Resolving multiple geological events using in situ Rb–Sr geochronology: implications for metallogenesis at Tropicana, Western Australia

Abstract. Dating multiple geological events in single samples using thermochronology and geochronology is relatively common, but it is only with the recent advent of triple quadrupole laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) that in situ rubidium–strontium (Rb–Sr) dating has become a more commonly applied and powerful tool to date K-rich or Rb-bearing minerals. Here, we date two generations of mineral assemblages in individual thin sections using the in situ Rb–Sr method. Two distinct mineral assemblages, both probably associated with Au mineralization, are identified in samples from the Tropicana gold mine in the Albany–Fraser Orogen, Western Australia. For Rb–Sr purposes, the key dateable minerals are two generations of biotite as well as additional phengite associated with the younger assemblage. Our results reveal that the first, coarse-grained generation of biotite grains records a minimum age of 2535±18 Ma, coeval with previous 40Ar∕39Ar biotite, rhenium–osmium (Re–Os) pyrite and uranium–lead (U–Pb) rutile results. The second, fine-grained and recrystallized generation of biotite grains record an age of 1207±12 Ma across all samples. Phengite and muscovite yielded broadly similar results at ca. 1.2 Ga, but data are overdispersed for a single coeval population of phengite and show elevated age uncertainties for muscovite. We propose that the ca. 2530 Ma age recorded by various geochronometers represents cooling and exhumation and that the age of ca. 1210 Ma is related to major shearing associated with the regional deformation as part of Stage II of the Albany–Fraser Orogeny. This is the first time that an age of ca. 1210 Ma has been identified in the Tropicana Zone, which may have ramifications for constraining the timing of mineralization in the region. The in situ Rb–Sr technique is currently the only tool capable of resolving both geological events in these rocks.

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Resolving multiple geological events using in situ Rb-Sr geochronology: implications for metallogenesis at Tropicana, Western Australia

10.5194/gchron-2020-7 ◽

2020 ◽

Author(s):

Hugo K. H. Olierook ◽

Kai Rankenburg ◽

Stanislav Ulrich ◽

Christopher L. Kirkland ◽

Noreen Evans ◽

...

Keyword(s):

Western Australia ◽

Coarse Grained ◽

Thin Sections ◽

Fine Grained ◽

Regional Deformation ◽

Mineral Assemblages ◽

Two Generations ◽

Minimum Age ◽

First Time

Abstract. Dating multiple geological events in single samples using thermochronology and geochronology is relatively common but it is only with the recent advent of triple quadrupole LA-ICP-MS that in situ Rb-Sr dating has become a more commonly applied and powerful tool to date K- and Rb-bearing minerals. Here, we date, for the first time, two generations of mineral assemblages in individual thin sections using the in situ Rb-Sr method. Two distinct mineral assemblages, both probably associated with Au mineralization, are identified in samples from the Tropicana gold mine in the Albany–Fraser Orogen, Western Australia. For Rb-Sr purposes, the key dateable minerals are two generations of biotite, and additional phengite associated with the second assemblage. Our results reveal that the first, coarse-grained generation of biotite grains records a minimum age of 2535 ± 18 Ma, coeval with previous 40Ar/39Ar biotite, Re-Os pyrite and U-Pb rutile results. The second, fine-grained and recrystallized generation of biotite grains record an age of 1207 ± 12 Ma across all samples. Phengite and muscovite yielded broadly similar results at ca. 1.2 Ga but data is overdispersed for a single coeval population of phengite and shows elevated age uncertainties for muscovite. We propose that the ca. 2530 Ma age recorded by various geochronometers represents cooling and exhumation, and that the age of ca. 1210 Ma is related to major shearing associated with the regional deformation associated with Stage II of the Albany–Fraser Orogeny. This is the first time that an age of ca. 1210 Ma has been identified in the Tropicana Zone, which may have ramifications for constraining the timing of mineralization in the region. The in situ Rb-Sr technique is currently the only tool capable of resolving both geological events in these rocks.

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In situ Rb-Sr dating by collision cell, multicollection inductively-coupled plasma mass-spectrometry with pre-cell mass-filter, (CC-MC-ICPMS/MS).

Journal of Analytical Atomic Spectrometry ◽

10.1039/d1ja00006c ◽

2021 ◽

Author(s):

Dan Bevan ◽

Christopher David Coath ◽

Jamie Lewis ◽

Johannes B Schwieters ◽

Nicholas Selwyn Lloyd ◽

...

Keyword(s):

Inductively Coupled Plasma ◽

Cell Mass ◽

Quadrupole Mass Filter ◽

Collision Cell ◽

Uv Laser ◽

Quadrupole Mass ◽

Mass Filter ◽

Inductively Coupled ◽

Plasma Mass Spectrometry

We document the utility for in situ Rb-Sr dating of a one-of-a-kind tribrid mass spectrometer, ‘Proteus’, coupled to a UV laser ablation system. Proteus combines a pre-cell quadrupole mass-filter,collision cell,...

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Spatially and time-resolved element-specific in situ corrosion investigations with an online hyphenated microcapillary flow injection inductively coupled plasma mass spectrometry set-up

Spectrochimica Acta Part B Atomic Spectroscopy ◽

10.1016/j.sab.2008.04.015 ◽

2008 ◽

Vol 63 (7) ◽

pp. 777-783 ◽

Cited By ~ 24

Author(s):

N. Homazava ◽

A. Ulrich ◽

U. Krähenbühl

Keyword(s):

Mass Spectrometry ◽

Flow Injection ◽

Inductively Coupled Plasma ◽

Time Resolved ◽

Inductively Coupled ◽

Plasma Mass Spectrometry ◽

Set Up

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In situ analysis of trace elements in quartz by using laser ablation inductively coupled plasma mass spectrometry

Chemical Geology ◽

10.1016/s0009-2541(01)00292-3 ◽

2002 ◽

Vol 182 (2-4) ◽

pp. 237-247 ◽

Cited By ~ 69

Author(s):

Belinda Flem ◽

Rune B Larsen ◽

Andreas Grimstvedt ◽

Joakim Mansfeld

Keyword(s):

Mass Spectrometry ◽

Trace Elements ◽

Laser Ablation ◽

Inductively Coupled Plasma ◽

In Situ Analysis ◽

Inductively Coupled ◽

Plasma Mass Spectrometry

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An investigation into LA-spICP-ToF-MS uses for in situ measurement of environmental multi-elemental nanoparticles

Journal of Analytical Atomic Spectrometry ◽

10.1039/d1ja00112d ◽

2021 ◽

Author(s):

Timothy R. Holbrook ◽

Doriane Gallot-Duval ◽

Thorsten Reemtsma ◽

Stephan Wagner

Keyword(s):

Mass Spectrometry ◽

Single Particle ◽

Inductively Coupled Plasma ◽

In Situ Measurement ◽

Inductively Coupled ◽

Plasma Mass Spectrometry ◽

Tof Ms

Characterization and investigation into complex nano-fraction samples have traditionally been done using nebulizer single particle inductively coupled plasma mass spectrometry (neb-spICP-MS). Here a method was developed and tested for the...

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Cationic Substitutions in Sphalerite from the Porgera Mine, Papua New Guinea

The Canadian Mineralogist ◽

10.3749/canmin.2000085 ◽

2021 ◽

Author(s):

Christopher H. Ingles ◽

John A. Mavrogenes

Keyword(s):

Solid Solution ◽

Papua New Guinea ◽

Solid Solutions ◽

Inductively Coupled Plasma ◽

New Guinea ◽

Inductively Coupled ◽

Cationic Substitution ◽

Plasma Mass Spectrometry ◽

Positive Correlations

ABSTRACT Laser ablation-inductively coupled plasma-mass spectrometry was used to traverse hydrothermal vein sphalerite from different ore-forming stages of the Porgera Au-Ag mine, Papua New Guinea. Elements were measured in situ over the growth of crystals to investigate the greatly varying concentrations of cations in sphalerite and their positions in the lattice. Traverse profiles for 16 elements were obtained and aligned to transmitted light images where possible. Each sample contained an array of elements, with many displaying orders of magnitude concentration differences. Results show the simultaneous incorporation of Cu and Sn in sphalerite, as well as Cu and Ag, In and Sn, As and Sb, Fe and Mn, and Cu and Ga. The relation [4Zn2+ ↔ 2Cu+ + Sn2+ + Sn4+] is proposed to explain the 1:1 Cu–Sn correlation. Further relations can be seen, including a Ga “ceiling” or Cu “floor”, where Ga incorporation becomes dependent on Cu concentrations. Furthermore, silver was also observed to correlate with Au, Mn, Ni, Pb, and Bi. Meta-stable solid solutions between pairs such as Cu, Ag; Fe, Mn; As, Sb; and In, Sn are also suggested. Each of these pairs are neighbors on the periodic table of elements, which suggests that simple solid solution can occur, and positive correlations for all four solid solutions were found in one sample alone. While the concept of charge-specific solid solutions in sphalerite has been discussed in the literature with reference to monovalent cations, the results presented herein also indicate solid solutions of higher oxidation states, containing many cations. Furthermore, while cations in charge-specific solid solutions have been proposed to compete for lattice sites in sphalerite, simultaneous in situ coupled concentrations at Porgera suggest otherwise. Cationic substitution equations displaying decimal ratios of each element in solid solution can then provide a novel method to distinguish between solid solution concentrations in different samples. For example, displaying 1:1 ratios of Cu–Ag and Sb–As: [2Zn2+ ↔ (Cu+0.5, Ag+0.5) + (As3+0.5, Sb3+0.5)], or for a 100:1 Fe–Mn ratio: [Zn2+ ↔ (Fe2+0.99, Mn2+0.01)].

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Effect of Annealing Conditions on the Dissolution Process of Complex Carbonitrides in a V-Nb-Ti Microalloyed Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.941.21 ◽

2018 ◽

Vol 941 ◽

pp. 21-26

Author(s):

Gloria Basanta ◽

Ana L. Rivas ◽

Ervis Díaz ◽

Carlos Parra

Keyword(s):

Inductively Coupled Plasma ◽

Microalloyed Steel ◽

Optical Emission ◽

Dissolution Process ◽

Emission Spectrometry ◽

Inductively Coupled ◽

Annealing Conditions ◽

Plasma Optical Emission Spectrometry

The present work has been undertaken to assess the evolution of dissolution process of large dendritic precipitates in a V-Nb-Ti microalloyed steel. The study was performed by reheating the samples at 1250°C, simulating the industrial reheating practices at laboratory scale and in situ, following industrial profile; afterwards the samples were quenched in 10%NaCl aqueous solution. The characterization of the material was carried out by scanning electron microscopy accompanied with dispersive energy spectrometry, and chemical analysis by inductively coupled plasma optical emission spectrometry. The results showed a partial dissolution of dendritic precipitates. This process ocurred by a progressive dissolving the Nb-rich shells formed over cuboidal particles and primary arm of well-faceted dendritic precipitates, and by fragmentation and spheroidization of secondary branches. These processes gave rise to spherical Nb rich precipitates and cuboidal particles at the reheating conditions used in this study. Both type of particles contain vanadium.

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

Economic Geology ◽

10.5382/econgeo.4818 ◽

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.

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High-resolution LA-ICP-MS trace-element mapping of magmatic biotite: A new approach for studying syn- to post-magmatic evolution

The Canadian Mineralogist ◽

10.3749/canmin.1900101 ◽

2020 ◽

Vol 58 (3) ◽

pp. 293-311 ◽

Cited By ~ 2

Author(s):

Zeinab Azadbakht ◽

David R. Lentz

Keyword(s):

New Brunswick ◽

Trace Element ◽

Inductively Coupled Plasma ◽

Fluid Phase ◽

New Approach ◽

Inductively Coupled ◽

Icp Ms ◽

Magma Crystallization ◽

Topaz Granite

ABSTRACT Biotite grains from 22 felsic intrusions in New Brunswick were mapped in situ using a laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS). We investigated the extent to which biotite can retain its magmatic zoning patterns and, where zoning does exist, how it can be used to elucidate early to late stage, syn-magmatic to post-crystallization processes. Although the major element and halogen contents of the examined biotite phenocrysts are homogeneous, two-thirds of the grains display trace-element zoning for Ba, Rb, and Cs. The results also indicated that zoning is better retained in larger grains (i.e., > 500 × 500 μm) with minimal alteration and mineral inclusions. An exceptionally well-zoned Li-rich siderophyllite from the Pleasant Ridge topaz granite in southwestern New Brunswick shows Ti, Ta, Sn, W, Cs, Rb, and V (without Li or Ba) zoning. Cesium values increase from 200 to 1400 ppm from core to rim. Conversely, Sn and W values decrease toward the rim (50 to 10 and 100 to 10 ppm, respectively). Tantalum and Ti values show fewer variations but drop abruptly close to the rim of the grain (100 to 20 and 2000 to 500 ppm, respectively). These observations may indicate crystallization of mineral phases with high partition coefficients for these highly incompatible elements (except Ti) (e.g., cassiterite and rutile) followed by fractionation of a fluid phase at a later stage of magma crystallization. The preservation of zoning may indicate rapid cooling post-crystallization of the parent magma.

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