Crustal recycling by subduction erosion in the central Mexican volcanic belt

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doi: 10.1016/j.gca.2015.06.001
Author(s): Straub, Susanne M.; Gómez Tuena, Arturo; Bindeman, Ilya N.; Bolge, Louise L.; Brandl, Philipp A.; Espinasa Perena, Ramón; Solari, Luigi; Stuart, Finlay M.; Vannucchi, Paola; Zellmer, Georg F.
Author Affiliation(s): Primary:
Lamont Doherty Earth Observatory, Palisades, NY, United States
Other:
Universidad Nacional Autónoma de México, Mexico
University of Oregon, United States
Australian National University, Australia
Centro Nacional de Prevención de Desastres, Mexico
Scottish Universities Research and Reactor Centre, United Kingdom
University of London, United Kingdom
Massey University, New Zealand
Volume Title: Geochimica et Cosmochimica Acta
Source: Geochimica et Cosmochimica Acta, Vol.166, p.29-52. Publisher: Elsevier, New York, NY, International. ISSN: 0016-7037 CODEN: GCACAK
Note: In English. Includes appendices. 104 refs.; illus., incl. 4 tables, sketch map
Summary: Recycling of upper plate crust in subduction zones, or 'subduction erosion', is a major mechanism of crustal destruction at convergent margins. However, assessing the impact of eroded crust on arc magmas is difficult owing to the compositional similarity between the eroded crust, trench sediment and arc crustal basement that may all contribute to arc magma formation. Here we compare Sr-Nd-Pb-Hf and trace element data of crustal input material to Sr-Nd-Pb-Hf-He-O isotope chemistry of a well-characterized series of olivine-phyric, high-Mg# basalts to dacites in the central Mexican Volcanic Belt (MVB). Basaltic to andesitic magmas crystallize high-Ni olivines that have high mantle-like 3He/4He = 7-8 Ra and high crustal δ18Omelt = +6.3-8.5 ppm implying their host magmas to be near-primary melts from a mantle infiltrated by slab-derived crustal components. Remarkably, their Hf-Nd isotope and Nd/Hf trace element systematics rule out the trench sediment as the recycled crust end member, and imply that the coastal and offshore granodiorites are the dominant recycled crust component. Sr-Nd-Pb-Hf isotope modeling shows that the granodiorites control the highly to moderately incompatible elements in the calc-alkaline arc magmas, together with lesser additions of Pb- and Sr-rich fluids from subducted mid-oceanic ridge basalt (MORB)-type altered oceanic crust (AOC). Nd-Hf mass balance suggests that the granodiorite exceeds the flux of the trench sediment by at least 9-10 times, corresponding to a flux of ≥79-88 km3/km/Myr into the subduction zone. At an estimated thickness of 1500-1700 m, the granodiorite may buoyantly rise as bulk 'slab diapirs' into the mantle melt region and impose its trace element signature (e.g., Th/La, Nb/Ta) on the prevalent calc-alkaline arc magmas. Deep slab melting and local recycling of other slab components such as oceanic seamounts further diversify the MVB magmas by producing rare, strongly fractionated high-La magmas and a minor population of high-Nb magmas, respectively. Overall, the central MVB magmas inherit their striking geochemical diversity principally from the slab, thus emphasizing the importance of continental crust recycling in modern solid Earth relative to its new formation in modern subduction zones. Abstract Copyright (2015) Elsevier, B.V.
Year of Publication: 2015
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 02 Geochemistry; 05 Petrology, Igneous and Metamorphic; Acapulco Mexico; Alkaline earth metals; Basalts; Basement; Crust; Crystallization; Dacites; Deep Sea Drilling Project; Diapirism; East Pacific; Erosion; Granodiorites; Hafnium; He-4/He-3; Helium; High-field-strength elements; IPOD; Igneous rocks; Island arcs; Isotope ratios; Isotopes; Lead; Leg 66; Lithophile elements; Magma contamination; Magmatism; Metals; Mexico; Mid-ocean ridge basalts; Neodymium; Noble gases; North Pacific; Northeast Pacific; O-18/O-16; Oxygen; Pacific Ocean; Plate tectonics; Plutonic rocks; Rare earths; Recycling; Sr-87/Sr-86; Stable isotopes; Strontium; Subduction; Subduction zones; Trans-Mexican volcanic belt; Volcanic belts; Volcanic rocks
Coordinates: N155000 N162300 W0983000 W0993000
N153000 N213000 W0970000 W1040000
Record ID: 2015102870
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands