@article{fdi:010082587,
  title = {{C}ontrasted chemical weathering rates in cratonic basins : the {O}gooue and {M}bei rivers, {W}estern {C}entral {A}frica},
  author = {{M}oquet, {J}. {S}. and {B}ouchez, {J}. and {B}raun, {J}ean-{J}acques and {B}ogning, {S}. and {M}bonda, {A}. {P}. and {C}arretier, {S}{\'e}bastien and {R}egard, {V}. and {B}ricquet, {J}ean-{P}ierre and {P}aiz, {M}. {C}. and {M}ambela, {E}. and {G}aillardet, {J}.},
  editor = {},
  language = {{ENG}},
  abstract = {{D}espite the absence of tectonic activity, cratonic environments are characterized by strongly variable, and in places significant, rock weathering rates. {T}his is shown here through an exploration of the weathering rates in two inter-tropical river basins from the {A}tlantic {C}entral {A}frica: the {O}gooue and {M}bei {R}iver basins, {G}abon. {W}e analyzed the elemental and strontium isotope composition of 24 water samples collected throughout these basins. {B}ased on the determination of the major element sources we estimate that the {O}gooue and {M}bei rivers total dissolved solids ({TDS}) mainly derive from silicate chemical weathering. {T}he chemical composition of the dissolved load and the area-normalized solute fluxes at the outlet of the {O}gooue are similar to those of other {W}est {A}frican rivers (e.g., {N}iger, {N}yong, or {C}ongo). {H}owever, chemical weathering rates ({TZ}(sil) +rate expressed as the release rate of the sum of cations by silicate chemical weathering) span the entire range of chemical weathering intensities hitherto recorded in worldwide cratonic environments. {I}n the {O}gooue-{M}bei systems, three regions can be distinguished: (i) the {E}astern sub-basins draining the {P}lateaux {B}ateke underlain by quartz-rich sandstones exhibit the lowest {TZ}(sil)(+) rates, (ii) the {N}orthern sub-basins and the {M}bei sub-basins, which drain the southern edge of the tectonically quiescent {S}outh {C}ameroon {P}lateau, show intermediate {TZ}(sil)(+) rates and (iii) the {S}outhern sub-basins characterized by steeper slopes record the highest {TZ}(sil)(+) rates. {I}n region (ii), higher {DOC} concentrations are associated with enrichment of elements expected to form insoluble hydrolysates in natural waters (e.g., {F}e, {A}l, {T}h, {REE}s) suggesting enhanced transport of these elements in the colloidal phase. {I}n region (iii), we suggest that a combination of mantle-induced dynamic uplift and lithospheric destabilization affecting the rim of the {C}ongo {C}uvette induces slow base level lowering thereby enhancing soil erosion, exhumation of fresh primary minerals, and thus weathering rates. {T}he study points out that erosion of lateritic covers in cratonic areas can significantly enhance chemical weathering rates by bringing fresh minerals in contact with meteoric water. {T}he heterogeneity of weathering rates amongst cratonic regions thus need to be considered for reconstructing the global, long-term carbon cycle and its control on {E}arth climate.},
  keywords = {chemical weathering ; river hydrochemistry ; {C}ongo craton ; {W}estern {C}entral {A}frica ; {O}gooue {R}iver basin ; regolith rejuvenation ; {AFRIQUE} {CENTRALE} ; {GABON} ; {CONGO} ; {CAMEROUN} ; {GUINEE} {EQUATORIALE} ; {OGOOUE} {COURS} {D}'{EAU} {BASSIN} ; {MBEI} {COURS} {D}'{EAU}},
  booktitle = {},
  journal = {{F}rontiers in {W}ater},
  volume = {2},
  numero = {},
  pages = {589070 [27 ]},
  year = {2021},
  DOI = {10.3389/frwa.2020.589070},
  URL = {https://www.documentation.ird.fr/hor/fdi:010082587},
}