Geology of the Mariana Trough

Abstract

The Mariana Trough is an actively spreading, crescent-shaped, backarc basin located in the western Pacific between the active Mariana volcanic island arc and the West Mariana Ridge, a remnant arc. The geologic evolution of the Mariana Trough varies along strike of the basin from the initial opening phase in the north to the mature seafloor spreading phase in the central latitudes. The opening of the basin began with an initial period of stretching and collapse of the preexisting arc followed by development of ridge/ transform structures along an active volcanic and tectonic zone on the eastern side of the basin. Eventually a true spreading center developed within the basin as the principal volcanic and tectonic zone diverged from the active volcanic front. The current along-strike variations in rifting/ spreading history define distinct geographic regions: the northern rifting apex, the central spreading basin, and the southern platform.