Comparing in situ U-Pb zircon and Th-Pb monazite ages from High Tatra granitoids, Slovakia

Abstract

The focus of this contribution is constraining the timing of the tectonic evolution of the High Tatra Mountains in Slovakia, which are located in the Western Carpathian Mountains. Both monazite (REEThPO4) and zircon (ZrSiO4) grains were dated in rock thin section from the same samples of High Tatra granitoids to understand not only the tectonic evolution of the range but also to compare the timing information provided by these accessory minerals.

Full text

Joint 5th Central-European Mineralogical Conference and
7th Mineral Sciences in the Carpathians Conference
1
Comparing in situ U-Pb zircon and Th-Pb monazite ages from High
Tatra granitoids, Slovakia
1Elizabeth J. Catlos#, 1Saloni Tandon, 1Thomas M. Etzel, 2Milan Kohút, 2Igor Broska, 1Daniel
Stockli, 3Brent A. Elliott, 1Kimberly Aguilera, and 1Zoe Yin
1 The University of Texas at Austin, Department of Geological Sciences, 23 San Jacinto Blvd. & E
23rd Street, Austin, TX 78712, USA #ejcatlos@jsg.utexas.edu
2 Earth Science Institute, Slovak Academy of Science, Dubravska cesta 9, 840 05 Bratislava,
Slovakia
3 The University of Texas at Austin, Bureau of Economic Geology, 10611 Exploration Way, Austin,
TX 78758, USA
Key words: High Tatra Mountains, zircon, monazite, geochronology
The focus of this contribution is
constraining the timing of the tectonic evolution
of the High Tatra Mountains in Slovakia, which
are located in the Western Carpathian
Mountains. Both monazite (REEThPO4) and
zircon (ZrSiO4) grains were dated in rock thin
section from the same samples of High Tatra
granitoids to understand not only the tectonic
evolution of the range but also to compare the
timing information provided by these accessory
minerals.
Overall, zircon and monazite grains were
dated in five samples from the vicinity of
Lomnický štít (Table 1). Zircon grains were
analyzed using Laser Ablation-Inductively
Coupled Plasma Mass Spectrometry (LA-ICP-
MS) at UT Austin, whereas monazite grains
from the same samples were dated in thin
section using Secondary Ion Mass Spectrometry
(SIMS) at UCLA. Entire rock thin sections were
then imaged in cathodoluminescence after
dating to decipher the textures and deformation
history of the samples.
We present the ages of the oldest and
youngest zircon and monazite grains from each
sample in the table. Most yield ages as expected
for the High Tatras, which has been reported to
largely record events centering around the
Carboniferous (e.g., Burda et al., 2013).
Zircons, as expected, record older ages than the
monazite, although in many cases they overlap.
The oldest zircon age is Early Devonian (n=2),
whereas the oldest monazite are Middle to Late
Devonian (n=4). Some monazite grains (n=4)
yield Permian results, up to 60 m.y. younger
than the time frame suggested to record the final
stages of Variscan collision in the range. The
younger monazite ages are ~30 m.y. older than
K-feldspar 40Ar/39Ar step-heating results of
~221 Ma reported by Etzel et al. (2018) in this
volume and provide important constraints to
decipher the thermal history of the range.
Table. Oldest and youngest U-Pb zircon and
Th-Pb monazite ages from High Tatra samples
Zircon age
(238U-206Pb) (±2)
Monazite
Th-Pb age (±1)
HT01A (49°11'19.98"N, 20°13'58.90"E)
387±19 Ma
348±18 Ma
343±22 Ma
316±13 Ma
HT01B (49°11'19.98"N, 20°13'58.90"E)
353±13 Ma
331±15 Ma
333±15 Ma
299±29 Ma
HT02 (49°11'42.80"N, 20°12'47.90"E)
n.m
380±17 Ma
n.m
254±28 Ma
HT03 (49° 9'55.50"N, 20°13'15.60"E)
410±14 Ma
377±22 Ma
321±14 Ma
276±12 Ma
HT04 (49° 9'46.90"N, 20°13'12.90"E)
415±41 Ma
351±14 Ma
358±16 ma
323±15 Ma
n.m. = not measured
Acknowledgment: This material is based
upon work supported by the NSF under grant
no. OISE 1460050. The SIMS facility UCLA
acknowledges support through NSF
Instrumentation and Facilities. We appreciate
field assistance facilitated by Dusan Catlos.
REFERENCES
Burda, J., Gaweda, A., Klotzli, U. (2013)
Geochronometria, 40(2): 134-144.