Late Pleistocene tephrochronology of marine sediments adjacent to Montserrat, Lesser Antilles volcanic arc

摘要

The recent history of the Soufrière Hills volcano, Montserrat, Lesser Antilles volcanic arc, is deduced using data obtained from a submarine core collected in 2002. The core contains concentrations of ash and several tephra layers, which are identified by the abundance of glass shards, dense and poorly vesiculated particles, and scoria. The tephra layers have been dated using micropalaeontology and stable isotope stratigraphy. Tephra layers in a marine sediment core off the coast of Montserrat record the volcanic history of South Soufrière Hills–Soufrière Hills volcano back to 250 ka. Eight layers are composed of dense juvenile ash related to dome eruptions, five of which can be directly correlated to dated domes or related pyroclastic flow sequences on land. Six layers are composed of pumiceous glassy ash and relate to significant explosive eruptions. A marker sequence of basalt tephra layers is dated at 124–147 ka and is correlated with construction of the South Soufrière Hills basaltic stratocone. Pelagic sediments between the main tephra layers have low abundances of volcanogenic components (<15%) and suggest long periods (c. 104 years) of dormancy or low activity.