Horizon / Plein textes La base de ressources documentaires de l'IRD

IRD

 

Publications des scientifiques de l'IRD

Genthon Pierre, Join J. L., Jeanpert J. (2017). Differential weathering in ultramafic rocks of New Caledonia : the role of infiltration instability. Journal of Hydrology, 550, 268-278. ISSN 0022-1694

Accès réservé (Intranet IRD) Demander le PDF

Lien direct chez l'éditeur doi:10.1016/j.jhydrol.2017.04.059

Titre
Differential weathering in ultramafic rocks of New Caledonia : the role of infiltration instability
Année de publication2017
Type de documentArticle référencé dans le Web of Science WOS:000404816000022
AuteursGenthon Pierre, Join J. L., Jeanpert J.
SourceJournal of Hydrology, 2017, 550, p. 268-278. ISSN 0022-1694
RésuméUltramafic rocks of New Caledonia present extensive pseudokarstic features: undulations of the base of the weathering profile, fractures enlarged by dissolution, dolines. Possible influence of the infiltrative instability on differential weathering of ultramafic rocks in tropical climate is investigated here, starting from the Tiebaghi case for which a groundwater model is available. Infiltration instability is governed by nondimensional numbers, i.e. the Damkohler and Peclet numbers, and by the permeability contrasts between the bedrock and the different layers of the weathering profile. These numbers are firstly estimated for the Tiebaghi case, and secondly a sensitivity study of the weathering style is achieved through numerical modeling. Computations are firstly carried out without the impervious laterite cover, and then the effect of this cover is considered. The 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. The 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. The Tiebaghi case lies at the limit of instability and dissolution fingers develop in a time lapse of 1 Ma. However, this requires the infiltration of nearly 800 mm of rainfall yearly, which is not the case presently. The 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 Ma. Extension of these results to other peridotite massifs in the tropical zone submitted to different temperatures and rainfalls is finally discussed.
Plan de classementHydrologie [062] ; Géologie et formations superficielles [064]
Descr. géo.NOUVELLE CALEDONIE
LocalisationFonds IRD [F B010070294]
Identifiant IRDfdi:010070294
Lien permanenthttp://www.documentation.ird.fr/hor/fdi:010070294

Export des données

Disponibilité des documents

Télechargment fichier PDF téléchargeable

Lien sur le Web lien chez l'éditeur

Accès réservé en accès réservé

HAL en libre accès sur HAL


Accès aux documents originaux :

Le FDI est labellisé CollEx

Accès direct

Bureau du chercheur

Site de la documentation

Espace intranet IST (accès réservé)

Suivi des publications IRD (accès réservé)

Mentions légales

Services Horizon

Poser une question

Consulter l'aide en ligne

Déposer une publication (accès réservé)

S'abonner au flux RSS

Voir les tableaux chronologiques et thématiques

Centres de documentation

Bondy

Montpellier (centre IRD)

Montpellier (MSE)

Cayenne

Nouméa

Papeete

Abidjan

Dakar

Niamey

Ouagadougou

Tunis

La Paz

Quito