@article{fdi:010090045,
  title = {{T}he origin and evolution of {DMM}-like lithospheric mantle beneath continents : mantle xenoliths from the {O}ku {V}olcanic {G}roup in the {C}ameroon {V}olcanic {L}ine, {W}est {A}frica},
  author = {{P}uziewicz, {J}. and {A}ulbach, {S}. and {K}aczmarek, {M}. {A}. and {N}taflos, {T}. and {G}erdes, {A}. and {M}azurek, {H}ubert and {K}ukula, {A}. and {M}atusiak-{M}alek, {M}. and {T}edonkenfack, {S}. {S}. {T}. and {Z}iobro-{M}ikrut, {M}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he lithospheric mantle as sampled by peridotite xenoliths in some continental settings resembles the source of mid-ocean ridge basalts ({MORB}). {W}hether this resemblance is a primary feature or the result of post-formation secondary processes remains controversial. {H}ere, the age, origin and thermochemical evolution of fertile continental mantle are constrained based on the chemical composition of minerals in spinel-facies lherzolite and websterite xenoliths from the {W}um maar and {B}efang cinder cone of the {O}ku {V}olcanic {G}roup ({C}ameroon {V}olcanic {L}ine, {W}est {A}frica), combined with in-situ {S}r isotope compositions of clinopyroxene and fabric investigation by {E}lectron {B}ackscatter {D}iffraction ({EBSD}). {T}he majority of lherzolites (here assigned to {G}roup {I}) consist of minerals with fertile composition (olivine {F}o89, {A}l-rich pyroxenes, spinel {C}r# 0.08-0.10). {C}linopyroxene is {LREE}-depleted and has depleted {S}r-87/{S}r-86 (0.7017-0.7020). {C}rystal-preferred orientation determined by {EBSD} reveals that clinopyroxene, and sporadically both clino- and orthopyroxene, post-date the olivine framework. {S}ubordinate {G}roup {II} lherzolites also contain secondary clinopyroxene which is {LREE}-enriched and has higher {S}r-87/{S}r-86 (0.7033). {I}n contrast, the scarce lherzolites of {G}roup {III} are more refractory: they contain 72-78 vol.% olivine, {A}l-poor pyroxenes, and spinel with {C}r$ 0.18. {C}linopyroxene ({S}r-87/{S}r-86 0.7021) is texturally coeval with olivine and orthopyroxene. {F}ew lherzolites contain amphibole ({S}r-87/{S}r-86 0.7031) which post-dates the nominally anhydrous minerals. {M}ost of the websterites ({G}roup {A}) are aluminous (spinel {C}r# 0.04-0.06) with {LREE}-depleted clinopyroxene having depleted {S}r-87/{S}r-86 ratios (0.7017-0.7020) similar to {G}roup {I} lherzolites. {C}hemical characteristics of minerals coupled with the crystal-preferred orientation data suggests that {G}roup {I} lherzolites originated in the spinel stability field by reactive intergranular percolation of an incompatible element-depleted {MORB}-like melt. {G}roup {A} websterites likely formed as cumulates from that melt. {T}he {G}roup {II} lherzolites supposedly occur close to lithosphere-asthenosphere boundary and record interaction with lavas of the {C}ameroon {V}olcanic {L}ine, whereas {G}roup {III} lherzolites occur in the shallow part of the mantle profile and represent the protolith from which the {G}roup {I} lherzolites were formed. {L}ocal crystallization of amphibole and concomitant recrystallization of the host lherzolite were driven by supply of water in an event post-dating the formation of {LREE}-depleted rejuvenated rocks. {M}igration of alkaline melts of the {CVL} apparently did not significantly affect the mineral and chemical composition of the lithospheric mantle, which allowed {G}roup {I} lherzolites and {G}roup {A} websterites to retain very low {R}b-87/{S}r-86 (average 0.002) and depleted {S}r-87/{S}r-86 ratios in clinopyroxene. {T}his not only indicates their formation in the {P}aleoproterozoic (similar to 2.0-2.25 {G}a), possibly during the {E}burnean orogeny at the margin of the {C}ongo craton, but also indicates surprisingly little influence of the regionally recognized {P}an-{A}frican event.},
  keywords = {{C}ameroon {V}olcanic {L}ine ; depleted melt ; refertilization ; subcontinental ; lithospheric mantle ; {DMM} ; {CAMEROUN}},
  booktitle = {},
  journal = {{J}ournal of {P}etrology},
  volume = {64},
  numero = {7},
  pages = {egad049 [25 p.]},
  ISSN = {0022-3530},
  year = {2023},
  DOI = {10.1093/petrology/egad049},
  URL = {https://www.documentation.ird.fr/hor/fdi:010090045},
}