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Stable silicon isotopes of groundwater, feldspars, and clay coatings in the Navajo Sandstone aquifer, Black Mesa, Arizona, USA

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dc.contributor.author Halliday, A. N.
dc.contributor.author Reynolds, B. C.
dc.contributor.author Zhu, Chen
dc.contributor.author Georg, R. B.
dc.date.accessioned 2011-12-13T03:06:04Z
dc.date.available 2011-12-13T03:06:04Z
dc.date.issued 2009-02-14
dc.identifier.citation Georg, R. B., Zhu, C. Reynolds, R.C., and Halliday, A.N. (2009) Stable silicon isotopes of groundwater, feldspars, and clay coatings in the Navajo Sandstone aquifer, Black Mesa, Arizona, USA. Geochimica et Cosmochimica Acta, v.73, 229-2241. en
dc.identifier.uri http://www.sciencedirect.com/science/article/pii/S0016703709000726 en
dc.identifier.uri http://hdl.handle.net/2022/13971
dc.description.abstract groundwater samples were from the Navajo Sandstone aquifer at Black Mesa, Arizona, USA, and the Si isotope composition of detrital feldspars and secondary clay coatings in the aquifer were also analyzed. Silicon isotope compositions were measured using high-resolution multi-collector inductively coupled mass spectrometry (HR-MC-ICP-MS) (Nu1700 & NuPlasma HR). The quartz dominated bulk rock and feldspar separates have similar d30Si of 0.09 ± 0.04&and 0.15 ± 0.04&(±95% SEM), respectively, and clay separates are isotopically lighter by up to 0.4& compared to the feldspars. From isotopic massbalance considerations, co-existing aqueous fluids should have d30Si values heavier than the primary silicates. Positive d30Si values were only found in the shallow aquifer, where Si isotopes are most likely fractionated during the dissolution of feldspars and subsequent formation of clay minerals. However, d30Si decreases along the flow path from 0.56& to 1.42&, representing the most negative dissolved Si isotope composition so far found for natural waters. We speculate that the enrichment in 28Si is due to dissolution of partly secondary clay minerals and low-temperature silcretes in the Navajo Sandstone. The discovery of the large range and systematic shifts of d30Si values along a groundwater flow path illustrates the potential utility of stable Si isotopes for deciphering the Si cycling in sedimentary basins, tracing fluid flow, and evaluating global Si cycle. en
dc.language.iso en_US en
dc.publisher Elsevier en
dc.rights Copyright 2009 Elsevier Ltd. All rights reserved. en
dc.title Stable silicon isotopes of groundwater, feldspars, and clay coatings in the Navajo Sandstone aquifer, Black Mesa, Arizona, USA en
dc.type Article en


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