Olivine and Cr-spinel as indicators of the petrogenesis and partial melting conditions of the high-MgO ultramafic volcanic rocks from NW Ad Dhala Province—Yemen

The high-MgO ultramafic volcanic rocks in the NW Ad Dhala province are classified as meimechite according to the IUGS classification scheme.This province represents the southeastern outcrops of the Yemen Volcanic Group(YVG),which constitutes part of the AfroArabian continental large igneous province(LIP) and located within the boundary of the Afar mantle plume.In this study,we present the chemical compositions of olivine and Cr-spinel in meimechite rocks from Bagah Village in NW Ad Dhala province,aiming to characterize the genesis and partial melting conditions and to estimate the crystallization temperatures of these high-MgO rocks.Olivine crystals are characterized by high forsterite,ranges from Mg-rich core(up to Fo_(89.69)) to relatively Fe-rich rim(down to Fo_(78.57)),high CaO,MgO and MnO whereas Cr-spinel crystals have high TiO_2 and Cr# values ranging from 0.49 to 0.63 which indicate that they are crystallized from primary magma and are typical of volcanic olivine and Crspinel that formed in intraplate tectonic setting.Olivine and Cr-spinel compositional data and primary melt composition(MgO ～ 23 wt.%) are compatible with the derivation of studied meimechite rocks from peridotite mantle source by small degrees of partial melting under conditions of high temperature and pressure at great depths,mostly within the garnet stability field.Also,these data provide a compelling indicator for the important role of upwelling Afar mantle plume in the genesis of these high-MgO ultramafic volcanic rocks.Finally,based on the different olivine-liquid equilibrium methods and Al-in-olivine thermometer approach the estimated crystallization temperature ranges from 1450 to 1490℃,and mantle potential temperature(Tp) ranges from 1617 to 1677℃,at high pressure(3-4.8 GPa).These high temperatures substantiate the existence of the Afar thermal mantle plume and its important role in the genesis of the studied meimechite rocks.     

Helium and argon isotopes of the Tertiary basic igneous rocks from Shandong Peninsula and implications for the magma origin

Helium (He) and Argon (Ar) isotopic compositions of the Tertiary basic igneous rocks were determined by the high temperature melting extraction method. The selected samples for the studies included al-kaline basalts and diabases from the Jiyang basin,and the surrounding Shanwang and Qixia outcrops in the Shandong Peninsula,eastern China. The results show that the Paleogene basalts and diabases from the Jiyang basin yielded a wide range of P4 PHe abundance of (73.70-804.16)×10 P-8 Pcm P3 P STP·g P-1 P,with P3 PHe/ P4 PHe ratios of 0.374-2.959 Ra,which was lower than the MORB but evidently higher than the con-tinental crust value. The Neogene alkaline basalts from the Jiyang basin,Shanwang and Qixia outcrops have variable P4 PHe abundances ((42.34-286.72)×10-8 Pcm P3 P STP·g-1 P),and "continental crust-like" P3 PHe/ P4 PHe ratios (0.013-0.074 Ra). All of them contain atmospheric-like P40 PAr/ P36 PAr ratio (395.4-1312.7),reflecting the mantle sources with air components. Their low P3 PHe/ P4 PHe ratios are interpreted as the enrichment of the radiogenic P4 PHe mainly inherited from the mantle. He and Ar systematics show the mixing of MORB-type,air and a P4 PHe enriched member in the mantle source,suggesting that these igneous rocks originated from the depleted asthenospheric mantle mixed with an EMI component. Therefore,the present He and Ar isotopes do not support the viewpoints that the Cenozoic igneous rocks of Eastern North China were the products of mantle plume(s) activities.     

Two types of the crust-mantle interaction in continental subduction zones

Plate subduction is an important mechanism for exchanging the mass and energy between the mantle and the crust,and the igneous rocks in subduction zones are the important carriers for studying the recycling of crustal materials and the crust-mantle interaction.This study presents a review of geochronology and geochemistry for postcollisional mafic igneous rocks from the Hong’an-Dabie-Sulu orogens and the southeastern edge of the North China Block.The available results indicate two types of the crust-mantle interaction in the continental subduction zone,which are represented by two types of mafic igneous rocks with distinct geochemical compositions.The first type of rocks exhibit arc-like trace element distribution patterns(i.e.enrichment of LILE,LREE and Pb,but depletion of HFSE)and enriched radiogenic Sr-Nd isotope compositions,whereas the second type of rocks show OIB-like trace element distribution patterns(i.e.enrichment of LILE and LREE,but no depletion of HFSE)and depleted radiogenic Sr-Nd isotope compositions.Both of them have variable zircon O isotope compositions,which are different from those of the normal mantle zircon,and contain residual crustal zircons.These geochemical features indicate that the two types of mafic igneous rocks were originated from the different natures of mantle sources.The mantle source for the second type of rocks would be generated by reaction of the overlying juvenile lithospheric mantle with felsic melts originated from previously subducted oceanic crust,whereas the mantle source for the first type of rocks would be generated by reaction of the overlying ancient lithospheric mantle of the North China Block with felsic melts from subsequently subducted continental crust of the South China Block.Therefore,there exist two types of the crust-mantle interaction in the continental subduction zone,and the postcollisional mafic igneous rocks provide petrological and geochemical records of the slab-mantle interactions in continental collision orogens.     

Major element, trace element, and Sr, Nd and Pb isotope studies of Cenozoic basalts from the South China Sea

The whole rock K-Ar ages of basalts from the South China Sea basin vary from 3.8 to 7.9 Ma, which suggest that intra-plate volcanism after the cessation of spreading of the South China Sea (SCS) is comparable to that in adjacent regions around the SCS, i.e., Leiqiong Peninsula, northern margin of the SCS, Indochina block, and so on. Based on detailed petrographic studies, we selected many fresh ba-saltic rocks and measured their major element, trace element, and Sr-Nd-Pb isotope compositions. Geochemical characteristics of major element and trace element show that these basaltic rocks belong to alkali basalt magma series, and are similar to OIB-type basalt. The extent of partial melting of mantle rock in source region is very low, and magma may experience crystallization differentiation and cu-mulation during the ascent to or storing in the high-level magma chamber. Sr-Nd-Pb isotopic data of these basaltic rocks imply an inhomogeneous mantle below the South China Sea. The nature of magma origin has a two end-member mixing model, one is EM2 (Enriched Mantle 2) which may be originated from mantle plume, the other is DMM (Depleted MORB Mantle). Pb isotopic characteristics show the Dupal anomaly in the South China Sea, and combined with newly found Dupal anomaly at Gakkel ridge in Arctic Ocean, this implies that Dupal anomaly is not only limited to South Hemisphere. In variation diagrams among Sr, Nd and Pb, the origin nature of mantle below the SCS is similar to those below Leiqiong peninsula, northern margin of the SCS and Indochina peninsula, and is different from those below north and northeast China. This study provides geochemical constraints on Hainan mantle plume.     

The inversion of density structure by graphic processing unit （GPU） and identification of igneous rocks in Xisha area

Organic reefs, the targets of deep-water petroleum exploration, developed widely in Xisha area. However, there are concealed igneous rocks undersea, to which organic rocks have nearly equal wave impedance. So the igneous rocks have become interference for future exploration by having similar seismic reflection characteristics. Yet, the density and magnetism of organic reefs are very different from igneous rocks. It has obvious advantages to identify organic reefs and igneous rocks by gravity and magnetic data. At first, frequency decomposition was applied to the free-air gravity anomaly in Xisha area to obtain the 2D subdivision of the gravity anomaly and magnetic anomaly in the vertical direction. Thus, the distribution of igneous rocks in the horizontal direction can be acquired according to high-frequency field, low-frequency field, and its physical properties. Then, 3D forward modeling of gravitational field was carried out to establish the density model of this area by reference to physical properties of rocks based on former researches. Furthermore, 3D inversion of gravity anomaly by genetic algorithm method of the graphic processing unit(GPU) parallel processing in Xisha target area was applied, and 3D density structure of this area was obtained. By this way, we can confine the igneous rocks to the certain depth according to the density of the igneous rocks. The frequency decomposition and 3D inversion of gravity anomaly by genetic algorithm method of the GPU parallel processing proved to be a useful method for recognizing igneous rocks to its 3D geological position. So organic reefs and igneous rocks can be identified, which provide a prescient information for further exploration.     

Thermal Structure and Rheology of the Upper Mantle Derived from Mantle Xenoliths from Gansu Province, Western China

Mantle xenoliths brought up by Cenozoic volcanic rocks onto the earth‘s surface may provide direct information about the upper mantle beneath the volcanic region. This paper presents the study on mantle xenoliths collected from Haoti village, Dangchang County, Gansu Province, western China. The main purpose of the study is to gain an insight into the thermal structure and rbeology of the upper mantle beneath the region. The results show that the upper mantle of the region is composed mainly of spinel lherzolite at shallower depth (52-75km), and garnet iberzolite at greater depth (greater than 75km), instead of harzburgite and dunite as proposed by some previous studies. The upper mantle geotherm derived from the equilibrium temperatures and pressures of xenoliths from the region is lower than that of North China, and is somewhat closer to the Oceanic geotherm. The crust-mantle boundary is determined from the geotherm to be at about 52km, and the Moho seems to be the transition zone of lower crust material with spinel iberzolite. If we take 1280℃ as the temperature of the top of asthenosphere, then the fithospbere-asthenosphere boundary should be at about 120km depth. The differential stress of the upper mantle is determined by using recrystallized grain size piezometry, while the strain rate and equivalent viscosity are determined by using the high temperature flow law of peridotite. The differential stress, strain rate and viscosity profiles constructed on the basis of the obtained values indicate that asthenospberic diapir occurred in this region during the Cenozoic time, resulting in the corresponding thinning of the lithosphere. However, the scale and intensity of the diapir was significantly less than that occurring in the North China region. Moreover, numerous small-scale shear zones with localized deformation might occur in the iithospberic mantle, as evidenced by the extensive occurrence of xenoliths with tabular equigranular texture.     

Subduction tectonics vs.plume tectonics——Discussion on driving forces for plate motion

Plate tectonics describes the horizontal motions of lithospheric plates,the Earths outer shell,and interactions among them across the Earths surface.Since the establishment of the theory of plate tectonics about half a century ago,considerable debates have remained regarding the driving forces for plate motion.The early"Bottom up"view,i.e.,the convecting mantledriven mechanism,states that mantle plumes originating from the core-mantle boundary act at the base of plates,accelerating continental breakup and driving plate motion.Toward the present,however,the"Top down"idea is more widely accepted,according to which the negative buoyancy of oceanic plates is the dominant driving force for plate motion,and the subducting slabs control surface tectonics and mantle convection.In this regard,plate tectonics is also known as subduction tectonics."Top down"tectonics has received wide supports from numerous geological and geophysical observations.On the other hand,recent studies indicate that the acceleration/deceleration of individual plates over the million-year timescale may reflect the effects of mantle plumes.It is also suggested that surface uplift and subsidence within stable cratonic areas are correlated with plumerelated magmatic activities over the hundred-million-year timescale.On the global scale,the cyclical supercontinent assembly and breakup seem to be coupled with superplume activities during the past two billion years.These correlations over various spatial and temporal scales indicate the close relationship and intensive interactions between plate tectonics and plume tectonics throughout the history of the Earth and the considerable influence of plumes on plate motion.Indeed,we can acquire a comprehensive understanding of the driving forces for plate motion and operation mechanism of the Earth's dynamic system only through joint analyses and integrated studies on plate tectonics and plume tectonics.     

Mesozoic tectono-magmatic activities in South China:Retrospect and prospect

The South China Block was formed through the collisional orogeny between the Cathaysia Block and the Yangtze Block in the Early Neoproterozoic.The northern,western and southern sides of the South China Block were affected by disappearance of the Paleo-Tethyan Ocean during the Paleozoic.The southern and northern sides of the South China Block were respectively collided with the Indo-China Block and North China Block in the latest Paleozoic to form the basic framework of the Eastern China.The Eastern China has been affected by the westward subduction of the Pacific Plate since the Mesozoic.Therefore,the South China Block was influenced by the three major tectonic systems,leading to a superposed compound tectonics.The comparative study of the Mesozoic geology between the South China Block and its surrounding areas suggests that although the Mesozoic South China Block was adjacent to the subduction zone of the western Pacific,no juvenile arc-type crust has been found in the eastern margin.The main Mesozoic geology in South China is characterized by reworking of ancient continental margins to intracontinental tectonics,lacking oceanic arc basalts and continental arc andesites.Therefore,a key to understanding of the Mesozoic geology in South China is to determine the temporal-spatial distribution and tectonic evolution of Mesozoic magmatic rocks in this region.This paper presents a review on the tectonic evolution of the South China Block through summarizing the magmatic rock records from the compressional to extensional tectonic process with the transition at the three juncture zones and using the deformation and geophysic data from the deep part of the South China continental lithosphere.Our attempt is to promote the study of South China’s geology and to make it as a typical target for development of plate tectonic theory.     

Geochemistry and chronology of the Jiehekou Group metamorphic basic volcanic rocks in the Lüliang Mountain area,Shanxi, China

Samples were systematically collected from metamorphic basic volcanic rocks in the Jiehekou and Xiyupi areas on both sides of the Lüliang Mountains, Shanxi Province and analyzed for their major elements, trace elements and rare earth elements (REE). The geochemical characteristics of their major, trace and rare-earth elements indicated that the metamorphic basic volcanic rocks in this area were emplaced in the tectonic environment like a modern continental rift. Sm-Nd and Rb-Sr isotope chronological studies demonstrated that the Jiehekou Group metamorphic basic volcanic rocks were formed during the 2600-Ma crust/mantle differentiation event, and were transformed by granulite facies metamorphism during the late Neo-Archaean period (2500 Ma ±), making the Sm-Nd systematics of the rocks reset. During the late Paleoproterozoic period (1800 Ma ±) the Rb-Sr systematics of the rocks were disturbed again in response to the Lüliang movement. Since the extent of disturbance was so weak that the Sm-Nd systematics was not affected, the age of 1600 Ma ± obtained from this area seems to be related to local magmatic activities within the craton. Research results lend no support to the idea that the Lüliang Group was formed during the Archaean. Instead, it should be formed during the Proterozoic.     

Helium and neon isotopic compositions in the ophiolites from the Yarlung Zangbo River,Southwestern China:The information from deep mantle

The ophiolites from the Yarlung Zangbo River (Tibet),Southwestern China,were analysed for the con-tents of helium and neon and their isotopic compositions by stepwise heating. The serpentinites from Bainang showed a high 3He/4He value of 32.66Ra (Ra is referred to the 3He/4He ratio in the present air) in 700 ℃ fraction. At lower temperature,all of the dolerites displayed as very high 3He/4He ratios as ones investigated for hotspots. It was clear that the high 3He/4He ratio was one of immanent characterics in the magma source formed the dolerites,suggesting that there was a large amount of deep mantle fluids in these rocks. In the three-isotope diagram of neon,the data points from the ophiolites of the Yarlung Zangbo River were arranged along the Loihi Line. This is in agreement with the characteristics of he-lium isotopes,revealing that the high-3He plume from deep mantle had played an important role in the formation of the Neo-Tethyan Ocean. The helium isotopic compositions in the basalts were far higher than atomospheric value but lower than the average value of MORB,although there were various de-grees of alteration. The possible reasons were that basaltic magmas     

地幔柱研究进展

地幔柱假设自提出以来,在学术界争议很大,对于其是否存在还没有统一答案。本文对地幔柱的起源做了详细阐述,将质疑者的观点和地幔柱假设自身存在的问题进行罗列,对地幔柱存在的证据进行汇总。从地球化学及岩石学方面对大陆溢流玄武岩和大洋岛玄武岩的分布进行研究,了解地幔柱在地表的形态;从大地构造学角度分析地幔柱如何使超大陆不断合并、分裂;从地球物理学方面以夏威夷地幔柱、非洲超级地幔柱、海南地幔柱等典型区域阐述地幔柱研究的最新成果及地幔柱存在的证据。最后,讨论了地幔柱的发展趋势。      

Petrogenetic model of the Permian Tarim Large Igneous Province

Over the last two decades great strides have been made in characterizing the spatial distribution, time sequence,geochemical characteristics, mantle sources, and magma evolution processes for various igneous rocks in the Early Permian Tarim Large Igneous Province(TLIP). This work has laid a solid foundation for revealing the evolutionary processes and genetic models of large igneous provinces(LIPs). This study systematically demonstrates the two-stage melting model for the TLIP based on our previous research work and predecessor achievements, and highlights the two types of magmatic rocks within the TLIP.The two-stage melting model suggests that the formation of the TLIP is mantle plume related. The early hot mantle plume caused the low-degree partial melting of the lithosphere mantle, while in the later stage, the plume partially melted due to adiabatic uplift and decompression. Therefore, this model carries signatures of both the "Parana" and "Deccan" models in terms of mantle plume activity. During the early stage, the mantle plume provided the heat required for partial melting of sub-continental lithosphere mantle(SCLM), similar to the "Parana Model", while later the plume acted as the main avenue for melting, as in the "Deccan Model". Basalts that erupted in the first stage have higher 87Sr/86 Sr, lower 143Nd/144 Nd ratios, and are enriched in large ion lithophile elements and high field strength elements, indicating a possible origin from the enriched continental lithosphere mantle,similar to the Parana type geochemical features. The basic-ultrabasic intrusive rocks in the second stage exhibit lower 87Sr/86 Sr,higher 143Nd/144 Nd ratios relative to the basalts, consistent with the involvement of a more depleted asthenospheric material,such as a mantle plume, similar to the Deccan type geochemical features. The first stage basalts can be further subdivided into two categories, i.e., Group 1 and Group 2 basalts. Group 2 basalts have lower 87Sr/86 Sr and higher 143Nd/144 Nd ratios than Group 1 basalts, and lie between compositions of the Group 1 basalts and second stage magmatism. Group 2 basalts may be the intermediate component of the TLIP, and the whole TLIP is the result of plume and lithosphere interaction. Developing this petrogenetic model for the TLIP aids in comprehensively understanding its magmatism and deep geological and geodynamic processes. Furthermore, this work enriches the theories describing the origin of large igneous province and mantle plume activity.     

动态地幔柱尾管结构

动态地幔柱模式被广泛用于讨论地球科学中的一些重要课题,如巨大火成区的成因,冈瓦纳古陆解体的原因,板块内中小尺度动力过程的驱动因素等．但是这个基于实验研究而建立的模式中,忽略了地幔柱尾管特征及其作用．地幔柱尾管内温度和速度分布是研究地幔柱上升过程的必要条件．本文从控制尾管结构的基本方程出发,给出了一个定常轴对称地幔柱温度和速度分布的近似分析解．从而得到尾管结构的基本特征：影响尾管内温度分布的主导因素是地幔柱的热流通量,而尾管内上涌速度的大小则不仅取决于热流通量,主要是取决于地幔粘度随深度的变化方式．结果表明,对弱地幔柱,尾管的热损失可能是不可忽略的,而对强地幔柱,径向质量传递可能是不可忽略的.     

On the possibility of crater formation associated with an ascending plume

A hypothetical possibility of a qualitative explanation of large crater formation on the surfaces of the Moon and Mercury is discussed in terms of the concept of thermal mantle plumes. Prerequisites to this hypothesis are revealed under the assumption that the model equation of state of SiO₂ exhibiting an anomaly (a negative coefficient of thermal expansion) in the range of states approximately corresponding to average conditions typical of mantles of minor planets is applicable, in a first approximation, to mantle material. The anomaly reduces the buoyancy of hot plume material in such a way that, under conditions of moderate overheating, only relatively high columns comparable in size to the mantle are capable of ascending from the mantle bottom to the crust; allows cold peripheral material surrounding the hot column to be pushed away; causes compaction of the vertical zone of the contact of the column with the surrounding medium at the first stages after the plume ascent; and leads to compaction of the deep mantle due to the long-term heat supply. Such phenomena can lead to vertical craterlike deformations of the crust in areas of ascending large plumes whose presence can be supposed at early stages of the existence of minor planets. Significant implications of such an anomaly for geophysical processes can also be postulated.     

华南岩石层与大陆动力学

华南大陆记录和保存了自太古代至今大陆生长层完整的历史过程.以杨子克拉通为核心，地壳不断向东南生长，古扬子块前寒武系以灰色片麻岩、古元古代科马提岩绿岩、新元古代蛇绿岩、绿岩为特征，为相对稳定高速高阻冷的残存地幔“残烃柱”；而沿海一带火成岩以中、新生代壳－幔混合源火山－侵入杂岩、碱性花岗岩和正长岩带以及不同类型的玄武岩类为特征，为相对活动低速高导热的超地幔柱．巨型裂解构造是物质热传输的主要形式，地幔柱迁移是华南大陆构造演化的原动力．     

On the rise of strongly tilted mantle plume tails

The rise of an initially horizontal, buoyant cylinder of fluid through a denser fluid at low Reynolds number is used to look at the ascent of strongly tilted mantle plumes through the mantle. Such ascents are characterized by (1) the growth of instabilities and (2) the development of a thermal wake downstream. Three-dimensional numerical experiments were carried out to examine these features. An hybrid particle-in-cell finite element method was used to look at the rise of non-diffusing cylinders and, a standard finite element method was used to look at the diffusing case. First the experiments show that the timescale of the fastest growing instability vary with the Rayleigh number and the viscosity ratio. In particular the growth rate decreases as the Rayleigh number decreases, in agreement with our analysis of the laboratory experiments of Kerr et al. (2008). Second the experiments show that the length of the thermal wake increases with the Rayleigh number but the change in viscosity has almost no influence on the wake length. Applied to strongly tilted mantle plumes we conclude that such plumes cannot be unstable given the plume timescales. We also discuss the application of this conclusion to weakly tilted plumes. Besides, this study allows to predict that mantle plumes are unlikely to have developed a significant thermal wake by the time they reach the surface. Finally, the resolution that is required to allow for the growth of mantle plume tails by combined diffusion and thermal entrainment is shown to represent a challenge for the large scale mantle convection simulations.     

图们江流域新生代火山岩Sr、Nd同位素初步研究

中国地震局地质研究所; 中国地震局地质研究所 北京     

Early Permian Tarim Large Igneous Province in northwest China

Tarim Large Igneous Province (TLIP) is the second Late Paleozoic LIPs in China after the recognition of Emeishan LIP, and is a hot research topic in geosciences. On the basis of the analysis of research history about TLIP, this paper summarizes the research result during last twenty years and suggests the key research area in the future. The residual distribution range of TLIP is up to 250000 km², and the largest residual thickness is 780 m. The eruption of basalt happened during 290–288 Ma and belongs to LIPs magmatic event with fast eruption of magma. The lithological units of the TLIP include basalt, diabase, layered intrusive rock, breccia pipe mica-olivine pyroxenite, olivine pyroxenite, gabbro, ultramafic dyke, quartz syenite, quartz syenite porphyry and bimodal dyke. The basalt and diabase of TLIP exhibit OIB-like trace element patterns and enrichment of LILE and HFSE, and mainly belong to high TiO₂ series. There is an obvious difference in isotope among the basalt from Keping and the basalt and dibase from the northern Tarim Basin. The basalt from Keping with negative ? _Nd and high REE value derives from enriched mantle, and the diabase and basalt from the northern Tarim Basin with positive ? _Nd and low REE value are related to depleted mantle. The crust uplifting in the Early Permian and the development of picrite and large scale dyke and formation of large scale V-Ti-Magnetite deposit in Wajilitag area support the view that the TLIP is related to mantle plume. The TLIP has a temporal-spatial relationship with Permian basic to ultra-basic igneous rock, which is distributed widely in Central Asia, and they represent a tectono-magmatic event with very important geodynamic setting. This paper also suggests that the deep geological process, the relation with mantle plume, mineralization, the relation with environmental change and biological evolution, and the geodynamics of the TLIP will be the key research topics in the future.     

Depleted sublithospheric mantle beneath the Bohemian Massif and Pannonian Basin: New data on the composition and helium isotopes of the mantle xenoliths and enclosed basalts and the problem of existence of mantle plumes in Central Europe

New data are presented on the chemical composition and helium isotopes for the mantle xenoliths and enclosed Cenozoic basalts of the Pannonian Basin and Bohemian Massif. New data on the helium isotopes in the basalts and mantle xenoliths of the Pannonian Basin and Bohemian Massif, which have been obtained for the first time, show very low R/Ra ratios close to or slightly above the typical values of the atmosphere. This indicates that the mantle beneath the considered areas is strongly degassed. The fact that, according to seismic tomography, the mantle plumes beneath the regions of recent volcanism in Central Europe are not traced below 200 km points to the extensive spreading of the plume material beneath the lithosphere of Europe, due to which the plume tail is too thin to be detectable by the existing methods.     

The low-velocity plume on the southwestern edge of Yangtze Craton and superlarge ore deposits

A map showing the three-dimensional velocity anomaly on the southwestern edge of Yangtze craton is first compiled. Based on the map, it is suggested that there is a low-velocity plume on the edge of Yangtze craton. The low-velocity plume is the effect of mantle plume, plays an important role in controlling the upwelling of asthenosphere, mantle rise and the formation of intracrustal low-velocity lens, and is also the carrier and provider of vast amount of fluids, mineralizers, minerogenetic materials and energy. Therefore, it is concluded that the low-velocity plume is closely related to Mesozoic and Cenozoic superlarge ore deposits in time and space and genesis.