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LA-ICP-MS U-Pb dating of apatite, titanite and zircon from the metamorphic cover of the Western Tatra granite was undertaken to constrain the timing of metamorphic events related to the final stages of Variscan orogenesis and subsequent post-orogenic exhumation. Zircon was found only in one sample from the northern metamorphic envelope. U-Pb ages from the outermost rims of zircons define a concordia age of 346 ± 6 Ma, while the inner rims yield a concordia age of 385 ± 8 Ma. Apatite from three samples from the northern metamorphic envelope yield U-Pb ages of 351.8 ± 4.4 Ma, 346.7 ± 5.9 Ma and 342.6 ± 7.1 Ma. Titanite from an amphibolite from the southern metamorphic envelope yields a U-Pb age of 345.3 ± 4.5 Ma. The age of c. 345 Ma is interpreted to represent the climax of metamorphism and the onset of simultaneous exhumation of the entire Tatra Mountains massif, and is recorded mainly in the northern part of the metamorphic cover. In the southern metamorphic envelope, distinct populations of apatite can be recognized within individual samples based on their rare earth element (REE) and actinide contents. One population of apatite (Ap1) yields a relatively imprecise U-Pb age of 340 ± 31 Ma. This population comprises apatite grains with very similar trace element compositions to apatite in the northern amphibolite samples, which suggests they crystallized under similar metamorphic conditions to their northern counterparts. A second apatite population (Ap2) yields an age of c. 328 ± 22 Ma, which is interpreted as neocrystalline apatite that formed during a late-Variscan (hydrothermal?) process involving (P, F, Ca, REE)-rich fluid migration. The youngest generation of apatite (Ap3) yields a U-Pb age of 260 ± 8 Ma and may have resulted from thermal resetting associated with the regional emplacement of Permian A-type granites. The proposed tectonic model assumes that rapid uplift (and cooling) of the Tatra block initiated at ca. 345 Ma, contemporaneous with anatexis. Subsequent fluid migration, possibly facilitated by extension related to the opening of Paleo-Tethys, affected only the southern part of the Tatra block. [ABSTRACT FROM AUTHOR]

This study presents apatite LA-ICP-MS U-Pb age and trace elements concentrations data from different granite types from the Tatra Mountains, Poland. Apatite from monazite and xenotime-bearing High Tatra granite was dated at 339 ± 5 Ma. The apatite LREE patterns reflect two types of magmas that contributed to this layered magma series. Apatite from a hybrid allanite-bearing diorite from the Goryczkowa Unit was dated at 340 ± 4 Ma with apatite LREE depletion reflecting the role of allanite and titanite during apatite crystallization. Apatite crystals from a hybrid cumulative rock from the Western Tatra Mountains were dated at 344 ± 3 Ma. Apatite is one of the main REE carriers in this sample and exhibit flat REE patterns. Taking into account the relatively low closure temperature of the U-Pb system in apatite (350-550°C), the c. 340 Ma apatite ages mark the end of high temperature tectonometamorphic activity in the Tatra Mountains. [ABSTRACT FROM AUTHOR]

In the bottom part of the tongue-shaped, layered granitoid intrusion, exposed in the Western Tatra Mts., apatite-rich granitic rocks occur as pseudo-layers and pockets between I-type hybrid mafic precursors and homogeneous S-type felsic granitoids. The apatite-rich rocks are peraluminous (ASI = 1.12-1.61), with PO contents ranging from 0.05 to 3.41 wt.% (<7.5 vol.% apatite), shoshonitic to high-K calc-alkaline. Apatite is present as long-prismatic zoned crystals (Ap) and as large xenomorphic unzoned crystals (Ap). Ap apatite and biotite represent an early cumulate. Feldspar and Ap textural relations may reflect the interaction of the crystal faces of both minerals and support a model based on local saturation of (P, Ca, F) versus (K, Na, Al, Si, Ba) in the border zones. Chondrite-normalized REE patterns for the apatite rocks and for pure apatite suggest apatite was a main REE carrier in these rocks. Minerals characteristics and the whole rock chemistry suggest both reduced S-type and I-type magma influenced the apatite-rich rocks. The field observations, mineral and rock chemistry as well as mass-balance calculations point out that the presence of apatite-rich rocks may be linked to the continuous mixing of felsic and mafic magmas, creating unique phosphorus- and aluminium-rich magma portions. Formation of these rocks was initially dominated by the complex flowage-controlled and to some extent also gravity-driven separation of early-formed zoned minerals and, subsequently, by local saturation in the border zones of growing feldspar and apatite crystals. Slow diffusion in the phosphorus-rich magma pockets favoured the local saturation and simultaneous crystallization of apatite and feldspars in a crystal-ladden melt. [ABSTRACT FROM AUTHOR]