Rb-Sr, Sm-Nd and Lu-Hf isotope systematics of the lunar Mg-suite: the age of the lunar crust and its relation to the time of Moon formation
Richard W. Carlson,Lars E. Borg,Amy M. Gaffney,Maud Boyet +3 more
TLDR
The Sm/Nd—142Nd/144Nd correlation shown by both ferroan anorthosite and Mg-suite rocks is coincident with the trend defined by mare and KREEP basalts, and is in accord with the model of lunar formation via giant impact into Earth at ca 4.4 Ga.Abstract:
New Rb-Sr, 146,147Sm-142,143Nd and Lu-Hf isotopic analyses of Mg-suite lunar crustal rocks 67667, 76335, 77215 and 78238, including an internal isochron for norite 77215, were undertaken to better define the time and duration of lunar crust formation and the history of the source materials of the Mg-suite. Isochron ages determined in this study for 77215 are: Rb-Sr=4450±270 Ma, 147Sm-143Nd=4283±23 Ma and Lu-Hf=4421±68 Ma. The data define an initial 146Sm/144Sm ratio of 0.00193±0.00092 corresponding to ages between 4348 and 4413 Ma depending on the half-life and initial abundance used for 146Sm. The initial Nd and Hf isotopic compositions of all samples indicate a source region with slight enrichment in the incompatible elements in accord with previous suggestions that the Mg-suite crustal rocks contain a component of KREEP. The Sm/Nd—142Nd/144Nd correlation shown by both ferroan anorthosite and Mg-suite rocks is coincident with the trend defined by mare and KREEP basalts, the slope of which corresponds to ages between 4.35 and 4.45 Ga. These data, along with similar ages for various early Earth differentiation events, are in accord with the model of lunar formation via giant impact into Earth at ca 4.4 Ga.read more
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Water in the Moon's interior: Truth and consequences
TL;DR: In this article, geochemical data for H 2 O and other volatiles, as well as major and trace elements, are reported for 377 samples of lunar volcanic glass from three chemical groups (A15 green, A15 yellow, A17 orange 74 220).
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Early formation of the Moon 4.51 billion years ago.
Mélanie Barboni,Patrick Boehnke,Patrick Boehnke,Brenhin Keller,Brenhin Keller,I. E. Kohl,Blair Schoene,Edward D. Young,Kevin D. McKeegan +8 more
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Origin and Evolution of the Cometary Reservoirs
TL;DR: Brasser et al. as mentioned in this paper proposed the Nice model, in which the giant planets formed closer together than they are now, and underwent a dynamical instability that led to a flood of comets and asteroids throughout the Solar System.
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Lunar tungsten isotopic evidence for the late veneer
TL;DR: Data independently show that HSE abundances in the bulk silicate Earth were established after the giant impact and core formation, as predicted by the late veneer hypothesis and constitutes a challenge to current models of lunar origin.
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A review of lunar chronology revealing a preponderance of 4.34–4.37 Ga ages
TL;DR: In this article, data obtained from Sm-Nd and Rb-Sr isotopic measurements of lunar highlands samples are renormalized to common standard values and then used to define ages with a common isochron regression algorithm.
References
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The Lu–Hf and Sm–Nd isotopic composition of CHUR: Constraints from unequilibrated chondrites and implications for the bulk composition of terrestrial planets
TL;DR: In this paper, the Lutetium-Hafnium radiogenic isotopic system is used as a chronometer and tracer of planetary evolution, and the Lu-Hf system parameters need to be more tightly constrained, in particular the LuHf isotopic composition of the chondritic uniform reservoir and, by extension, the bulk silicate Earth.
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Calibration of the lutetium-hafnium clock.
TL;DR: The existence of strongly unradiogenic hafnium in Early Archean and Hadean zircons implies that enriched crustal reservoirs existed on Earth by 4.3 billion years ago and persisted for 200 million years or more, and current models of early terrestrial differentiation need revision.
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The decay constant of 176Lu determined from Lu-Hf and U-Pb isotope systematics of terrestrial Precambrian high-temperature mafic intrusions
TL;DR: In this paper, a cross-calibration of U-Pb and Lu-Hf isotopic systems on mineral fractions from the Proterozoic Karlshamn and Sorkka dolerites in Sweden and Finland is presented.
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Lunar initial 143Nd/144Nd: Differential evolution of the lunar crust and mantle
G.W. Lugmair,Kurt Marti +1 more
TL;DR: In this paper, the authors studied the evolution of Apollo 15 green glass and found that the ICE age of 3.8 + or - 0.4 eons overlaps the range of reported (Ar-39)-(Ar-40) ages and implies a distinct source region for green glass.