In situ Rb-Sr dating of fine-grained vein mineralizations using LA-ICP-MS

M Tillberg, H Drake, T Zack, J Hogmalm… - Procedia Earth and …, 2017 - Elsevier
Procedia Earth and Planetary Science, 2017Elsevier
Direct mineral dating is critical for thorough understanding of the genesis of hydrothermal
mineralizations, ore forming processes and events of fracturing and related fluid-rock
interaction. Since minerals of suitable type and sample volume for conventional techniques
can be rare, development of high-precision in situ Rb-Sr dating of common rock-forming
minerals such as micas, feldspars and calcite offers possibilities to gain temporal constraints
of a wide variety of geological features with detailed spatial and depth resolution. This …
Abstract
Direct mineral dating is critical for thorough understanding of the genesis of hydrothermal mineralizations, ore forming processes and events of fracturing and related fluid-rock interaction. Since minerals of suitable type and sample volume for conventional techniques can be rare, development of high-precision in situ Rb-Sr dating of common rock-forming minerals such as micas, feldspars and calcite offers possibilities to gain temporal constraints of a wide variety of geological features with detailed spatial and depth resolution. This technique separates 87Sr from 87Rb by introducing a reaction gas between two quadropoles in a LA-ICP-MS system. In this study, in situ Rb-Sr geochronology distinguishes the timing of several different fracture-controlled hydrothermal events: 1 and 2) greisen mineralizations and associated far-field hydrothermal veins adjacent to a granite intrusion, 3) reactivation events within a mylonite shear zone and 4) low-temperature precipitation from saline organic-rich brines in thin veinlets. We demonstrate that in situ Rb-Sr dating is feasible for a broad range of mineral assemblages, textures, temperatures and ages, emphasizing the impending use of this new method in ore deposit exploration and many other research fields.
Elsevier
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