Lu-Hf geochronology on cm-sized garnets using microsampling: New constraints on garnet growth rates and duration of metamorphism during continental collision (Menderes Massif, Turkey)

摘要: Abstract This study shows Lu–Hf geochronology of zoned garnet crystals contained in mica schists from the southern Menderes Massif, Turkey. Selected samples are four 3–5 cm large megacrysts which several consecutive shells have been sampled with a micro-saw and analyzed for dating. The results used to extract growth rates garnet, also improve time constraint Alpine-aged overprint Pan-African basement Massif. ages determined by two-point garnet-only isochrons using garnets' Lu-depleted rim compositions. yields consistent decrease age information core segments individual calculated isochron propose frame between 42.6 ± 1.9 34.8 3.1  Ma . Major element profiles investigated garnets characterize zoning patterns indicative prograde conditions: Rayleigh fractionated bell-shaped Mn decreasing Fe/(Fe + Mg) recorded Therefore obtained record timing early cores garnets. Two yield 58.83 0.69 50.16 0.84 their innermost cores, appear an nucleation event. view, however, is not concordance observed major these garnets, therefore interpreted caution. Termination period through calculation radial based on size shells. Extrapolation potentially constrains total duration terminating at 31 6 Comparison variety slow fast growing similar previously Rb–Sr Sm–Nd isotope systems. new data provides precise determination Barrovian metamorphism so far was placed 63 27 Ma basis Ar–Ar constraints crucial understanding tectonic evolution southwest Anatolia Aegean realm, as it shorter outline Alpine aged continental collision.