Lecture: Jurassic mud volcanoes and methane
Speaker:
Entry Fee
Members: Free
Visitors: £5.00
Date and Time
19:30 -
Location
Bath Royal Literary and Scientific Institution, 16-18 Queen Square, Bath BA1 2HN
Lecture Description
Mud volcanoes are a global phenomenon formed where fluid and gas-rich sediments are extruded. The mainly conical shapes are caused by successive eruptions of mud that have built up over time. Generally, 90% of the gas volume emitted from modern mud volcanoes is methane, but this figure can vary and the methane emitted makes a significant contribution to the global atmospheric methane pool. Ancient methane seeps, have been documented previously, although they are still comparatively rare. In this presentation a series of mud volcano structures from Kilve, west Somerset, UK are described. They occur within the Bucklandi ammonite zone (Sinemurian) of the Lower Jurassic. The mud volcanoes contain mud breccias as well as abundant crinoidal fragments and benthic foraminifera (Involutina liassica). Evidence for methane associated with the mud volcanoes is derived from isotopic analysis. Compared to modern mud volcanoes the structures present in Somerset are small, which may indicate limited activity and limited volume extruded. Hence this may suggest that only a modest amount of methane may have reached the atmosphere during the Jurassic from this source.