Chemical alteration of sediments on early stage of existing of hydrothermal systems in spreading zones of sedimented ridges (hydrothermal field “Dead Dog”, Middle Valley, Juan de Fuca Ridge)

摘要

In sediments from Holes DSDP 858B, D, F, located near the active hot vent on the thermal field “Dead Dog” in the northern part of the Juan de Fuca Ridge, Middle Valley, a redistribution of chemical elements occurs as a result of solution-rock interaction. During this process, the increase/decrease of their content in hydrothermally altered sediments inversely reflects the decrease/increase of their content in the solution. Nonregular distribution of microelements and REE’s in hydrothermally altered sediments, like a layer pie, reflects the participation of both ascending hydrothermal fluids and lateral flows of hydrothermal solutions in alteration of chemical composition of sediments.