Scholarlink

Abstract <p>The supracrustal strata of the Larba block of the Dzhugdzhur–Stanovoy superterrane are dominated by crystalline schists and garnet-biotite-cordierite ± sillimanite gneisses, which are intruded by charnockites and enderbites. The studied metasedimentary aluminous gneisses underwent moderate-pressure granulite-facies metamorphism (7–8 kbar, 800–850°C) and regressive transformations under transitional conditions from the granulite to amphibolite facies (4–5 kbar, 620–730°C), with a subsequent decrease in parameters to the conditions of the chlorite-muscovite subfacies of the greenschist facies metamorphism. Chemical (Th–U–Pb) and isotope-geochemical (U–Pb ID-TIMS) analysis of monazite grains showed that the gneisses were metamorphosed in the Archean and Proterozoic. They underwent Archean granulite-facies metamorphism 2.65 Ga ago, and Proterozoic transformations of the granulites became intense ~1.8 Ga ago. The first direct dating of metasedimentary rocks reveals the earliest Archean metamorphic events, which is important for establishing the upper age limit for the accumulation of sedimentary strata in the Larba block.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Archean Metamorphism of Al-Rich Gneisses of the Larba Block in the Ilikan Zone of the Dzhugdzhur–Stanovoy Superterrane

  • 期刊论文

  • 发表日期：

    2026年6月15日

查看全文
  • A. V. Yurchenko,
  • N. G. Rizvanova,
  • O. L. Galankina,
  • Sh. K. Baltybaev

摘要

Abstract

The supracrustal strata of the Larba block of the Dzhugdzhur–Stanovoy superterrane are dominated by crystalline schists and garnet-biotite-cordierite ± sillimanite gneisses, which are intruded by charnockites and enderbites. The studied metasedimentary aluminous gneisses underwent moderate-pressure granulite-facies metamorphism (7–8 kbar, 800–850°C) and regressive transformations under transitional conditions from the granulite to amphibolite facies (4–5 kbar, 620–730°C), with a subsequent decrease in parameters to the conditions of the chlorite-muscovite subfacies of the greenschist facies metamorphism. Chemical (Th–U–Pb) and isotope-geochemical (U–Pb ID-TIMS) analysis of monazite grains showed that the gneisses were metamorphosed in the Archean and Proterozoic. They underwent Archean granulite-facies metamorphism 2.65 Ga ago, and Proterozoic transformations of the granulites became intense ~1.8 Ga ago. The first direct dating of metasedimentary rocks reveals the earliest Archean metamorphic events, which is important for establishing the upper age limit for the accumulation of sedimentary strata in the Larba block.