首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
赣东–浙西下寒武统荷塘组稀土元素特征及其地质意义   总被引：1，自引：0，他引：1  
为揭示下扬子下寒武统黑色岩系的物源属性、构造背景及其沉积环境等特征,对赣东-浙西地区下寒武统荷塘组野外露头及钻井岩心进行了系统采样与稀土元素分析测试。结果显示,荷塘组样品稀土元素总量变化波动大(16.83×10-6~321.22×10-6),均值低(103.11×10-6),轻稀土元素富集且分异明显,重稀土元素亏损但分异小,普遍存在Ce负异常和明显Eu正异常。研究表明:①荷塘组硅质泥页岩形成于缺氧还原的裂陷海盆环境,构造背景为被动大陆边缘,物源受陆源、海水和热液共同影响,横峰、上饶受热液和海水影响最大,受陆源碎屑影响最小,常山、江山与之相反;②沉积过程普遍有热液活动参与,在上饶存在热液活动中心,活动强度呈西强东弱特点,并发现低温热液活动有利于有机质的富集。  相似文献   

2.
西南印度洋中脊热液产物稀土元素组成变化及其来源   总被引：1，自引：1，他引：0  
对西南印度洋中脊热液区不同热液产物稀土元素(REE)进行了分析,探讨了热液产物形成过程中稀土元素组成变化及其来源。研究结果表明:不同热液产物稀土元素总量变化范围从3.47×10-7到4.80×10-5,轻重稀土比值(LREE/HREE)从2.06到6.16,表明轻重稀土有较大程度分异,δEu异常(δEu=0.86~3.88)和δCe异常(δCe=0.40~0.86)显示热液产物中REE呈Eu富集和Ce亏损特征。稀土元素球粒陨石标准化模式呈现两种类型:(1)呈轻微富集LREE的平坦模式,REE大于2×10-5;(2)呈显著富集LREE和正Eu异常模式,REE小于5×10-7。模式1类似于洋壳火山岩REE配分模式,而模式2与西南印度洋中脊黑烟囱REE模式相似,也与典型洋中脊热液喷口流体和硫化物LREE富集和正Eu异常模式类似。热液产物中稀土元素含量变化和模式特征以及Mg与LREE极强正相关关系可能反映了西南印度洋中脊硫化物形成在热液流体与海水混合沉淀的初始阶段,后期经历了广泛的热液流体再循环和海水蚀变过程。  相似文献   

3.
In Western Canada Sedimentary Basin (WCSB), large scale and focused fluid flow that caused hydrothermal dolomitization have been suggested with different timing and intensity. In this study, we conducted a petrographic and geochemical comparison between the Middle Devonian Sulphur Point and Slave Point carbonates from northwestern Alberta. The results demonstrate the presence of both an early fluid flow event associated with the Late Devonian to Mississippian Antler Orogeny as well as a later event coincident with the Late Cretaceous to Early Tertiary Laramide Orogeny. Early fluid flow event is characterized by high salinity fluids, and high temperatures and oxygen isotopic values of marine or slightly enriched values, as demonstrated in saddle dolomite from the Slave Point Formation. In contrast, later fluids that caused the precipitation of saddle dolomite in the Sulphur Point formation are characterized by having slightly saline values, comparable homogenization temperatures but more enriched δ18O values and slightly depleted δ13C signatures. Geochemical data indicate that this later hydrothermal fluid was mixture of Middle Devonian brines and radiogenic basement fluids.  相似文献   

4.
Subaerial erosion and continental sedimentation interbedded with shallow-water carbonates are unequivocal stratigraphic records to evaluate paleoenvironmental and paleoclimate evolution of emerged landmass.Stratigraphic analysis of the Cretaceous Monte Gallo section of the Mesozoic Panormide carbonate platform, in the northern side of the Palermo Mountains (NW Sicily) records a peculiar continental-derived clays that interrupted the shallow-water carbonate sedimentation. These clays rest, with lenticular geometries, above the tectonically-enhanced subaerial erosional unconformity of the Barremian-Lower Aptian Requienid limestones and are covered by the Upper Cretaceous Rudistid limestone.Sedimentological investigation combined with mineralogical and petrographic results reveal the occurrence of alkaline to saline lake clays deposition in pond-filling depositional environment recording stressed conditions (evaporation) especially in its final living phase. They were formed when a half graben/tilted-block tectonics produced footwall uplift of the Gallo faulted-blocks carbonate platform.Paleoclimate evaluations of the continental-derived clays highlighted that a period of warm-humid conditions, which favoured their formation, interrupted the uniform warm climate conditions highlighting a greenhouse climate phase.  相似文献   

5.
Samples of diagenetic and hydrothermal minerals from drillcores along the DEKORP 9601 seismic traverse in the North German Basin were investigated for their fluid inclusion and sulphur isotope composition to reconstruct the thermal and chemical evolution of fluid systems during basin evolution. The stages of basin subsidence and subsequent inversion are marked by fluid systems of distinct composition. The basinwide Zechstein evaporite units formed an aquiclude, disconnecting convecting fluids in the underlying Rotliegend volcanics from the overlying units. δ34S ratios of sulphides suggest a sedimentary sulphur source. δ34S ratios of diagenetic and hydrothermal sulphates indicate that sulphur was derived partly from Rotliegend volcanic units and partly from the evaporitic Zechstein.  相似文献   

6.
Controversies over the origin of globally distributed Cretaceous red beds have mainly focused on climate vs. weathering with potential hydrothermal influence. In comparison to Cretaceous Oceanic Red Beds, Cretaceous lacustrine red beds exhibit chronological inconsistencies and their diverse tectonic settings suggest differing genetic mechanisms. In this paper, Early Cretaceous red beds in the North Yellow Sea Basin, one of Mesozoic rift basins in eastern China that are associated with multi-phase magmatic activities, was chosen to document potential hydrothermal impact. Geological and geochemical analyses show that these red beds were syndepositional products developed in shallow to moderately deep lacustrine environments and that they were influenced by hydrothermal activity. Major and trace elements, including enhanced Al2O3-normalized Fe2O3 and Fe2O3 (total) values, Al/(Al + Fe + Mn) and (Fe + Mn)/Ti ratios, Ni-Co-Zn and Fe-Mn-(Ni + Co + Cu)*10, ∑REE-La/Yb, the concentrations of hydrothermally-related ions, invalid redox indicators of trace elements, abnormally high Fe2O3 (total) content, positive Eu anomaly, correlation of Fe2O3 (total) and Eu anomaly, and vitrinite reflectance (Ro) vs. total organic carbon (TOC), all show strong hydrothermal fluid influence and heating effects. By integrating and comparing data from previous studies, we propose a hydrothermally affected sedimentation model for Cretaceous red beds and associated sediments in magma-activated lacustrine basins, and conclude that the enriched metallic ions introduced by the hydrothermal fluids may be the most significant reason for the deposition of the red beds, and the flushed ferric ions, accompanied by hydrothermal fluid, are the main ions that are hosted inside hematite causing the red sediment. This model can be applied to similar lacustrine basins that experience strong magmatic activity.  相似文献   

7.
A field experiment was carried out to test the effect of pore water salinity on the macrobenthic assemblages in an estuarine region of the Tagus estuary (Portugal) subjected to wide fluctuations in salinity. The conditions at the experimental site ranged from freshwater (minimum salinity 0.2) to mesohaline (maximum salinity 15.3). The experimental site was affected by an unexpected deposition of fluid mud during summer. Redundancy Analysis discriminated the experimental treatments along the first canonical ordination axis. The analysis also revealed an experimental gradient of increasing environmental stress, in which the minimal presence of organisms corresponded to treatments representing a high level of environmental stress. Sediment dynamics and saline fluctuations were the major factors that, together, determined the low macrofaunal abundance and species diversity at the experimental site. The most abundant macrofaunal species in this harsh environment were the polychaetes Hediste diversicolor and Streblospio shrubsolii.  相似文献   

8.
根据2018年1月冬季航次的水文实测资料,详细分析了大亚湾海水温度(T)、盐度(S)的分布特征。整体而言,观测海区海表相对于海底具有高温低盐的特征;同时,无论是表层还是近底层,大亚湾湾内的海水相对于湾外都呈现高温低盐的特征。观测期间,应是受到大亚湾核电站温排水的影响,湾内西侧存在一个高温中心。盐度的差异在近底层更加明显,低盐中心位于大亚湾的湾顶和大亚湾的中部海域,而高盐中心则主要分布于湾口西侧及惠东以东附近海域。太阳辐射和潮流变化是影响大亚湾温度、盐度变化的两大重要因素。其中,太阳辐射的影响主要局限于表层3~4 m,对近底层海水的影响较小;其加热效应使湾内和湾口附近的表层海水都表现出明显的昼夜变化。由潮汐和温度、盐度的对应关系可知,潮流对湾内温度、盐度的影响较大,而对湾外温度、盐度的影响较小。  相似文献   

9.
The non-marine Fushun Basin in NE China is a fault-controlled basin filled with Eocene sediments. It hosts the largest opencast coal and oil shale mine in Asia. A single thick oil shale layer overlying sub-bituminous coal occurs within the Middle Eocene Jijuntun Formation. Based on mineralogy, inorganic and organic geochemistry, organic petrography, stable isotope geochemistry, and vitrinite reflectance measurements, the depositional environment and the oil shale potential of the oil shale-bearing succession were investigated. The Jijuntun Formation is subdivided into a lower and an upper unit characterized by a low and high quality oil shale, respectively. The thick oil shale layer of the Jijuntun Formation developed under long-lasting stable conditions in a deep freshwater lake, after drowning of a swamp. The organic matter in the lower unit is characterized by landplant-derived macerals. The sediments containing a type II kerogen (HI: ∼400 mgHC/gTOC) were deposited during warm and humid conditions. Lacustrine organisms predominant in the upper unit are forming kerogen type I (HI: ∼700 mgHC/gTOC). High bioproductivity and excellent preservation conditions resulted in high TOC contents up to 23.6 wt.% in the upper unit. The organic matter preservation was controlled by photic zone anoxia originating in a temperature stratified water column in the deep lake, without significant changes in bottom water salinity. Mid-Eocene cooling during deposition of the upper unit of the Jijuntun Formation is reflected by clay mineral composition. A hot and arid climate favoring brackish conditions in a shallow lake prevailed during accumulation of the overlying carbonate-rich Xilutian Formation. Individual geochemical parameters in the Fushun Basin have to be used with caution, e.g. the maturity proxy Tmax is affected by kerogen type, the redox proxy Pr/Ph ratio is probably biased by different sources of isoprenoids. This demonstrates the importance of multi-proxy studies.  相似文献   

10.
Fluctuations in lacustrine sedimentary environments significantly affect distributions of organic matter (OM), uranium, and other elements in shales. In this study a high-resolution geochemical record of fluctuations in the paleo-depositional environment of a terrestrial lake basin is provided on the basis of extensive samples collected from the Member 3 of the Paleogene Shahejie Formation (Es3) of the Niu-38 well in the Dongying Depression, Eastern China. These samples were tested for total organic carbon (TOC), element concentrations, and biomarkers to study the evolution and fluctuation in the depositional environments of an ancient lake basin and associated geochemical response. The evolution and fluctuation of the sedimentary environment from a deep lake to a semi-deep lake and then to a shallow lake delta were indicated by geochemical response. During this evolution, the values of TOC, S1, S2, Sr, and Ts/(Ts + Tm) remarkably decreased, whereas those of Co, Ni, Rb, Na, Fe/Mn, Fe/(Ca + Mg), and C29 mortane/C29 hopane significantly increased. The deep lake basin shows depositional fluctuations, as indicated by rock lithofacies and their geochemical parameters. A close interrelationship was observed among U concentration, TOC content, and inorganic element content. Uranium concentrations are positively correlated with TOC contents, Ca and Sr concentrations, and Sr/Ba and Ca/Mg ratios but negatively with K, Na, Ba, and Rb contents and Fe/(Ca + Mg) and Fe/Mn ratios. The observed increase in U concentration in the lower Es3 section is closely related to surface adsorption by clay minerals and OM, together with some replacements of Ca and Sr by U in the shales.  相似文献   

11.
Ecological research has been made for quite a long period in some marine-derived saline lakes in the Vest-fold Hills, Antarctica. The results show distinct succession of zooplankton community in those lakes. The change in community structure of zooplankton is related directly to environmental evolution in nature and the variation of lake conditions, such as physical and chemical factors as well. In the Burton Lake, there is a rather stable annual fluctuation in both temperature and salinity, and the community has probably been in the stage of climax succession. The Fletcher Lake is still undergoing a process by unregular tide flood from nearby bay, so that zooplankton community has been changing due to variance in temperature and salinity.  相似文献   

12.
A Tiburon ROV dive within the East Blanco Depression (EBD) increased the mapped extent of a known hydrothermal field by an order of magnitude. In addition, a unique opal-CT (cristobalite-tridymite)-hematite mound was discovered, and mineralized sediments and rock were collected and analyzed. Silica-hematite mounds have not previously been found on the deep ocean floor. The light-weight rock of the porous mound consists predominantly of opal-CT and hematite filaments, rods, and strands, and averages 77.8% SiO2 and 11.8% Fe2O3. The hematite and opal-CT precipitated from a low-temperature (≥ 115° C), strongly oxidized, silica- and iron-rich, sulfur-poor hydrothermal fluid; a bacterial mat provided the framework for precipitation.

Samples collected from a volcaniclastic rock outcrop consist primarily of quartz with lesser plagioclase, smectite, pyroxene, and sulfides; SiO2 content averages 72.5%. Formation of these quartz-rich samples is best explained by cooling in an up-flow zone of silica-rich hydrothermal fluids within a low permeability system. Opal-A, opal-CT, and quartz mineralization found in different places within the EBD hydrothermal field likely reflects decreasing silica saturation and increasing temperature of the mineralizing fluid with increasing silica crystallinity.

Six push cores recovered gravel, coarse sand, and mud mineralized variously by Fe or Mn oxides, silica, and sulfides. Total rare-earth element concentrations are low for both the rock and push core samples. Ce and Eu anomalies reflect high and low temperature hydrothermal components and detrital phases.

A remarkable variety of types of mineralization occur within the EBD field, yet a consistent suite of elements is enriched (relative to basalt and unmineralized cores) in all samples analyzed: Ag, Au, S, Mo, Hg, As, Sb, Sr, and U; most samples are also enriched in Cu, Pb, Cd, and Zn. On the basis of these element enrichments, the EBD hydrothermal field might best be described as a base- and precious-metal-bearing, silica-Fe-oxide-barite deposit. Such deposits are commonly spatially and temporally associated with volcanogenic massive sulfide (VMS) ores. A plot of data for pathfinder elements shows a large hot spot at the northwestern margin of the field, which may mark a region where moderate to high temperature sulfide deposits are forming at depth; further exploration of the hydrothermal field to the northwest is warranted.  相似文献   

13.
以深海热液区化能自养菌Caminibacter profundus为对象,采用扫描电镜和化学能谱分析,研究了菌株表面形态和矿物元素沉积;同时研究了菌株生长、甲基紫精(MV)还原的氢酶活性及膜结合的类型I NiFe氢酶基因(hynL)表达对盐度、pH和温度几种环境因子变化的响应特点。结果表明,菌株表面被Si、Ca、S和Fe等多种元素组成的矿物质层所包裹。不同条件下,菌株生长、MV还原的氢酶活性和hynL的表达趋势相一致,其最适条件为盐度30、pH5.5和55℃培养温度。研究结果表明,在环境改变时,C.profundus通过调控hynL的表达,以调整菌株的能量代谢,维系菌株的生长繁殖。  相似文献   

14.
Calanoida copepod, Drepanopus bispinosus occurred in both saline lakes, Burton ( S=40) and Fletcher ( S = 56) in Vestfold Hills, Antarctica. Evident differences between two populations in biology and physiology were observed in September and December, 1984. The population in the Burton lake was denser with stronger body and more tolerant to temperature and salinity than that in the Fletcher Lake, reflecting their possible differences of genetic or nongenetic adaptation. The population in the Burton lake has been adaptated to the lake environment, and the population in the Flethcer Lake is in the acclimatization course in the lake habitat.  相似文献   

15.
  相似文献   

16.
A computational fluid dynamics (CFD) model was developed to simulate the turbulent flow and species transport of deep-sea high temperature hydrothermal plumes. The model solves numerically the density weighted unsteady Reynolds-averaged Navier–Stokes equations and energy equation and the species transport equation. Turbulent entrainment and mixing is modeled by a k–ε turbulence closure model. The CFD model explicitly considers realistic vent chimney geometry, vent exit fluid temperature and velocity, and background stratification. The model uses field measurements as model inputs and has been validated by field data. These measurements and data, including vent temperature and plume physical structure, were made in the ABE hydrothermal field of the Eastern Lau Spreading Center. A parametric sensitivity study based on this CFD model was conducted to determine the relative importance of vent exit velocity, background stratification, and chimney height on the mixing of vent fluid and seawater. The CFD model was also used to derive several important scalings that are relevant to understanding plume impact on the ocean. These scalings include maximum plume rise height, neutrally buoyant plume height, maximum plume induced turbulent diffusivity, and total plume vertically transported water mass flux. These scaling relationships can be used for constructing simplified 1-dimensional models of geochemistry and microbial activity in hydrothermal plumes. Simulation results show that the classical entrainment assumptions, typically invoked to describe hydrothermal plume transport, only apply up to the vertical level of ~0.6 times the maximum plume rise height. Below that level, the entrainment coefficient remains relatively constant (~0.15). Above that level, the plume flow consists of a pronounced lateral spreading flow, two branches of inward flow immediately above and below the lateral spreading, and recirculation flanking the plume cap region. Both turbulent kinetic energy and turbulence dissipation rate reach their maximum near the vent; however, turbulent viscosity attains its maximum near the plume top, indicating strong turbulent mixing in that region. The parametric study shows that near vent physical conditions, including chimney height and fluid exit velocity, influence plume mixing from the vent orifice to a distance of ~10 times the vent orifice diameter. Thus, physical parameters place a strong kinetic constraint on the chemical reactions occurring in the initial particle-forming zone of hydrothermal plumes.  相似文献   

17.
Many of the deep basins filled by hot brines in the Red Sea have not been investigated since their discovery in the early 1970s. Twenty years later, in September 1992, six of these deeps were revisited. The temperature and salinity of the Suakin, Port Sudan, Chain B, and Nereus deeps ranged from 23.25 to 44.60°C and from 144 to 270‰. These values were approximately the same in 1972, indicating that the budget of heat and salt was quite balanced. We measured strong gradients of properties in the transition zone between brines and overlying seawater. The contribution of salinity to the density gradient was more than one order of magnitude higher than the opposite contribution of temperature across the seawater–brine interface. Therefore the interface was extemely stable, and the transfer of properties across it was considered to be controlled mostly by molecular diffusion. We calculate that the diffusional transport of salt from the brines to seawater cannot affect significantly the salinity of the brines over a 20 year period, which agrees with the observations. The brine pools can persist for centuries with no salt input. Therefore, the persisence of brines does not correspond to a steady balance between diffusional loss and continuous input of hydrothermal solutions. Deeps that experience only episodical hydrothermal brine supplies may persist for a long time with salt inherited from past inputs. The theoretical loss of heat by diffusion from the brine to seawater was higher than the observed decrease in temperature of the brine pool during the 20 year period of observation. We calculated that the heat flux out of the pools into the overlying seawater was compensated by a heat flux into the pools of about 250–600 mW/m2. This range of values corresponds to bottom heat flow values that have been reported earlier for the axial zone of the Red Sea. In contrast to the other brine pools, the temperature and salinity of the Valdivia Deep brine increased by 4.1°C and 10‰, respectively, between 1972 and 1992, which is explained by present-day hydrothermal brine discharge.  相似文献   

18.
24ka来冲绳海槽北部沉积物来源的高分辨率常量元素记录   总被引：3，自引：0，他引：3  
为进一步了解冲绳海槽北部24ka来柱状沉积物的常量元素组成特征及其物源和古环境指示意义,对PC-1孔进行了402个常量元素和粒度及344个浮游有孔虫氧同位素的综合分析,其平均样品分辨率高达百年时间尺度。结果表明:沉积物中的主要常量元素含量表现出明显的3段式垂向变化特征,并记录到了7.3和12.7cal.kaBP时的两次火山事件;物源判别图解及R型因子分析则揭示出主要氧化物含量在垂向上的变化主要受控于附近陆源物质输入,而热液活动和海洋生物沉积作用及火山物质的影响较小。特别是不同陆源物质对研究区的影响表现出明显的变化规律,与海平面波动及对马暖流形成演化间具有良好的耦合关系,但期间的典型古气候事件却并未明显改变沉积物中的陆源物质组成,从而为揭示24ka来冲绳海槽北部地区陆源物质输入演化历史,及其主要控制因素提供了新的高分辨率资料。  相似文献   

19.
The exceptional development of coeval hydrocarbon and aqueous fluid inclusions (FI) in fluorite from the MVT-type ore deposit of Koh-i-Maran, Baluchistan (North Kirthar range, Pakistan), provides samples which are representative of the ore-forming fluid and which support the hypothesis of petroleum migration in the province. Primary brines at 125°C (10 wt% equ. NaCl) and secondary CH4-rich brines at 135°C (7 wt% equ. NaCl), are recognised to be associated with oil migration in the fluid inclusions. They support the model of a per ascensum MVT (Mississippi Valley Type) stratabound hydrothermal deposit. A pressure–temperature path of 120–125°C to 165–200 bars is calculated from microthermometric data and PVT modelling of hydrocarbon FI using the modified Peng–Robinson Equation of State (IFP software) from primary cogenetic inclusions (oil and brines).The composition of gas and oil fractions is obtained by a combination of Synchrotron FTIR microanalysis and gas chromatography performed on individual fluid inclusions. The oil entrapped as a coeval primary fluid phase is a light aliphatic normal oil in the range C8–C35 with a high CO2 content. The brown solid phase found systematically in the oil is probably asphaltene resulting from precipitation after trapping of the heavy fraction, which commonly occurs by decreasing pressure and temperature and\or by CO2 injection. Later CH4-rich brine influx probably modified part of the oil in the primary fluid inclusions because degraded oil is observed within such inclusions. Biomarkers obtained by GC-MS analysis indicate a terpane distribution quite similar to the nearest oil seepage in the Gokurt area. This result and the high CO2 content of organic fluid inclusions indicate a restricted/confined sedimentary environment for the source rock, which could correspond to the Eocene Carbonate formation with type-II organic matter. A possible additional input of gas from the Sambar formation is suggested as feasible. The link between the fluid inclusion data and the geodynamic evolution lead us to propose a circulation of basinal fluids driven mainly by the fault system during dewatering in the foredeep. In Pakistan, they are coeval to major compressional NW–SE Oligocene episode in the thrust belt. The origin of the fluorine may be found in the basin sediments as well as near the basement. The brines originated in salt structures recognized in eocambrian at the decollement level, the source rock was already mature.  相似文献   

20.
A geochemical analysis of rare-earth elements(REEs) in 97 samples collected from the core of deep-water Well LS-A located at the Lingnan Low Uplift Area of the Qiongdongnan Basin is conducted, with the purpose of revealing the changes of sedimentary source and environment in the study region since Oligocene and evaluating the response of geochemical characteristics of REEs to the tectonic evolution. In the core samples, both ∑REE and ∑LREE(LREE is short for light-group REEs) fluctuate in a relatively wide range, while ∑HREE(HREE is short for heavy-group REEs) maintains a relatively stable level. With the stratigraphic chronology becoming newer, both ∑REE and ∑LREE show a gradually rising trend overall. The ∑REE of the core is relatively high from the bottom of Yacheng Formation(at a well depth of 4 207 m) to the top of Ledong Formation, and the REEs show partitioning characteristics of the enrichment of LREE, the stable content of HREE, and the negative anomaly of Eu to varying degrees. Overall the geochemical characteristics of REEs are relatively approximate to those of China's neritic sediments and loess, with significant "continental orientation". The ∑REE of the core is relatively low in the lower part of Yacheng Formation(at a well depth of 4 207–4 330 m), as shown by the REEs partitioning characteristics of the depletion of LREE, the relative enrichment of HREE, and the positive anomaly of Eu; the geochemical characteristics of REEs are approximate to those of oceanic crust and basalt overall, indicating that the provenance is primarily composed of volcanic eruption matters. As shown by the analyses based on sequence stratigraphy and mineralogy, the provenance in study region in the early Oligocene mainly resulted from the volcanic materials of the peripheral uplift areas; the continental margin materials from the north contributed only insignificantly; the provenance developed to a certain extent in the late Oligocene. Since the Miocene, the provenance has ceaselessly expanded from proximal to distal realm, embodying a characteristic of multi-source sedimentation. In the core strata with 31.5, 28.4, 25.5, 23, and 16 Ma from today, the geochemical parameters of REEs and Th/Sc ratio have significant saltation, embodying the tectonic movement events in the evolution of the Qiongdongnan Basin. In the tectonic evolution history of the South China Sea, the South China Sea Movement(34–25 Ma BP, early expansion of the South China Sea), Baiyun Movement(23 Ma BP), late expansion movement(23.5–16.5 Ma BP), expansion-settlement transition, and other important events are all clearly recorded by the geochemical characteristics of REEs in the core.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号