Journal of
GEOsciences
  (Formerly Journal of the Czech Geological Society)

Original Paper

High-pressure metabasic rocks from the Kutná Hora Complex: geological position and petrology of exotic lithologies along the segmented Moldanubian margin, Bohemian Massif

Authors:

Published in:

pages:

DOI:

Received:

Accepted:

Online:

H. Editor:

full text (PDF) | references | Supplementary material | Export to RIS

Abstract:
New occurrences of high-pressure metabasites in the Kutná Hora Unit (KHC) are described. These HP rocks include eclogites (± Ky), Cpx-Grt amphibolites, metagabbros and Cpx-bearing granulites. All the eclogite samples studied are formed of well-preserved HP mineral assemblages with variable degree of subsequent metamorphic overprint.
Eclogites from the inner part of the KHC (Roztěž, Bořetice) mostly had a Mg-rich tholeiitic protolith. Chemical, mineralogical and metamorphic data reveal that these eclogites are petrologically similar to the eclogite samples from the better known Běstvina Unit. Eclogites from Bořetice, Poličany and Roztěž preserve relict mineral assemblage from a pre-eclogite stage, enclosed in garnet with prograde zoning pattern. They bear mineralogical evidence of a very high-pressure history, even substantially higher (maximum 8.4 wt. % of Na₂O in Cpx, P˜ 4.3 GPa) than the previously described eclogites from Spačice and Úhrov in the Běstvina Unit.
A set of three eclogites from the northern margin of the Moldanubian Zone south of Chotěboř was used for comparison (Bída, Borovský Creek, Krátká Ves). They preserve also a peak pressure record that corresponds to minimum pressures above 2.0 GPa.
Better understanding of regional relationships amongst the discussed units can be achieved only using isotopic and geochronological data.