ライフサイエンスコーパス: MORB

1 MORBs generally exhibit a relatively low and narrow rang

2 MORBs vary in their abundances of incompatible elements

3 primitive magmas outgassed volatiles with a MORB-like helium isotopic signature ((3)He/(4)He ratio);

4 r the formation of the Solar System, OIB and MORB mantle sources must have differentiated by 4.45 bil

5 opic compositions of abyssal peridotites and MORB do not appear to be in equilibrium, raising questio

6 mixing between subducted atmospheric Xe and MORB Xe, which obviates the need for a less degassed dee

7 tabase for oceanic island basalts (OIBs) and MORBs.

8 s lower than that of mid-ocean ridge basalt (MORB) and comparable to the ultramobile pure carbonate m

9 tection of subducted mid-ocean ridge basalt (MORB) in the lower mantle is hindered by uncertainties i

10 re more oxidized than midocean ridge basalt (MORB) magmas, suggesting that the upper mantle sources o

11 wstone compared with mid-ocean ridge basalt (MORB) samples, this confirms that the deep plume and sha

12 ocess of the Pacific mid-ocean ridge basalt (MORB)-type mantle by the Indian MORB-type mantle.

13 otope variations in mid-ocean ridge basalts (MORB) are commonly attributed to compositional variation

14 more oxidized than mid-ocean ridge basalts (MORB), but it is debated whether this is a mantle featur

15 ces in the depleted mid-ocean ridge basalts (MORB)-source mantle, the enriched ocean island basalts (

16 than the source of mid-ocean ridge basalts (MORB).

17 (CSE) contents than mid-ocean ridge basalts (MORB).

18 differences between mid-ocean ridge basalts (MORBs) and ocean island basalts (OIBs) provide critical

19 Mid-ocean-ridge basalts (MORBs) are the most abundant terrestrial magmas and are

20 d isotope space for mid-ocean ridge basalts (MORBs) converge on a single end-member component that ha

21 We also find that mid-ocean-ridge basalts (MORBs) have (238)U/(235)U ratios higher than does the bu

22 OIBs) compared with mid-ocean-ridge basalts (MORBs) have been used as evidence for the existence of a

23 y uniform values in mid-ocean-ridge basalts (MORBs), are thought to result from a well mixed upper-ma

24 fold higher than in mid-ocean ridge basalts (MORBs).

25 e mantle residue of mid-ocean-ridge basalts (MORBs).

26 there is no true osmium isotopic gap between MORBs and abyssal peridotites.

27 dichotomy between solar plume and chondritic MORB mantle sources.

28 he rheniumosmium isotope system, constituent MORB phases are shown to possess exceptionally high Re/O

29 Here we present helium isotope data for MORB glasses recovered along approximately 5,800 km of t

30 lt from a well mixed upper-mantle source for MORB and a distinct deeper-mantle source for ocean islan

31 3He/4He ratios for MORBs show both positive and negative correlation with t

32 Globally, MORBs have near-uniform fO(2)s, whereas abyssal peridoti

33 ange of noble-gas concentrations observed in MORB and OIB glasses, can self-consistently be explained

34 ow that a higher CO2 content in OIBs than in MORBs leads to more extensive degassing of helium in OIB

35 OIBs are an order of magnitude lower than in MORBs.

36 the first time that the inflow of the Indian MORB-type mantle has reached the southern tip of tectoni

37 idge basalt (MORB)-type mantle by the Indian MORB-type mantle.

38 -called DUPAL isotopic anomaly in the Indian MORB-type mantle.

39 that observed in OIBs worldwide and indicate MORB-like (3)He/(4)He ratios in OIBs cannot be used to p

40 ity of Fe,Al,Mg,Ti-bearing davemaoite, a key MORB component.

41 tinct material, but do not account for lower MORB-like (3)He/(4)He ratios in OIBs, nor their observed

42 has led to a volatile-depleted upper mantle (MORB source) with low 3He concentrations and low 3He/4He

43 chondritic before 3.5 Ga and evolved to a N-MORB-like composition between approximately 3.5 and 2.7

44 +/- 0.006 per mille offset between BSE and N-MORBs requires that <30% of Earth's mantle equilibrated

45 sampled by normal mid-ocean ridge basalts (N-MORBs).

46 i/(47)Ti ratios ranging from chondritic to N-MORBs compositions, indicating continuing disruption of

47 model basalt, hydrous model basalt and near-MORB to assess the effects of iron and water on the melt

48 ontrast, the uranium isotopic composition of MORB requires the convective stirring of recycled uraniu

49 reases its fO(2), and that the uniformity of MORB fO(2)s is a consequence of the melting process and

50 ope and incompatible-element geochemistry of MORBs by a component of recycled crust that is variably

51 Here we show that (18)O/(16)O ratios of MORBs are correlated with aspects of their incompatible-

52 Compositional variations in the sources of MORBs could reflect recycling of subducted crustal mater

53 of mantle melts (mid-ocean ridge basalts, or MORBs) and their presumed mantle sources (abyssal perido

54 ternated with layers of sheared olivine plus MORB or of pure melt.

55 his confirms that the deep plume and shallow MORB mantles have remained distinct from one another for

56 rces of Hawaiian magmas have higher fO2 than MORB sources.

57 ng the plume source to be less degassed than MORBs, a conclusion that is independent of noble gas con

58 Our models show that MORB, containing 20 to 25 volume percent davemaoite, pot

59 The MORB data are consistent with the presence of a common m

60 ios between the Iceland mantle plume and the MORB source.

61 (3)He/(4)He ratio is 7.94 Ra, indicating the MORB mantle source.

62 ingly, estimates of the H(2)O content of the MORB mantle source based on H(2)O in abyssal peridotites

63 ith the 206Pb/204Pb ratios, depending on the MORB suite.

64 d to be chondritic in origin, similar to the MORB source mantle.

65 adiogenic values suggesting equilibrium with MORB.

66 plained solely by mixing atmospheric Xe with MORB-type Xe.