Liquid immiscibility in the parent bodies of ordinary chondrites and genetic types of iron
نویسندگان
چکیده
Introduction: The genesis of chondrites is a key problem in the concept of the planetary evolution of the solar system, but explanations proposed for the origin of the silicate chondrules and Fe-rich matrix of chondrites notably differ. Most cosmochemists deny genetic links between chondrules and their host matrix, with the chondrules and matrix considered to be genetically separated and generated and evolving under different conditions and according to different mechanisms. The fact that relations between silicates in chondrules and the matrix metallic phase is explained by the overprint of metamorphism, which is thought to be responsible for the origin of equilibrium chondrites of petrological types 4 7.
منابع مشابه
Identifying Asteroidal Ordinary Chondrite Assemblages and Petrographic Types from Vnir Spectra
Introduction: Because of a poor understanding of the delivery mechanisms of meteoroids from the asteroid belt, early asteroid spectral investigations often assumed that the abundance of various meteorite types among meteorite falls was approximately proportional to the abundance of such assemblages within the asteroid population. Based on that assumption, it was concluded that a large fraction ...
متن کاملHf-W chronometry and the accretion and early evolution of asteroids and terrestrial planets
We review the chronology for the accretion and earliest evolution of asteroids and terrestrial planets as obtained by applying Hf-W chronometry to meteoritic and planetary samples. Internal Hf-W isochrons for CAIs and angrites yield an absolute age for CAIs of 4568.6±0.7 Ma, which is ~1.5 Ma older than previously determined from PbPb ages for CAIs. Hafnium-tungsten isochrons for H chondrites co...
متن کاملMeteoritic Parent Bodies: Their Number and Identification
Extensive collection efforts in Antarctica and the Sahara in the past 10 years have greatly increased the number of known meteorites. Groupings of meteorites according to petrologic, mineralogical, bulkchemical, and isotopic properties suggest the existence of 100–150 distinct parent bodies. Dynamical studies imply that most meteorites have their source bodies in the main belt and not among the...
متن کاملFeierberg, Michael Andrew EVIDENCE FOR A COMPOSITIONAL RELATIONSHIP BETWEEN ASTEROIDS AND METEORITES FROM INFRARED SPECTRAL REFLECTANCES
High-resolution Fourier spectra in the 0.9-2.5 ym region were measured for sixteen asteroids. These data were combined with 0.3-1.1 um spectrophotometry and 3.0-3.5 urn narrowband photometry for compositional analysis. Comparison spectra of meteorites and terrestrial minerals were measured in the laboratory, some under simulated asteroidal conditions of pressure and temperature. Spectra of elev...
متن کاملFormation of Sulfates on Parent Bodies of Carbonaceous Chondrites, Ceres,
Introduction: Chemical compounds of S 6+ , sulfates and/or SO3, occur on Earth, Venus, Mars, parent bodies of carbonaceous chondrites, and icy surfaces of Europa and Ganymede. On the terrestrial planets, formation of S 6+ species is related to atmospheric photochemical processes that produce O2 and other O-rich oxidants. Here we explain the formation of sulfates within chondritic bodies through...
متن کامل