Abstract
Occurrences, lithofacies and K-Ar ages of clasts from Miocene conglomerates in the northeastern part of the Kanto Mountains are studied to reveal their provenance. Lithofacies and K-Ar ages of the most of clasts are similar to those of metamorphic and granitic rocks of the Ryoke Belt of central Japan. Provenance of the studied clasts are considered to be allochthonous geological bodies of the Ryoke Nappe which were previously located in the Kanto Mountains where Sanbagawa metamorphic rocks, the Atokura Nappe and Jurassic accretionary complex of the Chichibu Belt are presently exposed. The Ryoke Nappe is considered to be the uppermost structural unit in the Middle Miocene time. The Atokura Nappe near the Chichibu Belt was structurally covered by the Ryoke Nappe, and thus clasts derived from the Atokura Nappe were not found in most of Miocene conglomerates exposed in the Chichibu Belt.
