Tracing Highly Siderophile Elements through Subduction: Insights from High-pressure Serpentinites and ‘Hybrid’ Rocks from Alpine Corsica

2020 ◽  
Vol 61 (2) ◽  
Author(s):  
Rosalind J Crossley ◽  
Katy A Evans ◽  
Noreen J Evans ◽  
Alessandro Bragagni ◽  
Brad J McDonald ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Ore Deposits ◽  
Isotopic Signatures ◽  
Rock Samples ◽  
Inductively Coupled ◽  
Highly Siderophile Elements ◽  
Siderophile Elements ◽  
Platinum Group ◽  
Mineral Scale ◽  
Chlorite Schist

Abstract The highly siderophile elements (HSE) include the economically critical platinum group elements (PGE; Os, Ir, Ru, Rh, Pt, Pd, Au and Re), gold and rhenium. The HSE are redox sensitive in mantle and seafloor environments and have a strong affinity to iron and sulphur, therefore their distribution within the subducted mantle lithosphere record changes to oxidation state and sulphidation. The mobility of the HSE during subduction has important implications for Re–Os isotopic signatures in the mantle, and the formation of Cu–Au arc-related ore deposits. In this study, subducted rock samples from Alpine Corsica are used to track the HSE in serpentinites and hybrid ultramafic–mafic rocks through the subduction cycle. A comparison of bulk-rock HSE concentrations with those in pre-subduction analogues provides insights into the transfer of the HSE throughout the subduction cycle. Serpentinites subducted to blueschist–eclogite-facies conditions have similar HSE concentrations to primitive upper mantle (PUM) concentrations, therefore it is concluded that the HSE are not mobilized from serpentinites on the scale of the whole-rock or greater. Therefore, as suggested in previous studies, crustal lithologies may be more important contributors of the HSE to the sub-arc mantle, particularly Pt, Pd and Re. In contrast, HSE concentrations in hybrid rocks (talc schist and chlorite schist) deviate from protolith concentrations. Rhenium is higher in the talc schist, and Ir and Ru are lower in the chlorite schist than in the PUM, or possible mafic protoliths. Mineral parageneses place temporal constraints on the growth of hosts to the HSE (sulphides, oxides and metal alloys), and record changes to the activities of oxygen and sulphur (aO2–aS2), and hence redox conditions, from pre-subduction to exhumation. Laser ablation inductively coupled plasma mass spectrometry was used to determine the HSE concentrations in sulphides and oxides, and the detection of small (∼2–25 µm2) platinum group minerals utilized high-resolution SEM mapping techniques. The prograde and retrograde sulphides have lower HSE concentrations compared with sulphides from pre-subduction settings. Therefore, the redistribution of the HSE on a mineral scale from sulphides to alloys and/or other sulphides has occurred within the serpentinites, which may reflect more reducing conditions during serpentinization or subduction, consistent with the results of thermodynamic modelling. In contrast, the mineral assemblages in the hybrid rocks imply an increase in the extent of sulphidation and oxidation, and higher fluid:rock ratios during exhumation, coincident with Re enrichment in the talc schist, and a decrease in the concentrations of Ir and Ru in the chlorite schist, at length scales greater than those of the rock samples. Therefore, hybridization of lithologies at the slab–mantle interface may enhance the transfer of the HSE to the sub-arc mantle. If Re transfer from the slab to the sub-arc mantle is possible, this questions the robustness of Re–Os isotope signatures as tracers of crustal recycling.

scholarly journals The Role of Continental Crust in the Formation of Uraninite-Based Ore Deposits

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 136 ◽  
Author(s):  
Stefanie R. Lewis ◽  
Antonio Simonetti ◽  
Loretta Corcoran ◽  
Stefanie S. Simonetti ◽  
Corinne Dorais ◽  
...  
Keyword(s):  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Ore Deposits ◽  
Source Attribution ◽  
Rock Composition ◽  
Isotopic Signatures ◽  
Element Abundances ◽  
Inductively Coupled ◽  
Spatially Resolved ◽  
Icp Ms

This study reports trace element abundances and Pb, Sr, and U isotopic signatures of uraninite from a variety of ore deposits in order to establish baseline forensic information for source attribution of raw, natural U-rich samples. Trace element concentrations, reported here, provide insights into uraninite crystal substitution mechanisms and possible crustal sources of U, including mobility of trace elements between pristine versus altered fractions. Spatially resolved laser ablation (LA) multicollector (MC) inductively coupled plasma mass spectrometry (ICP-MS) analyses were used to determine secondary 207Pb-206Pb isochron ages, and these were validated by corroborative results obtained by solution mode (SM) MC-ICP-MS for the same sample. Secondary Pb-Pb isochron ages obtained, in this study, indicate that uraninite alteration occurs shortly after ore mineralization. Initial 87Sr/86Sr values correlate in general with host craton age, and therefore suggest that uraninite ore formation is closely linked to the nature of the bedrock geology. The δ238U values are explained by invoking multiple physicochemical conditions and parameters such as temperature, nuclear field shift, oxidation, and source rock composition. The δ234U values indicate that the uraninites, investigated here, have undergone recent alteration, but the latter has not perturbed the Pb-Pb secondary isochron ages.

scholarly journals Apatite U-Pb dating at UNAM laboratories: analytical protocols and examples of its application

2019 ◽  
Vol 36 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Carlos Ortega-Obregón ◽  
Fanis Abdullin ◽  
Luigi Solari ◽  
Peter Schaaf ◽  
Gabriela Solís-Pichardo
Keyword(s):  
Mass Spectrometry ◽  
Inductively Coupled Plasma ◽  
Ore Deposits ◽  
Ionization Mass ◽  
Medium Temperature ◽  
Rock Samples ◽  
Inductively Coupled ◽  
Advantages And Disadvantages ◽  
Icp Ms ◽  
Analytical Protocols

Apatite is the most common phosphate mineral in the Earth’s crust and can be found in practically all magmatic and metamorphic rocks, as well as in ancient and recent sediments and in certain ore deposits. Its effective closure temperature of 450–550 °C for the U-Pb system makes apatite an important natural medium-temperature thermochronometer that can be dated by both laser ablation inductively coupled plasma mass spectrometry (LA–ICP-MS) and isotope dilution thermal ionization mass spectrometry (ID–TIMS) techniques. Due to its low U content, coupled with high Pb contents incorporated during crystallization (also called common lead), apatite U-Pb dating is analytically challenging, and requires robust analytical protocols to achieve reliable ages. In this experimental study we obtained apatite U-Pb ages from six rock samples employing LA–ICP-MS (at Laboratorio de Estudios Isotópicos, Centro de Geociencias, UNAM), while one sample was also dated by ID–TIMS (at Laboratorio Universitario de Geoquímica Isotópica, UNAM). These samples have igneous emplacement or metamorphic ages broadly ranging from the Neoproterozoic to the Paleocene. The obtained apatite U-Pb ages agree well with other radioisotopic data (U-Pb on zircon and K-Ar or Ar-Ar on micas and hornblende) available for the same rock samples tested, or for the same geological units studied. These apatite U-Pb results, obtained for the first time at two main Mexican geochronology laboratories, are precise enough to be geologically meaningful and usually represent the cooling ages; though, in some cases they may also indicate the crystallization or the metamorphic age. Some advantages and disadvantages of LA–ICP-MS- and ID–TIMS-based methodologies were observed and outlined. Our results validate the analytical procedures used and will serve as an important trigger towards the development or improvement of medium-temperature thermochronology techniques in Mexico.

scholarly journals U–Pb age and Lu–Hf signatures of detrital zircon from Palaeozoic sandstones in the Oslo Rift, Norway

2013 ◽  
Vol 151 (5) ◽  
pp. 816-829 ◽  
Author(s):  
MAGNUS KRISTOFFERSEN ◽  
TOM ANDERSEN ◽  
ARILD ANDRESEN
Keyword(s):  
Detrital Zircon ◽  
Inductively Coupled Plasma ◽  
Late Carboniferous ◽  
Isotopic Signatures ◽  
Inductively Coupled ◽  
Source To Sink ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Isotope Analyses ◽  
Multiple Episodes

AbstractU–Pb and Lu–Hf isotope analyses of detrital zircon from the latest Ordovician (Hirnantian) Langøyene Formation, the Late Silurian Ringerike Group and the Late Carboniferous Asker Group in the Oslo Rift were obtained by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Overall the U–Pb dating yielded ages within the range 2861–313 Ma. The U–Pb age and Lu–Hf isotopic signatures correspond to virtually all known events of crustal evolution in Fennoscandia, as well as synorogenic intrusions from the Norwegian Caledonides. Such temporally and geographically diverse source areas likely reflect multiple episodes of sediment recycling in Fennoscandia, and highlights the intrinsic problem of using zircon as a tracer-mineral in ‘source to sink’ sedimentary provenance studies. In addition to its mostly Fennoscandia-derived detritus, the Asker Group also have zircon grains of Late Devonian – Late Carboniferous age. Since no rocks of these ages are known in Fennoscandia, these zircons are inferred to be derived from the Variscan Orogen of central Europe.

scholarly journals Antimony and Nickel Impurities in Blue and Green Copper Pigments

Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1236
Author(s):  
Sylwia Svorová Pawełkowicz ◽  
Barbara Wagner ◽  
Jakub Kotowski ◽  
Grażyna Zofia Żukowska ◽  
Bożena Gołębiowska ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Ore Deposits ◽  
Copper Ore ◽  
Inductively Coupled ◽  
Parish Church ◽  
Icp Ms ◽  
Plasma Mass Spectrometry ◽  
Quantitative Analyses ◽  
First Time

Impurities in paint layers executed with green and blue copper pigments, although relatively common, have been studied only little to date. Yet, their proper identification is a powerful tool for classification of paintings, and, potentially, for future provenance studies. In this paper, we present analyses of copper pigments layers from wall paintings situated in the vicinity of copper ore deposits (the palace in Kielce, the palace in Ciechanowice, and the parish church in Chotków) located within the contemporary borders of Poland. We compare the results with the analyses of copper minerals from three deposits, two local, and one historically important for the supply of copper in Europe, i.e., Miedzianka in the Holy Cross Mountains, Miedzianka in the Sudetes, and, as a reference, Špania Dolina in the Slovakian Low Tatra. Optical (OM) and electron microscopy (SEM-EDS), Raman spectroscopy, and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) have been used for a detailed investigation of the minute grains. Special attention has been devoted to antimony and nickel phases, as more unusual than the commonly described iron oxides. Analyses of minerals from the deposits helped to interpret the results obtained from the paint samples. For the first time, quantitative analyses of copper pigments’ impurities have been described.

The Giant Chalukou Porphyry Mo Deposit, Northeast China: The Product of a Short-Lived, High Flux Mineralizing Event

2021 ◽  
Author(s):  
Qingqing Zhao ◽  
Degao Zhai ◽  
Ryan Mathur ◽  
Jiajun Liu ◽  
David Selby ◽  
...  
Keyword(s):  
High Precision ◽  
Inductively Coupled Plasma ◽  
Hydrothermal Activity ◽  
Ore Deposits ◽  
Ionization Mass ◽  
Inductively Coupled ◽  
Fine Grained ◽  
Porphyry Cu ◽  
Icp Ms ◽  
Porphyry Mo Deposit

Abstract Whether giant porphyry ore deposits are the products of single, short-lived magmatic-hydrothermal events or multiple events over a prolonged interval is a topic of considerable debate. Previous studies, however, have all been devoted to porphyry Cu and Cu-Mo deposits. In this paper, we report high-precision isotope dilution-negative-thermal ionization mass spectrometric (ID-N-TIMS) molybdenite Re-Os ages for the newly discovered, world-class Chalukou porphyry Mo deposit (reserves of 2.46 Mt @ 0.087 wt % Mo) in NE China. Samples were selected based on a careful evaluation of the relative timing of the different vein types (i.e., A, B, and D veins), thereby ensuring that the suite of samples analyzed could be used to reliably determine the age and duration of mineralization. The molybdenite Re-Os geochronology reveals that hydrothermal activity at Chalukou involved two magmatic-hydrothermal events spanning an interval of 6.92 ± 0.16 m.y. The first event (153.96 ± 0.08/0.63/0.79 Ma, molybdenite ID-N-TIMS Re-Os age) was associated with the emplacement of a granite porphyry dated at 152.1 ± 2.2 Ma (zircon laser ablation-inductively coupled plasma-microscopic [LA-ICP-MS] U-Pb ages), and led to only minor Mo mineralization, accounting for <10% of the overall Mo budget. The bulk of the Mo (>90%) was deposited in less than 650 kyr, between 147.67 ± 0.10/0.60/0.76 and 147.04 ± 0.12/0.72/0.86 Ma (molybdenite ID-N-TIMS Re-Os ages), coincident with the emplacement of a fine-grained porphyry at 148.1 ± 2.6 Ma (zircon LA-ICP-MS U-Pb ages). The high-precision Re-Os age determinations presented here show, contrary to the finding of a number of studies of porphyry Cu and Cu-Mo systems, that the giant Chalukou porphyry Mo deposit primarily formed in a single, short-lived (<650 kyr) hydrothermal event, suggesting that this may also have been the case for other giant porphyry Mo deposits.

Mapping Magmatic and Hydrothermal Processes from Routine Exploration Geochemical Analyses

2020 ◽  
Vol 115 (3) ◽  
pp. 489-503 ◽  
Author(s):  
Scott Halley
Keyword(s):  
Inductively Coupled Plasma ◽  
Mining Industry ◽  
Analysis Data ◽  
Ore Deposits ◽  
Mineral Deposits ◽  
Geochemical Data ◽  
High Quality ◽  
Inductively Coupled ◽  
Hydrothermal Processes ◽  
Geochemical Analyses

Abstract Analytical methods used by commercial assay laboratories have improved enormously in recent years. Inductively coupled plasma-atomic emission spectroscopy and inductively coupled plasma-mass spectrometry methods now report analyses for half of the periodic table with exceptional detection limits and precision. It is becoming commonplace for mining companies to use such methods routinely for the analysis of drill samples throughout mineral deposits. Improvements in software and computing power now allow rapid interrogation of upward of 100,000 assay samples. Geochemical analyses are quantitative, are independent of observer bias, and can form the basis for robust geologic and mineralogical models of mineral deposits, as well as shed light on scientific questions. In particular, consistently collected, high-quality geochemical analyses can significantly improve and systematize logging of lithological and hydrothermal alteration mineralogic changes within drill core. In addition, abundant, high-quality geochemical data provide insights into magmatic and hydrothermal processes that were previously difficult to recognize and that have obvious applications to mineral exploration and improved genetic models of ore deposits. This paper describes a workflow that mining industry geologists can apply to their multielement analysis data to extract more information about magma compositions and gangue mineralogy.

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