The thermal history of rocks is an efficient recorder of tectonic and surface processes which affect the uppermost crust. In our lab, we utilize a geochronologic clock based on radioactive decay of uranium and thorium whose decay chain produces alpha particles (helium atoms). Helium starts to accumulate in the lattice of a given mineral only when the rocks cool below a certain “closure” temperature - as long as the rocks are held at higher temperatures, all the helium produced by radioactive decay diffuses away. The (U-Th)/He clock starts ticking at different temperatures for different minerals and thus enables to trace the temperature-time path of rocks. Since temperature can often be inverted to depth, low-temperature thermochronology provides important constraints on the Depth-Time path that rocks have taken on their journey towards the surface of the earth. We utilize the (U-Th)/He system to study the timing and rates of continental breakup processes (rifting), escarpment evolution due to normal faulting, shortening and uplift rates across orogens and more.
Our state-of-the-art laboratory includes a helium vacuum line equipped with a solid state diode laser and a Pfeiffer-Prisma mass spectrometer. Each single silt-size crystal is heated to temperature as high as 1000-1400o C in order to release all the gas from its lattice. The gas is then cleaned using two SAES getters before helium is measured with a detection limit better then 10-12 CC.
Following the helium measurement the same crystal is dissolved and spiked. Its uranium and thorium content is then measured using an Agilent 7700 Inductively Coupled Plasma Mass Spectrometer (ICP-MS).
Our on-going research currently spans the Red Sea rift (Sinai), the Dead Sea transform (Israel, Sinai, Jordan), the Lebanon and anti-Lebanon mountain ranges, convergence in Cyprus and active orogeny across the Himalaya in eastern Nepal.
Prospective students and postdocs as well as researchers interested in collaborative studies are welcome to contact Itai Haviv – haviv@bgu.ac.il.
Picking lab
Our picking lab is equipped with a Leica M205 C polarizing stereo microscope equipped with a rotating stage and a digital camera. Crystals for (U-Th)/He thermochronologic analysis are picked based on their size, morphology, transparency and lack of inclusions.
Mineral separation lab Our mineral separation lab is equipped with a jaw crusher and a disk mill for crushing and grinding rocks, two Frantz devices for magnetic separation based on the magnetic properties of different minerals, a Wilfley water table and a complete setup for heavy liquid mineral separation based on density criteria.
Our next door BGU Institute for Nano Scale Science and Technology hosts a scanning electron microscope which is available for geological research. The JSM-7400F (JEOL) ultrahigh resolution cold FEG-SEM is one of the most advanced instruments available in the world for imaging without sample coating. This UHR-SEM was custom designed with six different detectors, including conventional and in-lens SE and BSE detectors, cathodoluminescence mapping and a customized Noran Vantage EDS detector for elemental analysis of elements down to Boron.
