Pb-Pb and U-Pb Dating of Cassiterite by In Situ LA-ICPMS: Examples Spanning ~1.85 Ga to ~100 Ma in Russia and Implications for Dating Proterozoic to Phanerozoic Tin Deposits

Leonid A Neymark,Anatoly M Larin,Richard J Moscati

doi:10.3390/min11111166

Leonid A Neymark, Anatoly M Larin + Show 1 more

Open Access

https://doi.org/10.3390/min11111166

Copy DOI

Journal: Minerals	Publication Date: Oct 22, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: Denver Federal Center, United States Geological Survey

Abstract

This paper investigates applicability of cassiterite to dating ore deposits in a wide age range. We report in situ LA-ICPMS U-Pb and Pb-Pb dating results (n = 15) of cassiterite from six ore deposits in Russia ranging in age from ~1.85 Ga to 93 Ma. The two oldest deposits dated at ~1.83–1.86 Ga are rare metal Vishnyakovskoe located in the East Sayan pegmatite belt and tin deposits within the Tuyukan ore region in the Baikal folded region. Rare metal skarn deposits of Pitkäranta ore field in the Ladoga region, Fennoscandian Shield are dated at ~1.54 Ga. Cassiterite from the Mokhovoe porphyry tin deposit located in western Transbaikalia is 810 ± 20 Ma. The youngest cassiterite was dated from the deposits Valkumei (Russian North East, 108 ± 2 Ma) and Merek (Russian Far East, 93 ± 2 Ma). Three methods of age calculations, including 208Pb/206Pb-207Pb/206Pb inverse isochron age, Tera-Wasserburg Concordia lower intercept age, and 207Pb-corrected 206Pb*/238U age were used and the comparison of the results is discussed. In all cases, the dated cassiterite from the ore deposits agreed, within error, with the established period of magmatism of the associated granitic rock.

Highlights

Cassiterite (SnO2 ), a main ore mineral in tin deposits, is suitable for in situ U-Pb isotopic dating using laser ablation inductively coupled plasma mass spectrometry (LAICPMS) because of its relatively high U/Pb ratios and typically low initial “common”Pb (Pbc )
The data discussed in this paper show that the inverse 208 Pb/206 Pb-207 Pb/206 Pb isochron approach can be successfully applied to dating older (Proterozoic) cassiterite using spot analyses with low (
LA-ICPMS U-Pb and Pb-Pb ages of cassiterite from six ore deposits from Russia located in the Baltic Shield, Eastern Siberia, Russian North East, and the Russian far east range from ~1.85 Ga to ~93 Ma

Summary

Introduction

Cassiterite (SnO2 ), a main ore mineral in tin deposits, is suitable for in situ U-Pb isotopic dating using laser ablation inductively coupled plasma mass spectrometry (LAICPMS) because of its relatively high U/Pb ratios and typically low initial “common”Pb (Pbc ). Cassiterite (SnO2 ), a main ore mineral in tin deposits, is suitable for in situ U-Pb isotopic dating using laser ablation inductively coupled plasma mass spectrometry (LAICPMS) because of its relatively high U/Pb ratios and typically low initial “common”. Cassiterite is highly resistant to acid dissolution [17], which makes it difficult to achieve the complete acid digestion and spike homogenization needed for accurate isotope dilution and thermal ionization mass spectrometry (ID-TIMS) U-Pb dating. Several recent publications [18,19,20] showed that complete dissolution of cassiterite and reliable ID-TIMS dating results are achievable. These publications provide the basis for the usage of better characterized matrix-matched reference materials for in situ analyses of cassiterite

Methods

Results

Discussion

Conclusion