Laboratory infrastructure:

Alpha spectrometer ORTEC OCTETE PLUS

8 Detectors BR-024-450-100 allow us to perform radiometric dates using the Uranium series disequilibrium method (230Th/234U) of Ivanovich and Harmon (1992). This method is specially designed for dating carbonates (travertines, speleothems, endogenic lacustrine carbonates), although it is possible to date primary sulphates (gypsum) and chlorides (halite).
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The sample weight used to date depends on i) the quantity of uranium that contains the sample and ii) percentage of terrigenous minerals. Commonly we use 20 g of sample although we have successfully dated very small samples (about 0.2 g).

The chemical separation of the radioisotopes and purification follow the procedure described by Bischoff et al. (1988). The isotope electrodeposition is carried out using the method described by Talvite (1972) and modified by Hallstadius (1984). Age calculations are based on the computer program by Rosenbauer (1991).

This method allow us to obtain reliable chronologies within the range 5,000 - 300,000 yr.

References:

Bischoff, J.L., Julià, R., Mora, R., 1988. Uranium-series dating of the Mousterian occupation at Abric Romaní, Spain. Nature, 332, 68-70.

Hallstadius, L., 1984. A method for the electrodeposition of actinides. Nuclear Instruments and Methods in Physics Research 223, 266-267.

Ivanovich, M., Harmon, R.S., 1992. Uranium-series disequilibrium: applications to Earth, Marine, and Environmental Sciences. Oxford, Clarendon Press, 910 pp.

Rosenbauer, R.J., 1991. UDATE1: a computer program for the calculation of Uranium-series isotopic ages. Computers & Geosciences, 17(1), 45-75.

Talvitie, N.A., 1972. Electrodeposition of actinides for alpha spectrometric determination. Analytical Chemistry 44, 280-283.

Microsample device

A LEICA GZ6 Merchantek microdrill connected to a computer allow us to subsample thick sections (300 microns) of carbonate samples, such as old carbonate rocks, speleothems or present-day corals, and to obtain microsamples (about 60 - 100 micrograms) for analyses (stable isotopes, 230Th/234U dating, etc).

  This tool is very powerful to separate the different cement generations present in a carbonate rock previously identified by cathodoluminiscence.

Field infrastructure

Coring and water sampling devices

A UWITEC 60 mm gravity coring device system allows us to retireve up to 80 cm long sediment cores from the lake bottom with undisturbed water-sediment interphase. Water samples are obtained using a 4.2 l beta WILDCO bottle sampler and detailed temperature, dissolved oxygen, pH, turbidity and water depth profiles are measured with a TURO T-613 real time multiparameter probe.