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Book Chapter

A Hf-isotope perspective on continent formation in the south Peruvian Andes

By
Flora Boekhout
Flora Boekhout
Section of Earth and Environmental Sciences, rue des Maraîchers 13, CH-1205 Geneva, SwitzerlandPresent address: Case 115, IMPMC, 4 place Jussieu, 75005 Paris, Cedex 05, France
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Nick M. W. Roberts
Nick M. W. Roberts
NERC Isotope Geoscience Laboratory, Kingsley Dunham Centre, Keyworth, Nottingham NG12 5GG, UK
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Axel Gerdes
Axel Gerdes
Goethe-University Frankfurt, Institute of Geosciences, Altenhoeferallee 1, 60438 Frankfurt am Main, GermanyDepartment of Earth Sciences, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa
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Urs Schaltegger
Urs Schaltegger
Section of Earth and Environmental Sciences, rue des Maraîchers 13, CH-1205 Geneva, Switzerland
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Published:
January 01, 2015

Abstract

Convergent continental margins are the primary host of both growth and loss of continental crust. Continental growth largely occurs via subduction-driven magmatism, whereas continental loss largely occurs via subduction erosion and sediment subduction. Because the latter typically involves partial recycling into magmas, both growth and loss of continental crust can be represented in the magmatic record. The degree of crustal recycling can be estimated from the initial Hf isotope signatures in both magmatic and detrital zircon grains. Recent insights into the geodynamic evolution of the Peruvian margin, in combination with a new dataset of Hf isotopic data on zircon from the Carboniferous to Early Cretaceous, enable us to (1) compare the geodynamic history of the southern Peruvian margin with its Hf isotopic evolution, and (2) quantify the crustal growth between 500 and 135 Ma. The data exhibit a correlation with trends in isotope composition v. time and reflect the dominantly extensional regime that prevailed from the onset of subduction from 530 Ma to c. 135 Ma. This study demonstrates that the Peruvian margin experienced continental growth with juvenile input to arc magmatism of 30–45% on average, and illustrates the use of U–Pb and Hf isotopes in zircon as a tool to trace episodes of crustal growth through time.

Supplementary material:

Hf istopic analyses on zircon (A1 and A2) and new U–Pb zircon ages (A3) are available at http://www.geolsoc.org.uk/SUP18661.

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Contents

Geological Society, London, Special Publications

Continent Formation Through Time

N. M. W. Roberts
N. M. W. Roberts
NERC Isotope Geosciences Laboratory, UK
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M. Van Kranendonk
M. Van Kranendonk
University of New South Wales, Australia
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S. Parman
S. Parman
Brown University, USA
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S. Shirey
S. Shirey
Carnegie Institution of Washington, USA
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P. D. Clift
P. D. Clift
Louisiana State University, USA
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Geological Society of London
Volume
389
ISBN electronic:
9781862396654
Publication date:
January 01, 2015

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