Late Neoarchean magmatic – metamorphic event and crustal stabilization in the North China Craton

• DOI: 10.2475/01.2021.06
• Publication Date: 2021-04-23T13:30:52Z
• Authors: Mingguo Zhai; Lei Zhao; Xiyan Zhu; Yanyan Zhou; Peng Peng; Jinghui Guo; Qiuli Li; Taiping Zhao; Junsheng Lu; Xianhua Li
• Keywords: Felsic; Greenstone belt; Basement

The <i>ca</i>. 2.5 Ga as the time boundary between Archean and Proterozoic eons is a landmark, indicating most important continental crust evolving stage of Earth, that is, global cratonization or formation supercraton(s) was unseen before unrepeated in following history Earth9s evolution. North China Craton (NCC) one best recorders event, therefore studies thorough understanding early Precambrian evolution are continuous. period from 2.8 to 2.6 major crustal growth NCC formed seven micro-blocks. All micro-blocks were surrounded by 2.54 greenstone belts. clear geological presentations follows: (1) Archaic basement rocks (various micro-blocks) experienced strong partial melting migmatization. granitoid derived include potassium, TTG monzonitic granitoids, which come, respectively, (sedimentary with gneisses), juvenile (mafic gneisses) mixed crust; (2) BIF-bearing supracrustal mainly distribute lithologic associations belts within broadly similar, belonging volcano-sedimentary sequences, common bimodal volcanic (basalt dacite) interlayered minor amounts komatiites lower part, calc-alkalic (basalt, andesite felsic rocks) upper part; (3) nearly all old &gt;2.5 underwent ∼2.52 metamorphism amphibolite–granulite facies. Most metamorphosed show high-temperature-ultra-high-temperature (HT–UHT) characteristics record anticlockwise <i>P–T</i> paths, albeit small number granulites seemingly high-pressure granulite facies clockwise paths; (4) ∼2.5 mafic dikes (amphibolites), granitic (veins) syenitic–ultramafic developed across these archaic basements strongly deformed un-deformed; (5) extensive 2.52 2.48 low-grade metamorphic covers has been recognized eastern, northern central parts NCC, commonly composed bi-modal sedimentary rocks. above mentioned their characters imply have united through amalgamation form NCC. late Neoarchean belts, syn-formed mobile welded at end Neoarchean. However, thermal grades than those high-grade terranes micro-blocks, suggesting latter might under higher geothermal gradient former. Besides, surround various when both oceanic hotter. subduction during amalgamation, if it happened, must much smaller scale compared Phanerozoic plate tectonic regime, stages occurred crust-scale instead lithosphere-scale mantle-scale. This why HT-UHT anti-clockwise metamorphism, while only few samples paths. micro-block accompanied granitization, finally gave rise stabilization Except for vast intrusions, mafic-syenitic dike swarms also landmarks cratonization. epoch-making although accomplishment cratons somewhat different time. Cratonization declared global-scale supercratons cratonic groups coupling lithosphere, followed “silent period” rare tectonic-thermal action lasting 150 200 Ma (from – 2.3 2.35 Ga), then Great Oxidation Event (GOE).