Rapid cooling and geospeedometry of granitic rocks exhumation within a volcanic arc: A case study from the Central Slovakian Neovolcanic Field (Western Carpathians)

Abstract

U–Pb Sensitive High‐Resolution Ion MicroProbe (SHRIMP) dating of zircon in combination with (U–Th)/He dating of zircon and apatite is applied to constrain the emplacement and exhumation history of the youngest granitic rocks in the Western Carpathians collected in the Central Slovakian Neovolcanic Field. Two samples of diorite from the locality Banky, and granodiorite from Banská Hodruša yield the U–Pb zircon concordia ages of 15.21 ±0.19 Ma and 12.92 ±0.27 Ma, respectively, recording the time of zircon crystallization and the intrusions’ emplacement. Zircon (U–Th)/He ages of 14.70 ±0.94 (Banky) and 12.65 ±0.61 Ma (Banská Hodruša), and apatite (U–Th)/He ages of 14.45 ±0.70 Ma (diorite) and 12.26 ±0.77 Ma (granodiorite) are less than 1 Myr younger than the corresponding zircon U–Pb ages. For both diorite and granodiorite rocks their chronological data thus document a simple cooling process from magmatic crystallization/solidification temperatures to near‐surface temperatures in the Middle Miocene, without subsequent reheating. Geospeedometry data suggest for rapid cooling at an average rate of 678 ±158 °C/Myr, and the exhumation rate of 5 mm/year corresponding to active tectonic‐forced exhumation. The quick cooling is interpreted to record the exhumation of the studied granitic rocks complex that closely followed its emplacement, and was likely accompanied by a drop in the paleo‐geothermal gradient due to cessation of volcanic activity in the area.

Miocene Volcanism in the Slovenský Raj Mountains: Magmatic, Space, and Time Relationships in the Western Carpathians

“…A projection in Sr-Nd isotope space (Figure 13) with variable Sr contamination likely implies a composition similar to the mafic "granulite" xenoliths from the WPB and, thus, a more depleted mantle source for the SRM magmas than for the alkaline CPR 87 Sr/ 86 Sr contamination on the SRM volcanic rocks. Sources of 87 Sr/ 86 Sr and 143 Nd/ 144 Nd isotope data from the CPR are summarized in [14,[16][17][18][19][20][21][22]24,25,27,29,30,[35][36][37][38]40,43,44,90,91,95,[97][98][99][100][101][102][103][104][105][106][107].…”

“…The dashed arrow shows the effect of87 Sr/86 Sr contamination on the SRM volcanic rocks. Sources of87 Sr/86 Sr and 143 Nd/ 144 Nd isotope data from the CPR are summarized in[14,[16][17][18][19][20][21][22]24,25,27,29,30,[35][36][37][38]40,43,44,90,91,95,[97][98][99][100][101][102][103][104][105][106][107].…”

Evolution of a Shallow Volcanic Arc Pluton During Arc Migration: A Tectono‐Thermal Integrated Study of the St. Martin Granodiorites (Northern Lesser Antilles)

“…Along many volcanic arcs it has been demonstrated that active volcanoes were emplaced in their own metamorphosed magmatic basement that was promptly exhumed (Kuril: De Grave et al., 2016; Lesser Antilles: Favier et al., 2019). It is noteworthy that during arc migration, cooling of an arc pluton might be interpreted to record its exhumation, whereas it might be associated with a drop in the paleo‐geothermal gradient due to volcanic arc cessation (Kohút & Danišík, 2017). However, the effects on thermochronological ages of the evolution through time of the thermal structure of the crust can be investigated using a numerical modeling approach.…”