In Situ Rb-Sr Dating of Fine-grained Vein Mineralizations Using LA-ICP-MS

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• 作者：Mikael Tillberg^a ; ^{Mikael.tillberg@lnu.se} ; Henrik Drake^a ; Thomas Zack^b ; Johan Hogmalm^b ; Mats Å ; strö ; m^a
• 关键词：geochronology ; in situ Rb-Sr dating ; greisen ; hydrothermal veins ; LA-ICP-MS
• 刊名：Procedia Earth and Planetary Science
• 出版年：2017
• 出版时间：2017
• 年：2017
• 卷：17
• 期：Complete
• 页码：464-467
• 全文大小：308 K
• 卷排序：17

文摘

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.