检索结果-南通市图书馆

Origin of the llsvps at the base of the mantle is a consequence of plate tectonics-A petrological and geochemical perspective

引用

Geoscience Frontiers 2018年第5期9卷 1265-1278页

作者： Yaoling Niu China University of Geosciences Beijing 100083China Department of Earth Sciences Durham UniversityDurhamDH1 3LEUK Laboratory for Marine Geology Qingdao National Laboratory for Marine Science and TechnologyQingdao 266061China Institute of Oceanology Chinese Academy of SciencesQingdao 266071China

In studying the petrogenesis of intra-plate ocean island basalts(OIB) associated with hotspots or mantle plumes, we hypothesized that the two large-low-shear-wave-velocity provinces(llsvps) at the base of the mantle beneath the Pacific(Jason) and Africa(Tuzo) are piles of subducted ocean crust(SOC)accumulated over Earth's history. This hypothesis was formulated using petrology, geochemistry and mineral physics in the context of plate tectonics and mantle circulation. Because the current debate on the origin of the llsvps is limited to the geophysical community and modelling discipline and because it is apparent that such debate cannot be resolved without considering relevant petrological and geochemical information, it is my motivation here to objectively discuss such information in a readily accessible manner with new perspectives in light of most recent discoveries. The hypothesis has the following elements:(1) subduction of the ocean crust of basaltic composition to the lower mantle is irreversible because(2) SOC is denser than the ambience of peridotitic composition under lower mantle conditions in both solid state and liquid form;(3) this understanding differs from the widespread view that OIB come from ancient SOC that returns from the lower mantle by mantle plumes, but is fully consistent with the understanding that OIB is not derived from SOC because SOC is chemically and isotopically too depleted to meet the requirement for any known OIB suite on Earth;(4) SOC is thus the best candidate for the llsvps, which are, in turn, the permanent graveyard of SOC;(5) the llsvps act as thermal insulators, making core-heating induced mantle diapirs or plumes initiated at their edges, which explains why the large igneous provinces(LIPs) are associated with the edges of the llsvps;(6) the antipodal positioning of Jason and Tuzo represents the optimal momentum of inertia, which explains why the llsvps are stable in the spinning Earth.

关键词： llsvps Subducted ocean crust Subducted mantle lithosphere No superplumes Mantle chemical differentiation Optimal momentum of inertia

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

llsvps与全球热点空间叠置性再分析

引用

地质学报 2022年第12期96卷 4140-4148页

作者：党牛余星胡航许绪成何虎余娅娜福建师范大学地理科学学院福建福州350007 自然资源部海底科学重点实验室自然资源部第二海洋研究所浙江杭州310012 浙江大学海洋学院浙江舟山316021

地震层析成像显示在非洲和太平洋之下的核幔边界处(~2800km)存在两个大型低剪切波速省(llsvps),分别被命名为Tuzo和Jason,指示温度或成分的异常。前人通过研究发现,大火成岩省喷发的古位置以及现今活动热点位置多位于llsvps边界±10°... 详细信息

地震层析成像显示在非洲和太平洋之下的核幔边界处(~2800km)存在两个大型低剪切波速省(llsvps),分别被命名为Tuzo和Jason,指示温度或成分的异常。前人通过研究发现,大火成岩省喷发的古位置以及现今活动热点位置多位于llsvps边界±10°附近。由此,基于空间相关性,将llsvps狭窄的边界视为地幔热柱生成区,广泛用于解释地幔柱与热点的成因。但是,将一个深度2800km的地球物理异常与地表热点建立联系,仍存在诸多不确定性。而且llsvps作为全球尺度的异常区,在地表的映射范围巨大,不可避免地与大量热点存在天然的空间叠置性,这种空间关联的程度以及是否具有成因联系仍然未知。本文考虑随机状态下热点落入llsvps范围的概率,对全球热点与llsvps边界重新进行空间分析,判断两者之间的空间叠置性。统计结果显示,全球热点与llsvps边界的空间相关性不及预期,Tuzo和Jason之间存在较大差异,Jason与热点缺乏空间位置相关性,而Tuzo与热点空间相关性较强。热点的分布与成因可能并不完全受控于llsvps。研究结果对普遍认为的llsvps与热点分布之间的强相关性提出质疑,在具体的热点和地幔柱成因研究中,不能盲目认为热点与llsvps有关,而需要更加审慎的关注地质事实本身。

关键词： llsvps 全球热点热柱生成区地幔柱空间相关性

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

下地幔CaSiO_(3)钙钛矿的稳定性及其对llsvps的启示

引用

矿物学报 2022年第1期42卷 121-128页

作者：肖婷婷张飞武中国科学院地球化学研究所矿床地球化学国家重点实验室贵州贵阳550081 中国科学院大学北京100049

llsvps的成因是当前固体地球科学研究的前沿热点,对这一成因的认识仍然存在很大的争议。认识llsvps的成因,对了解全球地幔对流性质、下地幔热结构以及化学物质的运输和演化等具有重要的科学意义。CaSiO_(3)钙钛矿(Ca-Pv)作为下地幔最丰... 详细信息

llsvps的成因是当前固体地球科学研究的前沿热点,对这一成因的认识仍然存在很大的争议。认识llsvps的成因,对了解全球地幔对流性质、下地幔热结构以及化学物质的运输和演化等具有重要的科学意义。CaSiO_(3)钙钛矿(Ca-Pv)作为下地幔最丰富的矿物之一,也是近年来学术界关注的热点。Ca-Pv在下地幔条件下的晶体结构仍然是目前研究的主要问题之一,Ca-Pv能否与其结构和化学式都相近的含铁布里奇曼石形成固溶体?本文通过第一性原理地球化学计算,研究了Ca-Pv及固溶体的基态稳定性,弹性性质和地震波波速特性。研究结果表明,在20~120 GPa压力下,Ca-Pv最稳定的基态结构为四方结构。基态下Ca-Pv的弹性波速值低于Mg-Pv约5%。与非互溶体系相比,x(Fe)为0%~10%的固溶体体系,引起了-2%~0%的剪切波波速负异常;-1.2%~0%的纵波波速负异常;-0.45~0.15%的体波速异常。因此,推测固溶体Mg_(1-x-y)Ca_(x)Fe_(y)SiO_(3)可能作为下地幔llsvps的候选矿物组分之一。

关键词：下地幔 CaSiO_(3)钙钛矿固溶体 llsvps

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

由俯冲洋壳形成的llsvps及其在动力学模型中的长期存在

由俯冲洋壳形成的LLSVPs及其在动力学模型中的长期存在

引用

2016中国地球科学联合学术年会

作者：黄川冷伟吴忠庆中国科技大学

地震学层析成像揭示了非洲和太平洋下两个巨大低剪切波速度区（llsvps）的存在。而波形拟合结果进一步表明这两个速度体有着陡峭的边界,同时剪切波速度在边界里外呈尖锐跳变而非平滑过渡,这说明llsvps是热化学异常而非热异常。这两个LLS... 详细信息

地震学层析成像揭示了非洲和太平洋下两个巨大低剪切波速度区（llsvps）的存在。而波形拟合结果进一步表明这两个速度体有着陡峭的边界,同时剪切波速度在边界里外呈尖锐跳变而非平滑过渡,这说明llsvps是热化学异常而非热异常。这两个llsvps（Burke将其分别命名为TUZO和JASON）的总体积约为14.2×10～9 km,是目前已知的下地幔最大的结构体。同时该结构体也是地幔中极稳定的存在,因为其保持形态和位置稳定超过了550 Ma（Torsvik et a.,2010）或甚至可能始于地幔

关键词：俯冲洋壳热化学结构体 llsvps 动力学模型长期存在

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

下地幔成分差异引起的热导率变化对llsvps长期演化的动力学影响

下地幔成分差异引起的热导率变化对LLSVPs长期演化的动力学影响

引用

作者：李杨中国科学院地质与地球物理研究所

地球的地幔经历了长期的热-化学演化,其动力学过程受到诸多因素的影响。对于地幔的热演化,除了多种尺度的热对流之外,不同界面之间的热传导也是一种重要的能量传递方式。在地球的深部,核幔边界之上的非洲及太平洋下方,存在着两个大型剪... 详细信息

地球的地幔经历了长期的热-化学演化,其动力学过程受到诸多因素的影响。对于地幔的热演化,除了多种尺度的热对流之外,不同界面之间的热传导也是一种重要的能量传递方式。在地球的深部,核幔边界之上的非洲及太平洋下方,存在着两个大型剪切波低速省(Large Low Shear Velocity Provinces, llsvps),其覆盖了接近30%的核幔边界区域,并且垂向向上延伸数百至上千公里(Garnero et al., 2016)。更有地震学研究指出其低速特征反应了llsvps与周围地幔的成分差异所引起的密度差异(Ishii and Tromp, 1999),更深入的研究指出这种密度差异与其含铁量相关(Trampert et al., 2004)。

关键词：下地幔 llsvps 核幔边界长期演化成分差异热导率

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

由超大陆循环引起的长期稳定的llsvps

由超大陆循环引起的长期稳定的LLSVPs

引用

2017中国地球科学联合学术年会

作者：黄川冷伟吴忠庆北京大学中国科技大学

位于非洲和太平洋下的两个llsvps(Burke将其分别命名为TUZO和JASON)是目前已知的下地幔最大的两个结构体。地震学层析成像和波形拟合结果认为这两个结构体为热化学异常,同时也有地质学的证据支持这两个结构体为地幔中较为稳定的存在—... 详细信息

位于非洲和太平洋下的两个llsvps(Burke将其分别命名为TUZO和JASON)是目前已知的下地幔最大的两个结构体。地震学层析成像和波形拟合结果认为这两个结构体为热化学异常,同时也有地质学的证据支持这两个结构体为地幔中较为稳定的存在——即该二者已经保持形态和位置稳定超过了550 Ma(Torsvik et a.,2010)或甚至可能始于地幔对流的早期(Dziewonski et al.,2010)。地

关键词：结构体 llsvps 长期稳定

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Effects of depth-and composition-dependent thermal conductivity and the compositional viscosity ratio on the long-term evolution of large thermochemical piles of primordial material in the lower mantle of the Earth:Insights from 2-D numerical modeling

引用

Science China Earth Sciences 2023年第8期66卷 1865-1876页

作者： Yang LI Zhigang ZHANG Juan LI Zhidong SHI Liang ZHAO State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Science University of Chinese Academy of SciencesBeijing 100049China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519080China

Thermal conductivity plays an important role in the thermochemical evolution of Earth’s *** mineral physics studies suggest that the thermal conductivity of the mantle varies with pressure and composition,and this may play an important role in the evolution of the Earth’s ***,the rheology of the deep mantle is also supposed to be ***,the dynamic influences of these factors remain not well *** this study,we performed numerical experiments of thermochemical mantle convection in 2-D spherical annulus geometry to systematically investigate the effects of depth-and composition-dependent thermal conductivity and the compositional viscosity ratio on the long-term evolution of the large thermochemical structure of primordial material in Earth’s *** results show that increasing the depth-dependent thermal conductivity leads to a larger core-mantle boundary(CMB)heat flow and allows the formation of more stable large thermochemical piles(e.g.,Large Low Shear Velocity Provinces,llsvps);while decreasing the composition-dependent thermal conductivity would slightly destabilize the primordial thermochemical piles,increase the altitude of these piles and the temperature differences between the piles and the ambient *** the primordial mantle material is compositionally more viscous(e.g.,20 times than that of the ambient mantle),the long-term stability of the thermochemical piles of primordial material decreases,and this destabilizing effect will be enhanced by decreasing the composition-dependent thermal *** a result,the thermochemical piles would be unstable in the core-mantle boundary ***,our study indicates that the combined effects of depth-and composition-dependent thermal conductivity and compositional viscosity ratio are pronounced to the thermochemical evolution of the mantle.

关键词： Mantle convection Thermal conductivity Core-mantle boundary heat flow Primordial mantle material llsvps

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effects of thermal, compositional and rheological properties on the long-term evolution of large thermochemical piles of primordial material in the deep mantle

引用

Science China Earth Sciences 2022年第12期65卷 2405-2416页

作者： Min HUANG Yang LI Liang ZHAO State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Zhuhai 519080China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

Seismic tomography observations have shown that there are two large low shear velocity provinces(llsvps)above the core-mantle boundary beneath Africa and the *** thermal and compositional properties of these two llsvps may differ from those of the ambient mantle,and they are suggested to be thermochemical piles of primordial material in the lower *** evolution is of great importance to our understanding of mantle *** this study,we systematically conducted numerical experiments to investigate the effects of the buoyancy ratio(B),compositional viscosity ratio(Δη_(c)),and heat-producing ratio(Λ)of the primordial material on the long-term evolution of thermochemical *** results show that the buoyancy ratio plays the most important role in the stability of these *** the buoyancy ratio is small,and the primordial material is enriched in heat-producing elements(Λ>1),the stability of these piles decreases with increasing compositional viscosity ratio or heat-producing *** cases with homogeneous heat production(Λ=1),the stability of these piles increases with increasingΔη*** further compare constant internal heating with radioactive decay internal heating,and find that the longterm stability of thermochemical piles slightly decreases with radioactive decay heating,but the overall differences between these two internal heating modes are relatively small.

关键词： llsvps Primordial material Thermochemical piles Thermochemical structure of the deep mantle

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Dupal Anomaly and Identification using Nd-Hf Isotopes

引用

Acta Geologica Sinica(English Edition) 2022年第2期96卷 416-429页

作者： TIAN Ye XU Jifeng LIU Xijun School of Earth Science and Resources and State Key Laboratory of Geological Processes and Mineral ResourcesChina University of GeosciencesBeijing 100083China Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration College of Earth SciencesGuilin University of TechnologyGuilinGuangxi 541004China

The Dupal anomaly has attracted widespread attention since being discovered and is regarded as the most direct manifestation of mantle inhomogeneity at present. From the initially defined anomalies limited to the southern hemisphere to the global scale, the criteria for identifying anomalies defined by Pb isotopes have also been adjusted, providing an important method and reference for the study of the mantle evolution. Pearce and Peate(1995) proposed the method of NdHf isotope and element ratio to identify the Dupal anomaly. The Nd-Hf method also offers a possible way to discriminate the mantle region of arc magmatism through the correction of Nd in the subduction process. This paper introduces the concepts and determination methods of the Dupal anomaly, and reports new Hf isotopic data of MORB-type rocks with Dupal signature in the several Tethys ophiolites. Our results of Nd-Hf method are in good agreement with those of previous Pb isotope identification. Moreover, origins and their controversy of Dupal anomaly are reviewed, and possible internal connections between Dupal anomalies and the two Large Low Shear Velocity Provinces(llsvps) in the lower mantle are discussed in depth. Further studies on origin and evolution of the Dupal anomaly are suggested, especially using integrated approach of Hf-Nd and Pb isotopes.

关键词： Dupal anomaly llsvps Pb isotope Nd-Hf isotope mantle heterogeneity

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Trial by fire:Testing the paleolongitude of Pangea of competing reference frames with the African LLSVP

引用

Geoscience Frontiers 2020年第4期11卷 1253-1256页

作者： Ross N.Mitchell Lei Wu J.Brendan Murphy Zheng-Xiang Li State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijingChina Earth Dynamics Research Group The Institute for Geoscience Research(TIGeR)School of Earth and Planetary SciencesCurtin UniversityGPO Box U1987PerthWAAustralia Department of Earth Sciences St.Francis Xavier UniversityAntigonishNova ScotiaCanada

Paleogeography can be reconstructed using various crust-or mantle-based reference frames that make fundamentally different *** various reconstruction models differ significantly in continental paleolongitude,but it has been difficult to assess which models are more *** suggest here a "LLSVP test",where an assumed correlation between present-day large low velocity shear-wave provinces and the paleogeography of supercontinent Pangea at breakup ca.200 million years ago can be used to assess the relative accuracy of published *** correlations between continental paleolongitude and the African LLSVP are achieved with mantle-based reference frames(moving hotspots and true polar wander),whereas shallower crustbased reference frames are shown to be *** relative success of mantle-based frames,and thus the importance of the depth of reference frame,supports the notion that mantle convection is largely vertical compared to the horizontal plate motion of tectonics.

关键词： Palaeogeography Plate tectonics llsvps Reference frames

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：