 |
| Titel |
Geodynamic implications of Collo-Bougaroun Miocene magmatic complex (Eastern Algerian margin): a review of U-Pb, K-Ar chronology and geochemistry |
| VerfasserIn |
Fatiha Abbassene, Ouabadi Aziouz, Gilles Chazot, Hervé Bellon, Maury René, Olivier Bruguier |
| Konferenz |
EGU General Assembly 2014
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250095847
|
| Publikation (Nr.) |
 EGU/EGU2014-11322.pdf |
|
|
|
|
|
| Zusammenfassung |
| The ‘’Petite-Kabylie” comprises all eastern Algerian coastal magmatic chain outcropping
from Jijel to the west, up to the plain of Annaba, to the east. At the western part of this area,
the Kabylie of Collo stretches between 6° and 7° E and 36° 30 ’and 37° 06’ N towards
Skikda.
The Bougaroun magmatic complex form a large elliptical batholith oriented
ENE-WSW over 20 km that intrudes serpentinized peridotites and kinzigites of
the Bougaroun basement to the east. This granitic pluton gives time constraints as
it induces deformation and contact metamorphism of the Oligo-Miocene Kabyle
sedimentary cover which are well observed at ‘’Collo-Oued Zhour” basin in the
south.
The Collo-Bougaroun volcano-plutonic complex, of ca. 300 km2, comprises (1) granular
rocks, mainly cordierite bearing peraluminous granites (Bougaroun pluton to the north, the
BeniToufout to the south and the Filfila to the east), (2) gabbros that occur at the northern and
southern parts of Cap Bougaroun pluton where they are associated with ultramafic (3)
microgranular rocks, mainly microgranites, that outcrop at the eastern part of the Bougaroun
pluton, in Collo basin and El Milia, microdiorites in Bouserdoum and some doleritic or
microgabbroic metric veins at Cap Bougaroun and (4) of lava in the Kef Cheraïa rhyolitic
complex.
Rocks from Collo-Bougaroun sites belong either to low-K, medium-K or high-K
calc-alkaline series. The geochemistry of basic rocks (gabbros and dolerites) places strong
constraints on their origin. Their LREE-depleted patterns, enrichment in LILE and
slight depletion in HFSE are discussed in the very particular geodynamic context of
the northern Algerian margin. Indeed, such depleted magmas could hardly have
been emplaced over the African basement without experiencing any contamination
imprint.
Whole rock K/Ar ages were performed on 150-300 μm grains from a set of
representative magmatic rocks from Collo-Bougaroun region. The mafic rocks ages show
a probable rejuvenation from (21.25 ± 6.01 (large error linked to the K2O wt%
of 0.04) to 16.45 ± 0.52 Ma). This feature is attributed to a late K-gain during
hydrothermal processes. This interpretation is supported by the occurrence of low
temperature minerals (Adularia) in microgabbros and fine grained gabbros (microprobe
analyses).
The granite ages scatter between 20.85 ± 0.51 and 17.88 ± 0.5 Ma. The latter is
consistent with 206U–238Pb age of 16.96±0.09 Ma obtained from 28 laser ablation spots
analyses performed on zircon grains. Microgranites usually outcropping in Langhian
‘’post-nappes” basins, yield ages ranging from 14.17 ± 0.35 to 13.59 ± 0.33 Ma. |
|
|
|
|
|
|