| 攀西裂谷及邻区构造应力场演化与叠加断裂作用 |
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| 引用本文： | 李兴唐,古迅.攀西裂谷及邻区构造应力场演化与叠加断裂作用[J].地质科学,1988,0(1):25-37. |
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| 作者姓名： | 李兴唐 古迅 |
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| 作者单位： | 中国科学院地质研究所 |
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| 摘 要： | 攀西裂谷形成和演化包含四个构造期:1)加里东期;2)海西晚期;3)印支早期和4)印支晚期。加里东期和海西晚期,地壳受近东西向张应力。印支早期区域张应力方向为北西西—南东东,裂谷断陷。印支晚期构造运动应力特征是北西西—南东东方向压缩,裂谷闭合、消亡。燕山期区域最大主应力方向仍是北西西—南东东。喜山期以块断作用为主。喜山期、燕山期和印支期的构造应力使它们古老的断裂产生叠加断裂作用。
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| 关 键 词： | 深断裂 裂谷 攀西 叠加断裂 |
| 收稿时间： | 1986-02-01 |
| 修稿时间： | 1986-02-01; |
EVOLUTION OF TECTONIC STRESS FIELD IN PANXI RIFT AND ADJACENT AREA WITH REFERENCE TO SUPERIMPOSITION FAULTING |
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| Li Xingtang Gu Xun.EVOLUTION OF TECTONIC STRESS FIELD IN PANXI RIFT AND ADJACENT AREA WITH REFERENCE TO SUPERIMPOSITION FAULTING[J].Chinese Journal of Geology,1988,0(1):25-37. |
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| Authors: | Li Xingtang Gu Xun |
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| Institution: | Institute of Geology, Academia Sinica, Beijing |
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| Abstract: | The Panxi rift was a Caledonian-Indochinese continental paleorift, whose development and evolution can be divided into three stages, i.e. pre-rift, rift and post-rift stages.The pre-rift stage belongs to the Chengjiangian orogeny during which the crust in the rift zone was uplifted and ruptured in the N-S direction.The development and evolution of the rift involved four episodes, i.e. Caledonian (500 -370 Ma. B. P.), Late Herdynian (270-230 Ma. B. P.), Early Indochinese (230-190 Ma. B. P.), and Late Indochinese (190 Ma. B. P.). During the Caledonian the crust was subjected to nearly E-W extensional stress, thus forming nearly N-S striking deep extensional faults as a rift. During late Hercynian episode the rift was further developed and oxpanded, and the abyssal extensional and shear-extensional fractures came into appearance in the area studied. During this episode the regional tensile stress was in the NWW-SEE direction and the magnitude of the stress was more of less increased in comparison with that of the Caledonian. During Early Indochinese episode the regional extensional stress was directed NWW-SEE and the rift was subsided.From Caledonian to Early Indochinese episodes the diastrophism was characterized by vertical uplift and subsidence; and nearly horizontal tensile stress directed in NWW and NW was dominant. As a result, nearly N- and NE- striking extensional fractures and rift were formed. The later superimposed faults were also extensional in nature. For this reason the rift could be further developed and expanded. Furthermore, such stress conditions might be due to E-W or NW extension exerted by the adjacent tectonic units to the West and the North.The Late Indochinese tectonic movement made the most of the area compressed and large-seale horizontal movement taking place. The deformation of rocks was manifested as NNE-and NE- trending folds, nappe structure, thrusts and the southeastward sliding of the sedimentary cover over the basement. The tectonic stress of this stage was characterized by the joint action of NWW-SEE compression and NNE-SSW extension. The stress originated from the eastward subduction of the oceanic plate to the west and northwest. In such stress conditions the previous NNE- and NE- striking extensional faults were changed to be compres-sional or shear-compressional in nature. As a consequence the rift was closed, vanished and came to an end.After the rift failed, the area studied was subjected to the Yanshanian and Himalayan movements with the former as the predominant one. The maximum principal compressional stress was NWW-SEE trending and produced folds and faults. The Himalayan movement was dominated by block-faulting leading to the whole area uplifting and local fault-depression. |
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| Keywords: | deep faults rift Panxi superimposition faulting |
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