The Early Permian Woniusi Flood Basalts from the Baoshan Terrane, SW China: Petrogenesis and Geodynamic Implications

• 作者: CAO Jun CHEN Jun WANG Xuan ZHANG Gaizhi
• 来源期刊: 地质学报（英文版）
• 年，卷（期）: 2020,（6）
• 所属期刊栏目: Special Issue in Honor of Professor CHANG Yinfo's 90th Birthday
• 页码范围: 2091-2114
• 页数: 24页
• 语种: 英文

摘要

The Woniusi flood basalts from the Baoshan terrane, SW China, represent a significant eruption of volcanic rocks which were linked to the Late Paleozoic rifting of the Cimmeria from the northern margin of East Gondwana. However, the precise mechanism for the formation and propagation of the rifting is still in debate. Here we report 40Ar/39Ar dating, whole-rock geochemistry, and Sr-Nd-Pb isotopes for the Woniusi basalts from the Baoshan terrane of SW China, with the aim of assessing if a mantle plume was related to the formation of the continent Cimmeria. 40Ar/39Ar dating of the Woniusi basalts yielded ages of 279.3 ± 1.1 Ma and 273.9 ± 1.5 Ma, indicating they were emplaced during the Early Permian. Whole-rock geochemistry shows that these basalts have subalkaline tholeiitic affinity, low TiO2 (1.2-2.2 wt％), and fractionated chondrite-normalized LREE and nearly flat HREE patterns [(La/Yb)N = 2.86-5.77; (Dy/Yb)N = 1.21-1.49] with noticeable negative Nb and Ta anomalies on the primitive mantle-normalized trace element diagram. The ?Nd(t) values (-4.76 to +0.92) and high (206Pb/204Pb)i (18.40-18.66) along with partial melt modeling indicates that the basalts were likely derived from a sub-continental lithospheric mantle (SCLM) source metasomatized by subduction-related processes. On the basis of a similar emplacement age to the Panjal basalts and Qiangtang mafic dykes and flood basalts in the Himalayas, combined with a tectonic reconstruction of Gondwana in the Early Permian, we propose that the large-scale eruption of these basalts and dykes was related to an Early Permian mantle plume that possibly initiated the rifting on the northern margin of East Gondwana.

作者信息

序号	姓名	单位	发文数	被引次数	H指数	G指数
1	CAO Jun	中国科学院广州地球化学研究所	1	0	0.0	0.0
2	ZHANG Gaizhi	中国科学院广州地球化学研究所	1	0	0.0	0.0
3	WANG Xuan	中国科学院广州地球化学研究所	1	0	0.0	0.0
4	CHEN Jun	中国科学院广州地球化学研究所	1	0	0.0	0.0