U-Th-Pb isotope study of mafic dykes in the superior Province, Ontario, Canada: uniformity of initial Pb isotope ratios of the Hearst dykes

ABSTRACTThe lead isotope compositions of 61 galenas from central and southern Scotland vary markedly between different regions. Most galenas from the southern Grampian Highlands yield isotope ratios (206Pb/204Pb 17·77 ± 0·25, 207Pb/204Pb 15·47 ± 0·05, 208Pb/204Pb 37·63 ± 0·26) less radiogenic than those from Midland Valley galenas (18·22 ± 0·12, 15·55 ± 0·05, 38·13 ± 0·14) whilst galena lead from the Southern Uplands (18·28 ± 0·12, 15·56 ± 0·03, 38·21 ± 0·18) is more radiogenic than that from the southern Midland Valley (18·12 ± 0·06, 15·52 ± 0·02, 38·06 ±0·10). The change in isotopie composition across the Highland Boundary fault reflects the presence or absence of Dalradian rocks which included a magmatic component of lead. Galenas from the Dalradian sequence in Islay, where igneous rocks are lacking, have a composition (18·14±0·04, 15·51±0·01, 37·90±0·02) more like Midland Valley galenas. In the Southern Uplands, galenas yield lead isotope ratios similar to those of feldspars from Caledonian granite (18·30 ± 0·14, 15·57 ± 0·04, 37·96 ± 0·15) analysed by Blaxland et al. (1979). The similar ratios reflect the incorporation of Lower Palaeozoic sedimentary rocks into the granite magma, rather than a granitic source for the mineralisation. The granites were then thermal-structural foci for later mineralising fluids which leached metals from the surrounding rocks. Within the Midland Valley, galenas hosted in Lower Devonian-Lower Carboniferous lavas are notably more radiogenic (18·31 ±0·12, 15·58 ± 0·06, 38·20 ± 0·16) than sediment-hosted galenas (18·14 ± 0·07, 15·52 ± 0·02, 38·08 ± 0·10). The Devonian lavas at least may have inherited lead from subducted (? Lower Palaeozoic) rock incorporated in the primary magma.

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Pb isotope ratios of lake sediments in West Greenland: inferences on pollution sources

Atmospheric Environment ◽

10.1016/s1352-2310(01)00115-7 ◽

2001 ◽

Vol 35 (27) ◽

pp. 4675-4685 ◽

Cited By ~ 77

Author(s):

Richard Bindler ◽

Ingemar Renberg ◽

N. John Anderson ◽

Peter G. Appleby ◽

Ove Emteryd ◽

...

Keyword(s):

Lake Sediments ◽

Isotope Ratios ◽

Pollution Sources ◽

Pb Isotope ◽

West Greenland

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Nd and Pb isotope ratios of the Abitibi greenstone belt: new evidence for very early differentiation of the Earth

Earth and Planetary Science Letters ◽

10.1016/0012-821x(94)90146-5 ◽

1994 ◽

Vol 128 (3-4) ◽

pp. 215-229 ◽

Cited By ~ 43

Author(s):

Jeffrey D. Vervoort ◽

William M. White ◽

Ralph I. Thorpe

Keyword(s):

Greenstone Belt ◽

Isotope Ratios ◽

Pb Isotope ◽

Early Differentiation ◽

Abitibi Greenstone Belt ◽

The Earth ◽

New Evidence

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Study of Pb sources by Pb isotope ratios in the airborne PM10 of Zaragoza, Spain

Journal of Environmental Monitoring ◽

10.1039/b912274e ◽

2009 ◽

Vol 11 (11) ◽

pp. 2052 ◽

Cited By ~ 11

Author(s):

María Teresa de la Cruz ◽

Francisco Laborda ◽

María Soledad Callén ◽

José Manuel López ◽

Ana María Mastral

Keyword(s):

Isotope Ratios ◽

Pb Isotope

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Erratum to M. F. Thirlwall, M. A. M. Gee, R. N. Taylor, and B. J. Murton (2004) “Mantle components in Iceland and adjacent ridges investigated using double-spike Pb isotope ratios”, Geochimica et Cosmochimica Acta 68, 361–386

Geochimica et Cosmochimica Acta ◽

10.1016/j.gca.2005.02.015 ◽

2005 ◽

Vol 69 (21) ◽

pp. 5139-5140

Author(s):

Frank A. Podosek

Keyword(s):

Isotope Ratios ◽

Pb Isotope

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ANTHROPOGENIC IMPACTS ON THE WESTERN SECTOR OF SEPETIBA BAY (SE DO BRAZIL) ACCESSED BY THE PB ISOTOPE COMPOSITION OF SURFACE SEDIMENTS

Journal of Sedimentary Environments ◽

10.12957/jse.2019.45269 ◽

2019 ◽

Vol 4 (3) ◽

pp. 291-311 ◽

Cited By ~ 2

Author(s):

Shéron Joyce Díaz Morales ◽

Josefa Varela Guerra ◽

Márcia Andréia Da Silva Nunes ◽

Maria Virgínia Alves Martins ◽

Ariadne Marra de Souza ◽

...

Keyword(s):

Rio De Janeiro ◽

Surface Sediments ◽

Isotope Ratios ◽

Pb Isotope ◽

Sepetiba Bay ◽

Isotope Signature ◽

Western Sector ◽

Internal Region ◽

Se Brazil ◽

Total Dissolution

This work analyses lead concentrations and isotope ratios 204Pb,206Pb,207Pb,208Pb, determined by leaching and total dissolution techniques from surface bottom sediment samples collected in the western sector of Sepetiba Bay, Rio de Janeiro (SE Brazil). The main aim of this work was to identify possible sources of Pb, particularly those related to anthropogenic activities for the study area located in the external region of this bay. Isotope ratios of 206Pb, 207Pb ranged from 1.160 to 1.259 for the total dissolution technique and from 1.175 to 1.188 for the leaching technique. The Pb isotope signature of the surface sediments of the western sector of Sepetiba Bay were compared with that obtained in other studies performed in Sepetiba Bay, including records of pre- and pos-industrial activity, and in other Brazilian regions. The isotope signature of the analyzed sediments in the western sector of Sepetiba Bay is similar to that obtained in previous works realized in the eastern and northeastern internal region of this bay which is under strong urbanization and industrial pressure. The results of Pb isotope signature obtained by the integrated use of total dissolution and leaching techniques allowed to trace the presence of sediments dredged from highly contaminated areas located in the eastern and north-eastern internal region of Sepetiba Bay probably as a consequence of dredging activities and natural processes of sediment dispersion. IMPACTOS ANTROPOGÊNICOS NO SETOR OESTE DA BAÍA DE SEPETIBA (SE DO BRASIL) ACESSADOS PELA COMPOSIÇÃO ISOTÓPICA DE PB DE SEDIMENTOS SUPERFÍCIAIS ResumoEste trabalho analisa as concentrações de chumbo (Pb) e isótopos de Pb (204Pb, 206Pb, 207Pb, 208Pb) determinados por técnicas de lixiviação e dissolução total de amostras de sedimentos de fundo, coletadas no setor oeste (região externa) da Baía de Sepetiba, no Rio de Janeiro (SE Brasil). O principal objetivo deste trabalho foi identificar possíveis fontes de Pb, principalmente aquelas relacionadas a atividades antropogênicas na área de estudo. A assinatura do isótopo Pb dos sedimentos analisados foi comparada com os dados obtidos em outros estudos realizados na Baía de Sepetiba e em outras regiões brasileiras, incluindo registros de atividade pré e pós-industrial. Na região externa da Baía de Sepetiba, os valores de 206Pb/207Pb variaram de 1.160 a 1.259 para a técnica de dissolução total e de 1.175 a 1.188 para a técnica de lixiviação. A assinatura isotópica dos sedimentos analisados é semelhante à obtida em trabalhos anteriores realizados na região interna leste e nordeste desta baía, que está sob forte influência da urbanização e pressão industrial. Os resultados da assinatura dos isótopos de Pb obtidos pelo uso integrado das técnicas de dissolução total e lixiviação permitiram rastrear, no setor oeste (região externa) da Baía de Sepetiba, a presença de sedimentos provinientes de áreas altamente contaminadas localizadas na região interna leste e nordeste da baía de Sepetiba, provavelmente como conseqüência das atividades de dragagem e processos naturais de dispersão de sedimentos. Palavras-chave: Isótopos de Pb. Geoquímica. Atividades antropogênicas. Fonte de sedimentos. Impacto de dragagem. Litoral.

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Trace-Element and Pb Isotope Evidence on Extracting Sulfides from Potassic Melts beneath Longmenshan and Molabushan Volcanoes, Wudalianchi, Northeast China

Minerals ◽

10.3390/min10040319 ◽

2020 ◽

Vol 10 (4) ◽

pp. 319 ◽

Cited By ~ 1

Author(s):

Sergei Rasskazov ◽

Yi-Min Sun ◽

Irina Chuvashova ◽

Tatyana Yasnygina ◽

Chen Yang ◽

...

Keyword(s):

Trace Element ◽

Volcanic Rocks ◽

Volcanic Field ◽

Lava Flows ◽

Pb Isotope ◽

Linear Pattern ◽

Wide Range ◽

Mantle Sources ◽

Isotope Evidence ◽

Isotope Study

In the Wudalianchi volcanic field, eruptions started with low-Mg potassic lava flows 2.5–2.0 Ma ago and later changed to both low- and moderate-Mg potassic compositions. Volcanic rocks from the Molabushan and Longmenshan volcanoes record an unusually wide range of Pb abundances (from 3.7 ppm to 21 ppm relative to predominant range of 10–15 ppm). To determine the cause of these, we performed a comparative trace-element and Pb isotope study of rocks from these volcanoes and older lava flows. On a uranogenic lead diagram, older low-Mg lavas from lithospheric mantle sources plot on a secondary isochron with a slope corresponding to an age of 1.88 Ga. This contrasts with moderate-Mg volcanic rocks from the Molabushan cone, interpreted to have been derived from a recent convective mantle source, which define a flat linear pattern. Low-Mg rocks from the Molabushan flow have lead isotopic compositions that indicate mixed Gelaqiu and Molabu sources. Relative to rocks from the Molabushan cone, moderate-Mg lavas and slags from the East Longmenshan volcano have modified compositions characterized by Pb, S, and Ni abundances, Ni/Co, Ni/MgO ratios as well as 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb, Ce/Pb, Th/Pb, and U/Pb ratios. We infer that the older Wudalianchi magmas were likely derived from a Paleoproterozoic lithospheric fragment, related to the evolved primordial mantle, and that later magmas were generated in the convecting mantle. These were influenced by segregation of small amounts of sulfides.

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