Where on Earth is the enriched Hadean reservoir?

Andreasen, R.; Sharma, Mukul; Subbarao, Kakarla; Viladkar, Shrinivas G.

doi:10.1016/j.epsl.2007.10.009

Cited by 50 publications

(35 citation statements)

References 71 publications

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“…An EER is only needed if the BSE has chondritic relative abundances of refractory lithophile elements (Figure 2). This study and previous studies have identified no geochemical evidence that any surface rock has been derived from the EER [e.g., Boyet and Carlson, 2006;Caro et al, 2006;Andreasen et al, 2008;Murphy et al, 2010]. Either the EER has been convectively isolated from participating in surface magmatism throughout Earth history, or there is no EER and the BSE does not have chondritic relative abundances of the refractory lithophile elements.…”

Section: Resultsmentioning

confidence: 87%

Homogeneous superchondritic ¹⁴²Nd/¹⁴⁴Nd in the mid‐ocean ridge basalt and ocean island basalt mantle

Jackson

Carlson

2012

Geochem Geophys Geosyst

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Nd measurements on 11 different lavas from five hot spots, and one lava each from the Indian and Atlantic ridges. The lavas examined in this study bracket much of the known Sr-Nd-Pb-He isotopic variability the in mantle. These data complement existing high-precision 142 Nd/ 144Nd data on MORB and OIB lavas. In agreement with previous studies, we find that MORB and OIB lavas examined for high-precision 142 Nd/ 144 Nd exhibit ratios that are indistinguishable from the terrestrial standard and are 15-20 ppm higher than the average obtained for ordinary and enstatite chondrites. The uniform, superchondritic 142 Nd/ 144 Nd data in OIB and MORB are consistent with derivation from a common, early formed (<30 Ma after accretion) progenitor reservoir with Sm/Nd $6% higher than chondrites. If there exists any variability in 142 Nd/ 144 Nd in the OIBs and MORBs examined to date, it is too small to be resolved with the precision currently available.

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Section: Resultsmentioning

confidence: 87%

Homogeneous superchondritic ¹⁴²Nd/¹⁴⁴Nd in the mid‐ocean ridge basalt and ocean island basalt mantle

Jackson

Carlson

2012

Geochem Geophys Geosyst

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“…The reported differences in the isotopic abundances of refractory elements such as barium (Andreasen et al 2008;Carlson et al 2007;Ranen & Jacobsen 2006), neodymium, and samarium (Andreasen & Sharma 2006;Boyet & Carlson 2005;Carlson et al 2007) between bulk meteorites and the Earth, suggest that heterogeneity in the solar nebula was preserved through part of the accretion process. These recent observations support earlier barium isotope measurements of chondrite leaches by Hidaka et al (2003) and contrast to some degree with predictions based on dynamical models that mixing and homogenization of the nebula was highly efficient (cf.…”

Section: Introductionmentioning

confidence: 99%

Calcium Isotope Composition of Meteorites, Earth, and Mars

Simon

DePaolo

Moynier

2009

ApJ

150

163

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The relative abundances of calcium isotopes in the mass range 40-44 were measured in primitive and differentiated meteorites and igneous rocks from Earth and Mars in search of non-mass-dependent variations that could provide clues about early solar system processes. 40 Ca abundance found in some chondrites and all differentiated meteorites studied. It appears that isotopic heterogeneity in calcium was still present at the completion of disk formation but was homogenized during planetary accretion.

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“…Though the suggestion has been made (Andreasen et al 2008), there is not yet any convincing evidence that the REE will gain siderophile or chalcophile tendencies at the high pressures and temperatures expected for terrestrial core formation. Thus, the abundance of REE in the core is expected to be very low with the implication that fractionation of Sm from Nd by core formation is unlikely.…”

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confidence: 99%

Composition of the Earth's interior: the importance of early events

Carlson

Boyet

2008

Phil. Trans. R. Soc. A.

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The detection of excess 142 Nd caused by the decay of 103 Ma half-life 146 Sm in all terrestrial rocks compared with chondrites shows that the chondrite analogue compositional model cannot be strictly correct, at least for the accessible portion of the Earth. Both the continental crust (CC) and the mantle source of mid-ocean ridge basalts (MORB) originate from the material characterized by superchondritic 142 Nd/ 144 Nd. Thus, the mass balance of CC plus mantle depleted by crust extraction (the MORB-source mantle) does not sum back to chondritic compositions, but instead to a composition with Sm/Nd ratio sufficiently high to explain the superchondritic 142 Nd/ 144 Nd. This requires that the mass of mantle depleted by CC extraction expand to 75–100 per cent of the mantle depending on the composition assumed for average CC. If the bulk silicate Earth has chondritic relative abundances of the refractory lithophile elements, then there must exist within the Earth's interior an incompatible-element-enriched reservoir that contains roughly 40 per cent of the Earth's 40 Ar and heat-producing radioactive elements. The existence of this enriched reservoir is demonstrated by time-varying 142 Nd/ 144 Nd in Archaean crustal rocks. Calculations of the mass of the enriched reservoir along with seismically determined properties of the D″ layer at the base of the mantle allow the speculation that this enriched reservoir formed by the sinking of dense melts deep in a terrestrial magma ocean. The enriched reservoir may now be confined to the base of the mantle owing to a combination of compositionally induced high density and low viscosity, both of which allow only minimal entrainment into the overlying convecting mantle.

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Where on Earth is the enriched Hadean reservoir?

Cited by 50 publications

References 71 publications

Homogeneous superchondritic ¹⁴²Nd/¹⁴⁴Nd in the mid‐ocean ridge basalt and ocean island basalt mantle

Homogeneous superchondritic ¹⁴²Nd/¹⁴⁴Nd in the mid‐ocean ridge basalt and ocean island basalt mantle

Calcium Isotope Composition of Meteorites, Earth, and Mars

Composition of the Earth's interior: the importance of early events

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Where on Earth is the enriched Hadean reservoir?

Cited by 50 publications

References 71 publications

Homogeneous superchondritic 142Nd/144Nd in the mid‐ocean ridge basalt and ocean island basalt mantle

Homogeneous superchondritic 142Nd/144Nd in the mid‐ocean ridge basalt and ocean island basalt mantle

Calcium Isotope Composition of Meteorites, Earth, and Mars

Composition of the Earth's interior: the importance of early events

Contact Info

Product

Resources

About

Homogeneous superchondritic ¹⁴²Nd/¹⁴⁴Nd in the mid‐ocean ridge basalt and ocean island basalt mantle

Homogeneous superchondritic ¹⁴²Nd/¹⁴⁴Nd in the mid‐ocean ridge basalt and ocean island basalt mantle