Petrogenesis and tectonic implications of Late-Triassic high eNd(t)-eHf(t) granites in the Ailaoshan tectonic zone (SW China)
MetadataShow full item record
High eNd(t)-eHf(t) granites are robust evidence for crustal growth. In this paper we report results of petrologic, geochronological and geochemical investigations on the Huashiban granites from the Ailaoshan tectonic zone in western Yunnan (SW China). Zircon grains separated from the two samples (10HH-119A and 10HH-120A) yield the weighted mean 206Pb/238U ages of 229.9 ± 2.0 Ma and 229.3 ± 2.3 Ma, respectively, interpreted as the crystallization ages of the granites. Based on our results, in combination with the existing U-Pb geochronological data for the Ailaoshan metamorphic rocks, we propose that the Ailaoshan Group might be a rock complex composed of the Mesoproterozoic, Neoproterozoic, Hercynian, Indosinian and Himalayan components, rather than a part of the crystalline basement of the Yangtze block. The zircon grains show highly depleted Lu-Hf isotope compositions, with positive ? Hf(t) values ranging from 8.4 to 13.1. The Huashiban granites have high SiO2 (72.66 wt%–73.70 wt%), low Mg# (0.28–0.34) with A/CNK=1.01–1.05, and can be classified as peralumious high-K calc-alkaline I-type granites. A synthesis of these data indicates that the Ailaoshan tectonic zone had evolved into a post-collisional setting by the Late-Triassic (229 Ma). Genesis of the Huashiban high ? Nd(t)-? Hf(t) granites involved into two processes: (1) underplating of the sub-arc mantle into the lower crust, and (2) remelting of the juvenile crustal materials in response to the upwelling of the asthenospheric mantle in the post-collisional setting.
Showing items related by title, author, creator and subject.
Geodynamics of the Indosinian orogeny between the South China and Indochina blocks: Insights from latest Permian- Triassic granitoids and numerical modelingLiu, H.; Wang, Y.; Li, Z.; Zi, Jianwei; Huangfu, P. (2018)The Indosinian orogeny experienced multiple subduction-collisional events along the Jinshajiang-Ailaoshan-Song Ma tectonic zone in response to closure of the Paleotethyan Ocean/back-arc basin, but the associated geodynamic ...
Sources and conditions for the formation of Jurassic post-orogenic high-K granites in the Western Guangdong Province, SE ChinaHuang, Hui-Qing (2012)High-K granites have become volumetrically important since at least Proterozoic. Their study bears important implications to crustal and tectonic evolutions. Despite of intensive research, sources and conditions for the ...
De Waele, Bert (2004)The Irumide belt is an elongate crustal province characterised by Mesoproterozoic tectonism and magmatism that stretches over a distance of approximately 900 kilometers from central Zambia to the Zambia-Tanzania border ...