Petrogenesis of Paleo-Mesoproterozoic mafic rocks in the southwestern Yangtze Block of South China: Implications for tectonic evolution and paleogeographic reconstruction
- Wang, Wei
- Ernst, Richard E.
- Söderlund, Ulf
- Lan, Zufan
- Huang, Sifang
- Xue, Erkun
- Lu, Guimei
DOIAbstract
Three episodes of mafic magmatism are identified by zircon and baddeleyite U-Pb dating at 2299 ± 17 Ma, 1703 ± 8 Ma and 1511 ± 14 Ma in the southwestern Yangtze Block. These mafic rocks have tholeiitic compositions with enrichment of LILE but an absence of Nb, Ta, Zr, Hf anomalies, features similar to E-MORB. They have La/Ta (<22) and La/Nb (<1.5) ratios similar to asthenosphere-derived mafic melts. The ca. 2.3 Ga, ca. 1.7 Ga and ca. 1.5 Ga mafic rocks have εNd (t) values of +0.2 to +4.3, −2.8 to +2.8 and +0.7 to +5.8, respectively. Furthermore, the ca. 2.3 Ga and ca. 1.7 Ga mafic rocks have εHf (t) values varying from −3.6 to +0.8 and +0.1 to +9.2. All these geochemical and isotopic data indicate that the studied mafic rocks may be dominan...
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