TY - JOUR
KW - Coesite
KW - Erzgebirge (U)H province
KW - Granulite
KW - Monazite
KW - REE
KW - Thorium
AU - Prokop Závada
AU - Pavla Štípská
AU - Pavlína Hasalová
AU - Martin Racek
AU - Petr Jeřábek
AU - Karel Schulmann
AU - Andrew Kylander-Clark
AU - Robert Holder
AB - Coupled age and trace element mapping in monazite grains using the Laser-Ablation Split-Stream ICP-MS technique was carried out for a sequence of samples from (U)HP crustal section in the Eger Crystalline Complex interpreted as a Variscan continental subduction wedge. The sampled section comprises banded orthogneiss with monazite protolith ages of 486 ± 3[10] Ma. The orthogneiss was heterogeneously transformed to migmatite, HP felsic granofels and U(HP) fine-grained Ky-Kfs granulite during coupled deformation and percolation of silicate melts in a subduction channel. Age of the (U)HP metamorphism and related melt percolation in the granulite is dated by Th-rich and HREE-poor monazite cores at 353.6 ± 2.7[8] Ma, that are in equilibrium with HREE-rich garnets. Th-rich cores of monazites in the migmatite, granofels and granulite that lack the (U)HP signatures show younger ages of 347.8 ± 3.4[8] Ma, 345.8 ± 2.4[8] Ma and 339.3 ± 1.3[7] Ma, respectively. The monazite rims with lower Th and higher HREE contents than the monazite cores are likely a result of (re)crystallization in equilibrium with melt that partly dissolved the HREE-rich prograde garnet during decompression. This (re)crystallization is constrained by ages of 344.2 ± 1.6[8] Ma in (U)HP granulites and 338–340 ± [8] Ma in migmatites, granofelses and granulites without the (U)HP signature. The groups of ages from 353 Ma to 338 Ma, are significantly different when only their in-run uncertainties (7–10 Ma) are compared and indicate a 15 ± 3 Ma period of monazite (re)crystallization from burial/peak to exhumation.
BT - Chemical Geology
DA - 2021/01/05/
DO - https://doi.org/10.1016/j.chemgeo.2020.119919
N2 - Coupled age and trace element mapping in monazite grains using the Laser-Ablation Split-Stream ICP-MS technique was carried out for a sequence of samples from (U)HP crustal section in the Eger Crystalline Complex interpreted as a Variscan continental subduction wedge. The sampled section comprises banded orthogneiss with monazite protolith ages of 486 ± 3[10] Ma. The orthogneiss was heterogeneously transformed to migmatite, HP felsic granofels and U(HP) fine-grained Ky-Kfs granulite during coupled deformation and percolation of silicate melts in a subduction channel. Age of the (U)HP metamorphism and related melt percolation in the granulite is dated by Th-rich and HREE-poor monazite cores at 353.6 ± 2.7[8] Ma, that are in equilibrium with HREE-rich garnets. Th-rich cores of monazites in the migmatite, granofels and granulite that lack the (U)HP signatures show younger ages of 347.8 ± 3.4[8] Ma, 345.8 ± 2.4[8] Ma and 339.3 ± 1.3[7] Ma, respectively. The monazite rims with lower Th and higher HREE contents than the monazite cores are likely a result of (re)crystallization in equilibrium with melt that partly dissolved the HREE-rich prograde garnet during decompression. This (re)crystallization is constrained by ages of 344.2 ± 1.6[8] Ma in (U)HP granulites and 338–340 ± [8] Ma in migmatites, granofelses and granulites without the (U)HP signature. The groups of ages from 353 Ma to 338 Ma, are significantly different when only their in-run uncertainties (7–10 Ma) are compared and indicate a 15 ± 3 Ma period of monazite (re)crystallization from burial/peak to exhumation.
PY - 2021
SN - 0009-2541
EP - 119919
T2 - Chemical Geology
TI - Monazite geochronology in melt-percolated UHP meta-granitoids: An example from the Erzgebirge continental subduction wedge, Bohemian Massif
UR - http://www.sciencedirect.com/science/article/pii/S0009254120304587
VL - 559
ER -