TY - JOUR
T1 - Characterization of the sub-continental lithospheric mantle beneath the Cameroon volcanic line inferred from alkaline basalt hosted peridotite xenoliths from Barombi Mbo and Nyos Lakes
AU - Pintér, Zsanett
AU - Patkó, Levente
AU - Tene Djoukam, Joëlle Flore
AU - Kovács, István
AU - Tchouankoue, Jean Pierre
AU - Falus, György
AU - Konc, Zoltán
AU - Tommasi, Andréa
AU - Barou, Fabrice
AU - Mihály, Judith
AU - Németh, Csaba
AU - Jeffries, Teresa
N1 - Funding Information:
The work was supported by the Marie Curie International Reintegration Grant ( NAMS-230937 ), Bolyai Fellowship Program and OTKA ( Hungarian Scientific Research Fund (grant number: PD 101683 ) of István Kovács, György Falus (F67917) and Synthesys Project (GB-TAF-3033) to Levente Patkó.
Publisher Copyright:
© 2015.
PY - 2015/11/1
Y1 - 2015/11/1
N2 - We carried out detailed petrographic, major and trace element geochemical, microstructural and FTIR analyses on eight characteristic ultramafic xenoliths from Nyos and Barombi Mbo Lakes in the continental sector of the Cameroon Volcanic Line (CVL). The studied xenoliths are spinel lherzolites showing lithologies similar to the other xenoliths reported previously along the CVL. They have protogranular and porphyroclastic textures. One of the Barombi xenolith contains amphibole, which had not been previously reported in this locality. Amphibole is common in the Nyos xenoliths suite. Peridotite xenoliths from both localities show some chemical heterogeneity, but Barombi xenoliths generally are less depleted in basaltic elements with respect to Nyos xenoliths. Trace element compositions of Nyos spinel lherzolites show a moderately depleted initial (premetasomatic) composition and variable enrichment in REE. Evidence for both modal and cryptic metasomatism is present in Nyos xenoliths. Rare earth element patterns of clinopyroxene suggest that interaction between mafic melts and the upper mantle occurred beneath the Nyos locality. Barombi Mbo xenoliths, on the other hand, record a small degree of partial melting. The Barombi Mbo xenoliths have weak, dominantly orthorhombic olivine crystal preferred orientations, whereas Nyos ones have strong axial-[010] patterns, which may have formed in response to transpression. Nominally anhydrous mantle minerals (NAMs) of the Barombi Mbo xenoliths show generally higher bulk concentrations of 'water' (70-127 ppm) than Nyos xenoliths (32-81 ppm). The Barombi Mbo xenoliths could originate from a juvenile segment of the lithospheric mantle, which had been originally part of the asthenosphere. It became a part of the lithosphere in response to thermal relaxation following the extension, forming a weakly deformed lower lithospheric mantle region along the CVL. The Nyos xenoliths, however, represent a shallow lithospheric mantle bearing imprints of several depletion and enrichment events probably prior or following the extension (at ~30 Ma).
AB - We carried out detailed petrographic, major and trace element geochemical, microstructural and FTIR analyses on eight characteristic ultramafic xenoliths from Nyos and Barombi Mbo Lakes in the continental sector of the Cameroon Volcanic Line (CVL). The studied xenoliths are spinel lherzolites showing lithologies similar to the other xenoliths reported previously along the CVL. They have protogranular and porphyroclastic textures. One of the Barombi xenolith contains amphibole, which had not been previously reported in this locality. Amphibole is common in the Nyos xenoliths suite. Peridotite xenoliths from both localities show some chemical heterogeneity, but Barombi xenoliths generally are less depleted in basaltic elements with respect to Nyos xenoliths. Trace element compositions of Nyos spinel lherzolites show a moderately depleted initial (premetasomatic) composition and variable enrichment in REE. Evidence for both modal and cryptic metasomatism is present in Nyos xenoliths. Rare earth element patterns of clinopyroxene suggest that interaction between mafic melts and the upper mantle occurred beneath the Nyos locality. Barombi Mbo xenoliths, on the other hand, record a small degree of partial melting. The Barombi Mbo xenoliths have weak, dominantly orthorhombic olivine crystal preferred orientations, whereas Nyos ones have strong axial-[010] patterns, which may have formed in response to transpression. Nominally anhydrous mantle minerals (NAMs) of the Barombi Mbo xenoliths show generally higher bulk concentrations of 'water' (70-127 ppm) than Nyos xenoliths (32-81 ppm). The Barombi Mbo xenoliths could originate from a juvenile segment of the lithospheric mantle, which had been originally part of the asthenosphere. It became a part of the lithosphere in response to thermal relaxation following the extension, forming a weakly deformed lower lithospheric mantle region along the CVL. The Nyos xenoliths, however, represent a shallow lithospheric mantle bearing imprints of several depletion and enrichment events probably prior or following the extension (at ~30 Ma).
KW - 'Water' content of nominally anhydrous minerals
KW - Cameroon volcanic line
KW - Crystal preferred orientation
KW - Mantle metasomatism
KW - Ultramafic xenolith
UR - http://www.scopus.com/inward/record.url?scp=84939185856&partnerID=8YFLogxK
U2 - 10.1016/j.jafrearsci.2015.07.006
DO - 10.1016/j.jafrearsci.2015.07.006
M3 - Article
AN - SCOPUS:84939185856
SN - 1464-343X
VL - 111
SP - 170
EP - 193
JO - Journal of African Earth Sciences
JF - Journal of African Earth Sciences
ER -