期刊文献+
共找到6篇文章
< 1 >
每页显示 20 50 100
地幔Sr-Nd-Pb同位素演化的综合模型与n维同位素空间“地幔面”的地质意义
1
作者 隋建立 樊祺诚 +1 位作者 赵勇伟 杜星星 《岩石学报》 SCIE EI CAS CSCD 北大核心 2008年第11期2615-2620,共6页
在 n 维的 Sr-Nd-Pb 同位素空间中,几乎所有的大洋中脊玄武岩(MORB)和洋岛玄武岩(OIB)都落在一个虚拟平面上,被称为"地幔面(mantle plane)"。"地幔面"描述了大部分玄武岩的同位素地球化学特征,是最重要的、也是最... 在 n 维的 Sr-Nd-Pb 同位素空间中,几乎所有的大洋中脊玄武岩(MORB)和洋岛玄武岩(OIB)都落在一个虚拟平面上,被称为"地幔面(mantle plane)"。"地幔面"描述了大部分玄武岩的同位素地球化学特征,是最重要的、也是最早提出的地幔动力学演化特征之一,但是长期以来关于"地幔面"的内涵和意义并不清楚。本文通过一个综合模型,反演受岩浆作用控制的地幔微量元素(包括各种同位素母体元素)分异、Sr-Nd-Pb同位素演化,并推导出地幔 Sr-Nd-Pb 同位素演化的二元参数方程形式。模型表明,通过部分熔融向地壳输出相对富硅、富碱的物质成分,是地幔长期演化的主要特点,这个过程受到两个参数—部分融融程度(F)和岩浆分离的时间(t)—的控制,即 n 维参数可化为2维,因此在 n 维同位素空间出现"地幔面"的特征。壳源物资循环,能够使局部地幔偏离"地幔面",就地幔总体统计特征而言,地壳混染的比例很低,不同的统计数据显示大约1%~6%的系统偏差,即可能的地壳混染程度;进一步模拟,可能作出更加精确的估算。 展开更多
关键词 地幔面 SR-ND-PB同位素 大洋玄武岩 化学地球动力学 部分熔融
下载PDF
超级地幔树对全球构造的控制作用
2
作者 於文辉 何发岐 +6 位作者 袁茂山 王杰 刘德民 张世晖 卞爱飞 杨屿 杨力行 《地质学报》 EI CAS CSCD 北大核心 2024年第3期653-661,共9页
全球横波低速异常体成像发现:Jason超级地幔柱与Tuzo超级地幔柱彷佛植根于地球外核顶部、生长在核幔边界(core-mantle boundary,CMB)上的两株榕树,我们将其命名为超级地幔树(super mantle tree),以突出Jason超级地幔柱与Tuzo超级地幔柱... 全球横波低速异常体成像发现:Jason超级地幔柱与Tuzo超级地幔柱彷佛植根于地球外核顶部、生长在核幔边界(core-mantle boundary,CMB)上的两株榕树,我们将其命名为超级地幔树(super mantle tree),以突出Jason超级地幔柱与Tuzo超级地幔柱连接地核与地壳的纽带特征,强调它们在地球演化过程中对全球构造的作用。地幔柱仅是超级地幔树的局部分支。我们定义超级地幔树为4层结构:(1)植根于地球外核顶部;(2)1600~2890 km为“树干”;(3)110~1600 km为“树冠”;(4)110 km以上为“树枝”。“树枝”平面分布形态与全球板块轮廓大致相似,意味着板块构造可能起始于地球110 km处。推测地球深度1550~1600 km之间可能存在一个地球化学过渡层;Jason超级地幔树与Tuzo超级地幔树之间可能存在地球化学分隔面(简称地幔分隔面),地幔分隔面将地球划分为太平洋半球与大西洋半球;它的地面投影北端大致指向地磁北极,南端基本指向地磁南极。外核顶部脉动作用可能是地幔运动的动因,地核运动控制地幔运动。Tuzo超级地幔树逆时针旋转控制大西洋半球旋转形态,Tuzo超级地幔树的“细树干”伸向南大西洋,Tuzo超级地幔树“粗树干”伸向北大西洋,使得中大西洋脊减薄。Jason超级地幔树顺时针旋转控制太平洋半球旋转形态以及环太平洋地区地貌构造形态。青藏高原及邻区地质地球物理三维构造模型说明:向北运动的Tuzo超级地幔树“树枝”与向西运动的Jason超级地幔树“树枝”共同作用,形成青藏高原东构造结。 展开更多
关键词 超级地幔 全球构造 地幔分隔 地幔运动 青藏高原三维构造模型
下载PDF
利用海底电缆探测太平洋地区地幔结构的研究进展
3
作者 梁朋飞 师学明 《地球物理学进展》 CSCD 北大核心 2013年第3期1584-1595,共12页
介绍了地幔电性结构、地幔温度、地幔含水量等参数对地球动力学和地幔动力学过程的重要科学意义,综述了近年来利用海底电缆在该领域的主要研究进展.本文首先介绍了日本利用海底电缆探测地幔深部结构的方法原理与发展历程,然后阐述了该... 介绍了地幔电性结构、地幔温度、地幔含水量等参数对地球动力学和地幔动力学过程的重要科学意义,综述了近年来利用海底电缆在该领域的主要研究进展.本文首先介绍了日本利用海底电缆探测地幔深部结构的方法原理与发展历程,然后阐述了该方法的观测方式、观测系统与仪器,综述了国际上近年来利用海底电缆在环太平洋地区海底的观测资料进行地幔一维电导率结构、三维电导率分布的研究进展.基于海底电缆的观测数据进行反演的结果表明,太平洋海域地区地球深部存在410km,660km的电导率不连续面,此不连续面与地震资料的波速不连续面基本一致,为地幔不连续面提供了新的地球物理证据.在根据由海底电缆观测数据反演得到的太平洋地区地球内部电导率分布基础上,综述了综合深部地震波速、岩石高温高压实验等,将电导率的分布转换为地球内部的温度场分布、推导地幔过渡带水的浓度进而转换为地幔过渡带的含水百分比(含水量)的方法技术与研究进展.研究结果表明,夏威夷和北日本海地幔过渡带电导率异常主要受温度控制,菲律宾海域地幔过渡带的电导率异常除了和温度有关外,还受含水量影响,该处地幔过渡带的含水量大约在1%左右.这些研究表明,海底电缆探测方法,在地球深部探测尤其是地幔不连续面的探测、地幔温度场分布与特征、地幔含水量等方面有重要的作用.最后,展望了海底电缆探测方法的研究与发展,这些研究方法及成果对认识中国海域地球内部机构提供一定的参考. 展开更多
关键词 海底电缆技术 壳幔结构 电导率模型 含水量 地幔不连续
下载PDF
S-wave Q structure of the crust and upper mantle beneath Yunnan from surface waves 被引量:4
4
作者 CHEN Jia HU JiaFu +3 位作者 YANG HaiYan ZHANG XiaoMan WEN LiMin PENG HengChu 《Science China Earth Sciences》 SCIE EI CAS 2012年第5期858-868,共11页
A phase-matched filtering technique is applied to extract fundamental mode signals from Rayleigh waves recorded at 62 digital seismic stations in the Yunnan and Sichuan regions.We use the fundamental mode of vibration... A phase-matched filtering technique is applied to extract fundamental mode signals from Rayleigh waves recorded at 62 digital seismic stations in the Yunnan and Sichuan regions.We use the fundamental mode of vibrations at two stations that are located on the same great circle as the focus to calculate an inter-station attenuation coefficient of the Rayleigh wave with periods between 0.40 and 80.64 s,and invert for the inter-station S-wave Q-factor (Qβ) at depths of 0-200 km.The results indicate that Qβ in Yunnan is 20-140,presenting a low Qβ background with apparent lateral variation.Taking the Honghe Fault as the boundary,Qβ of the crust is only 20 on the west side,extending to a depth of 120 km.The distribution of Qβ is consistent with large-scale Cenozoic volcanic and intrusive rocks in western Yunnan,implying that the crust and mantle are in the thermally active state.In the eastern Yunnan Block,east of the Xiaojiang Fault,Qβ in the upper 120 km is 140 in the south but only 20 in the north.Additionally,around the Dukou-Chuxiong in the mid-Yunnan Block,Qβ in the lithosphere is relatively high at 60-100,corresponding to a stiff crust.This is because the suture between the Indian and Eurasian plates reversed the tension in the rifting stage into the compression of orogenesis,leading to the closure of a gap in the crust.After some time,interstitial fluids gradually disappeared,resulting in a high velocity layer in the crust and low heat flow on the surface.The Yunnan region consists of an obvious block of elevated Qβ,distributed within the low background,consistent with the distribution of heat-flow values on the surface.The Honghe and Xiaojiang faults are tectonic boundaries in addition to being boundaries between regions of high and low crustal Qβ.The low Qβ is probably the result of crustal rupture and disturbance caused by strong earthquakes and the upwelling of hot substances along the deep fault zones. 展开更多
关键词 Yunnan region attenuation of surface wave phase-matched filtering S-wave Q-factor
原文传递
Mid-mantle water transportation implied by the electrical and seismic properties ofε-FeOOH
5
作者 Yukai Zhuang Bo Gan +8 位作者 Zhongxun Cui Ruilian Tang Renbiao Tao Mingqiang Hou Gang Jiang Catalin Popescu Gaston Garbarino Youjun Zhang Qingyang Hu 《Science Bulletin》 SCIE EI CSCD 2022年第7期748-754,共7页
Water in the mantle transition zone and the core-mantle boundary plays a key role in Earth’s stratification,volatile cycling,and core formation.If water transportation is actively running between the aforementioned l... Water in the mantle transition zone and the core-mantle boundary plays a key role in Earth’s stratification,volatile cycling,and core formation.If water transportation is actively running between the aforementioned layers,the lower mantle should contain water channels with distinctive seismic and/or electromagnetic signatures.Here,we investigated the electrical conductivity and sound velocity ofε-FeOOH up to 71 GPa and 1800 K and compared them with global tomography data.An abrupt threeorder jump of electrical conductivity was observed above 50 GPa,reaching 1.24(12)×10^(3)S/m at 61 GPa.Meanwhile,the longitudinal sound velocity dropped by 16.8%in response to the high-to-low spin transition of Fe^(3+).The high-conductivity and low-sound velocity ofε-FeOOH match the features of heterogenous scatterers in the mid-lower mantle.Such unique properties of hydrousε-FeOOH,or possibly other Fe-enriched phases can be detected as evidence of active water transportation in the mid-lower mantle. 展开更多
关键词 Mid-lower mantle Electrical conductivity Seismic velocity HETEROGENEITY
原文传递
The ONAD method for solving the SH-wave equation and simulation of the SH-wave propagation in the Earth's mantle
6
作者 LI XiaoXiao YANG DingHui TONG Ping 《Science China Earth Sciences》 SCIE EI CAS 2013年第6期913-921,共9页
The optimal nearly-analytic discrete(ONAD) method is a new numerical method developed in recent years for solving the wave equation.Compared with other methods,such as popularly-used finite-difference methods,the ONAD... The optimal nearly-analytic discrete(ONAD) method is a new numerical method developed in recent years for solving the wave equation.Compared with other methods,such as popularly-used finite-difference methods,the ONAD method can effectively suppress the numerical dispersion when coarse grids are used.In this paper,the ONAD method is extended to solve the 2-dimensional SH-wave equation in the spherical coordinates.To investigate the accuracy and the efficiency of the ONAD method,we compare the numerical results calculated by the ONAD method and other methods for both the homogeneous model and the inhomogeneous IASP91 model.The comparisons indicate that the ONAD method for solving the SH-wave equation in the spherical coordinates has the advantages of less numerical dispersion,small memory requirement for computer codes,and fast calculation.As an application,we use the ONAD method to simulate the SH-wave propagating between the Earth's surface and the core-mantle boundary(CMB).Meanwhile,we investigate the SH-wave propagating in the mantle through analyzing the wave-field snapshots in different times and synthetic seismograms. 展开更多
关键词 numerical dispersion spherical coordinates SH wave ONAD method MANTLE
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部