996 resultados para Nd YV O4
Resumo:
Na_2WO_4LiClNaLn(WO_4)_2(Ln=La,Pr,Nd)NaLa(WO_4)_2NaPr(WO_4)_2NaNd(WO_4)_2,,I4_1/a,(LaPrNd),Ln~(3+),LnO,NaLn(WO_4)_2NaPr(WO_4)_2
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Nd(C_8H_(11))Cl_23THFEt_3Al,i-Bu_3Al,HAl(i-Bu_2),,,(9798)
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AlCl_3,2RE(C_6H_6)(AlCl_4)_3C_6H_6(RE=LaNd)Nd2,,
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,LaNd,
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Ziegler-NattaNd-Al,,,;Ziegler-Natta,GPC,
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(NdCl_33p_(350))(AlR_3)Nd-A]Ndcl_33P_(350)-Al[(CH_2)_7-CH_3]_3Al(C_2H_5)_3,,Nd-(CH_2)_7CH_3Nd-CH_2CH_3,AlR_3,,
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Nd-Al,,,,,,,;,,,,
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LaNd YbBa_2Cu_3O(7-) Yb (0.1) YbBa_2Cu_3O(7-), Cu~(3+)/Cu~(2+)
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(Nd,Ce) :YAG Nd:YAG ,80%,,, YAG Ce~(3+) Nd~(3+)
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Nd-Fe-BT_C, ,SiT_C,Nd-Fe-B-Si. , Nd_(15)Fe_(77-x)Si_xB_8(x=481618 at),Ar.T-MB-2;x-JXA-8402028x-.
Resumo:
,1:0.5,(PrCeNd),1:0.25LnCl_3LiCl(Ln=LaNd)C_5H_5Na,[Li(THF)_2]_2(-Cl)_4C_5LnTHF,
Resumo:
Clay fractions in the non-calcareous surface sediments from the eastern Pacific were analyzed for clay minerals, REE and Nd-143/Nd-144. Montmorillonite/illite ratio (M/I ratio), total REE contents (Sigma REE), LREE/HREE ratio and cerium anomaly (delta Ce) may effectively indicate the genesis of clay minerals. Clay fractions with M/I ratio > 1, delta Ce < 0.85, Sigma REE > 400 mu g/g, LREE/HREE ratio approximate to 4, and REE patterns similar to those of pelagic sediments are terrigenous and autogenetic mixed clay fractions and contain more autogenetic montmorillonite. Clay fractions with M/I ratio < 1, delta Ce=0.86 to 1.5, Sigma REE=200 to 350 mu g/g, LREE/HREE ratio approximate to 6 and REE distribution patterns similar to that of China loess are identified as terrigenous clay fraction. The Nd-143/Nd-144 ratios or epsilon(Nd) values of clay fractions inherit the features of terrigenous sources of clay minerals. Clay fractions are divided into 4 types according to epsilon(Nd) values. Terrigenous clay minerals of type I with the eNd values of -8 to -6 originate mainly from North American fluvial deposits. Those of type 11 with the epsilon(Nd) Values of -9 to -7 are mainly from the East Asia and North American fluvial deposits. Those of type III with epsilon(Nd) values of -6 to -3 could come from the central and eastern Pacific volcanic islands. Those of type IV with epsilon(Nd) values of -13 to -12 may be from East Asia eolian. The terrigenous and autogenetic mixed clay fractions show patchy distributions, indicating that there are volcanic or hot-spot activities in the eastern Pacific plate, while the terrigenous clay fractions cover a large part of the study area, proving that the terrigenous clay minerals are dominant in the eastern Pacific.
Resumo:
Fifty-six samples of nannofossil ooze were collected from Core PC5794 in the northern equatorial Pacific at 5 em intervals. With the methods of mass spectrometer (VG354) and ICP, the Nd isotopic compositions (epsilon(Nd)(t)), Mn contents and Mg/Sr ratios of carbonate phase have been analyzed. CaCO3 contents of bulk sediments were obtained by dissolution of 0.5 mol/L HCl. Based on these data, the high-resolution epsilon(Nd)(t) profile of seawater in early Miocene with core depth(or time) have been established. The values of epsilon(Nd)(t) range from -6.2 to -2.97 and 4 fluctuation cycles existed during 24.06-22.02 Ma. 4 low epsilon(Nd)(t) values (about -6.4) correspond to high CaCO3 contents, which implicates that there were 4 cold epochs or 4 times of Antarctic Bottom Water activity. They occurred at the time of 24.06 Ma, 23.85 Ma, 22.88 Ma and 22.26 Ma, respectively. High epsilon(Nd)(t) values correspond to the high Mn contents and high values of Mg/Sr ratio, which indicates the existence of 4 intense hydrothermal activity periods during 24.06-22 Ma, the durations of them are 4.05-23.98 Ma, 23.69-23.15 Ma, 22.74-22.37 Ma and 22.06-22.02 Ma, respectively.
Resumo:
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 basaltic 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 cumulation 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.
