Origin of unusual fractionation of Pb isotope ratios with calcium in thallium-spiked multiple collector-inductively coupled plasma mass spectrometry

2016 ◽  
Vol 50 (5) ◽  
pp. 423-429 ◽  
Author(s):  
Bogdan Stefanov Vaglarov ◽  
Jun-ichi Kimura ◽  
Takashi Miyazaki ◽  
Qing Chang
Keyword(s):  
Mass Spectrometry ◽  
Inductively Coupled Plasma ◽  
Isotope Ratios ◽  
Pb Isotope ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry

Contact Metamorphic and Metasomatic Processes at the Kharaelakh Intrusion, Oktyabrsk Deposit, Norilsk-Talnakh Ore District: Application of LA-ICP-MS Dating of Perovskite, Apatite, Garnet, and Titanite

2020 ◽  
Vol 115 (6) ◽  
pp. 1213-1226 ◽  
Author(s):  
Alexander E. Marfin ◽  
Alexei V. Ivanov ◽  
Vadim S. Kamenetsky ◽  
Adam Abersteiner ◽  
Tamara Yu. Yakich ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Inductively Coupled Plasma ◽  
Metamorphic Rocks ◽  
Complete Agreement ◽  
Ionization Mass ◽  
Pb Isotope ◽  
Inductively Coupled ◽  
Prolonged Duration ◽  
Plasma Mass Spectrometry ◽  
Ore District

Abstract The Norilsk-Talnakh ore district in the northwestern Siberian platform contains globally unique reserves of Cu-Ni-sulfides with Pt and, especially, Pd. The Oktyabrsk deposit, which is one of the largest in the district, is spatially and genetically associated with the Kharaelakh mafic-ultramafic intrusion and its exceptionally large metamorphic and metasomatic aureoles. In this study, we employed in situ laser ablation-inductively coupled plasma-mass spectrometry U-Pb isotope dating of apatite, titanite, garnet, and perovskite that cocrystallize with disseminated sulfides within the aureole of metasomatic and contact metamorphic rocks. The calculated isotopic ages for apatite (257.3 ± 4.5 and 248.9 ± 5.1 Ma), titanite (248.6 ± 6.8 and 249.1 ± 2.9 Ma), garnet (260.0 ± 11.0 Ma), and perovskite (247.3 ± 8.2 Ma), though with large uncertainties, indicate that sulfide mineralization within metasomatic and contact-metamorphic rocks is coeval with the emplacement of the Kharaelakh intrusion. These isotopic dates are in complete agreement with the published isotope dilution-thermal ionization mass spectrometry U-Pb zircon ages for the Norilsk intrusions and, at the same time, notably older than available Re-Os isochron ages of sulfides. The latter ages have been long interpreted as evidence for a prolonged duration of magmatic ore-forming processes; however, our data narrow their life span. Trace elements in titanite and garnet allow distinguishing late- and postmagmatic grains, which show indistinguishable U-Pb isotope ages.

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