Interpretation of lead isotope data from zinc–lead mineralization in the northern part of the western Canadian Cordillera

1982 ◽  
Vol 19 (5) ◽  
pp. 1070-1078 ◽  
Author(s):  
D. W. Morrow ◽  
G. L. Cumming
Keyword(s):  
British Columbia ◽  
Lead Isotope ◽  
Isotope Composition ◽  
Canadian Cordillera ◽  
Pb Isotope ◽  
Linear Arrays ◽  
Group Of Seven ◽  
Isotope Data ◽  
Devonian Shale ◽  
Linear Trends

Lead isotope data, from a group of seven zinc–lead deposits in Devonian carbonate strata of northeastern British Columbia, have very radiogenic and variable compositions and form a series of parallel linear arrays on Pb/Pb diagrams. These arrays are entirely separate from the less radiogenic and much less variable lead compositions of the Devonian shale-hosted zinc–lead deposits in the laterally adjacent Paleozoic basinal sequence, which themselves define steeply dipping linear trends. Both of these types of arrays reflect multistage histories during the evolution of Pb compositions. One stage may have been a period of residence of Pb in uranium-rich Paleozoic shale, which caused the development of the radiogenic leads that were emplaced later in the carbonate-hosted zinc–lead deposits.Unlike the Devonian carbonate-hosted deposits the "Silver-rich vein" group of deposits is homogeneous in Pb isotope composition. This contrast in the isotopic homogeneity between deposits may reflect differences in the mechanisms by which these deposits formed.

Isotopic Compositions of Selected Ore Leads from Northeastern Washington

1973 ◽  
Vol 10 (5) ◽  
pp. 670-678 ◽  
Author(s):  
W. D. Small
Keyword(s):  
Isotopic Composition ◽  
Lead Isotope ◽  
Isotope Composition ◽  
Canadian Cordillera ◽  
Basement Structure ◽  
Late Mesozoic ◽  
Sedimentary Structures ◽  
Lead Isotope Composition ◽  
Isotopic Abundances ◽  
Primary Type

Isotopic composition of ore leads from four districts in northeastern Washington has been measured with a precision in the ratios of about 0.1‰. Results indicate that the mineralization in the Marshall Diorites of Pend Oreille County is by a primary type lead with a model age of about 1300 to 1500 m.y. The remainder of the measured leads from Pend Oreille and Stevens Counties have a radiogenic component which could have developed in a closed system during the interval 1370 to about 250 m.y. ago. Leads from Ferry and Okanogan Counties have only slight variations in their isotopic abundances. These latter leads could have been produced by an homogenization of the leads from Pend Oreille and Stevens Counties through the mechanism of a late Mesozoic metamorphism of Mesozoic sedimentary structures in Ferry and Okanogan Counties, these latter sedimentary structures being the products of erosion of rocks in Pend Oreille and Stevens Counties. There is no evidence of an ancient basement structure under Ferry and Okanogan Counties from the data presented herein. The lead isotope composition of the ores from northeastern Washington is compatible with the current concepts of the crustal structure across the Canadian Cordillera.

Mixing line isochrons; a new interpretation of galena lead isotope data from southeastern British Columbia

1984 ◽  
Vol 79 (5) ◽  
pp. 919-932 ◽  
Author(s):  
Anne Andrew ◽  
Colin I. Godwin ◽  
Alastair J. Sinclair
Keyword(s):  
British Columbia ◽  
Lead Isotope ◽  
Isotope Data ◽  
New Interpretation

scholarly journals The U-Pb Zircon Geochronology (LA-ICP-MS) of Geological Processes in Granulites of Middle Bouh Area. Article 3. Rock association in the lower reaches of the Yatran river

2021 ◽  
Vol 43 (1) ◽  
pp. 34-50
Author(s):  
L.M. STEPANYUK ◽  
L.V. SHUMLYANSKYY ◽  
S.I. KURYLO ◽  
V.O. SYOMKA ◽  
S.M. BONDARENKO ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Hf Isotope ◽  
Zircon Geochronology ◽  
Pb Isotope ◽  
Isotope Data ◽  
Geological Processes ◽  
Icp Ms ◽  
Isotope Systematics ◽  
Isotope Analyses ◽  
Rock Association

LA-ICP-MS method was applied to investigate U-Pb and Lu-Hf isotope systematics of zircon crystals from charnockitic gneiss and biotite-garnet-hypersthene enderbite that occur in the lower reaches of the Yatran river (Yatran block of the Bouh river area). According to the obtained isotope data, charnockitic gneiss hosts three zircon populations. The oldest one is represented by three crystals that have isotope age between 3125 and 3300 Ma, and εHf values between –2.3 and –7.5. The next population is well-defined, it has an age of 2038±25 Ma and large variations of Hf isotope composition: 176Hf/177Hf — from 0.28122 to 0.28261, εHf — from –9.3 до 4.6. However, the ages of most of the analyzed zircons spread along the concordia between 2300 and 2800 Ma. All zircons in this population have a similar Hf isotope composition 176Hf/177Hf = 0.28072 to 0.28092, which does not depend on the age. It is characteristic that the oldest (with preserved U-Pb isotope systematics) crystals have positive or slightly negative εHf values. Most of the U-Pb isotope analyses of zircons from enderbite fall on the discordia line that has an upper interception age of 2029 ± 18 Ma. A small number of discordant grains have 207Pb/206Pb ages up to 2500 Ma. Hafnium isotope composition in zircons from enderbite varies widely: 176Hf/177Hf = 0.28131 to 0.28151, and εHf from –6.2 to 1.8.

New lead isotope data on Cretaceous volcanic rocks of Mongolia: the sources and the origin of the magmatic melts

2021 ◽  
Author(s):  
Maksim Kuznetsov ◽  
Valery Savatenkov ◽  
Shpakovich Lidia ◽  
Kozlovskiy Alexander ◽  
Kudryashova Ekaterina
Keyword(s):  
Late Cretaceous ◽  
Lithospheric Mantle ◽  
Lead Isotope ◽  
Isotope Composition ◽  
Volcanic Rocks ◽  
Volcanic Area ◽  
Sr Isotope ◽  
Pb Isotope ◽  
Eastern Mongolia

<p>The Eastern Mongolia Volcanic Area (EMVA) and the Gobi-Altai Volcanic Area (GAVA) are large parts of the Late Mesozoic volcanic-plutonic belt which is located in northeast Asia. The main value of the EMVA and the GAVA was formed during the Cretaceous. Previous research devoted to Cretaceous volcanic rocks of both volcanic areas has focused mainly on its geochemical features of main and trace components, and Nd – Sr isotope composition (Bars et al., 2018; Dash et al., 2015; Sheldrick et al., 2018; Sheldrick et al., 2020). At the same time, the published data on the Pb isotope composition of volcanic rocks of the EMVA and the GAVA is too scarce (Sheldrick et al., 2018; Sheldrick et al., 2020). However, the Pb isotope characteristic can be a key to the understanding of parent melts sources of the EMVA and the GAVA rocks.  Therefore, the goal of the presented work is a more extensive study of the Pb isotope systematics of the Cretaceous volcanic complexes within the EMVA and the GAVA.</p><p>Obtained data on Pb isotope characteristics of the EMVA volcanic rocks demonstrate the role of the upper crust terrigenous component (UCC) in magma generation. The role of the UCC in the EMVA formation is consistent with the Nd – Sr isotope composition and elevated LILE contents in rock samples. In contrast to the EMVA the Pb isotope features of the same aged GAVA rocks (135 – 120 Ma) with the enriched Nd – Sr composition point to the role of the lower crust component in their formation. Thus, there is a difference between the sources of the coeval rocks of two volcanic areas reflecting the difference in the melts source composition between the two areas.</p><p>The Late Cretaceous rocks of the GAVA (about 90 Ma), as well as the Early Cretaceous rocks of the EMVA, lie nearby a field of lithospheric mantle xenoliths on the Pb isotope ratios diagram. In turn, the obtained Pb isotope data on the lherzolite xenoliths as well as that on paleooceanic complexes of Mongolia reveal the obvious difference of Pb isotope composition of the lithospheric mantle of the region from that of the Paleo-Asian ocean mantle. The observed difference can be explained by the metasomatic alteration of the suboceanic mantle during accretion and subduction processes before the EMVA and the GAVA formation. Thus, the conclusion about the key role of the metasomatized lithospheric mantle in the GAVA Late Cretaceous rocks formation can be made.</p><p>The study was supported by the RFBR (20-05-00401).</p><p>KEYWORDS: Eastern Mongolia, Gobi-Altai, Cretaceous volcanic rocks, lead isotope composition.</p>

Status of the Jurassic in the Canadian Cordillera of British Columbia, Alberta, and southern Yukon

1970 ◽  
Vol 7 (1) ◽  
pp. 1-21 ◽  
Author(s):  
Hans Frebold ◽  
H. W. Tipper
Keyword(s):  
British Columbia ◽  
Fossil Record ◽  
Canadian Cordillera ◽  
Tectonic Events ◽  
Source Of Information

Jurassic index fossils of the Canadian Cordillera indicate the presence of some zones of most Jurassic stages. In this report the more important localities are listed, the source of information, published and unpublished, is indicated, and an up-dated correlation chart is presented. The importance of tectonic events and their effect on the completeness of the Jurassic fossil record and on the Jurassic paleogeography are stressed.

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.

scholarly journals Comment on “Origin of water in the Badain Jaran Desert, China: new insight from isotopes” by Wu et al. (2017)

2018 ◽  
Vol 22 (8) ◽  
pp. 4449-4454 ◽  
Author(s):  
Lucheng Zhan ◽  
Jiansheng Chen ◽  
Ling Li ◽  
David A. Barry
Keyword(s):  
Lake Water ◽  
Meteoric Water ◽  
Isotope Composition ◽  
Qilian Mountains ◽  
Precipitation Rate ◽  
Badain Jaran Desert ◽  
Isotopic Evidence ◽  
Isotope Data ◽  
Local Areas ◽  
The Qilian Mountains

Abstract. Precipitation isotope data were used to determine the origin of groundwater in the Badain Jaran Desert (BJD) in the study of Wu et al. (2017). Both precipitation and its isotope composition vary seasonally, so arithmetic averages of precipitation isotope values poorly represent the isotope composition of meteoric water. Their finding that the BJD groundwater is recharged by modern meteoric water from local areas including the southeastern adjacent mountains was based on arithmetic averaging. However, this conclusion is not supported by the corrected mean precipitation isotope values, which are weighted by the precipitation rate. Indeed, the available isotopic evidence shows that modern precipitation on the Qilian Mountains is more likely to be the main source of the groundwater and lake water in the BJD, as found by Chen et al. (2004).

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