1. Devonian–Carboniferous Pillow OIB-Type Basalts in the Youjiang Basin, SW China: Implications for the Eastern Extension of the Paleo-Tethys Branch Ocean.
- Author
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Yang, Jie, Du, Yuansheng, Huang, Hu, Yang, Jianghai, Huang, Hongwei, and Huang, Zhiqiang
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BASALT , *SUTURE zones (Structural geology) , *CONTINENTAL margins , *PILLOWS , *MAGMAS - Abstract
Late Paleozoic pillow basalts are well preserved in the Youjiang Basin of SW China. In this study, we conducted geochemical and Sr−Nd isotopic study on the Late Devonian and Late Carboniferous basalts in Napo area, Youjiang Basin. The analyzed samples comprise moderate SiO2, TiO2, Mg#, and REE contents, with slightly positive or negative Eu anomalies, similar to the chemical nature of OIB (Oceanic island basalt). All basalts show low (143Nd/144Nd)i and (87Sr/86Sr)i values, close to EMI-type (I-type Enriched Mantle) magma source. Late Carboniferous basalts display higher (87Sr/86Sr)i, Nb/Th, and lower εNd(t), Zr/Nb values than those of the Late Devonian basalts, implying progressively decreased enrichment components in the magma source processes. Such evolution trend reflects a continuous lithospheric thinning event, supporting a progressive rifting setting of the Youjiang Basin along the southwestern margin of the Yangtze Block in Late Paleozoic. Combined with regional geological background, the Youjiang Basin is viewed as a continental rift basin related to the opening of the Paleo-Tethys Ocean in Late Devonian and became a passive continental margin basin in Carboniferous. The Paleo-Tethys branch ocean probably extended further to the southern Youjiang Basin, likely corresponding to the Song Ma suture zone. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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