Semarkona meteorite: first recorded occurrence of smectite in an ordinary chondrite, and its implications

Journal Article · Wed Jul 01 00:00:00 EDT 1987 · Geochim. Cosmochim. Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(87)90178-5· OSTI ID:7252256

Hutchison, R; Alexander, C M.O.; Barber, D J

Semarkona is an unshocked unequilibrated ordinary chondrite. Much of the interchondrule matrix and the mesostases of some chondrules and clasts have been hydrothermally altered. Analyses of altered materials and opaque matrix are presented. Ca and Fe have been redistributed from primary, anhydrous phases into calcite and Na, Fe smectite, respectively. In Semarkona the process possibly requires open system behavior inconsistent with the conventional view of metamorphism of the ordinary chondrites. The low petrologic type previously assigned to Semarkona is the result of retrograde metamorphism, under aqueous conditions, of a higher temperature mineral assemblage. Semarkona, and possibly Bishunpur, should be assigned to petrologic type 2.

• Research Organization: British Museum (Natural History), London (England)
• OSTI ID: 7252256
• Journal Information: Geochim. Cosmochim. Acta; (United States), Vol. 51:7
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CHONDRITES
CHEMICAL COMPOSITION
COSMOCHEMISTRY
HYDROTHERMAL ALTERATION
PETROLOGY
CALCITE
CALCIUM
CHEMICAL ANALYSIS
IRON
METAMORPHISM
MINERALOGY
SMECTITE
SODIUM
ALKALI METALS
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHEMISTRY
CLAYS
ELEMENTS
GEOLOGY
METALS
METEORITES
MINERALS
OXYGEN COMPOUNDS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
STONE METEORITES
TRANSITION ELEMENTS
580400* - Geochemistry- (-1989)