TY - CHAP
T1 - Chemical and Isotopic Cycling in Subduction Zones
AU - Bebout, G. E.
N1 - Funding Information:
Most of the author's research presented in this chapter was funded by the National Science Foundation, most recently by NSF grants EAR-0711355 and EAR-1119264. The author also acknowledges many years of discussions with Eizo Nakamura and other colleagues at the Pheasant Memorial Laboratory, Institute for Study of the Earth's Interior (ISEI; Okayama University, Misasa, Japan), and financial support from the ISEI and the Japanese government (most recently, the COE-21 program). Special thanks are extended to Roberta Rudnick for her assistance (and patience) as the editor for this manuscript.
PY - 2013/11
Y1 - 2013/11
N2 - Subduction zones are avenues for the delivery of crustal, atmospheric, and oceanic (including organic) components to the mantle and understanding of subduction zone chemical and isotopic cycling is central to many models of crust-mantle-atmosphere evolution. During subduction, diagenetic and metamorphic reactions and related geochemical effects can profoundly influence the element inventory and isotopic composition of subducting slabs to depths beneath volcanic arcs and as they enter the deeper mantle. Physical juxtaposition of chemically disparate rocks and the generation and mobility of various fluids lead to myriad metasomatic effects in subduction zones. Larger scale manifestations of such processes include the mass transfer that leads to arc magmatism and convergent margin volatile cycling. Subduction zone metasomatism is initiated at very shallow levels, as oceanic slabs entering trenches bend and are infiltrated by seawater, and as sedimentary sections experience physical compaction, fluid expulsion, and diagenetic alteration. Studies of forearc fluid geochemistry track this shallow-level metasomatic alteration, and high- and ultrahigh-pressure metamorphic rock suites provide records of fluid generation and flow, and related metasomatism, to depths exceeding those beneath volcanic fronts. Subduction zone processes act as a geochemical filter, altering the compositions of deeply subducting rocks and generating outputs such as arc magmas (and associated volcanic gases) and chemically and isotopically modified rocks. The latter enter the deeper mantle and influence its long-term geochemical evolution.
AB - Subduction zones are avenues for the delivery of crustal, atmospheric, and oceanic (including organic) components to the mantle and understanding of subduction zone chemical and isotopic cycling is central to many models of crust-mantle-atmosphere evolution. During subduction, diagenetic and metamorphic reactions and related geochemical effects can profoundly influence the element inventory and isotopic composition of subducting slabs to depths beneath volcanic arcs and as they enter the deeper mantle. Physical juxtaposition of chemically disparate rocks and the generation and mobility of various fluids lead to myriad metasomatic effects in subduction zones. Larger scale manifestations of such processes include the mass transfer that leads to arc magmatism and convergent margin volatile cycling. Subduction zone metasomatism is initiated at very shallow levels, as oceanic slabs entering trenches bend and are infiltrated by seawater, and as sedimentary sections experience physical compaction, fluid expulsion, and diagenetic alteration. Studies of forearc fluid geochemistry track this shallow-level metasomatic alteration, and high- and ultrahigh-pressure metamorphic rock suites provide records of fluid generation and flow, and related metasomatism, to depths exceeding those beneath volcanic fronts. Subduction zone processes act as a geochemical filter, altering the compositions of deeply subducting rocks and generating outputs such as arc magmas (and associated volcanic gases) and chemically and isotopically modified rocks. The latter enter the deeper mantle and influence its long-term geochemical evolution.
KW - Arc volcanism
KW - Chemical cycling
KW - Chemical geodynamics
KW - Eclogite
KW - Metamorphism
KW - Subduction zone
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U2 - 10.1016/B978-0-08-095975-7.00322-3
DO - 10.1016/B978-0-08-095975-7.00322-3
M3 - Chapter
AN - SCOPUS:84903807435
SN - 9780080983004
VL - 4
SP - 703
EP - 747
BT - The Crust
PB - Elsevier Inc.
ER -