261 research outputs found
Core Formation and Mantle Differentiation on Mars
Geochemical investigation of Martian meteorites (SNC meteorites) yields important constraints on the chemical and geodynamical evolution of Mars. These samples may not be representative of the whole of Mars; however, they provide constraints on the early differentiation processes on Mars. The bulk composition of Martian samples implies the presence of a metallic core that formed concurrently as the planet accreted. The strong depletion of highly siderophile elements in the Martian mantle is only possible if Mars had a large scale magma ocean early in its history allowing efficient separation of a metallic melt from molten silicate. The solidification of the magma ocean created chemical heterogeneities whose ancient origin is manifested in the heterogeneous 142Nd and 182W abundances observed in different meteorite groups derived from Mars. The isotope anomalies measured in SNC meteorites imply major chemical fractionation within the Martian mantle during the life time of the short-lived isotopes 146Sm and 182Hf. The Hf-W data are consistent with very rapid accretion of Mars within a few million years or, alternatively, a more protracted accretion history involving several large impacts and incomplete metal-silicate equilibration during core formation. In contrast to Earth early-formed chemical heterogeneities are still preserved on Mars, albeit slightly modified by mixing processes. The preservation of such ancient chemical differences is only possible if Mars did not undergo efficient whole mantle convection or vigorous plate tectonic style processes after the first few tens of millions of years of its histor
Study of fusion crust in ureilite and H-chondrites
第6回極域科学シンポジウム[OA] 南極隕石11月16日(月) 国立国語研究所 2階 講
Relationship between winonaites and IAB irons, and among IAB irons inferred from metal composition and partial melting model calculation
第6回極域科学シンポジウム[OA] 南極隕石11月16日(月) 国立国語研究所 2階 講
REE and Hf distribution among accessory phases in H and CK chondrites.
第2回極域科学シンポジウム/第34回南極隕石シンポジウム 11月17日(木) 国立国語研究所 2階講
Asuka 12325: A new depleted shergottite
The Tenth Symposium on Polar Science/Special session: [OA] Antarctic meteorites, Thur. 5 Dec. / 3F Multipurpose conference room, National Institute of Polar Researc
An Antarctic chondrite story: from the field to the lab
第6回極域科学シンポジウム[OA] 南極隕石11月16日(月) 国立国語研究所 2階 講
From olivine to ringwoodite: a complex process investigated by TEM
info:eu-repo/semantics/publishe
26Al-26Mg and stable isotopes investigated in ureilites
第6回極域科学シンポジウム[OA] 南極隕石11月17日(火) 国立国語研究所 2階 講
New geochronological history of the Mbuji-Mayi Supergroup (Proterozoic, DRC) through U-Pb and Sm-Nd dating
peer reviewe
- …