山东临朐、昌乐地区晚第三纪火山地貌

山东临朐、昌乐地区是渤海盆地南缘,郯庐断裂带中段西侧晚第三纪火山地貌集中分布的地区之一。本文对区内火山地貌类型和地貌发育过程作了重点探讨。

THE NEOCENE VOLCANIC LANDFORMS IN LINQU AND CHANGLO DISTRICTS OF SHANDONG PROVINCE

This paper gives a preliminary analysis on the types and evolutional processes of the volcanic landforms in the area of Linqu and Chanhlo.According to the topographic features, genesis, and material components, the volcanic landforms in this area can be divided into the following types. i. volcanic cones-including caldera cones, composite cones and lava cones, ii. lava landforms-including lava domes., inclined lava plateau, lava mesas, erosion and denudation lava hills.Most types of landforms mentioned above are distributed along the NW dierction of faults., The lava cones and mesas have been mainly discussed in the paper.Volcanoes and lava landforms are formed from Miocere to early pliocene in the area. According to the types and intensity of volcanic activities, etc, the geomorphic developing processes in the area are divided into three stages.i. Early Miocene. The volcanic activities of this period are characterized by fissure eruption, and the wide lava plateaus are shapedii. Mid-Miocene. The volcanic activity is featured by relative stability. In most lake basins of the area, it takes form of the lake-facies deposit which contains rich fossils of plants and animals.iii. From late Miocene to early pliocene. The volcanoes erupt as centers, and form many lava cones on the lava plateaus of early Miocene.Since the early pilcene, the crust has risen, The lave plateaus have been eroded by the running water, and hava gradually become mesas and hills.