Pseudo-3D seismic imaging of Geolin Mounds hydrothermal field in the Southern Okinawa Trough offshore NE Taiwan

Abstract

To explore a new discovering hydrothermal field Geolin Mounds in the Southern Okinawa Trough (SOT), a multi-scale geophysical investigation cruise including single-beam echo sounder, sub-bottom profiler (SBP) and multi-channel seismic (MCS) surveys were conducted in 2018 in a new discovering hydrothermal field we named Geolin Mounds. Taking advantage of streamer feathering caused by strong Kuroshio Current during MCS data acquisition, we performed a pseudo-3D processing and produced a pseudo-3D seismic cube. In addition to flare features in water column, "rock grove" like morphological feature above seafloor, widely-distributed amplitude anomalies including blanking zone and high-amplitude reflectors are observed around the Geolin Mounds hydrothermal field in our 2D MCS data. Pseudo- 3D seismic cube, on the other hand, provide estimation of the areas of blanking zone on selected time slice; furthermore, better characterize the fault structures in the hydrothermal field. The Geolin Mounds is the first disclosed site in the SOT where a hydrothermal field is without underlying submarine volcanos. We thus suggest that the Geolin Mounds hydrothermal field is in its embryo stage of evolution and is constantly supported by vigorous subsurface hydrothermal circulation. Consequently, the Geolin Mounds hydrothermal field may grow sustainably and serves as a good observatory for development of the seafloor edifice and ore mineralization associated with hydrothermal circulation activities.