The Oldest Grey Gneisses and Tonalite-Trondhjemite Granodiorites in the Fennoscandian Shield: ID-TIMS and SHRIMP Data
The Oldest Grey Gneisses and Tonalite-Trondhjemite Granodiorites in the Fennoscandian Shield: ID-TIMS and SHRIMP Data作者机构：Geological Institute KSC RAS Apatity Russian Federation A.P. Karpinsky Russian Geological Research Institute (VSEGEI) St. Petersburg Russian Federation Institute of Geology and Mineralogy Siberian Branch RAS Novosibirsk Russian Federation
出 版 物：《Open Journal of Geology》 (地质学期刊（英文）)
年 卷 期：2020年第10卷第2期
页 面：124-136页
学科分类：070902[理学-地球化学] 0709[理学-地质学] 07[理学]
主 题：Fennoscandian Shield Geochronology Hadean ID-TIMS SHRIMP TTG Grey Gneiss
摘 要：Genesis of the oldest continental crust retains a marked trace in the Earth’s evolution over its 4.5 Ga history. Despite ample isotope data on the role of the continental crust in the Earth’s evolution, there has been much debate on the origin of grey gneisses and tonalite-trondhjemite-granodiorites (TTG). Precise U-Pb (ID-TIMS) and SHRIMP data on single zircon for paragneisses and TTG (3158.2 ± 8.2 Ma) have indicated the Central-Kola and Belomorian (White Sea) megablocks of the Fennoscandian Shield to be 3.16 Ga and 3.70 Ga, respectively. The newly obtained ages of zircon from these megablocks indicate the origin of the discrete continental crust to be 3.16 and 3.70 Ga. It is close to the Nordsim zircon data on the Siurua TTG (Finland), which are 3.45 and 3.73 Ga in the core. The new summarized data on the Earth’s oldest rocks (basement and continental crust) indicate the younger age of the rocks in the Fennoscandian Shield as compared to those in Australia (Kronendonk et al., 2019).
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