内蒙达里诺尔火山群晚第四纪火山地质特征与岩浆裂隙通道研究

Study on volcanic geology characteristics and magma feeding fractures of Late Quaternary volcanoes in Dalinor volcanic field,Inner Mongolia

达里诺尔火山群位于中亚造山带中部以及大兴安岭-太行山重力梯度带中部的西侧。该区拥有上百座第四纪火山,其中不乏全新世仍有过喷发的年轻火山。本文选取以鸽子山、锡塔特乌拉等形成时代最晚,推测形成于中更新世晚期至全新世的晚第四纪火山作为研究对象,从火山锥形貌和定向排列两方面推断岩浆补给裂隙通道的几何特征。结果发现,这些火山具有较为一致的NE和NEE两个方向的裂隙通道。这些方向与区域构造最大主压应力方向相近。本文提出在NE向区域主压应力作用下,在研究区域发生NEE走向的左行剪压走滑。在这个走滑带上,瑞德尔断裂提供岩浆补给裂隙通道。而局部连通瑞德尔断裂的断裂提供了NEE向通道。

Dalinor volcanic field is located in the middle of the Central Asia Orogen Belt, and on the west of middle part of Greater Hinggan Mt.-Taihang Mt. Gravity Lineament. It is composed of more than one hundred volcanoes, which erupted since Pliocene to Holocene period. This study focused on the magma feeding fractures of Late Quaternary volcanoes based on two lines of evidence：crater elongation and cone alignments. The data revealed NE and NEE were two preferred azimuths for these feeding fractures, consistent with the azimuth of regional maximum principal stress. It is inferred that a NEE trending sinistral transpressional stress field worked on the study area. The resulting Reidel fractures and Y fractures provided the favorable path for magma upwelling.