Determination of erosion rate at Allchar region with cosmogenic Nuclides

Pavicevic, Miodrag and Vermeesch, P. and Amthauer, Georg and Niedermann, Samuel and Boev, Blazo and Jelenkovic, Rade and Pejovic, Vladan (2010) Determination of erosion rate at Allchar region with cosmogenic Nuclides. In: 88th annual meeting of the German Mineralogical Society, 19-22 Sept 2010, Münster, Germany.

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Abstract

Allchar is a Sb-As-Tl-Au deposit located at the north - western margin of the Kozuf Mountains in Macedonia, close to the Greek border. The mine contains the world’s largest known concentration of thallium-bearing minerals, especially lorandite (TlAsS2). LOREX, the acronym for LORandite EXperiment, is the only geochemical solar neutrino experiment still actively pursued. It addresses the determination of the long-term average of the solar neutrino flux, based on the neutrino-capture reaction 205 Tl + νe → 205 Pb + e - occurring in the lorandite of the Allchar mine. The final step of LOREX will be the extraction of the lorandite and the quantitative determination of the 205Pb / 205Tl ratio, thus providing the product of solar neutrino flux and neutrino-capture cross section, integrated over the lorandite age of 4.31 · 106 yr. Based on the present-day solar luminosity, it is expected that about 23 atoms of 205Pb of solar neutrino origin will be found per gram of lorandite. In contrast with the production of 205 Pb by solar neutrinos, which is independent of depth, cosmogenic 205Pb produced from fast muons of cosmic ray origin is strongly depth-dependent and very sensitive to the longterm erosion history of the field area. For erosion rate determination, we have so far applied three independent series of measurements of cosmogenic 26Al, 10Be and 53Mn. Firstly, the 26Al concentration in quartz was determined using the AMS system at VERA (Vienna Environmental Research Accelerator). Secondly, a series of measurements of the 10Be and 26Al contents was performed at the AMS of PRIME Lab, Purdue University, and finally AMS measurements at the Tandem facility of the TU Munich provided the concentration of 53 Mn in pyrite (FeS2). For the two ore bodies containing lorandite, we derived lower limits of the erosion rate of ~33 m/Myr at Crven Dol (NW part of Allchar deposit) and 67 m/Myr in the central part (SE part of Allchar deposit), in fair agreement with quantitative geomorphologic studies.

Item Type: Conference or Workshop Item (Paper)
Subjects: Natural sciences > Other natural sciences
Divisions: Faculty of Natural and Technical Sciences
Depositing User: Blazo Boev
Date Deposited: 28 May 2013 10:46
Last Modified: 21 Oct 2014 13:01
URI: http://eprints.ugd.edu.mk/id/eprint/6432

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