Geochronologic interpretations of Pb isotope ratios in nickel sulfides of the Thompson Belt, Manitoba

1982 ◽  
Vol 19 (12) ◽  
pp. 2306-2324 ◽  
Author(s):  
G. L. Cumming ◽  
O. R. Eckstrand ◽  
W. V. Peredery
Keyword(s):  
Lead Isotopes ◽  
Isotope Ratios ◽  
Probable Error ◽  
The Other ◽  
Dyke Swarm ◽  
Pb Isotope ◽  
Geological Evidence ◽  
Metasedimentary Rocks ◽  
Nickel Deposits ◽  
Nickel Ores

Lead isotopes in nickel sulfides from seven deposits in the Thompson Belt appear to record events of four distinct ages. The earliest and most prominent of these may represent the emplacement of the nickel ores and their ultramafic hosts.Typical massive and disseminated low-lead nickeliferous sulfides were selected for analysis, and several partitioning techniques were used in order to obtain information about the range of isotope ratios in different phases and fractions of the samples. The data were interpreted in terms of the isotopic systematics discussed by Gale and Mussett.Data from four deposits produce two well defined, parallel "primary" isochrons whose calculated mean slope corresponds to an age of 2320 ± 30 Ma. Interpretation of this date as the time of emplacement of the nickel deposits and their ultramafic hosts is consistent with geological evidence that points to a post-Archean, pre-Hudsonian age. The 2320 Ma date may be consistent, within probable error limits, with the age inferred from Rb/Sr data (2100 Ma) for deposition of metasedimentary rocks of the Thompson Belt, into which the ultramafic lenses were intruded (Brooks and Theyer).The other isotopically recorded events occurred at 2015 ± 15 Ma (possibly early folding of the Thompson Belt supracrustal rocks), 1620 ± 25 Ma (probably a late retrograde stage of the Hudsonian Orogeny), and 1125 ± 60 Ma (possibly a thermal event associated with emplacement of the Mackenzie dyke swarm).

scholarly journals Lead Isotopes in Exploration for Basement-Hosted Structurally Controlled Unconformity-Related Uranium Deposits: Kiggavik Project (Nunavut, Canada)

Minerals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 512
Author(s):  
David Quirt ◽  
Antonio Benedicto
Keyword(s):  
Inductively Coupled Plasma ◽  
Structural Control ◽  
Lead Isotopes ◽  
Isotope Ratios ◽  
Uranium Content ◽  
Weak Acid ◽  
Pb Isotopes ◽  
Pb Isotope ◽  
Acid Leach ◽  
Partial Digestion

Pb-isotopes have been proposed as pathfinders for sandstone-hosted unconformity-related U deposits, with isotope ratios providing information on mineralization timing and element remobilization and migration. Pb-isotopes proximal to mineralization display radiogenic signatures, often with ‘excess Pb’ suggestive of derivation from greater U concentrations than are currently present. The U deposits in the Kiggavik project area (west of Baker Lake, NU, Canada) are basement-hosted, contain several generations of pitchblende mineralization, display a strong structural control, and are located in fault-related fracture systems and foliation-parallel veinlets. Drill core samples were analysed by Inductively-Coupled Plasma-Mass Spectrometer (ICP-MS) for Pb isotopes following multi-acid total-digestion, reverse Aqua Regia partial-digestion, and weak-acid-leach attacks, to evaluate the utility of the respective dissolution methods in Pb-isotope pathfinder geochemistry. Partial-digestion results are similar to weak-acid-leach results, indicating that interpretation of Pb-isotope signatures can be carried out from partial-digestion data if weak-acid-leach data are unavailable. Application of this pathfinder method at Kiggavik shows that Pb-isotope ratios display systematic trends useful for exploration vectoring. Uranium-content-adjusted 206Pb/204Pb ratios and 206Pb/204Pb ‘excess-lead’ data highlight anomalous isotopic values. 207Pb/206Pb ratios display downhole trends complementary to location of mineralization. Three-dimensional (3D) distributions of Pb-isotope data at the Contact U prospect show systematic trends and form halos around the mineralization. Isotopic footprints are limited to <50 m from the mineralization outline, reflecting host-rock and structural control, but indicate areas with elevated potential for U mineralization and provide vectoring information within basement lithologies.

scholarly journals Determination of Lead Elemental Concentration and Isotopic Ratios in Coal Ash and Coal Fly Ash Reference Materials Using Isotope Dilution Thermal Ionization Mass Spectrometry

2019 ◽  
Vol 16 (23) ◽  
pp. 4772 ◽  
Author(s):  
Chaofeng Li ◽  
Huiqian Wu ◽  
Xuance Wang ◽  
Zhuyin Chu ◽  
Youlian Li ◽  
...  
Keyword(s):  
Lead Isotope ◽  
Thermal Ionization Mass Spectrometry ◽  
Environmental Science ◽  
Coal Fly Ash ◽  
Lead Isotopes ◽  
Coal Ash ◽  
Isotope Ratios ◽  
Ionization Mass ◽  
Pb Isotope ◽  
Lead Isotope Ratios

The rapid expansion of coal-fired power plants around the world has produced a huge volume of toxic elements associated with combustion residues such as coal fly ash (CFA) and coal ash (CA), which pose great threats to the global environment. It is therefore crucial for environmental science to monitor the migration and emission pathway of toxic elements such as CFA and CA. Lead isotopes have proved to be powerful tracers capable of dealing with this issue. Unfortunately, up to now, few high precision lead isotope data of CFA and CA certified reference materials (CRMs) determined by using the double spike technique have been reported. Hence, to facilitate the application of lead isotopes in environmental science, it is indispensable and urgent to determine a suite of high precision Pb isotope ratios and Pb elemental contents for CFA and CA CRMs. Here, we measured lead isotope ratios from four CFA and CA CRMs using thermal ionization mass spectrometry (TIMS) combined with the 204Pb–207Pb double spike method. Lead isotope ratios values of CRMs (GBW11124, GBW08401, GBW11125d, and JCFA-1) covered wide variation ranges from 17.993 to 19.228 for 206Pb/204Pb, from 15.513 to 15.675 for 207Pb/204Pb, and from 38.184 to 39.067 for 208Pb/204Pb. Lead isotope ratios of these CRMs, except for GBW11124, show good external reproducibility (2 RSD, n = 8), which is better than 0.05% for 206Pb/204Pb and 207Pb/204Pb, 0.07% for 208Pb/204Pb, 0.04% for 206Pb/207Pb, and 0.05% for 208Pb/206Pb. The Pb concentrations of these CRMs were determined using 207Pb single spike method. The reproducibility (1 RSD, n = 4) of Pb elemental content was <0.60%. This indicates the distribution of Pb elements in these CRMs is homogeneous. With the exception of GBW11124, the suite of CRMs can be used for determining CFA and CA matrix composition for quality control of Pb isotope analyses.

The Magmatic Origin of the Sudbury Nickel Ores

1926 ◽  
Vol 63 (3) ◽  
pp. 108-112 ◽  
Author(s):  
A. P. Coleman
Keyword(s):  
The Other ◽  
Magmatic Origin ◽  
Interesting Paper ◽  
Nickel Deposits ◽  
Nickel Ores ◽  
The Subject

Professor Gregory, in a very interesting paper published in the Transactions of the Faraday Society, has advanced various arguments against the theory of the magmatic origin of the Sudbury nickel deposits and has quoted several authorities as opposing that theory. His brief account of the subject presents, unintentionally of course, only one side of the controversy in regard to those ores, and lest the deservedly great authority of his opinion should seem to settle the question, I wish to place before English geologists an outline of the arguments on the other side.

Interpretation of Pb isotope compositions of galenas from the Midland Valley of Scotland and adjacent regions

1984 ◽  
Vol 75 (2) ◽  
pp. 85-96 ◽  
Author(s):  
John Parnell ◽  
Ian Swainbank
Keyword(s):  
Lower Devonian ◽  
Lead Isotope ◽  
Sedimentary Rocks ◽  
Isotope Ratios ◽  
Igneous Rocks ◽  
Pb Isotope ◽  
Lower Carboniferous ◽  
Granite Magma ◽  
Lower Palaeozoic ◽  
Caledonian Granite

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.

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

2001 ◽  
Vol 35 (27) ◽  
pp. 4675-4685 ◽  
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

scholarly journals Sulfur and lead isotopic evidence of relic Archean sediments in the Pitcairn mantle plume

2016 ◽  
Vol 113 (46) ◽  
pp. 12952-12956 ◽  
Author(s):  
Hélène Delavault ◽  
Catherine Chauvel ◽  
Emilie Thomassot ◽  
Colin W. Devey ◽  
Baptiste Dazas
Keyword(s):  
Lead Isotopes ◽  
Pb Isotope ◽  
Walvis Ridge ◽  
Enriched Mantle ◽  
Mass Independent Fractionation ◽  
Deep Earth ◽  
Source Component ◽  
Oceanic Island Basalts ◽  
Isotopic Mixing ◽  
Subcontinental Lithosphere

The isotopic diversity of oceanic island basalts (OIB) is usually attributed to the influence, in their sources, of ancient material recycled into the mantle, although the nature, age, and quantities of this material remain controversial. The unradiogenic Pb isotope signature of the enriched mantle I (EM I) source of basalts from, for example, Pitcairn or Walvis Ridge has been variously attributed to recycled pelagic sediments, lower continental crust, or recycled subcontinental lithosphere. Our study helps resolve this debate by showing that Pitcairn lavas contain sulfides whose sulfur isotopic compositions are affected by mass-independent fractionation (S-MIF down to Δ33S = −0.8), something which is thought to have occurred on Earth only before 2.45 Ga, constraining the youngest possible age of the EM I source component. With this independent age constraint and a Monte Carlo refinement modeling of lead isotopes, we place the likely Pitcairn source age at 2.5 Ga to 2.6 Ga. The Pb, Sr, Nd, and Hf isotopic mixing arrays show that the Archean EM I material was poor in trace elements, resembling Archean sediment. After subduction, this Archean sediment apparently remained stored in the deep Earth for billions of years before returning to the surface as Pitcairn´s characteristic EM I signature. The presence of negative S-MIF in the deep mantle may also help resolve the problem of an apparent deficit of negative Δ33S anomalies so far found in surface reservoirs.

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

2009 ◽  
Vol 11 (11) ◽  
pp. 2052 ◽  
Author(s):  
María Teresa de la Cruz ◽  
Francisco Laborda ◽  
María Soledad Callén ◽  
José Manuel López ◽  
Ana María Mastral
Keyword(s):  
Isotope Ratios ◽  
Pb Isotope

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

2019 ◽  
Vol 4 (3) ◽  
pp. 291-311 ◽  
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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