| 大陆岩石圈在张裂和分离时的变形模式 |
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| 引用本文： | 姚伯初.大陆岩石圈在张裂和分离时的变形模式[J].海洋地质与第四纪地质,2002,22(3):59-67. |
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| 作者姓名： | 姚伯初 |
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| 作者单位： | 广州海洋地质调查局,广州,510075 |
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| 基金项目： | 国家重大基础研究发展计划资助项目 (G2 0 0 0 0 4670 5 ) |
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| 摘 要： | 通过对南海南北共轭边缘地壳剖面的对比研究，发现大陆岩石圈的物理性质是分层的：上、中地壳呈脆性，下地壳表现出塑性，而岩石圈上地幔则仍呈脆性。因此，在它受张性应力场作用时，其变形和破裂分离方式也是分层进行的：上、中地壳能发生犁式断裂，产生的断块沿断面转动在地表产生一系列半地堑，并使地壳厚度减薄；如拉张应力继续作用时，上、中地壳将沿犁式断裂被拉开，从而形成上、下板块边缘，并彼此分开。下地壳则发生塑性变形，使地壳厚度减薄，并最终将其拉断。岩石圈上地幔亦可产生陡倾断裂，形成的断块沿断面转动亦使其厚度减薄，并最终沿陡倾断裂被拉断。这就是我们称之为岩石圈变形和破裂分 离时的分层变形及分层破裂分离模式。
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| 关 键 词： | 大陆岩石圈 张裂 分离 变形模式 脆性 塑性 南海 |
| 文章编号： | 0256-1492(2002)03-0059-09 |
| 修稿时间： | 2001年12月24 |
DEFORMATION CHARACTERISTICS OF CONTINENTAL LITHOSPHERE WHEN RIFTING AND BREAKING-UP |
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| YAO Bo,chu.DEFORMATION CHARACTERISTICS OF CONTINENTAL LITHOSPHERE WHEN RIFTING AND BREAKING-UP[J].Marine Geology & Quaternary Geology,2002,22(3):59-67. |
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| Authors: | YAO Bo chu |
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| Abstract: | We have studied characters of the crustal profiles on the margins of the southern and northern sides of the South China Sea.According to the seafoor spreading history of the South China Sea,these two margins are conjugate ones.We find that the continental lithosphere are subdivided into three sub layers in physical nature.Therefore,when the extensional stress field affects the lithosphere,it should deform in the form of three layers.Crustal profiles between northern and southern margins are different.In the northern profile,there are a lot of normal faults in the upper crust,and many faults of them have extended to the surface between middle and lower crust,and it then becomes a shear zone.In the lower crust there are no faults,but many sub horizontal reflections exist.In the lithospheric upper mantle,there exist steeply inclining fault reflections.The upper crust there only has one layer whose internal velocity is 6 0 km/s,and is short of 5 2~5 6 km/s crustal layers.In the crustal profile of the southern margin in the Liyue Bank,the water depth is 300 m,and drops steeply to 4 000 m,20 km northwards.Six faults steeply inclining northward exist in the upper crust within 20 km distance.Therefore,we believe that the continent lithosphere of South China block has rifted and broken into three layers:the upper and middle crustal layers have rifted and broken up according to brittle style of faulting;the lower crust has deformed and broken down in ductile form;the lithospheric upper mantle has rifted and broken up in faulting style.We call our lithospheric deformation style "the layered shear and broke up model".Our model is different from Mckenzie's pure shear model and Wernicke's simple shear model. |
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| Keywords: | lithosphere brittle ductile deformation rifting the South China Sea |
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