Comparative penological investigations of metagabbros from Western Alps ophiolites
Data on field relation, petrography and tiace element geochemistry are presented for metagabbro bodies from a few small tectonic slices in the Piedmont oceanic — type sequence. They are from east Arc valley and Monviso from the eastern internal Piedmont unit and from middle Arc valley, Montgenevre,...
Elmentve itt :
| Szerzők: | |
|---|---|
| Dokumentumtípus: | Cikk |
| Megjelent: |
University of Szeged, Department of Mineralogy, Geochemistry and Petrology
Szeged
1989
|
| Sorozat: | Acta mineralogica-petrographica
30 |
| Kulcsszavak: | Kőzettan, Ásványtan, Földtan |
| Tárgyszavak: | |
| Online Access: | http://acta.bibl.u-szeged.hu/24767 |
| Tartalmi kivonat: | Data on field relation, petrography and tiace element geochemistry are presented for metagabbro bodies from a few small tectonic slices in the Piedmont oceanic — type sequence. They are from east Arc valley and Monviso from the eastern internal Piedmont unit and from middle Arc valley, Montgenevre, and Cristillan from western external Piedmont unit. The metagabbros from Monviso are re-equilibrated under early Alpine eclogitic conditions and were successively involved in a polyphase retrograde tectono-metamorphic evolution. They include eclogitic — and smaragdite — metagabbros which underwent into greenschist facies metamorphism of a later stage. Some gabbros have partially escaped the Alpine metamorphism. The Arc metagabbros are characterized by glaucophaneschist facies which retrogressed to greenschist facies. The well-preserved gabbroic sequence ranging from talc serpentine metagabbro to late gabbroic differentiated products (albitite) are present in Chenaillet. In these gabbros, the early — Alpine HP prográde metamorphic events produced blueschist and eclogitic mineral assemblages (glaucophane, phengite, clinozoisite and omphacite±zoisite±garnet±rutile) while the HP retrograde events produced blueschist, greenschist and amphibolite mineral assemblages. These gabbros appear to be derived from different magma sources in different geotectonic environments and suffered different kinds of metamorphism. Moreover during the early stage of crystallization, Mg—A1 gabbros were produced, characterizing a primitive magma while late stage crystallization produced more differentiated Fe—Ti gabbros. KEYWORDS: petrology, trace element geochemistry, metamorphic evolution, ophiolite metagabbros, Piedmont Zone, Western Alps. |
|---|---|
| Terjedelem/Fizikai jellemzők: | 19-34 |
| ISSN: | 0365-8066 |