Ultrahigh-temperature granites and a curious thermal eye in the post-collisional South Bohemian batholith of the Variscan orogenic belt (Europe)

Abstract Comprehensive zircon thermometry that takes into account saturation temperatures, Ti-in-zircon measurements, and morphologies microstructures can provide key information on the thermal evolution of a granite batholith. The Variscan South Bohemian batholith (Germany, Austria, Czech Republic) comprises series granitoid units intruded between ca. 330 300 Ma. We categorize granitic rocks according to their emplacement temperature very low (T) (VLT; <750 °C), T (LT; 750–800 medium (MT; 800–850 high (HT; 850–900 ultrahigh (UHT; >900 °C). first stage formation (ca. 330–325 Ma) is characterized by LT MT melting mainly metasedimentary sources driven isothermal exhumation. In turn, 322 Ma HT UHT granites in southern half reveal an ephemeral anomaly subbatholithic crust, which presumably linked hidden mafic intrusion. are weakly peraluminous, high-K, I-type rocks. Although sharing some features with A-type such as Zr rare earth element contents, they differ from classical being magnesian, not enriched Ga over Al, having Ba Sr contents. A ring structure 317 and/or plutons observed around complex interpreted aftermath hotspot event. This study example how deep-crustal hotspots, caused mantle magmatism, significantly enhance effects decompressional crustal post-collisional setting.