The control of weathering processes on riverine and seawater hafnium isotope ratios

Type Article
Date 2006-06
Language English
Author(s) Bayon Germain1, Vigier Nathalie2, Burton Kevin W.3, Brenot Agnès2, Carignan Jean2, Etoubleau Joel1, Chu Nan-Chin4
Affiliation(s) 1 : IFREMER, Dept Geosci Marines, F-29280 Plouzane, France.
2 : Ctr Rech Petrog & Geochim, F-54501 Vandoeuvre Les Nancy, France.
3 : Open Univ, Dept Earth Sci, Milton Keynes MK7 6AA, Bucks, England.
4 : Univ Oxford, Dept Earth Sci, Oxford OX1 3PR, England.
Source Geology (0091-7613) (Geological Society of America), 2006-06 , Vol. 34 , N. 6 , P. 433-436
DOI 10.1130/G22130.1
WOS© Times Cited 62
Keyword(s) Ocean chemistry, Silicate weathering, Rivers, Hafnium isotopes
Abstract Hafnium Hf-176/Hf-177 isotope ratio variations in marine records are thought to reflect changes in continental weathering through time, but the behavior of Hf in rivers, and during weathering, is not well understood. Here, we present Hf-176/Hf-177 data for rivers, bedrock, soils, and leaching experiments for the Moselle basin, Vosges, France. These data strongly suggest that the Hf-176/Hf-177 composition of river waters is controlled by preferential dissolution of accessory phases (i.e., apatite, sphene) versus more resistant minerals (e.g., K-feldspar) and linked to the intensity of silicate weathering. Estimates for the global isotopic composition of riverine Hf suggest that the ocean Hf budget may be dominated by river input, and variations seen in marine records can be directly related to changes in silicate weathering intensity.
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