Strontium isotopes in Chilean rivers: The flux of unradiogenic continental Sr to seawater

Fiege, K.; Miller, Christian A.; Robinson, Laura F.; Figueroa, Ricardo; Peucker‐Ehrenbrink, Bernhard

doi:10.1016/j.chemgeo.2009.09.013

Cited by 15 publications

(8 citation statements)

References 28 publications

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“…For instance, 24 rivers representing 78% of the drainage area of, and 51% of the water discharging from eastern North America have been characterized for dissolved 87 Sr/ 86 Sr. In contrast, the dissolved 87 Sr/ 86 Sr of runoff from western South America has been characterized in only 9 rivers that represent only 17% of this drainage area, and 10% of the total water discharge [ Fiege et al , 2009]. In total, data for 193 rivers representing 50.3% of the exorheic land surface and 48.3% of the global exorheic water discharge (38,900 km 3 yr −1 ) define the flux and isotope composition of continental Sr to the ocean.…”

Section: Results: Bedrock Ages Lithology and Isotope Systematics Ofmentioning

confidence: 99%

“…The drainage region of western South America that drains the Andean Cordillera into the southeastern Pacific is notable for its unradiogenic 87 Sr/ 86 Sr and young mean bedrock age of 96 Myr [ Fiege et al , 2009]. The position of this region in the 87 Sr/ 86 Sr bedrock age diagram makes it difficult to discern whether this region is part of the “steep” (Fraser‐like) or the “shallow” (Mississippi‐Nelson‐like) correlation.…”

Section: Results: Bedrock Ages Lithology and Isotope Systematics Ofmentioning

confidence: 99%

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Continental bedrock and riverine fluxes of strontium and neodymium isotopes to the oceans

Peucker‐Ehrenbrink

Miller

Arsouze

et al. 2010

Geochem Geophys Geosyst

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[1] Realistic models of past climate and ocean chemistry depend on reconstructions of the Earth's surface environments in the geologic past. Among the critical parameters is the geologic makeup of continental drainage. Here we show, for the present, that the isotope composition of dissolved strontium in rivers increases linearly with the age of bedrock in drainage basins, with the notable exception of the drainage area of Arabia, India, and Southeast Asia that is affected by unusually radiogenic dissolved Sr from the Himalaya. We also demonstrate that the neodymium isotope compositions of suspended matter in rivers as well as clastic sediments deposited along the ocean margins decrease linearly with the bedrock ages of river drainage basins and large-scale continental drainage regions, as determined from digital geologic maps. These correlations are used to calculate the present-day input of dissolved Sr (4.7 × 10 10 mol yr −1 , 87 Sr/ 86 Sr of ∼0.7111) and particulate Nd isotopes (" Nd of approximately −7.3 ± 2.2) to the oceans. The fact that the regionally averaged " Nd of the global detrital input to the global coastal ocean is identical to globally averaged seawater (" Nd of −7.2 ± 0.5) lends credence to the importance of "boundary exchange" for the Nd isotope composition of water masses. Regional biases in source areas of detrital matter and runoff are reflected by the observation that the average age of global bedrock, weighted according to the riverine suspended sediment flux, is significantly younger (∼336 Myr) than the age of global bedrock weighted according to water discharge (394 Myr), which is younger than the average bedrock age of the nonglaciated, exorheic portions of the continents (453 Myr). The observation that the bedrock age weighted according to Sr flux is younger (339 Myr) than that weighted according to water flux reflects the disproportionate contribution from young sedimentary and volcanic rocks to the dissolved Sr load. Neither the isotope composition of the dissolved nor the particulate continental inputs to the ocean provide unbiased perspectives of the lithologic makeup of the Earth's surface. Temporal changes in bedrock geology as well as the shifting focal points of physical erosion and water discharge will undoubtedly have exerted strong controls on temporal and spatial changes in the isotope chemistry of past global runoff and thus seawater.

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Section: Results: Bedrock Ages Lithology and Isotope Systematics Ofmentioning

confidence: 99%

Section: Results: Bedrock Ages Lithology and Isotope Systematics Ofmentioning

confidence: 99%

Continental bedrock and riverine fluxes of strontium and neodymium isotopes to the oceans

Peucker‐Ehrenbrink

Miller

Arsouze

et al. 2010

Geochem Geophys Geosyst

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“…However, if the marine Sr isotope budget is currently at steady state, a major flux of relatively non-radiogenic Sr remains unaccounted for. Island arcs probably contribute significantly to this flux (Fiege et al, 2010;Allègre et al, 2010), although Sr 490 concentrations (~0.4 µM) and isotope ratios (>0.704) in waters from these sources are unlikely to fully account for the deficit, and subaerial contributions (rivers) from such areas are included in the river end-member values we use in this study (Peucker-Ehrenbrink et al, 2009). …”

Section: Sgd-driven Sr Flux -Meteoric Groundwater Dischargementioning

confidence: 99%

Dissolved strontium in the subterranean estuary – Implications for the marine strontium isotope budget

Beck¹,

Charette²,

Cochran³

et al. 2013

Geochimica et Cosmochimica Acta

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15Submarine groundwater discharge (SGD) to the ocean supplies Sr with less radiogenic 87 Sr/ 86 Sr than seawater, and thus constitutes an important term in the Sr isotope budget in the modern ocean. However, few data exist for Sr in coastal groundwater or in the geochemically dynamic subterranean estuary (STE). We examined Sr concentrations and isotope ratios from nine globally-distributed coastal sites and characterized the behavior of Sr in the STE. Dissolved Sr 20 generally mixed conservatively in the STE, although large differences were observed in the meteoric groundwater end-member Sr concentrations among sites (0.1 -24 µM Sr). Strontium isotope exchange was observed in the STE at five of the sites studied, and invariably favored the meteoric groundwater end-member signature. Most of the observed isotope exchange occurred in the salinity range 5-15, and reached up to 40% exchange at salinity 10.

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“…Figure modified from Fiege et al . [] to include data from this study as well as recent Sr data from Schopka et al . [], from Luzon Island in the Philippines.…”

Section: Discussionmentioning

confidence: 99%

“…Average specific yields of Sr for the NINZ (star symbols) plotted with other arc and volcanic terrains.Figure modifiedfromFiege et al [2009] to include data from this study as well as recent Sr data fromSchopka et al [2011], from Luzon Island in the Philippines. The Hikurangi accretionary prism has an extremely high Sr flux, about 1000 mol yr À1 km À2 more than those reported for Luzon.…”

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Chemical weathering on the North Island of New Zealand: CO₂ consumption and fluxes of Sr and Os

Blazina

Sharma

2013

Geochem Geophys Geosyst

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[1] 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 À2 yr À1 and 95 to 1900 Â 10 3 mol CO 2 km À2 yr À1 , respectively. Strontium flux for the island range from 177 to 16,100 mol km À2 yr À1 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.

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Strontium isotopes in Chilean rivers: The flux of unradiogenic continental Sr to seawater

Abstract: 17Analyses of Chilean river waters indicate that the average yield of unradiogenic Sr (~517 18 moles Sr km -2 yr -1

Cited by 15 publications

References 28 publications

Continental bedrock and riverine fluxes of strontium and neodymium isotopes to the oceans

Continental bedrock and riverine fluxes of strontium and neodymium isotopes to the oceans

Dissolved strontium in the subterranean estuary – Implications for the marine strontium isotope budget

Chemical weathering on the North Island of New Zealand: CO₂ consumption and fluxes of Sr and Os

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Strontium isotopes in Chilean rivers: The flux of unradiogenic continental Sr to seawater

Abstract: 17Analyses of Chilean river waters indicate that the average yield of unradiogenic Sr (~517 18 moles Sr km -2 yr -1

Cited by 15 publications

References 28 publications

Continental bedrock and riverine fluxes of strontium and neodymium isotopes to the oceans

Continental bedrock and riverine fluxes of strontium and neodymium isotopes to the oceans

Dissolved strontium in the subterranean estuary – Implications for the marine strontium isotope budget

Chemical weathering on the North Island of New Zealand: CO2 consumption and fluxes of Sr and Os

Contact Info

Product

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Chemical weathering on the North Island of New Zealand: CO₂ consumption and fluxes of Sr and Os