| 活动海岭俯冲对岛弧地质过程的影响 |
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| 引用本文： | 张健,石耀霖.活动海岭俯冲对岛弧地质过程的影响[J].地质力学学报,1997,3(2):1-10. |
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| 作者姓名： | 张健 石耀霖 |
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| 作者单位： | 中国科技大学研究生院地学部, 北京 |
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| 摘 要： | 本文研究了海岭-岛弧体系的地质演化和海岭俯冲过程,通过有限元法对海岭俯冲的全过程进行了热模拟,分析了海岭俯冲过程中岛弧岩浆活动、变质作用及周围地区地表地形的变化。热模拟的计算结果表明:在海岭俯冲之前和俯冲完成之后,摩擦剪切生热使岛弧下100km深度形成温度反转,俯冲海洋板片内角闪岩相矿物在850-1000℃的相对高温下脱水,释放的水进入其上覆板块内热的地幔楔状体降低地幔岩石的熔点造成部分熔融,形成岛弧火山活动;而当热的活动海岭俯冲期间,近海岭处的年轻海洋地壳在较浅深度达到较高温度而提前脱水,原来的地幔楔状体内部分熔融区因缺水而使熔融停止,岛弧火山活动中断。但此时,活动海岭俯冲产生的热将会使前弧一定区域出现低温变质作用。在整个俯冲过程中,随海岭逼近海沟,温度升高,岛弧将因此逐渐抬升,因热作用而致的抬升高度可达440m左右.
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| 关 键 词： | 热模拟 海岭俯冲 岩浆活动 低温变质 岛弧抬升 |
| 收稿时间： | 1997/3/18 0:00:00 |
THE GEOLOGICAL EFFECT OF RIDGE SUBDUCTION IN ARC AREA |
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| Zhang Jian and Shi Yaolin.THE GEOLOGICAL EFFECT OF RIDGE SUBDUCTION IN ARC AREA[J].Journal of Geomechanics,1997,3(2):1-10. |
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| Authors: | Zhang Jian and Shi Yaolin |
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| Institution: | Graduate School, USTC, Academia Sinica, Beijing |
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| Abstract: | Ridge subduction is an important stage of Wilson cycle.If the spreading rate of the active ridge is smaller than the rate of subduction,the subducting oceanic plate will decrease in size,and the ridge itself will be eventually subducted.There are four possible kinematic scenarios of ridge subduction,we investigate one of the possibility:both the leading and the trailing plates are subducted.Subduction of a hot active ridge will significantly affect the thermal state of the subduction zone,and leave tectonic and petrologic signatures.In this study,we use twodimensional finite element method to calculate the thermal consequence of an active ridge subduction.Upwind technique is adopted to secure a stable and accurate solution for advective heat transfer.Frictional/shear heating is included in our modeling.The shear stress is limited by the friction law in the brittle regime and by the flow law in the ductile regime.Sequential changes of temperature created by ridge subduction are calculated,and the resulting geological consequences at arc areas are discussed.The results of computation can well explain cessation of arc volcanism,low-temperature metamorphism,uplift and subsidence of arc-trench margin. |
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| Keywords: | thermal modeling ridge subduction magmatic activity low-temperature metamorphism arc uplift |
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