Abstract
Seamount chain–subduction zone interactions: Implications for accretionary and erosive subduction zone behavior
Highlights
Subduction of bathymetric highs has traditionally been thought to be associated with tectonic erosion of the overriding forearc
Topographic highs such as large seamount complexes are commonly associated with significant volumes of flanking volcaniclastic sediments in the form of >100-kmwide debris aprons, with the largest deposits found in flexural moat basins
We propose that subduction of these sediment accumulations promotes localized frontal accretion, even in otherwise non-accretionary margins
Summary
Subduction of bathymetric highs has traditionally been thought to be associated with tectonic erosion of the overriding forearc. The subduction of a seamount chain’s debris apron and/or moat sediments (hereafter referred to as “moat”) offers a hitherto unconsidered opportunity for accretion of oceanic sediments at an otherwise “erosive” subduction margin. By this process, geologically significant volumes of volcaniclastic marine sediment may be transferred from the oceanic to the overriding plate. The matrix consists of clay minerals (smectite and illite) and angular to subrounded grains of feldspar and clinopyroxene; quartz grain content varies from 0% to 5% ± 2% This mélange exhibits notable variation of the matrix and block populations and their relative proportions; the matrix to block ratio is high throughout. The Osa mélange lacks pervasive recrystallization or greenschist facies minerals and contains abundant veins with calcite showing twinning types indicating the maximum experienced temperature was ~200–250 °C (Burkhard, 1993; Meschede et al, 1999)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
