А History of Coronitic Metagabbronorites in the Belomorian Province, Fennoscandian Shield: U-Pb (CA-ID-TIMS) Dating of Zircon–Baddeleyite Aggregates

IF 1 4区地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS

Petrology Pub Date : 2022-11-15 DOI:10.1134/S0869591122060066

E. B. Salnikova, A. V. Stepanova, P. Ya. Azimov, M. A. Sukhanova, A. B. Kotov, S. V. Egorova, Yu. V. Plotkina, E. V. Tolmacheva, A. V. Kervinen, N. V. Rodionov, V. S. Stepanov

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引用次数: 2

Abstract

The estimation of crystallization and metamorphic reworking ages of mafic rocks in the polycyclic Precambrian areas is a difficult problem. Magmatic baddeleyite can be partially or completely replaced by polycrystalline zircon within a wide range of temperature and pressures, from greenschist to granulite facies. Evaluation of the age of each phase of the zircon–baddeleyite aggregates can provide information on both the age of the magmatic crystallization and metamorphism. U-Th-Pb (SHRIMP-II) and U-Pb (ID-TIMS) geochronological studies were carried out for single baddeleyite grains and zircon–baddeleyite aggregates from gabbronorites (“drusites”) of the Ambarnsky massif (Belomorian Province, Fennoscandian Shield). The petrological studies indicate the simultaneous growth of coronas at the olivine–plagioclase boundary and zircon rims around baddeleyite. U-Pb (ID-TIMS) dating of single baddeleyite grains yielded 2411 ± 6 Ma crystallization age of gabbronorites of the Ambarnsky massif. U-Pb (ID-TIMS) dating coupled with the discrete chemical abrasion give an age of 1911 ± 35 Ma for metamorphic zircon rims. The obtained results indicate that coronitic textures in the gabbronorites were formed 500 million years later than the magmatic crystallization of rocks as a result of the granulite-facies metamorphism that was probably related to the Lapland-Kola orogeny.

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А Fennoscandian地盾Belomorian省冠状变辉长岩的历史:锆石- baddeleite聚落的U-Pb (CA-ID-TIMS)定年

多旋回前寒武纪地区基性岩结晶和变质改造时代的确定是一个难题。从绿片岩到麻粒岩相，多晶锆石在温度和压力范围内均可部分或完全取代岩浆坏辉岩。对锆石-坏辉石集合体各相年龄的评价可以提供岩浆结晶和变质作用年龄的信息。对Fennoscandian地盾省Belomorian省Ambarnsky地块辉长岩(“drusites”)中的单个坏辉长岩颗粒和锆石-坏辉长岩聚集体进行了U-Th-Pb (SHRIMP-II)和U-Pb (ID-TIMS)年代学研究。岩石学研究表明，在橄榄石-斜长石边界和坏长岩周围的锆石边缘同时生长。U-Pb (ID-TIMS)定年法测定了Ambarnsky地块辉长岩的结晶年龄(2411±6 Ma)。U-Pb (ID-TIMS)测年与离散化学磨损相结合，确定变质锆石的年龄为1911±35 Ma。结果表明，辉长岩中的冕状结构形成时间比岩石岩浆结晶晚5亿年，其成因可能与拉普兰—科拉造山运动有关。

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来源期刊

Petrology 地学-地球科学综合

CiteScore

2.40

自引率

20.00%

发文量

审稿时长

>12 weeks

期刊介绍： Petrology is a journal of magmatic, metamorphic, and experimental petrology, mineralogy, and geochemistry. The journal offers comprehensive information on all multidisciplinary aspects of theoretical, experimental, and applied petrology. By giving special consideration to studies on the petrography of different regions of the former Soviet Union, Petrology provides readers with a unique opportunity to refine their understanding of the geology of the vast territory of the Eurasian continent. The journal welcomes manuscripts from all countries in the English or Russian language.