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Sources and sinks of unradiogenic osmium runoff from Papua New Guinea

Martin, Candace; Peucker-Ehrenbrink, Bernhard; Brunskill, Gregg; Szymczak, Ron

Description

The Fly and Sepik are two of the largest rivers draining the island of New Guinea and among the world's large rivers in discharge and sediment yield. Sediment from the upper Fly River and its delta have low187Os/188Os of 0.511-0.560, and sediments from the upper and lower Sepik River have even lower ratios of 0.294-0.418. Filtered waters (<0.45 μm) from the Fly and Sepik rivers have187Os/188Os of 0.616 and 0.335, respectively. Osmium isotopic compositions of surficial sediments from the Gulf of...[Show more]

dc.contributor.authorMartin, Candace
dc.contributor.authorPeucker-Ehrenbrink, Bernhard
dc.contributor.authorBrunskill, Gregg
dc.contributor.authorSzymczak, Ron
dc.date.accessioned2015-12-13T23:17:59Z
dc.identifier.issn0012-821X
dc.identifier.urihttp://hdl.handle.net/1885/89958
dc.description.abstractThe Fly and Sepik are two of the largest rivers draining the island of New Guinea and among the world's large rivers in discharge and sediment yield. Sediment from the upper Fly River and its delta have low187Os/188Os of 0.511-0.560, and sediments from the upper and lower Sepik River have even lower ratios of 0.294-0.418. Filtered waters (<0.45 μm) from the Fly and Sepik rivers have187Os/188Os of 0.616 and 0.335, respectively. Osmium isotopic compositions of surficial sediments from the Gulf of Papua (187Os/188Os of 0.394-0.961) further demonstrate that the sediment currently supplied to the oceans from New Guinea is unradiogenic. The particulate and dissolved loads supplied by these rivers are significantly less radiogenic than that contributed to the oceans by rivers draining regions of old continental crust (187Os/188Os > 1.2). Burial of Os of both seawater and riverine derivation occurs in conjunction with organic carbon burial in the Gulf of Papua. There is a negative correlation between the Os isotopic composition of the bulk sediment and the fraction of organic matter of terrestrial origin based on C isotopes. The systematic relationship between C and Os isotopic compositions in these samples indicates that organic matter is the major host of Os in tropical estuarine sediments. The Os/C(org) of Gulf of Papua surface sediments is intermediate between that of other modern and ancient sediments. Approximately 1011 mol/yr of C(org) and 20-57 mol/yr of Os are buried in the inner shelf (< 50 m depth) of the Gulf of Papua over an area of only 21 000 km2, corresponding to 1-3% of the global marine Os burial flux in 0.006% of the total sea surface area. These results suggest that a large proportion of the global burial flux of Os may take place in conjunction with the deposition of low-C(org) sediments. Lowering of the Os isotopic composition of ambient seawater due to a large flux of unradiogenic riverine Os may be indicated by the Os isotopic composition of water from the Coral Sea (187Os/188Os = 0.844) and marine sediments within the Gulf of Papua. The island of New Guinea is estimated to provide 4-5% of the global riverine Os flux. Given the very large particulate and dissolved flux to the oceans from rivers in the wet tropics, the effect of the weathering of young arc-related crust in the SW Pacific is an important source of unradiogenic Os to modern seawater. (C) 2000 Elsevier Science B.V. All rights reserved.
dc.publisherElsevier
dc.sourceEarth and Planetary Science Letters
dc.subjectKeywords: osmium; river discharge; runoff; sediment yield; stable isotope; Papua New Guinea C-13/C-12; Os-188/Os-187; Papua New Guinea; Rivers; Runoff
dc.titleSources and sinks of unradiogenic osmium runoff from Papua New Guinea
dc.typeJournal article
local.description.notesImported from ARIES
local.description.refereedYes
local.identifier.citationvolume183
dc.date.issued2000
local.identifier.absfor040307 - Ore Deposit Petrology
local.identifier.ariespublicationMigratedxPub20206
local.type.statusPublished Version
local.contributor.affiliationMartin, Candace, College of Physical and Mathematical Sciences, ANU
local.contributor.affiliationPeucker-Ehrenbrink, Bernhard, Woods Hole Oceanographic Institution
local.contributor.affiliationBrunskill, Gregg, Australian Institute of Marine Science
local.contributor.affiliationSzymczak, Ron, Australian Nuclear Science and Technology Organisation
local.description.embargo2037-12-31
local.bibliographicCitation.issue1-2
local.bibliographicCitation.startpage261
local.bibliographicCitation.lastpage274
local.identifier.doi10.1016/S0012-821X(00)00281-8
dc.date.updated2015-12-12T08:55:06Z
local.identifier.scopusID2-s2.0-0034534244
CollectionsANU Research Publications

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