Convergence structures of the Peru trench between 10°S and 14°S     

Waris E.K. Warsi  Thomas W.C. Hilde  Roger C. Searle 《Tectonophysics》1983,99(2-4)

High resolution seafloor studies of the Peru Trench between 10°S and 14°S with the GLORIA long-range side-scan sonar system show that the Nazca plate is broken by numerous normal faults as it bends into the trench. These bending-induced faults strike subparallel to the trench axis and overprint and cut across spreading fabric structures of the plate. They commonly form grabens having widths and spacings of 3–5 km and extend for as much as 100 km along strike. Vertical displacements are generally 200 m or more by the time they reach the trench axis. Turbidite deposits are found in the trench north of 11.5°S. Both turbidite and pelagic sediments are folded and temporarily accreted to the base of the overriding plate along the length of the trench axis. They are apparently subsequently implaced in the grabens by slumping and subducted with the Nazca plate. The Mendaña Fracture Zone, which intersects the trench between 9°40′S and 10°35′S, appears to be the locus of a seaward propagating rift that is forming in response to subduction-induced extensional stresses in the Nazca plate.  相似文献   

The geology of Raoul Island,Kermadec group,Southwest Pacific     

R. N. Brothers  E. J. Searle 《Bulletin of Volcanology》1970,34(1):7-37

Cauldron collapse and voluminous pumice eruptions, some 2000 years ago, indicate a mature stage in the summit cone of a volcano rising 8000 feet above the ocean floor. Volcanic rocks ranging from early submarine tholeiitic basalts to young subaerial dacite obsidians have been mapped in chronologic sequence through five formations; plutonic rocks, found as accidental blocks and as disrupted cumulates, are gabbros or diorites. Twenty-three new analyses are listed.  相似文献