| 控制中国东部中-新生代盆地的铲形断裂构造 |
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| 摘要点击次数: 1887 |
| 全文下载次数: 1940 |
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| THE LISTRIC FAULT STRUCTURES CONTROLLING THE FORMATION AND EVOLUTION OF MESOZOIC-CENOZOIC BASINS IN EAST CHINA |
| According to length of extension, cutting depth, intensity of activity, sequence of formation and different roles in controlling the basins, the faults may be divided into basement faults and syndepositional ones.Basement faults refer to those that control the formation and distribution of the basins, and often make up boundaries of these basins or of the se-condorder structure units within them. They are characterized by early occurrence, prolonged activity, long extension, large throw and, consequently, greater cutting depth.Syndepositional faults refer to some faults in the basin which occurred somewhat later than the basement faults. They are of smaller extension and cutting depth; their downward extension usually fails of reach the basement of the basin, and gradually disappears in the sedimentary cover. It is obvious that they have controlled such sedimentation as lithofacies and variation of thickness in the basin.These two types of faults not only were extensively distributed but also occurred in great quantities in the process of the formation and evolution of the Mesozoic-Ceuozoic basins in east China. As for the characteristics of their forms, the fault surfaces are generally curved upward, and become gentle in dip with depth, possessing the features of normal fault. Therefore, they are called listric faults.Some ideas are put forward in this paper as to the formation mechanism this sort of listric faults as well as their association with the extension of the basins: 1. The formation of the listric basement faults is closely related to the "thermal events". The transmission of thermal energy from the asthenosphe-re to the earth's crust softens the lower part of the crust and makes it ductile, with the ductility dependent on the temperature. As the temperature rises with the depth, it is reasonably presumed that the ductility will increase to some extent at the greater depths of the crust. A preferred interpretation nowadays is that the listric faults formed through extension in the brittle upper crust was actually the products of ductile stretching in the lower crust, while the formation of the basins was controlled by these faults. 2. On the base of the listric basement fault, there may further occur the listric growth fault. Their formation mechanism was remarkably different from the listric basement fault in that they not only were controlled by extension, buy, what is more important, could be formed mainly as a result of gravity or pressure difference of sediments. This sort of faults are rather widespread in Mesozoic-Cenozoic basins in east China. 3. In the large-size basins of east China, the downward extension or the bottom of the listric normal faults is generally in the range of 5-15 km below the surface, as can be examplified by the well-known Cangdong and Shengbei basement faults. 4. Jn the basin controlled by extension and stretching, the original geological boundaries, such as bedding surface, boundary between the cover and the basement, and large paleofault surface, might have played an important xole in the formation and distribution of the listric fault system. |
| FU De-rong.1987.THE LISTRIC FAULT STRUCTURES CONTROLLING THE FORMATION AND EVOLUTION OF MESOZOIC-CENOZOIC BASINS IN EAST CHINA[J].Acta Geoscientica Sinica,9(3):33-48. |
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