See more from this Division: Topical Sessions
See more from this Session: Southwest Pacific Cenozoic Tectonics and Comparisons with Other Orogenic Belts
Abstract:
Our survey of the Nankai prism reveals three distinct structural fabrics in the vicinity of Tenryu Canyon. First, bedding within the prism (elsewhere dated at 0.12-0.46 Ma) strikes southwest to northwest and dips predominantly to the north towards the arc, which suggests strata are involved in a series of east-west trending, kilometer-scale folds in the hanging-walls of north dipping thrust faults. Second, strata are also involved in an unusual series of north-northeast trending folds that have 20 to 50 m wavelengths and deform preexisting structures. Finally, prominent northeast trending scarps truncate all other structures. Some of these scarps were formed by thrusts, but others may be the trace of trench-parallel strike-slip faults. While kilometer-scale thrust related folds are typical in accretionary prisms, the origins of the possible strike-slip faults and north-northeast trending folds are unclear. However, it is likely that these structures are essentially active and associated with out-of-sequence thrusting, oroclinal bending, and gravitational collapse associated with the frequent subduction of seamounts in the Zenisu Ridge Complex.
See more from this Division: Topical Sessions
See more from this Session: Southwest Pacific Cenozoic Tectonics and Comparisons with Other Orogenic Belts