Chemical and Isotopic Cycling in Subduction Zones Chapter uri icon

DCO ID 11121/7161-2987-3216-5479-CC

in language

  • English

is Contribution to the DCO

  • YES

year of publication

  • 2014

abstract

  • This chapter provides a synthesis of current knowledge regarding the changes in the physical, petrologic, and geochemical state of subducting oceanic crust that result from diagenesis and metamorphism along the subduction pathway. One focus in this contribution is on discussion of metamorphic suites for which it is possible to evaluate chemical changes in subducting oceanic crust and overlying sediments as they transit forearcs to subarc depths. Emphasis is placed on elucidating connections between the metamorphic geochemical record and other subduction-related products such as décollement fluids, forearc serpentinite seamounts and mud volcanoes, arc volcanic lavas and gases, and deep mantle geochemical signatures that bear signatures of the deep subduction of oceanic lithosphere and sediment.  For a number of important chemical tracers (e.g., boron, lithium, nitrogen, organic carbon and nitrogen, perhaps large-ion lithophile elements [LILE], particularly cesium, rubidium, barium, and strontium), significant changes occur during the earliest stages of subduction due to pore water expulsion and diagenesis (and for mafic rocks, possibly hydration).  Discussion of the metamorphic record is focused primarily on HP and UHP suites in the circum-Pacific, Cyclades, and European Alps, which have seen the most geochemical study focused on issues of ocean-to-mantle chemical cycling.

publication date

  • 2014

volume

  • 4