The Rb-Sr Geochronology and Isotopic Geochemistry of Ore-Hosting Rocks and Wall-Rock Metasomatites of the Mesothermal Taloveis Gold Deposit, Western Karelia

摘要

Archean greenstone-hosted mesothermal deposits referred to as "lode-gold deposits" are of great importance among economic-grade gold deposits. Differently sized deposits of this type (including large and unique ones) have been scrutinized and exploited in the majority of the world's granite-greenstone terranes (GGT) except the Karelian GGT (Baltic Shield), where only a few small gold deposits and occurrences have been found. The question arises as to whether this is related to specifics of tectonic evolution and gold deposit formation in the Karelian GGT in Archean or lithostructural reworking of Archean gold deposits and redistribution of Au in Paleoprotero-zoic. There are grounds to suppose a significant contribution of redistribution, since the Karelian Block is distinguished from other Archean cratons with a large-scale gold mineralization by intense reworking during the Svecofennian orogeny 1.95-1.80 Ga ago. This was accompanied by the formation of mesothermal gold mineralization in both Archean and Paleoproterozoic complexes. The estimation of scales of Svecofennian ore processes in the Karelian block and their influence on Archean gold mineralization is of great practical significance. The mineralization age is the main criterion for selecting tectonic structures that show promise of having mesothermal deposits. In addition, the mineralization scale can be preliminarily estimated based on its age, since Paleoproterozoic gold deposits are significantly less productive than Archean ones.