ADDITIONAL MEASUREMENTS OF THE ISOTOPIC COMPOSITION OF LEAD FROM STRATIFORM DEPOSITS

This paper pursues the study of an apparent correlation between lead isotope abundance characteristics and features of the deposits in which the lead is discovered. New and precise analyses have been carried out on 55 galena samples, mostly From Australasian ore deposits classified as stratiform. To help clarify the interpretation, certain vein leads related to those which are stratiform have been included, as has one analysis of volcanic cotunnite.New evidence is offered that all leads began their isotopic evolution in a unique primary system which has very restricted spatial variation in the ratios U/Pb and Th/Pb. Leads from certain stratiform deposits approach more closely in isotopic composition the products of the primary system than do vein leads, many of which involve extensive crustal histories thai further modify the isotope ratios. The analyses presented here have sufficient precision to permit a close examination of the differences in isotope ratios between stratiform leads and the products of a simplified model for the primary system. The differences are significant and important.Novel aspects of the experimental technique are discussed.

Download Full-text

Application of lead isotope ratios for pollution source investigation in the marine environment

10.5194/egusphere-egu2020-22611 ◽

2020 ◽

Author(s):

Emiliya Vassileva ◽

Anna Maria Orani ◽

Sergey Assonov

Keyword(s):

Isotopic Composition ◽

Lead Isotope ◽

Isotope Ratios ◽

Environmental Matrices ◽

Total Uncertainty ◽

Lead Isotope Ratios ◽

Icp Ms ◽

Seawater Samples ◽

Biota Samples

Lead is a non-essential toxic element that at high levels of human exposure causes damage to many organs of the human body. This element naturally occurs in the Earth crust, but its biogeochemical cycle has been altered by anthropogenic activities, which have introduced high amount of this element from different sources. Among inorganic contaminants, Pb is perhaps the most studied, but the determination of its total concentration only is not sufficient for a proper evaluation of contamination sources. Discrimination of anthropogenic and geogenic lead sources requires both precise and accurate isotope ratio determination as well as high versatility due to the complexity of environmental matrices, such as sediments, biota and seawater. This element has a partially radiogenic isotopic composition with 208Pb, 206Pb and 207Pb originating from the radioactive decay of 238U, 235U and 232Th respectively and 204Pb representing the only natural stable isotope. This characteristic isotopic composition represents a powerful analytical tool as it allows to trace the sources, fate and effects of possible Pb contamination. The most common way to express the Pb isotopic composition is using the ratio 206Pb/207Pb, because of the easy interference-free determination and isotopes&#8217; abundance. The determination of 204Pb by ICP-MS is quite challenging as this is also the least abundant among Pb isotopes (about 1.4%) and it is also affected by isobaric interference from 204Hg. The latter derives from both sample matrices and from plasma/sweep gas supplies and it represents a big analytical challenge, especially for marine biota samples, where the amount of Hg can be up to 100 times higher than Pb. In this work we present the development and the application of analytical methodology for the accurate and precise determination of Pb isotope ratios by HR-ICP-MS in different marine environmental matrices (sediments, seawater and biota). Analytical procedures are involving a separation of Pb from the sample matrix and mercury, present in the sample. For seawater samples, the use of the SeaFAST automated system allowed simultaneous matrix separation and analyte pre-concentration before ICP-MS analysis. A comparison of results for lead isotope ratios obtained with MC-ICP-MS and HR ICP-MS in the same samples, in all cases, showed very good agreement . The total uncertainty associated to each result was estimated and all major contributions to the combined uncertainty of the obtained results were identified. As all such studies involve companions of different datasets, the uncertainty estimation is critical to ensure correct companions.&#160; The developed methodology was applied to different marine samples, namely sediments from Caribbean, Baltic and Namibian coasts, biota samples from French Polynesia, seawater samples from Mediterranean and Arctic seas.&#160;

Download Full-text

The Determination of Lead Isotope Ratios by Multiple Collector Icp-Ms: A Case Study of Early Bronze Age Artefacts and their Possible Relation With Ore Deposits of the Erzgebirge*

Archaeometry ◽

10.1111/1475-4754.00097 ◽

2003 ◽

Vol 45 (1) ◽

pp. 61-100 ◽

Cited By ~ 91

Author(s):

E. Niederschlag ◽

E. Pernicka ◽

Th. Seifert ◽

M. Bartelheim

Keyword(s):

Bronze Age ◽

Lead Isotope ◽

Isotope Ratios ◽

Ore Deposits ◽

Early Bronze Age ◽

Lead Isotope Ratios ◽

Icp Ms

Download Full-text

Lead- and sulfur-isotope ratios from the Great Slave Lake area, Canada

Canadian Journal of Earth Sciences ◽

10.1139/e68-125 ◽

1968 ◽

Vol 5 (5) ◽

pp. 1269-1276 ◽

Cited By ~ 7

Author(s):

D. K. Robertson ◽

G. L. Cumming

Keyword(s):

Lead Isotope ◽

Sulfur Isotope ◽

Isotope Ratios ◽

Ore Deposits ◽

Lake Area ◽

Iron Sulfides ◽

Tectonic Event ◽

Slave Province ◽

Great Slave Lake ◽

Lead Line

Lead- and sulfur-isotope ratios have been determined for some galenas and iron sulfides from two regions around Yellowknife, Northwest Territories. For the ore deposits, sulfur-isotope ratios are close to the meteoritic value or slightly positive. Lead-isotope ratios fall into two groups, one derived from a source with Th/U = 4.3 and μ = 9–11, and the other from a source with Th/U = 3.5 and μ = 9.0. The ratios fall on an anomalous lead line, which indicates one event of great antiquity (approximately 4000 m.y.), and another about 2800 m.y. ago.Other sulfide samples from areas around Great Slave Lake, primarily outside the ancient (2800 m.y.) Slave Province, indicate events at 2800 m.y. and 1550 m.y., the latter date probably representing the time of the last major tectonic event in the Slave Province. Sulfur-isotope ratios for these samples vary from +1‰ to −13‰ relative to the meteoritic value, suggesting that these leads may have been remobilized by thermal metamorphism, and recombined with crustal sulfur enriched in 32S.

Download Full-text

Lead- and strontium-isotope geochemistry of Paleozoic Sicker Group and Jurassic Bonanza Group volcanic rocks and Island Intrusions, Vancouver Island, British Columbia

Canadian Journal of Earth Sciences ◽

10.1139/e89-072 ◽

1989 ◽

Vol 26 (5) ◽

pp. 894-907 ◽

Cited By ~ 5

Author(s):

Anne Andrew ◽

Colin I. Godwin

Keyword(s):

Lead Isotope ◽

Isotope Geochemistry ◽

Lead Isotopes ◽

Volcanic Rocks ◽

Isotope Ratios ◽

Ore Deposits ◽

Island Arc ◽

Lead Isotope Ratios ◽

Rock Suite ◽

Isotope Analyses

Whole-rock and galena lead-isotope analyses have been obtained from the Sicker Group Paleozoic island-arc volcanic package and from a Jurassic island-arc represented by the Bonanza Group volcanics and Island Intrusions. Galena lead-isotope analyses from the volcanogenic ore deposits at the Buttle Lake mining camp in the Sicker Group provide estimates of the initial lead ratios for the Sicker Group. Lead-isotope signatures are uniform within each of the major orebodies, but the Myra orebody is less radiogenic than the older H–W orebody. This has major significance in terms of ore genesis for these important deposits.There are significant differences in isotopic composition between the Sicker Group and Devonian island-arc type rocks in the Shasta district, California, which rules out direct correlations between the rock units of these two areas. Relatively high initial values of 207Pb/204Pb (> 15.56) and 208Pb/204Pb (> 38.00) suggest that large quantities of crustal lead must have been involved in the formation of the Sicker Group volcanic rocks. Thus it is proposed that the trench related to the Paleozoic island arc had a substantial input of continental detritus and may have lain near a continent.The Jurassic island arc is characterized by low 207Pb/204Pb ratios (< 15.59), suggesting a more primitive arc environment than for the Paleozoic arc. Bonanza Group volcanic rocks contain lead that is less radiogenic than lead in the Island Intrusions. Present and initial lead-isotope ratios of both the Bonanza Group volcanics and Island intrusions follow the same trend, supporting the hypothesis that they are comagmatic. Lead isotopes from a galena vein within the Island Copper porphyry deposit plot with the initial ratios for Bonanza Group volcanics and Island Intrusions. This confirms the hypothesis that this mineralization is related to the Jurassic island-arc volcanic event.Initial lead-isotope ratios for the Jurassic rock suite form a linear array on both 207Pb/204Pb versus 206Pb/204Pb and 208Pb/204Pb versus 206Pb/204Pb plots. If interpreted as due to isotopic mixing, the more radiogenic end member has a composition that is lower in 207Pb/204Pb and higher in 206Pb/204Pb than typical upper continental crust. Assimilation of Sicker Group material during the emplacement of the Jurassic arc can explain the mixing trend.

Download Full-text

Isotopic composition of lead from Balmat, New York

Canadian Journal of Earth Sciences ◽

10.1139/e68-121 ◽

1968 ◽

Vol 5 (5) ◽

pp. 1239-1245 ◽

Cited By ~ 9

Author(s):

P. H. Reynolds ◽

R. D. Russell

Keyword(s):

New York ◽

Lead Isotope ◽

Isotope Ratios ◽

Primary System ◽

Rock System ◽

Geophysical Model ◽

Gas Source ◽

General Terms ◽

Short Period ◽

The One

Isotopic data obtained by means of gas-source mass spectrometric analyses of tetramethyllead are reported for rock and ore leads from Balmat, New York. On the basis of these new precise analyses (an uncertainty in measured isotope ratios of approximately ± 0.10% at the 95% confidence level), the Balmat ores were formed from lead isotopically of the type observed by Ostic et al. (1967) in certain conformable deposits. In a case where there is a low concentration of lead in the ore, contamination of the ore lead by lead from a rock system is apparent. The rock leads (from potassium feldspars and from marbles) form a short-period anomalous suite apparently derived from source material with a μ-value of about 8.75. This short-term development took place approximately 1100 m.y. ago. It is clear that the primary system postulated for the rock leads (μ = 8.75) is distinctly different from the one associated with the ores (μ = 9.0); hence the ore lead is not genetically related to the lead in the rock system. The apparent existence of two primary lead systems in the earth must be explained by any geophysical model that attempts to describe in general terms the evolution of lead isotope ratios.

Download Full-text

A study of radionuclides, metals and stable lead isotope ratios in sediments and soils in the vicinity of natural U-mineralisation areas in the Northern Territory

Journal of Environmental Radioactivity ◽

10.1016/j.jenvrad.2010.04.003 ◽

2011 ◽

Vol 102 (10) ◽

pp. 911-918 ◽

Cited By ~ 13

Author(s):

A. Frostick ◽

A. Bollhöfer ◽

D. Parry

Keyword(s):

Lead Isotope ◽

Isotope Ratios ◽

Northern Territory ◽

Lead Isotope Ratios

Download Full-text

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

Transactions of the Royal Society of Edinburgh Earth Sciences ◽

10.1017/s0263593300013754 ◽

1984 ◽

Vol 75 (2) ◽

pp. 85-96 ◽

Cited By ~ 9

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.

Download Full-text