title: Copper systematics in arc magmas and implications for crust-mantle differentiation.
abstract: Arc magmas are important building blocks of the continental crust. Because many arc lavas are oxidized, continent formation is thought to be associated with oxidizing conditions. On the basis of copper's (Cu's) affinity for reduced sulfur phases, we tracked the redox state of arc magmas from mantle source to emplacement in the crust. Primary arc and mid-ocean ridge basalts have identical Cu contents, indicating that the redox states of primitive arc magmas are indistinguishable from that of mid-ocean ridge basalts. During magmatic differentiation, the Cu content of most arc magmas decreases markedly because of sulfide segregation. Because a similar depletion in Cu characterizes global continental crust, the formation of sulfide-bearing cumulates under reducing conditions may be a critical step in continent formation.
authors.affiliation: Department of Earth Science, Rice University, MS-126, 6100 Main Street, Houston, TX 77005, USA. ctlee@rice.edu
authors.forename: Cin-Ty A
authors.initials: CT
authors.lastname: Lee
authors.forename: Peter
authors.initials: P
authors.lastname: Luffi
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Chin
authors.forename: Romain
authors.initials: R
authors.lastname: Bouchet
authors.forename: Rajdeep
authors.initials: R
authors.lastname: Dasgupta
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Morton
authors.forename: Veronique
authors.initials: V
authors.lastname: Le Roux
authors.forename: Qing-zhu
authors.initials: QZ
authors.lastname: Yin
authors.forename: Daphne
authors.initials: D
authors.lastname: Jin