Acoustic evidences of gas in the continental slope sediments of the Gulf of Cadiz (E Atlantic)

摘要

Detailed reviews of high-resolution acoustic studies in the continental slope of the Gulf of Cadiz has revealed the following gas-related features: acoustic turbidity and blanking, bright spots, ancient and modern pockmarks, high-amplitude diffractions, acoustic plumes and turbidity in the water column, and BSRs. The origin of the gas is believed to be biogenic and thermogenic. The BSR-like acoustic anomalies occur intermittently in some areas of the upper slope and tend to occur in the volcanoes/diapirs. The pressure-temperature conditions deduced for the location of those acoustic anomalies do not correspond to the conditions of stability of gas hydrates. It is suggested that these volcanoes/diapirs intrusions may locally induce anomalously higher pore pressure conditions on the immediately surrounding sediments, affecting the stability field of the gas hydrates. [References: 50]