@article{fdi:010070294,
  title = {{D}ifferential weathering in ultramafic rocks of {N}ew {C}aledonia : the role of infiltration instability},
  author = {{G}enthon, {P}ierre and {J}oin, {J}. {L}. and {J}eanpert, {J}.},
  editor = {},
  language = {{ENG}},
  abstract = {{U}ltramafic rocks of {N}ew {C}aledonia present extensive pseudokarstic features: undulations of the base of the weathering profile, fractures enlarged by dissolution, dolines. {P}ossible influence of the infiltrative instability on differential weathering of ultramafic rocks in tropical climate is investigated here, starting from the {T}iebaghi case for which a groundwater model is available. {I}nfiltration instability is governed by nondimensional numbers, i.e. the {D}amkohler and {P}eclet numbers, and by the permeability contrasts between the bedrock and the different layers of the weathering profile. {T}hese numbers are firstly estimated for the {T}iebaghi case, and secondly a sensitivity study of the weathering style is achieved through numerical modeling. {C}omputations are firstly carried out without the impervious laterite cover, and then the effect of this cover is considered. {T}he characteristic time constant for weathering of peridotites is directly estimated at around 7 yrs from the thickness of the weathering front and the fluid velocity. {T}he results show that a permeability contrast of at least 100 between the most pervious layer in the weathering front and bedrock and a diffusivity of chemical species lower than 2.5 x 10-8 m(2)/s are required to allow instability. {T}he {T}iebaghi case lies at the limit of instability and dissolution fingers develop in a time lapse of 1 {M}a. {H}owever, this requires the infiltration of nearly 800 mm of rainfall yearly, which is not the case presently. {T}he development of dissolution fingers is promoted by any initial pervious zone such as fracture concentration around a faulted zone and the characteristic time for instability development drops to 0.1-0.3 {M}a. {E}xtension of these results to other peridotite massifs in the tropical zone submitted to different temperatures and rainfalls is finally discussed.},
  keywords = {{W}eathering ; {U}ltramafic rocks ; {I}nfiltration instability ; {P}seudokarst ; {N}ew {C}aledonia ; {NOUVELLE} {CALEDONIE}},
  booktitle = {},
  journal = {{J}ournal of {H}ydrology},
  volume = {550},
  numero = {},
  pages = {268--278},
  ISSN = {0022-1694},
  year = {2017},
  DOI = {10.1016/j.jhydrol.2017.04.059},
  URL = {https://www.documentation.ird.fr/hor/fdi:010070294},
}