This field trip will make observations from superbly exposed outcrops along the north Somerset coast (inverted southern margin of the Bristol Channel Basin) that reveal interactions between hydrocarbon generation, elevated pore pressures and resultantly enhanced deformation. We will infer the migration of overpressured fluids through the crust from a diversity of phenomena including sandstone dykes, reduction zones and mineralized hydrofractures (see photo), mud volcanoes (see photo), and low-angle faulting. Understanding links between maturation of organic matter and brittle deformation is of wide interest because it is increasingly clear that hydrocarbon generation and expulsion is a central process in creating the pathways that allow fluids to migrate from source to reservoir.

The north Somerset coast is one of the best places in the world to examine brittle deformation processes and many generations of MSc students have been there. Like a 3D seismic survey, it combines a continuous cliff line (‘vertical seismic profile’) and extensive foreshore (‘time slice’). We will stay in a traditional hotel-pub in the small market town of Dunster, in the shadow of the Quantock hills, with all the outcrops to be visited located within a 40-minute drive from the hotel. Distances to be walked are no more than a few kilometres but the foreshore can be uneven and slippery in places. Dunster is famous for its imposing Norman castle with ruined tower and impressive medieval gateway, now owned by the National Trust and with opportunities to visit in the evenings.

Visit https://www.ges-gb.org.uk/events/event-388/ for more information or to register