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地质力学学报:1999,5(3):13-21
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鄂尔多斯块体新生代构造活动和动力学的讨论
(中国地震局地质研究所, 北京 100029)
DISCUSSION ON CENOZOIC TECTONICS AND DYNAMICS OF ORDOS BLOCK
(Institute of Geology, China Seismological Bureau, Beijing 100029, China)
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投稿时间:1999-07-20    
中文摘要: 鄂尔多斯块体除西南边界为挤压边界外,四周被共轭剪切拉张带所围限,东西和南北两侧分别为右旋和左旋剪切拉张带,全新世水平和垂直滑动速率分别达5mm/a和0.3~3mm/a。鄂尔多斯块体自始新世起从西南挤压边界两端开始发育,逐渐向远端发展,至上新世最后形成山西断陷盆地带。新生代以来块体不断缓慢上升,距今1.40Ma以来的隆起总量为160m.形变测量说明块体现代隆升速率为1~2.8mm/a,周缘断陷盆地带现代下降速率为-4~-5mm/a。块体内部莫霍面变化平缓,埋深40km~42km,上地幔高导层埋深123km~131km,它们在周缘断陷盆地带相对隆起,前者隆起幅度1.5km~6km,后者埋深仅70km~100km.6级以上地震均发生在块体周边活动构造带内,块体内部无6级以上地震发生,4~5级地震也很少。震源机制、地应力和断层滑动矢量测量等得到的主压应力方位为NE-NEE向,与控制块体周边活动构造的区域应力场一致,主要与青藏块体的NE向挤压作用相关,盆地地下深部物质上涌产生的垂直力也起着重要作用。所以,区域性水平应力场和深部物质运动产生的垂直力联合作用是本区新构造活动的动力条件。
Abstract:The Ordos block is peripherally surrounded by fault zones and faulted basin zones of Cenozoic age.Its southwestern boundary is a compressional tectonic belt trending NW, along which left-lateral strike-slip fault zones with thrust components, such as the HaiyuanLiupanshan fault zone, and corresponding faulted basins have developed, with both the maximum left-lateral strike-slip rate and the maximum horizontal shortening rate of 10mm/a. Both the Yinchun-Jilantai faulted basin zone of its western boundary and the Shanxi faulted basin zone of its eastern boundary are NNE-trending right-lateral shear zones with extension components, while both the Weihe faulted basin zone of its southern boundary and the Hetao faulted basin zone of its northern boundary are nearly EW-trending left-lateral shear zones with extensional components.All these shear zones have Holocene horizontal and vertical slip rates of 5mm/a and 0.3~3mm/a, respectively.With regard to the history of their development these faulted basin zones have a different timing of initiation.The Weihe and Yinchuan faulted basin zones have at first initiated in Eocene, the Hetao faulted basin zones in Oligocene, and the Shanxi faulted basin zones in Pliocene.During the Cenozoic, the Ordos block has been a situation of slow uplift, with an amount of uplift of 160m since 1.4Ma B.P. For the Ordos internor, the Moho discontinuity is 40~42km in depth, with a gentle variance, and the high conductive layer of the upper mantle is 123~131km in depth, while for the peripheral faulted basin zones of the block, the Moho discontinuity has relatively uplifted about 1.5~6km, and the high conductive layer of the upper mantle is only 70~100km in depth.Deformation analysis from geodetic surveying indicates that the Ordos block and its southwestern boundary area now are still uplifting, with uplift rates of 1~2.8mm/a and 4.4mm/a, respectively, and that the peripheral faulted basin zones are relatively subsiding, with an amount of -4~-5mm/a.Within the internor of the Ordos block, there are a few earthquakes of magnitude 4~5, and no earthquakes magnitude equal to and more than 6. All the earthquakes whose magnitudes are equal to and more than 6 in this area have occurred along peripheral active fault zones and in faulted basin zones.The results of the solutions of mechanism at the sources and the measurments of ground stress and the fault-slip vector indicate that the principle compressional stress in the Ordos area is oriented in NE-NEE, consisting with the regional stress field showed by the kinematic characterics of the peripharal active fault zones of the Ordos block.Such a stress regime may probably come from the Qingzang Block movement which is towards the northeast.On the other hand, the upwelling of deep materials beneath the faulted basins could play an important role in the neotectonic movement of the Ordos block.So the combination of the regional stress field with the upwelling of deep materials controls the dynamics of the Cenozoic Ordos block movements.
文章编号:     中图分类号:P546    文献标志码:
基金项目:国家自然科学基金项目(49672150)
引用文本:
邓起东,程绍平,闵伟,等,1999.鄂尔多斯块体新生代构造活动和动力学的讨论[J].地质力学学报,5(3):13-21.DOI:
DENG Qi-dong,CHENG Shao-ping,MIN Wei,et al,1999.DISCUSSION ON CENOZOIC TECTONICS AND DYNAMICS OF ORDOS BLOCK[J].Journal of Geomechanics,5(3):13-21.DOI:

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