Abstract:
This paper is the result of geological survey engineering.
Objective To better understand the Paleo–Mesoproterozoic tectonic evolution of the Dabie orogen in the northern margin of Yangtze Block, we demonstrated the geological and geochronological characteristics for sedimentary rocks in the Lüwang–Gaoqiao mélange.
Methods Geological mapping for the mélange was conducted. LA–ICP–MS zircon U–Pb isotopic analyses were carried out on the graphite−bearing quartzite.
Results The graphite−bearing sedimentary rocks in Lüwang–Gaoqiao mélange are dominated by sandstones with high maturity, siliceous argillaceous rock, and carbonaceous. U–Pb dating reveals that the graphite−bearing quartzite has original deposition age of ~1.43 Ga, displaying detrital zircon age peaks at 2.55 Ga, 2.06 Ga, 1.86 Ga and 1.43 Ga. The sedimentary materials mainly came from the basement of the Yangtze Block.
Conclusions The Mesoproterozoic clastic sedimentary rocks and carbonates from the Lüwang–Gaoqiao mélange were formed in a continental margin setting. They recorded an extensional regime for the Dabie orogen in the northern margin of Yangtze Block, during the break−up of the Columbia supercontinent.
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