Development of an improved analytical technique for lead determination, and its application to studies in lead content in seafloor hydrothermal chimneys from Guaymas Basin, Gulf of California; PACMANUS, Eastern Manus Basin; and the southern East Pacific Rise
grantor: University of Toronto Analysis by solution methods of Pb in seafloor sulfides has been unreliable due to incomplete dissolution, frustrating attempts to understand the geochemistry of Pb in seafloor hydrothermal systems. Bulk Pb recoveries were improved by fully digesting samples prior to a...
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| Format: | Thesis |
| Language: | English |
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1999
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| Online Access: | http://hdl.handle.net/1807/13347 http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0002/MQ45526.pdf |
| Summary: | grantor: University of Toronto Analysis by solution methods of Pb in seafloor sulfides has been unreliable due to incomplete dissolution, frustrating attempts to understand the geochemistry of Pb in seafloor hydrothermal systems. Bulk Pb recoveries were improved by fully digesting samples prior to analysis by ICP-AES. Following decomposition by HNO3-HF-HClO4, insoluble (Pb,Ba)SO4 residues were digested in microwave-heated Na2CO3(aq). Lead recoveries averaged 88% from an in-house standard and 91%-98% from CANMET ore standards. Recovery was influenced by variations in [HNO3] and Na2CO 3(aq) temperature. Chimneys from three vent sites--PACMANUS, Guaymas Basin, and Pito Deep--were analysed for Pb, resulting in concentrations of 0.005-1.3 wt.% (PACMANUS) and 0.009-0.4 wt.% (Guaymas Basin). Sulfides from Pito Deep yielded a mean result of 0.06 wt.% (n = 2). Pb in felsic volcanics from the Pacific Antarctic Rise was in the range <0.006-1.2 ppm. Pb correlates with Na, Cd, As, Sb, Ag, and Zn in PACMANUS chimneys (95% confidence). Correlation with these elements in Guaymas Basin samples was not significant. M.Sc. |
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