The Hf-Nd isotopic composition of marine sediments

Online Access: Get full text
doi: 10.1016/j.gca.2011.07.046
Author(s): Vervoort, Jeffrey D.; Plank, T.; Prytulak, J.
Author Affiliation(s): Primary:
Washington State University, School of Earth and Environmental Sciences, Pullman, WA, United States
Lamont Doherty Earth Observatory, United States
Volume Title: Geochimica et Cosmochimica Acta
Source: Geochimica et Cosmochimica Acta, 75(20), p.5903-5926. Publisher: Elsevier, New York, NY, International. ISSN: 0016-7037 CODEN: GCACAK
Note: In English. Includes appendices. 102 refs.; illus., incl. 1 table
Summary: This paper presents new major and trace-element data and Lu-Hf and Sm-Nd isotopic compositions for representative suites of marine sediment samples from 14 drill sites outboard of the world's major subduction zones. These suites and samples were chosen to represent the global range in lithology, Lu/Hf ratios, and sediment flux in subducting sediments worldwide. The data reported here represent the most comprehensive data set on subducting sediments and define the Hf-Nd isotopic variations that occur in oceanic sediments and constrain the processes that caused them. Using new marine sediment data presented here, in conjunction with published data, we derive a new Terrestrial Array given by the equation, εHf = 1.55 x εNd + 1.21. This array was calculated using >3400 present-day Hf and Nd isotope values. The steeper slope and smaller y-intercept of this array, compared to the original expression (εHf = 1.36 x εNd + 2.89; Vervoort et al., 1999) reflects the use of present day values and the unradiogenic Hf of old continental samples included in the array. In order to examine the Hf-Nd isotopic variations in marine sediments, we have classified our samples into 5 groups based on lithology and major and trace-element geochemical compositions: turbidites, terrigenous clays, and volcaniclastic, hydrothermal and hydrogenetic sediments. Compositions along the Terrestrial Array are largely controlled by terrigenous material derived from the continents and delivered to the ocean basins via turbidites, volcaniclastic sediments, and volcanic inputs from magmatic arcs. Compositions below the Terrestrial Array derive from unradiogenic Hf in zircon-rich turbidites. The anomalous compositions above the Terrestrial Array largely reflect the decoupled behavior of Hf and Nd during continental weathering and delivery to the ocean. Both terrigenous and hydrogenetic clays possess anomalously radiogenic Hf, reflecting terrestrial sedimentary and weathering processes on the one hand and marine inheritance on the other. This probably occurs during complementary processes involving preferential retention of unradiogenic Hf on the continents in the form of zircon and release of radiogenic Hf from the breakdown of easily weathered, high Lu-Hf phases such as apatite. Abstract Copyright (2011) Elsevier, B.V.
Year of Publication: 2011
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 06 Petrology, Sedimentary; Chemical composition; Clastic sediments; Clay; Crystal chemistry; DSDP Site 174; DSDP Site 183; DSDP Site 211; DSDP Site 286; DSDP Site 291; DSDP Site 294; DSDP Site 295; DSDP Site 321; DSDP Site 495; DSDP Site 595; Deep Sea Drilling Project; East Pacific; Geochemistry; Hafnium; Hf-177/Hf-176; Hydrothermal conditions; ICP mass spectra; IPOD; Indian Ocean; Isotope ratios; Isotopes; Leg 114; Leg 138; Leg 145; Leg 18; Leg 19; Leg 22; Leg 30; Leg 31; Leg 34; Leg 67; Leg 91; Lutetium; Major elements; Marine sediments; Mass spectra; Metals; Nd-144/Nd-143; Neodymium; Nesosilicates; North Pacific; Northeast Pacific; ODP Site 701; ODP Site 801; ODP Site 844; ODP Site 881; Ocean Drilling Program; Orthosilicates; Pacific Ocean; Rare earths; Samarium; Sediments; Silicates; Spectra; Stable isotopes; Subduction zones; Trace elements; Turbidite; Volcaniclastics; Weathering; World ocean; Zircon; Zircon group
Coordinates: N445330 N445330 W1262048 W1262048
N223444 N223445 E1312308 E1312307
N223346 N223346 E1312202 E1312202
Record ID: 2012022298
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands