Geological and geophysical signatures of the East Pacific Rise 8°–10°N

Abstract

The East Pacific Rise (EPR) 8°–10°N is an archetype for fast-spreading mid-ocean ridge (MOR), and has been one of the most comprehensively studied MOR sections for over four decades. It covers all orders of ridge discontinuities: first-order transform faults, second-order overlapping spreading centers, third-order small offset tectonic discontinuities, and fourth-order discontinuities of eruptive fissure zones. This section has been selected as a multi-disciplinary integrated study site because of its abundance of hydrothermal vents where scientists are investigating the linkages between mantle flow, crustal accretion, volcanic, hydrothermal, and biological processes that result in chemical and physical exchanges of energy and matter between the Earth's mantle and oceans. In particular, the segment near 9°50′N is one of the only two sites where repeated seafloor volcanic eruptions were onsite observed along the MOR. In this paper, we investigate the geological and geophysical signatures of the EPR 8°–10°N on behalf of the fast-spreading MOR, present the seismic signatures of the hydrothermal pathways through full waveform inversion, and put forward some thoughts on the remaining questions to be addressed. The skewness of mantle upwelling, on- and off-axis magmatism, are playing a critical role in shaping the crustal architecture. The spatial distribution and physical property of the crustal melt lens are mutually related to the hydrothermal system. The mechanism of hydrosphere-lithosphere interaction beneath the MOR is worth further studying. This compilation should be useful to investigators new to the MOR topic but we also target advanced researchers in presentation and synthesis of findings to date.