@article{PAR00013208,
  title = {{R}esolving mantle and magmatic processes in basalts from the {C}ameroon volcanic line using the {R}e-{O}s isotope system},
  author = {{G}announ, {A}. and {B}urton, {K}. {W}. and {B}arfod, {D}. {N}. and {S}chiano, {P}ierre and {V}lastelic, {I}. and {H}alliday, {A}. {N}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}his study presents major-, trace element and {R}e-{O}s isotope and elemental data for young alkaline basalts (<10 {M}a) from oceanic ({A}nnobon, {S}. {T}ome, {P}rincipe), continental ({M}anengouba) and continent-oceanic boundary ({COB}, {M}t. {C}ameroon) sectors of the {C}ameroon volcanic line ({CVL}). {T}he {CVL} is a chain of {T}ertiary to recent, transitional to strongly alkaline intraplate volcanoes extending from the south {A}tlantic island of {A}nnobon to the continental interior of {W}est {A}frica ({B}iu {P}lateau). {T}he basalts from the oceanic sector display a range of initial {O}s-187/{O}s-188 ratios between 0.128 and 0.190 and those from the {COB} and continental sector range between 0.142 and 0.560. {T}he samples with high (206)pb/(204)pb (e.g. ratios >20) possess {O}s-187/{O}s-188 isotope compositions between 0.14 and 0.18 (e.g., basalts from {M}t {C}ameroon and {S}ao {T}ome) which reflect the chemical characteristics that are more likely to be primary features of {CVL}, and are close to the value of 0.153 attributed to the {HIMU} end-member ({T}ubuai-{M}angaia). {H}owever, most of the lavas from the continental sector show highly radiogenic initial {O}s-187/{O}s-188 ratios (0.36 to 0.56) that are outside the range previously observed for ocean island basalts, with shifts to radiogenic {O}s isotope compositions accompanied by less radiogenic (206)pb/{P}b-204 and increasing {S}i{O}2 contents. {T}he increase in {O}s-187/{O}s-188 is also associated with the decrease of {O}s, {N}i, {M}g{O} and phenocryst abundances. {T}hese data can be explained by fractional crystallisation and assimilation of continental crust by the ascending magma. {T}he systematic shift to unradiogenic lead isotope compositions from the {COB} into the oceanic sector is positively correlated with variations in ({OS})-{O}-187/({OS})-{O}-188 isotope composition (from 0.140 to 0.128). {A}t first sight this covariation might be attributed to the mixing of {HIMU} material with the ambient upper mantle ({DMM}). {H}owever, there is a clear covariation of the {O}s isotope and elemental composition, best explained with contamination of the oceanic basalts by the physical entrainment of xenoliths and xenocrysts of mantle origin. {O}verall, these results indicate that {O}s in {CVL} basalts is highly susceptible to contamination from both oceanic and continental lithospheres, under these circumstances covariations with other isotopes and elements must be interpreted with caution.},
  keywords = {{R}e-{O}s isotopes ; {P}b isotopes ; {C}ameroon volcanic line ; {MORB} ; {HIMU} ; {CAMEROUN}},
  booktitle = {},
  journal = {{L}ithos},
  volume = {224},
  numero = {},
  pages = {1--12},
  ISSN = {0024-4937},
  year = {2015},
  DOI = {10.1016/j.lithos2015.02.017},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00013208},
}