| 川西宝兴灵关晚二叠世玄武岩成因机制——对松潘—甘孜地块起源的约束 |
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| 关键词:geochemistry Emeishan Large Igneous Province mantle plume Songpan–Ganzi Terrane Lingguan area |
| 基金项目:本文由自然资源部科技创新发展项目(编号: 102121191130000009001)、自然资源部部门预算项目(编号: 12111300000018001-02)和国家自然科学基金项目(编号: 41772057; 42572028)联合资助。 |
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| Petrogenesis of the Late Permian Basalts in Lingguan Area, Baoxing, Western Sichuan: Implications for the Origin of the Songpan–Ganzi Terrane |
| In this study, we report the mineralogical, geochemical, and Sr-Nd isotopic data of Late Permian basalts in Lingguan, Baoxing, western Sichuan Province. These basalts belong to the high-Ti alkaline basalt series. Based on the machine learning clinopyroxene thermobarometer, we estimated the crystallization temperatures and pressures to be 1 056–1 078 °C and 1.24–2.53 kbar, respectively. The chondrite-normalized rare earth element patterns and primitive mantle-normalized spidergrams showed that the Lingguan basalts have affinities with oceanic island basalt. The rocks have age-corrected 87Sr/86Sr(i) ratios of 0.705 34 to 0.705 93 and positive εNd(t) values of 2.09 to 3.42. The primary magmas of the Lingguan basalts were generated by low-degree partial melting (9%–10%) of the Emeishan mantle plume within the garnet stability field (78–85 km). Subsequently, the magma underwent slight crustal contamination (1%–2%) and fractional crystallization of olivine, pyroxene, feldspar, and Fe-Ti oxides. The geochemical and isotopic characteristics of the Late Permian Lingguan basalts indicate that they are petrogenetically related to high-Ti basalts in the Outer Zone of the Emeishan Large Igneous Province and to high-Ti basalts of the Dashibao Formation in the Songpan-Ganzi Terrane (SGT). All these basalts were formed in an intraplate-rift tectonic setting and are products of magmatism associated with the Emeishan mantle plume. At approximately 260 Ma, the upwelling of the Emeishan mantle plume triggered lithospheric extension and thinning, large-scale volcanism, and rifting along the northwestern margin of the Yangtze Craton and the southeastern margin of the SGT, leading to the following separation of the SGT from the Yangtze Craton. During the subsequent tectonic movements, some flood basalts at the northwestern margin of the Yangtze Craton overthrusted into the Lingguan area. |
| LI Hongbo,ZHOU Xiangke,HAN Liu,LI Changquan.2026.Petrogenesis of the Late Permian Basalts in Lingguan Area, Baoxing, Western Sichuan: Implications for the Origin of the Songpan–Ganzi Terrane[J].Acta Geoscientica Sinica,47(5):987-1004. |
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