地理科学 ›› 1982, Vol. 2 ›› Issue (2): 125-134.doi: 10.13249/j.cnki.sgs.1982.02.125

• 论文 • 上一篇    下一篇

巴基斯坦波特瓦尔高原构造地貌研究

徐叔鹰, 李吉均, 艾南山   

  1. 兰州大学地质地理系
  • 出版日期:1982-03-20 发布日期:1982-03-20

STUDIES OF THE STRUCTURAL LANDFORMS OF THE POTWAR PLATEAU,PAKISTAN

Xu Shuyihg, Li Jijun, Ai Nanshan   

  1. Department of Geology and Geography, Lanzhou University
  • Online:1982-03-20 Published:1982-03-20

摘要: 西喜马拉雅山前的波特瓦尔(Potwar)高原是亚洲南部晚新生代标准地层——著名的西瓦利克(Siwalik)沉积最发育的区域。它位于巴基斯坦北部,在喜马拉雅山和旁遮普(Punjab)平原之间狭长地带的西端。

Abstract: The Potwar Plateau in the north of Pakistan is the region where the Siwalik Group(regarded as the standard strata of Late Cenozoic in South Asia)is most widely distributed and the part most recently uplifted in the Himalayan Orogenic Zone.The two of the writers(Xu and Li)have had the opportunity of visiting this region during the summer of 1980.Basing on our own on the spot invostiga-tion and the works of predecessors,we attempt to make a systematic exposition of the structural relief and its evolution in the region investigated.The Siwalik Group was deposited during the period from middle Miocene to middle Pleistocene dated as 10.2—1.8 m.y.B.P.by paleomagnetic data.The lower beds of this group are fine clastics,but on the top,they change abruptly to boulder beds dated as 1.8 m.y.B.P..The temporal and spatial variations in the rate of deposition in the Siwalik Group reflect the uplift history and the extent of the Himalayan Orogenic Zone.The Potwar Plateau belongs to one of the blocks of the imbricating thrust faults of the Himalaya-Salt Range.The times of intensive activity of its southern principal border fault and its northern front fault have been dated as 2 and 0.7—0.4 m.y.B.P.respectively.The time when the Siwalik Group was first folded is dated as 2.7—1.2 m.y.B.P..While its turning into hills is dated as 1.5—0.4 m.y.B.P..The rate of uplift has been increasing.Judging from the variations of sedimentary facies of the Group with time and the time of faulting activities,we can consider that the two peneplains in this re-gion were formed in the early Pliocene and in the early Pleistocene respectively.The general altitudes of these peneplains are 1600m and 500m.above sea level.They form the bases for the later relief evolution in the foreland of the Himalayas and in the Potwar Plateau.In early Pleistoncene the Potwar Plateau was deeply dissected by the Indus and its tributaries forming 3—5 terraces.It has been determined from the valley trends of this region that the principal compression diretion of the neotectonic stress field of the region in question is N 10°E showing that the Indian Plate is moving due north to collide with the Asian Plate.