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1.
A heavy mineral (HM) study and light and heavy rare earth elements (LREE and HREE) analysis were performed in coastal and inland dune sands, El Vizcaino Desert, Central Baja California Peninsula, Mexico. Our study shows high abundances of hornblende and apatite in the El Vizcaino dune sands, suggesting a dominance of granodiorites/intermediate plutonic rocks and marine authigenic phosphorite in the dune sands. There is a relationship between unstable heavy minerals like hornblende, pyroxenes, and sphene, and heavy rare earth elements (HREE) that suggests that unstable heavy minerals are potential carriers of HREE in the dune fields. However, there is a slight depletion of HREE in relation to LREE, especially in one locality of the inland dunes probably associated with the wind regime and weathering of unstable heavy minerals in the sands. Inland, transitional, and coastal dune fields can be observed as different dune provinces by means of grouping HM and REE data in two separate dendograms. It seems that HREE are correlated with fine-grained sand sizes and correlated with high CIA values linked to slightly weathered sands.  相似文献   

2.
Rare earth elements (REEs: La-Lu) in surface sediments collected from the mouth and middle tidal flats of Gomso Bay, South Korea, in August 2011 and May 2012 were analyzed to investigate the fine-grained sediment provenance. The upper continental crust (UCC)-normalized light REEs (LREEs: La to Nd) were more enriched than the middle REEs (MREEs: Sm to Dy) and heavy REEs (HREEs: Ho to Lu), resulting in large (La/Yb)UCC (1.9 ± 0.4) to (Gd/Yb)UCC (1.4 ± 0.2) ratios. The monthly (La/Yb)UCC values differed between the mouth and middle tidal flats due to deposition of fine-grained sediments that originated from distant rivers (the Geum and Yeongsan) and the Jujin Stream, located on the southern shore of the inner bay. We observed relative reductions in the (La/Yb)UCC value and REE content in the sediments from the mouth of the bay compared with those from Jujin Stream sediments. Confined to the middle tidal flat around the KH Line of Jujin Stream, the sediments, most enriched in LREEs but depleted in Eu, were distributed in August as strong Jujin Stream runs. Here, we suggest that an increase in LREE/HREE and decrease in MREE/LREE ratios can be used as a proxy to identify the Jujin Stream provenance in mixed riverine sediments and to trace Jujin Stream sediments within the Gomso Bay tidal flat, especially in the summer rainy season.  相似文献   

3.
The geochemical composition of phosphorites and phosphatic sediments in the Baja California peninsula is studied and used to assess the environment in which phosphogenesis took place. The deposits are classified in three groups: (1) stratified phosphorites, (2) phosphatic sandy sediments from beaches and dunes, and (3) submarine sediments. Some of the elements that might have substituted Ca and PO4 during francolite mineralization were studied by means of ICP-AES. Significant differences are seen in the concentration of these metals (e.g., Cr = 72-406 μg g?1 and V = 17-198 μg g?1), indicating that their concentration is not only controlled by the P2O5 concentration, but also by paleo-environmental conditions existing during francolite precipitation. Shale normalized REE patterns suggest two main environments of formation: (1) a strong negative Ce anomaly (< ? 0.3) and La enrichment (La/Nd ≥ 1) enrichment, suggesting well oxygenated shelf environments and probably lower light REE weathering, and (2) a weak negative Ce anomaly (> ? 0.3) and La depletion (La/Nd ≤ 1) suggesting shallower waters or restricted circulation and probably LREE weathering.  相似文献   

4.
Rare earth elements (REEs) of 91 fine-grained bottom sediment samples from five major rivers in Korea (the Han, Keum, and Yeongsan) and China (the Changjiang and Huanghe) were studied to investigate their potential as source indicator for Yellow Sea shelf sediments, this being the first synthetic report on REE trends for bottom sediments of these rivers. The results show distinct differences in REE contents and their upper continental crust (UCC)-normalized patterns: compared to heavy rare earth elements (HREEs), light rare earth elements (LREEs) are highly enriched in Korean river sediments, in contrast to Chinese river sediments that have a characteristic positive Eu anomaly. This phenomenon is observed also in primary source rocks within the river catchments. This suggests that source rock composition is the primary control on the REE signatures of these river sediments, due largely to variations in the levels of chlorite and monazite, which are more abundant in Korean bottom river sediments. Systematic variations in ΣLREE/ΣHREE ratios, and in (La/Yb)–(Gd/Yb)UCC but also (La/Lu)–(La/Y)UCC and (La/Y)–(Gd/Lu)UCC relations have the greatest discriminatory power. These findings are consistent with, but considerably expand on the limited datasets available to date for suspended sediments. Evidently, the REE fingerprints of these river sediments can serve as a useful diagnostic tool for tracing the provenance of sediments in the Yellow Sea, and for reconstructing their dispersal patterns and the circulation system of the modern shelf, as well as the paleoenvironmental record of this and adjoining marginal seas.  相似文献   

5.
魏杰瑞  黄朋 《海洋科学》2021,45(12):8-17
冲绳海槽中段热液活动区表层沉积物的主、微量和稀土元素分析结果表明:区内沉积物主要由陆源物质与热液源物质组分组成,Hg、Au、Sb、Cu、Pb、Zn、Ba、As、Fe和Co等微量元素富集;沉积物的化学风化程度中等,A-CN-K图解表明其暂未受到钾交代影响,且其母岩成分接近花岗闪长岩;北美页岩标准化稀土配分模式曲线整体较为平坦,轻重稀土分馏较弱,部分样品具有与热液流体类似的明显正铕异常.受热液活动影响,部分沉积物中的Fe、Cu、As、Pb和Zn显著富集,结合样品所处站位,整体显示含金属沉积物-过渡沉积物-正常沉积物的空间分配模式.结合(La/Sm)N、(La/Yb)N比值指示区内沉积物的陆源物质主要来自于黄河与台湾岛河流.  相似文献   

6.
The contents of seven major components (TiO2, Fe2O3, MgO, CaO, Na2O, K2O and P2O5) and 15 trace elements (Sc, V, Cr, Ni, Cu, Sr, Y, Zr, Ba, La, Ce, Nd, Eu, Yb and Th) were determined by ICP-AE spectrometry in 27 samples of manganese nodules, micronodules as well as abyssal clay collected by dredging from an area of nearly 1,9802 nautical miles in the central Clarion-Clipperton abyssal plain at a depth of about 4,500 m. Statistical analyses were used to compare among individual as well as pooled datasets, in addition to different indicators such as La/Th, Ni/Cu and LREE/HREE ratios for the Clarion-Clipperton samples, as well as between these and corresponding values for the upper continental crust (UCC), North America Shale Composite (NASC), and igneous Indian and Pacific Mid-Ocean Ridge Basalts (MORBs). The results show significant correlations between major components in the Clarion-Clipperton samples and Pacific Ocean MORB, whereas trace elements (excepting Ni and Cu) correlate better with the UCC and NASC. There is also depletion in LREEs, together with a Ce negative anomaly for all Clarion-Clipperton samples. The nodule, micronodule and abyssal clay datasets each reveal typical clusters of components such as P2O5 and Y, La, Nd, Eu, Tb, or Ni and Cu. Compared to abyssal clay, the nodule as well as micronodules show significant enrichment in Ni and Cu; nevertheless, an essentially constant Ni/Cu ratio indicates that all samples come from the sediment surface. The distributions of major components as well as trace elements for the Clarion-Clipperton samples present, to different degrees, characteristics common to both the upper continental crust and Mid-Ocean Ridge Basalt, strongly implying a hydrothermal origin, most probably from East Pacific Rise material transported by the Pacific North Equatorial Current.  相似文献   

7.
The Inductively Coupled Plasma Optical Emission Spectrometer was used to analyze sediment samples collected from the Hangzhou Bay to determine major and trace elemental concentrations. Based on these concentrations, the study area can be classified into three geochemical provinces. Province I covers the northern Hangzhou Bay area and contains high concentrations of Al2 O3 , Fe2 O3 , MgO, Na2 O, K2 O, MnO, Cr, Cu, Ni, Pb, V, Co and Zn. Province III is located in the western Hangzhou Bay, near the Qiantang River mouth, and contains high concentrations of SiO2 , Na2 O, P2 O5 , TiO2 , Cr, Sr, Zr. Province II is located in the middle and eastern Hangzhou Bay, with the medium concentrations of major and trace elements. The results also demonstrate that the grain size is the dominating factor controlling the spatial variations of elemental concentrations, and the Changjiang River （Yangtze River） and Qiantang River sediments play an important role in the distribution of these elements. Anthropogenic impact on heavy metal concentrations （especially Cr, Sr and Zr） can be detected in the surface sediments near the Qiantang River mouth.  相似文献   

8.
对东马努斯盆地高镁安山岩做了全岩主微量和Sr-Nd-Pb同位素分析,并结合前人测试数据,探究了岩浆物质来源及演化过程。由主量元素[MgO、CaO、FeOT(全铁)、Al_2O_3、TiO_2和P_2O_5]含量随着硅含量的升高而降低和La/Sm随着La含量的升高而保持不变可知,岩浆在演化过程中只发生了矿物的分离结晶,分离的矿物可能为橄榄石、辉石、斜长石、钛铁矿和磷灰石。东马努斯盆地高镁安山岩的Pb和大离子亲石元素(K,Rb,Sr,Ba和U)的富集、高场强元素(Nb,Th,Ta和Ti)的亏损说明岩浆受到了俯冲板块脱水作用的影响。推测该区高镁安山岩是流体交代的地幔楔部分熔融形成的。由Sr-Nd同位素混合模拟结果可知东马努斯盆地高镁安山岩主要来源于马努斯MORB(洋中脊玄武岩),少量来自于太平洋蚀变洋壳和海底沉积物。根据Sr-Nd-Pb同位素特征推测岩浆混合作用发生在地幔源区,属于源区混染,岩浆在喷发的过程中没有发生同化混染作用,也没有加入其他体系的物质。  相似文献   

9.
Abstract

The U.S. Bureau of Mines conducted beneficiation and digestion tests to evaluate the potential of recovering P2O5 from an apatite deposit located 10 nautical miles offshore Savannah, GA, in the Exclusive Economic Zone (EEZ). A 1.8 metric ton sample containing 1.0–1.5% P2O5 was obtained in a cooperative drilling project involving the Bureau of Mines, the Marine Minerals Technology Center‐Continental Shelf Division, the Minerals Management Service, and the Georgia Nonenergy Minerals Offshore Task Force. Beneficiation methods were evaluated with the goal of producing a 29–31% P2O5 concentrate with a CaO: P2O5ratio of less than 1.6: 1. These specifications were obtained using a combination of gravity separation and flotation. Comparative leaching tests conducted using EEZ, Idaho, and Florida phosphate concentrates showed that these EEZ phosphates behaved similarly to land‐based phosphates. The results suggest that as land‐based phosphate deposits are depleted, ocean phosphates represent a feasible alternate source.  相似文献   

10.
We sampled zooplankton and fecal pellets in the upper 200 m of Monterey Bay and nearby coastal regions in California, USA. On several occasions, we observed high concentrations of large pellets that appeared to be produced during night-time by dielly migrating euphausiids. High concentrations of pellets were found in near-surface waters only when euphausiids co-occurred with high concentrations of large (>10 μm) phytoplankton. Peak concentrations of pellets at mid-depth (100 or 150 m) during the day were consistent with the calculated sinking speeds of pellets produced near the surface at night. At these high flux locations (HI group), pellet concentrations declined below mid-depth. In contrast, at locations where the phytoplankton assemblage was dominated by small phytoplankton cells (<10 μm), pellet production and flux were low (LO group) whether or not euphausiid populations were high. Protozooplankton concentrations did not affect this pattern. We concluded that the day and night differences in pellet concentration and flux in the HI profiles were mostly due to sinking of dielly-pulsed inputs in the surface layer, and that small zooplankton (Oithona, Oncaea), heterotrophic dinoflagellates, and bacterial activity probably caused some pellet degradation or consumption below 100 m. We estimated that consumption of sinking pellets by large copepods was insignificant. High fluxes of pellets were episodic because they required both high concentrations of large phytoplankton and large stocks of euphausiids. Under these conditions, flux events overwhelmed retention mechanisms, resulting in large exports of organic matter from the upper 200 m.  相似文献   

11.
海南岛三亚小东海岸礁礁坪沉积物的稀土元素分布特征   总被引：1，自引：0，他引：1  
对海南岛三亚小东海东北岸礁礁坪表面沉积物的稀土元素进行了分析,结果表明,沉积物的∑REE为80.22mg/kg,稀土元素含量球粒陨石标准化分布模式呈现轻稀土富集、重稀土亏损,Eu明显负异常(0.58),Ce无异常,Y/Ho低(27.60)的陆相模式特征.根据小东海礁坪沉积样品稀土元素的空间分布情况可以推测出礁坪珊瑚表面...  相似文献   

12.
Uranium in coastal sediments of Tokyo Bay and Funka Bay   总被引：2，自引：0，他引：2  
The sediment cores from Tokyo Bay and Funka Bay were analyzed for U and its isotopic ratio,234U/238U, after dissolving them in 0.1 M HCl, and 30% H2O2 in 0.05 M HCl. A small fraction of U in the anoxic sediments was dissolved in 0.1M HCl and even the added yield tracer,232U, was lost. The isotopic ratio of H2O2 soluble U in the sediments was equal to that of seawater, suggesting that the H2O2 soluble U in the sediments is authigenic. The 6M HCl solution dissolved part of the lithogenic U besides the authigenic U. The depth profiles of U from the two bays resembled each other. The authigenic U comprised more than half of the total U even at the surface and increased with depth down to 70 cm, showing small maxima at about 20 cm. The concentration of refractory U was nearly constant with depth and similar to that of the pelagic sediments. The highest U concentration, 6 µg g–1 which was about 5 times that of the pelagic sediments, was observed in the layer between 70 and 160 cm depth in Tokyo Bay. The annual sedimentation rates of U in the Tokyo Bay sediments were 2.6 tons at the surface and 7.0 tons at the 70–160 cm depth. The increase in U with depth should be due to the deposition of interstitial U either diffusing downward from the surface indicating the trapping of seawater U, or otherwise diffusing upward from the deeper layer indicating the internal cycling of U within the sediments.  相似文献   

13.
Zooplankton was sampled through eight depth intervals above about 500 m along a transect of the eastern tropical Pacific (ETP), 23°N to 3°S, encompassing four environments. (1) The California Current—ETP transition off Baja California and the mouth of the Gulf of California is inhabited by California Current species at their southern limits, and by the galatheid ‘red crab’ Pleuroncodes planipes together with euphausiids (e.g. Euphausia eximia) of an abundance-based recurrent group of species, distinguished using the criterion of > x abundance (Numbers under unit area of sea surface) at common localities, adapted to productive zones marginal to the O2-deficient part of the ETP. Tropical species appear here where water with surface temperature > 26°C and [O2] of < 0.1 ml l?1 beneath a shoaling thermocline replaces the upwelling environment off Baja California. (1) The zone 22° to 10°N harbors euphausiids of two groups: the vertically migrating tropical species (e.g. Euphausia diomedeae) which tolerate intense O2-deficiency at their daytime depths and enter the oxygenated mixed layer at night, and non-migrating Stylocheiron species which have vertical ranges extending up into the mixed layer. Nevertheless, most of these ‘ETP-adapted’ species are denser farther south, in the north equatorial countercurrent, but three ETP endemics (e.g. E. distinguenda), all vertical migrators belonging in one subgeneric division of Euphausia, are densest in the O2-deficient regions. (3) The zone of the North Equatorial Countercurrent maintains high densities of three groups: the widely-ranging, ETP-adapted tropical species, the four common Stylocheiron species which, while recurring in abundance at the same localities, differ in depth and the mesopelagic tropical-subtropical species, not tolerant of O2-deficiency, which occur here in easterly tongues of range. (4) At the equator (93°W), easterly ranging species (e.g. E. paragibba) and westerly Nyctiphanes simplex appear to migrate between equatorial currents which differ in direction with depth, thereby maintaining their narrow ranges along the equator. The ‘marginal proliferators’ such as E. eximia, prominent off Baja California, are again abundant here, availing of the equatorial divergence for high productivity and of the oppositely-directed currents for geographical stability.A second recurrent grouping of species, based on presence of their larvae at common localities, yielded groups also distinguishable by whether the larvae lived within or beneath the mixed layer.Ontogenetic strengthening of vertical migration capability is demonstrated by many species, with older larvae, juveniles and adults showing ranges, respectively, increasing from a few meters to up to 400 m. The pattern is the same in O2-deficient regions as elsewhere.Regional distribution of euphausiid volume (wet displacement biomass) tended to agree with zooplankton volume, with maxima at the equator, 8°N, and at some localities off Baja California and the Gulf of California where red crab volume peaked. The depth at which euphausiid volume is equal in amount day and night, across which vertical migration takes place, is designated the equilibrium depth (EqD) for euphausiid volume. EqD for euphausiids generally agreed with EqD for zooplankton volume, indicating that euphausiids play a role in determining depth of EqD for zooplankton volume. Euphausiids comprised 13% (x) of zooplankton volume. 80% (x) of euphausiid volume migrated across EqD, the value showing no significant regional differences. 37% (x) of zooplankton volume engaged in such migration, but in the region south of 14°N encompassing the broad O2-deficient zone, the value was 26%, which compares with 18% previously determined for biomass transferring in a comparable way between epiplankton and planktostad in the same region.  相似文献   

14.
对取自渤海湾的307个表层沉积物进行了元素测试和粒度分析。渤海湾表层沉积物的常微量元素呈现4种组合:富集于粗粒沉积区的SiO_2、Na_2O亲碎屑元素组合;富集于细粒沉积区的以Al_2O_3和重金属元素为代表的亲黏土元素组合;与缺氧环境有关的MnO、V、TOC元素组合和与河流输入有关的陆源CaO、TiO_2元素组合。粒度粗细主导了渤海湾元素含量分布的整体格局;海域河流物源供应不同较大影响了渤海湾南部(富Na_2O、CaO和SiO_2)和北部(富Ba和P_2O_5)在元素含量上的差异;高流速潮流对海底的冲刷再分配导致曹妃甸南侧Sr、Ca元素的条带状富集异常;有机质在细粒沉积区的富集导致缺氧环境的形成和K_2O、Mn、V、自生黄铁矿的海洋自生化学沉积;人类活动导致以Pb为代表的重金属污染在河流入海口、港口及沿岸海域的元素分布异常;曹妃甸沙坝内侧的泻湖(海洋钙质生物沉积)与沙坝外侧水下岸坡(陆源碎屑沉积)的截然不同的物源,导致了独特地貌沉积环境下元素分布的局部差异。  相似文献   

15.
山东半岛东部海域表层沉积物元素组成及物源指示意义   总被引：1，自引：1，他引：0  
窦衍光  李军  杨守业 《海洋学报》2012,34(1):109-119
通过对山东半岛东部海域表层沉积物常量、微量元素、有机碳(TOC)以及碳酸盐(CaCO3)等指标的分析,研究了该海域表层沉积物元素组成特征及其控制因素,并对物质来源进行了探讨。结果表明,山东半岛东部海域表层沉积物元素的平均组成与上陆壳(UCC)相比Al,K,Na,Mg,Fe,Ca,Cu和Zn等元素,相对较低,而Mn,Co,Ni,Cr以及REE元素含量较高,Si和Ti与UCC的含量相当。研究区砂粒级沉积物轻重稀土分异明显,(La/Yb)N值与韩国河流的非常相近;其余粒级沉积物LREE分异较弱,标准化曲线与黄河沉积物的具有相似性。研究区沉积物的元素含量主要受控于源岩组成,存在明显的"粒级效应"。除此之外,Fe-Mn氧化物、生物碳酸盐等因素对元素组成产生一定影响。沉积物物源判别结果显示,山东半岛近岸及其东南部沉积物主要来源于黄河,该区域沉积物分布受山东半岛沿岸流及近岸潮流影响。研究区东北部为残留砂,其沉积物元素组成特征与朝鲜半岛和鸭绿江沉积物组成相近,表明研究区东北部砂质区沉积物代末次冰期低海平面时可能由朝鲜半岛或鸭绿江供应。  相似文献   

16.
The information on the transitional areas between the temperate and tropical domains at the southern extent of the California Current System is reviewed and described, particularly searching for the relative isolation or interchange between the western coast of the Baja California peninsula and the Gulf of California, as well as mechanisms that permit the existence of sizeable stocks of California sardine. Biological Action Centers that have high productivity throughout the year, as opposed to the rest of the coastal area, are found in both the western coast of the peninsula at the Sebastián Vizcaíno—Punta Eugenia region and in the Ballenas Channel inside the gulf; these features support large biomasses of sardine throughout the full year and serve as long term refuges during adverse periods. The role of the Sebastián Vizcaino sardine stock as the primary group for expansion is examined. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

17.
Petroleum-derived hydrocarbons have been identified in sediments by analysis of the n-alkanes, aromatic hydrocarbons and branched and cyclic components (humps). The detection of low levels of petroleum input to sediments can be ambiguous due to the presence of syngenetic biolipids. Triterpenoids, especially the (17αH, 21βH)-hopanes, have been proposed as sensitive molecular markers of petroleum pollution.Recent sediments from the Southern California Bight to subbottom depths of about 30 cm (pre-anthropogenic) contain lipids of syngenetic origin with major humps of branched and cyclic material and triterpenoids consisting mainly of the (17αH, 21βH)-hopanes ranging from C27 to C35. Extended hopanes (> C31) are found as 1:1 mixtures of the 22R and 22S diastereomers. The 17α(H),18α(H), 21β(H)-28,30-bisnorhopane is the dominant triterpane for most of these sediments and appears to be a potential molecular marker characteristic of the Southern California petroleums. Extended tricyclic diterpanes ranging from C19 to C27 are also present and their structures make them further possible indicators of petroleum. Southern California Bight sediments therefore appear to contain petroleum products from both seepage and anthropogenic activity.Recent sediments from other areas (e.g. Guaymas Basin, Gulf of California; Cook Inlet, Alaska; Eastern Bering Sea; Walvis Bay, Southwest Africa; and Mangrove Lake, Bermuda) contain predominantly (17βH, 21βH)-hopanes and hopenes, indicating recent synthesis and no petroleum pollution.  相似文献   

18.
通过提取黄河、辽河和鸭绿江表层沉积物中的碎屑矿物角闪石,对单矿物采用电子探针,对群体角闪石采用ICP-MS和ICP-AES分析其常量元素及微量元素组成。结果表明:角闪石单矿物主成分在一定范围内有较大变化,都具有高Si、Ca、Mg和低Na、K的特征;3条河流的角闪石晶体化学都归属钙角闪石组,半数以上矿物种为镁角闪石;角闪石群体矿物化学显示黄河角闪石的稀土元素浓度明显高于黄土和黄河全岩沉积物,而且重稀土比轻稀土更富集,说明角闪石是黄河和黄土沉积物稀土元素的主要载体之一,角闪石含量变化会对全岩样品稀土元素含量造成重要影响。微量元素特征显示新旧黄河样品间差别很小,与其同一来源物质的事实相符。虽然黄河、辽河和鸭绿江河流样品角闪石主成分相近,但微量元素方面(元素含量、元素含量对比值及特征值)显示较明显不同,样品间多种数值指标相对偏差在20%以上,可作为物源识别的判别标志,如微量元素Ba、Li、Rb、Cs、Ta、Tl、Pb、La、Ce、Pr、Nd等含量的差异,元素对比值c(La)/c(Y)、c(Sr)/c(Rb)、c(Zn)/c(Cu)、c(Gd)/c(Cd)、c(Li)/c(Be)、c(Rb)/c(Cs)、c(Sr)/c(Ba)、c(Hf)/c(Ta)、c(Pb)/c(Bi)等的差异;特征值∑c(REE)、Σc(LREE)、∑c(HREE)、∑c(LREE)/∑c(HREE)、[c(La)/c(Lu)]N、[c(La)/c(Yb)]N、[c(La)/c(Sm)]N等的差异。  相似文献   

19.
东海内陆架泥质区表层沉积物稀土元素的分布特征   总被引：3，自引：0，他引：3  
通过对东海内陆架泥质区30个表层沉积物样品中的稀土元素、主微量元素、TOC、CaCO3、沉积物粒度进行了分析,讨论了影响稀土元素分布的原因。结果显示东海内陆架中ΣREEs为182.8～221μg/g,均值为206.5μg/g,明显高于黄土、黄河及雅鲁藏布江中稀土元素的含量,与长江、瓯江中稀土元素含量接近。稀土元素的球粒陨石标准化配分模式及(La/Yb)N比值显示,轻稀土显著富集,存在显著的δEu异常。稀土元素上地壳标准化配分模式显示稀土元素与上地壳之间不存在显著的分馏,稀土元素存在显著的"四分性"。稀土元素与粒径、有机质、CaCO3之间不存在相关性,表明研究区中稀土元素含量不受上述3个因素的控制。元素比值及稀土元素上地壳标准化配分模式显示研究区稀土元素主要源于长江。  相似文献   

20.
根据对长江等5条河流和东海陆架区总计146个沉积物样品的稀土元素和粒度分析结果,借助统计学方法,讨论了河流和东海近岸沉积物稀土元素分布格局的形成因素及其对沉积动力作用的响应,结果表明,各河流沉积物在稀土元素总量和轻重稀土分异等参数上有差异;在长江口沉积物中稀土元素在小于2和2~31μm粒级中较富集,全岩稀土元素含量受物质组成占优的粒级控制;在东海陆架研究区稀土元素含量由岸向海有减小的趋势,在河口附近相对较高,轻重稀土分异自28°N向南有增大的趋势。  相似文献   

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