Age of hydrothermal processes in the Central Iberian zone (Spain) according TO U-Pb dating of cassiterite and apatite
- 1 — Ph.D. Senior researcher Institute of Precambrian Geology and Geochronology of Russian Academy of Sciences
- 2 — Ph.D., Dr.Sci. Leading researcher Institute of Precambrian Geology and Geochronology of Russian Academy of Sciences
- 3 — geologist Mineral Exploration Network Ltd.
Abstract
Results of isotope-geochemical studies by PbLS step-leaching method of cassiterite from greisens located in Logrosán granite massif (Central Iberian Zone, Spain) and apatite from hydrothermal quartz-apatite vein on its exocontact indicate that in both cases a hydrothermal event is recorded in the interval of 114-126 Ma, which has been accompanied by lead supply. Within the limits of estimation error, the same age around 120 Ma corresponds to crystallization of hydrothermal apatite, formation of sticks and micro-inclusions in cassiterite from greisens and is suggested for Au-As-Sb-Pb ore mineralization, which calls for further confirmation. Xenogenous zircon from quartz-apatite vein does not react to this relatively low-temperature hydrothermal event either with building up new generations (sticks, areas of recrystallization) or with rebalancing of U-Pb isotope system. The age of greisen formation has been confirmed to be around 305 Ma by PbLS method on final phases of cassiterite leaching. Earlier it was estimated with 40Ar/39Ar method on muscovite.
Funding
Authors thank O.L.Galankina, E.S.Bogomolov (Institute of Precambrian Geology and Geochronology of Russian Academy of Sciences), S.G.Simakin, E.V.Potapov (Yaroslavl Branch of the Institute of Physics and Technology) and colleagues from the Center of Isotope Research, Russian Geological Research Institute for undertakenanalytical studies. This research has been carried out with financial support from the Ministry of Education and Science of Russian Federation as a basic design part of the state assignment in the field of science N5.9248.2017/VU for the period 2017-2019.