| 西北太平洋边缘海热流特征研究 |
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| 引用本文： | 蒋德鑫,姜鹍鹏,张贺,姜正龙.西北太平洋边缘海热流特征研究[J].现代地质,2020,34(1):117-129. |
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| 作者姓名： | 蒋德鑫 姜鹍鹏 张贺 姜正龙 |
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| 作者单位： | 1.中国地质大学(北京) 海洋学院,北京 1000832.中国地质调查局 油气资源调查中心,北京 100083 |
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| 基金项目： | 中国地质大学(北京)发展基金项目(F13011) |
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| 摘 要： | 西北太平洋各边缘海及其相应俯冲系统受深部构造活动等地质条件的控制,热流变化较大。在收集整理该区域最新的热流数据基础上,重点探讨西北太平洋俯冲带热结构相关理论、边缘海大洋岩石圈热演化理论模型和局部高异常热流的影响因素,总结了西北太平洋边缘海热流所反映的地质意义。研究结果表明,在西北太平洋“沟-弧-海”体系中,从“沟”到“弧”再到“边缘海”,热流密度呈“低-高-较高”的变化趋势,弧后地区整体表现为“均一高热”特征;千岛海沟、日本海沟和琉球海沟热流密度值在30.0 mW/m2左右,而对应的岛弧值为其2~3倍。弧后热流大小受到汇聚型俯冲带热结构的影响,俯冲带脱水作用导致的弧后上地幔黏度变化,地震速度降低,岩石圈弹性厚度减薄,引起小尺度地幔对流,形成弧后“均一高热”的热状态。热流的时空分布与岩石圈年龄也有关,随着岩石圈年龄增大,地表热流密度值会随之降低,热流密度值大小和离散性与其形成时间大致呈负相关。鄂霍次克海形成时代(30~65 Ma)较早,其热流密度值(86.8 mW/m2)和离散性(标准差3.727)相对较低;冲绳海槽目前还处于扩张阶段,其热流密度值(139.0 mW/m2)和离散性(标准差7.001)较高。浅层的地下水循环、断裂活动,深层的地幔部分熔融岩浆活动、弧后小尺度地幔对流、俯冲带拐角流等对局部异常热流起到一定程度的控制作用。
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| 关 键 词： | 边缘海 热流密度 “沟-弧-海”体系 热结构 俯冲作用 |
| 收稿时间： | 2018-09-30 |
| 修稿时间： | 2019-06-27 |
Heat Flow Characteristics in Marginal Seas of the Northwestern Pacific Ocean |
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| JIANG Dexin,JIANG Kunpeng,ZHANG He,JIANG Zhenglong.Heat Flow Characteristics in Marginal Seas of the Northwestern Pacific Ocean[J].Geoscience——Journal of Graduate School,China University of Geosciences,2020,34(1):117-129. |
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| Authors: | JIANG Dexin JIANG Kunpeng ZHANG He JIANG Zhenglong |
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| Institution: | 1. School of Ocean Sciences, China University of Geosciences, Beijing 100083,China2. Oil and Gas Survey, China Geological Survey, Beijing 100083,China |
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| Abstract: | In this study,we combined the latest collected heat flow data to illustrate the heat flow characteristics of the marginal seas and their corresponding subduction systems in the northwestern Pacific Ocean.We analyzed the relationship between the heat flow distribution and the geological background of the deep tectonic activities,mainly focusing on the thermal structural theory of Northwestern Pacific subduction zone,the theoretical model of the thermal evolution of the marginal oceanic lithosphere,and the controlling factors of the local high anomalous heat flow.We summarized the geological significance of the heat flow in the northwestern Pacific Ocean.The results show that the heat flux is characterized by“low-high-relatively high”from“trench”to“arc”to“marginal sea”of the“Trench-Arc-Sea”system in the northwestern Pacific Ocean,and overall the back-arc region is uniformly hot.Heat flux of the Kuril-Kamchatka,Japan and Ryukyu trenches is about 30.0 mW/m2,and their corresponding island arc heat flux value is two to three times above this value.The back-arc heat flow is likely affected by the thermal structure of the subduction zone.The small-scale mantle convection,caused by the changes of upper mantle viscosity because of the subducting slab dehydration,the decrease of seismic velocity and the lithosphere elastic thickness,can explain the uniformly-hot thermal state in the back-arc environment.The spatial-temporal heat flux distribution is also related to the age of the lithosphere.As the age of the lithosphere increases,the surface heat flux decreases.Magnitude and dispersibility of the heat flux in the marginal seas are in general negatively correlated with their formation time.Formation of the Sea of Okhotsk is relatively early(30-65 Ma),and thus the heat flux(86.8 mW/m2)and standard deviation(3.727)are relatively low.In contrast,the Okinawa Trough is still expanding,thus its heat flux(139.0 mW/m2)and standard deviation(7.001)are relatively high.Shallow groundwater circulation,fault,partial melting and magma activity in the deep mantle,small-scale mantle convection and the corner flow likely control the local anomalous heat flow in the back-arc systems. |
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| Keywords: | marginal sea heat flux “Trench-Arc-Sea”system thermal structure subduction |
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