Inhaltsbereich
ICDP SAFOD Gas and Fluid Geochemistry
Information on fault zone permeability structure and the origin of fault zone gases in seismogenic depths of the San Andreas Fault (SAF) were obtained by analyzing the composition and spatial distribution of gas extracted from returning drill-mud during drilling of the SAFOD wells (San Andreas Fault Observatory at Depth) and from drill core samples.
SAFOD, a component of U.S. research initiative EarthScope and supported by the ICDP (International Continental Drilling Program) consists of a straight pilot hole and a deviated main hole that intersects the SAF between approx. 3100 –3425 m depth.
Our investigation reveal separation of two individual hydrogeologic systems by a low-permeable fault centre with different bulk gas composition and helium isotope composition on the Pacific Plate (<3100m) and the North American Plate (>3500m). Further investigation will bring new insights on the permeability behaviour in the centre of the SAF on small spatial scale.
- Contact: Prof. Jörg Erzinger, Dr. Thomas Wiersberg