag. tongue, etc. The size is generally of (0.3-1.5)×(1 - 5)m. They are superimposed on each other and down like a stair case with the bottom sticky to the lava basement. The surface of the pillow structure is made into the shape of paratle wrinkles ripples and strings, In ternally they reveal concentric structure with cavity at the centre. Radiating cracks and discontinous ring cracks are always to be seen.The formation of the pillow lava is conditioned by the tensile stress occurring in the lava in quick flowing and slow cooling on the land surface.