Open AccessChemical weathering on the North Island of New Zealand: CO 2 consumption and fluxes of Sr and Os
Author(s) -
Blazina Tim,
Sharma Mukul
Publication year - 2013
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/ggge.20222
Subject(s) - weathering , geology , trace element , strontium , radiogenic nuclide , leaching (pedology) , isotopes of strontium , flux (metallurgy) , geochemistry , oceanography , physical geography , mantle (geology) , soil science , chemistry , soil water , geography , organic chemistry
We present Os and Sr isotope ratios and Os, Sr and major/trace element concentrations for river waters, spring waters and rains on the North Island of New Zealand. The Os and Sr data are used to examine whether the NINZ is a significant contributor of unradiogenic Os and Sr to the oceans. Major element chemistry is used to quantify weathering and CO 2 consumption rates on the island to investigate relationships between these processes and Os and Sr behavior. Chemical erosion rates and CO 2 consumption rates across the island range from 44 to 555 km −2 yr −1 and 95 to 1900 × 10 3 mol CO 2 km −2 yr −1 , respectively. Strontium flux for the island range from 177 to 16,100 mol km −2 yr −1 and the rivers have an average flux normalized 87 Sr/ 86 Sr ratio of 0.7075. In agreement with the previous studies these findings provide further evidence that weathering of arc terrains contributes a disproportionally large amount of Sr to the oceans and consumes very large amounts of CO 2 annually compared to their areal extent. However, the 87 Sr/ 86 Sr from the NINZ is not particularly unradiogenic and it is likely not contributing significant amounts of unradiogenic Sr to the oceans. Repeated Os analyses and bottle leaching experiments revealed extensive and variable sample contamination by Os leaching from rigorously precleaned LDPE bottles. An upper bound on the flux of Os from NINZ can nevertheless be assessed and indicates that island arcs cannot provide significant amounts of unradiogenic Os to the oceans.