@article{fdi:010046093,
  title = {{B}ehaviour of elements in soils developed from nephelinites at {M}ount {E}tinde ({C}ameroon) : {I}mpact of hydrothermal versus weathering processes},
  author = {{E}ame, {J}. and {G}{\'e}rard, {M}artine and {B}ilong, {P}. and {S}uh, {C}. {E}.},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he progressive weathering of 0.65 {M}a nephelinites from {M}ount {E}tinde ({S}outh {W}estern {C}ameroon) in a humid tropical setting has resulted in the formation of a 150 cm thick weathering crust. {T}he soil profiles consist of three horizons: {A}h/{B}w/{C}. {A} major differentiation of the chemical and mineralogical parameters is related to the complexity of the saprolites, some of which were hydrothermally altered. {B}ulk geochemical and microgeochemical analyses were performed on selected minerals from the different horizons of two reference profiles, of which one ({E}-4) was developed from unaltered nephelinite (nephelinite({U})) while the other ({BO}1) formed from hydrothermally altered nephelinite (nephelinite({H})). {T}he results show that the primary minerals (clinopyroxene, nepheline, leucite, hauyne, titanomagnetite, perovskite, apatite and sphene) experienced differential weathering rates with primary minerals rich in rare earth elements (titanomagnetite, perovskite, apatite and sphene) surviving in the saprolite and the {B}w horizons. {T}he weathering of the primary minerals is reflected in the leaching of alkaline and alkaline-earth elements, except for {B}a and {R}b in the hydrothermalised nephelinite soil. {T}he order of mobility is influenced by hydrothermal processes: {N}a > {K} > {R}b > {C}a > {C}s > {S}r in nephelinite({U}) soil. {N}a > {K} > {S}r > {C}a > {M}g in nephelinite({H}) soil; {R}b/{S}r and {S}r/{M}g can be used as indicators of the kinetic of the weathering on nephelinite({U}) and on nephelinite({H}). {B}arium enrichment is related to variable concentrations in the nephelinites, to the formation of crandallites and the leaching of surface horizons. {T}he content of metallic elements is higher in nephelinite({H}) soil than in the nephelinite({U}) soil. {R}esults show that hydrothermal alteration leads to an enrichment of light ({L}a, {C}e, {N}d) and intermediate ({S}m, {E}u, {D}y) rare earth elements. {T}he enrichment in {C}r and {P}b in the surface horizons is discussed in relation to organic matter activity, the dissolution of magnetites, and the impact of hydrothermal processes as well as atmospheric pollution in the case of lead.},
  keywords = {{H}umid tropical climate ; {H}ydrothermal alteration ; {A}lkali and alkaline-earth elements ; {M}etals - {REE}},
  booktitle = {},
  journal = {{J}ournal of {A}frican {E}arth {S}ciences},
  volume = {54},
  numero = {1-2},
  pages = {37--45},
  ISSN = {1464-343{X}},
  year = {2009},
  DOI = {10.1016/j.jafrearsci.2009.02.002},
  URL = {https://www.documentation.ird.fr/hor/fdi:010046093},
}