Fission-track dating of detrital zircons from sandstone of the Lesnaya Group, northern Kamchatka

Flyschoid deposits of the Lesnaya Group that are exposed within northern Ka mchatka are almost barren of identifiable fossils. The group is considered to be of the Late Cretaceous age on the basis of geological correlation. Ag es of detrital zircons from nine sandstone samples of the Lesnaya Group are determined using the fission-track dating. The youngest population of colo rless idiomorphic zircon crystals, which experienced no secondary annealing , is from 43.7 +/- 3.4 to 58.1 +/- 4.2 Ma old. Morphological features of zi rcons allow us to relate their formation to the volcanic activity synchrono us to accumulation of the Lesnaya Group flysch. Hypabyssal intrusions and b locks of older rocks that experienced rapid exhumation from the depth, wher e thermal parameters exceeded the blocking temperature, could be the source rocks for younger zircons. The age of the youngest zircon population can b e interpreted as corresponding to sedimentation time of the Lesnaya Group t hat lasted, according to our data, until the mid-Middle Eocene.