Intrusive calcite-carbonatite occurrence from Mt. Vulture volcano, southern Italy.
615 - 624.
Intrusive calcite-carbonatite ejecta (sovite) in the lowermost tephra layers of the Mr. Vulture alkaline mafic-ultramafic volcano (Upper Pleistocene), is the first intrusive carbonatite sample from southern Europe. The sovite is of coarse granularity and shows some textural and mineralogical layering. It is mainly formed of calcite (up to 3.5 wt.% MgO, and 0.53 wt.% SrO), less dolomite (average 18.2 wt.% MgO, and up to 2.1 wt.% SrO), spinel (60 wt.% Al2O3, 26.5 wt.% MgO, 10.7 wt.% FeO) and olivine (Fo(99)). Perovskite and apatite have been found only as microlites. Intergranular vugs are scattered throughout the rucks and small composite inclusions occur in calcite. The mineral chemistry, high temperature melt inclusions, overall isotopic compositions, and the REE distribution are consistent with a primary igneous origin. Compared with world average sovite compositions, the Vulture sovite has lower LILE and HFSE but Rb, Sr, Th and U are high. The REE abundance is typical of carbonatites, having an LREE/HREE value of similar to 100. The delta(13)C (-4.8 parts per thousand SMOW) is in the range for mantle-derived carbonatites. The Nd-143/Nd-144 (0.512648+/-15) and Sr-87/Sr-86 (0.705978+/-10) ratios show close similarity between the sovite and the Vulture alkaline mafic rocks. The sovite ejecta are interpreted as a crystallization product of carbonate ultramafic liquid. In common with many shallow-level carbonatites from other localities, the recrystallization of rather pure Ma-calcite, the presence of dissolution vugs and the depletion of some HFSE and the relatively high delta(18)O values, suggest that a secondary process, such as hydrothermal leaching, affected the rock.
|Title:||Intrusive calcite-carbonatite occurrence from Mt. Vulture volcano, southern Italy|
|Location:||UNIV COLL LONDON, LONDON, ENGLAND|
|Keywords:||intrusive carbonatite, alkali-mafic rocks, Mt. Vulture, Italy, WEST-EIFEL, GERMANY, XENOLITHS, GLASS, ROCKS|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Maths and Physical Sciences
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