Preface Zircon multichronology: Fission-track, U-Pb, and combined fission-track–U-Pb studies Zircon is a tiny and ubiquitous mineral in the Earth’s crust that is a versatile multichronological archive. Zircon contains significant amounts of radioactive thorium and uranium that decay to various radiogenic daughter isotopes. From this mineral, it is possible to obtain U–Th–Pb, (U–Th)/ He, and fission-track (FT) ages from a single small crystal. Zircon is found in most rocks and is the only mineral that is sufficiently resistant to weathering to have survived for much of the 4.56 billion years of Earth’s history. The zircon U–Pb system has a very high closure temperature of 900°C and can reveal the history of rocks that date back to the earliest formation of the Earth. Other zircon chro- nometers have lower closure or annealing tem- peratures, which are suitable for revealing the thermal history of rocks. For example, the zircon FT system is easily reset at low temperatures of approximately 200–300°C on geological timescales and the zircon (U–Th)/He system is reset at even lower temperatures. The high-temperature U–Pb and low- temperature FT methods have been simulta- neously used for thermochronological studies of detrital zircon (Carter & Moss 1999; Carter & Bristow 2000). The novel application of multiple zircon chronometers can be used to better under- stand the igneous and metamorphic crystallization history of zircons, tectonic geomorphology (e.g., uplift and denudation), and the provenance of sedi- mentary rocks (Rahl et al. 2003; Anma et al. 2006; Bernet et al. 2006; Dias et al. 2011; Imayama et al. 2012). The zircon (U–Th)/He dating method (Tagami et al. 2003; Reiners 2005) and FT dating using laser ablation–inductively coupled plasma– mass spectrometry (LA-ICP-MS) have been established in the past decade (Košler & Sylvester 2003; Hasebe et al. 2004, 2009; Donelick et al. 2005), allowing multichronological studies of zircon based on state-of-the-art mass spectrometry (Shen et al. 2012; Sueoka et al. 2012). In September 2011, a special session entitled ‘Zircon and Multichronology’ was held during the Fall Meeting of the Geological Society of Japan. The meeting brought together specialists in this research field to review and debate the latest developments in zircon dating methods. This special issue of Island Arc is a compilation of eight papers written by researchers who contributed to this session. Danhara and Iwano (2013) have devel- oped an independent age calibration for FT dating based on physical constants. The agreement between FT and U–Pb ages for the same zircon standard indicates that both methods function as an independent geochronometer. Hasebe et al. (2013) review the FT dating method using the LA-ICP-MS technique for measurements of uranium concentrations, which does not require thermal neutron irradiation in a nuclear reactor. These authors showed that this method makes it possible to perform FT and U–Pb double dating on a single zircon grain. Horie et al. (2013) describe a new microbeam U–Pb dating zircon standard (OT4; 191 Ma), which has been thoroughly charac- terized in terms of its crystallinity and its REE, Hf, and Ti concentrations using a sensitive high- resolution ion microprobe. Ogasawara et al. (2013) prepared and documented a secondary zircon standard (SoriZ93) from a Cretaceous granodior- ite that has previously yielded a standard biotite (GJ-1) for K–Ar age calibration. This work pro- vides a standard suitable for calibration of differ- ent dating methods. Takagi et al. (2013) show how zircon FT ages from a pseudotachylyte along the Atotsugawa Fault, which is one of the most active faults in Japan, have been reset, and for the first time apply the Shapiro–Wilk test to identify mixed FT age distributions. Sakai et al. (2013a,b) present applications of zircon multichronology using a combination of inherited U–Pb ages and reset FT dates to show that a hot metamorphic nappe covering the lesser Himalayas cooled laterally; the authors provide a new hypothesis for the extrusion of metamorphic rocks in an active nappe. Finally, Iwano et al. (2013) report the results of an interlaboratory dating study of OD-3 zircon (33 Ma) separated from a granodiorite, as a poten- tial multi-grain secondary standard for U–Pb dating. Characterization of the OD-3 zircon Island Arc (2013) 22, 261–263 © 2013 Wiley Publishing Asia Pty Ltd doi:10.1111/iar.12042