9 - Submarine hydrothermal activity in coastal zones

Abstract

This chapter discusses the submarine hydrothermal activity in coastal zones. Coastal hydrothermal acitivity is observed at several sites in the Mediterranean Sea and western Pacific and is almost always associated with arc volcanism at subduction zones. While deep-sea hydrothermal fluids are mainly derived from the circulation of seawater beneath the seafloor, coastal hydrothermal fluids are derived from a complex mixture of seawater, meteoric water (groundwater), and magmatic fluids. In addition, tidal forcing, sea level change, and earthquake activity may significantly affect the rates of fluid venting and dispersion of hydrothermal plumes. The chemical composition of coastal hydrothermal fluids is therefore variable because it depends not only on fluid–rock interaction at high temperatures but also on the rate of subduction of the slabmaterial at the convergent plate margin and the decomposition of organic matter within the coastal sediments through which the fluids pass.