O/O ratios in anhydrous spinel lherzolite xenoliths from the Shavaryn-Tsaram volcano, Mongolia     

R.S. Harmon  P.D. Kempton  H.-G. Stosch  J. Hoefs  V.I. Kovalenko  D. Eonov 《Earth and Planetary Science Letters》1987,81(2-3)

Anhydrous spinel lherzolite xenoliths from the Shavaryn-Tsaram volcano, which represent unusually clinopyroxenerich samples of upper mantle beneath the Tariat Depression in north-central Mongolia, have particularly low δ¹⁸O values of +4.9 to +5.7‰ SMOW. Constituent minerals exhibit small (ca. 0.5–0.7‰) variations in¹⁸O content (olivine = +4.6 to +5.3‰, clinopyroxene = +5.6 to +6.1‰, orthopyroxene = +5.8 to +6.5‰), that are unrelated to xenolith modal mineralogy, chemical composition, radiogenic isotope character, or pyroxene equilibration temperature. This O-isotope character of the Tariat xenoliths is interpreted to reflect the closed-system distribution of oxygen isotopes in a slowly cooling mantle diapir emplaced into the lithosphere from a relatively primitive region of the asthenosphere.  相似文献   

A stable isotope study of serpentinization and metamorphism in the Highland Border Suite,Scotland, U.K.     

Nicholas P Ikin  Russell S Harmon 《Geochimica et cosmochimica acta》1983,47(2):153-167

$\text{D}\text{H}$ and ${}^{18}\text{O}{}^{16}\text{O}$ ratios have been measured for whole-rock samples and mineral separates from the mafic and ultramatic rocks of the Cambro-Ordovician Highland Border Suite. The H- and O- isotopic compositions of these rocks record individual stages in a relatively complex 500 Myr old hydrothermal/metamorphic history. Lizardite serpentinites (δD ～ ? 105‰; δ¹⁸O ～ + 6.2‰) record a premetamorphic history and indicate that parent harzburgites, dunites, and pyroxenites were serpentinized through low-temperature interaction with meteoric waters during cooling. The other rocks of the Highland Border Suite record subsequent interaction with metamorphic fluids. Amphibolite facies hornblende schists were produced through thrust-related (dynamothermal) metamorphism of spilitic pillow lavas. During dehydration, D-enriched fluids were driven off from the spilites thus leaving the hornblende schists to equilibrate with a relatively D-depleted internal fluid reservoir (δD ～ ? 45‰). The expelled D-enriched fluids may have mixed with more typical Dalradian metamorphic waters which then exchanged with the remaining mafic rocks and lizardite serpentinites during greenschist facies regional metamorphism to produce antigorite serpentinites (δD ～ ? 62‰; δ¹⁸O ～ + 8‰) and greenschist metaspilites (δD ～ ? 57‰; δ¹⁸O ～ + 7.3‰) with similar H- and O-isotopic compositions. Serpentinites which have been only partially metamorphosed show intermediate H-isotopic compositions between that of metamorphic antigorite (δD ～ ? 62‰) and non-metamorphic lizardite δD ～ ? 105‰) end members.  相似文献   

Major element chemistry of glasses in Apollo 14 soil 14156     

Arch M. Reid  W.I. Ridley  Russell S. Harmon  Pete Jakes̆ 《Geochimica et cosmochimica acta》1973,37(3):695-699

Glasses in a soil sample (14156) from the middle layer of the trench at the Fra Mauro landing site show a wide range of compositions clustered around certain preferred compositions. Ninety per cent of the glasses are of two major types—Fra Mauro basalt (63 per cent) with high K and 17 weight per cent Al₂O₃ and Highland basalt or anorthositic gabbro (27 per cent) with low K and 25–26 weight per cent Al₂O₃. The glass population is almost identical with that of the comprehensive soil 14259 (Apollo Soil Survey, 1971).  相似文献