Isotopic character and origin of brine leaks in the Avery Island salt mine, south Louisiana, U.S.A.

Abstract

Twelve brine leaks in the Avery Island salt mine have the isotopic signature of meteoric waters and are isotopically similar to shallow wells around the salt dome. The mine leaks are interpreted as meteoric waters which have penetrated the salt. One leak at the 275 m (∼ 900 ft.) level is drastically enriched in 18O relative to the other waters. This water is similar to 18O-rich waters in other Gulf (of Mexico) coast salt domes and is interpreted as formation water which became incorporated in the salt during diapiric rise of the dome. While water encounterd in other salt domes is primarily formation water, the water encountered in the Avery Island salt is primarily meteoric. This may be related to the shallow depth of the mine, close proximity of the salt top to the surface, absence of caprock, and/or duration and technique of mining.