Abstract Neoproterozoic ophiolites in the southeastern margin of the Yangtze Block record tectonic evolution of South China. The ∼1.0 Ga Xiwan ophiolite and the ca. 830 Ma Fuchuan ophiolite indicate a long-term assembly of the Yangtze and Cathaysia blocks during the Neoproterozoic time. Peridotites from the Xiwan ophiolite show high Al2O3 (1.24–2.67 wt%) and low MgO contents (39.61–44.26 wt%), similar to the abyssal and back-arc peridotites that experienced low degrees of partial melting. Their U-shaped REE patterns and HFSE enrichment indicate weak melt metasomatism. Whole rock 187Re/188Os (0.09–0.29) and 187Os/188Os ratios (0.11526–0.12193) yield a melt-extraction age of 1.8–2.1 Ga. However, peridotites from the Fuchuan ophiolite are more refractory and have low Al2O3 (0.51–0.95 wt%) and high MgO contents (43.99–48.24 wt%), similar to the forearc peridotites that underwent high degrees of melt extraction. Their 187Re/188Os (0.01–1.08) and 187Os/188Os (0.11852–0.12867) variations may have resulted from fluxed melting induced by the subduction-related fluids. The peridotites, in combination with the overlying mafic oceanic crustal rocks, suggest that the Xiwan and Fuchuan ophiolites are SSZ-type ophiolites which were formed in back-arc and forearc settings, respectively, followed by the collision between the Yangtze and Cathaysia blocks at ca. 830 Ma.

中文翻译：

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华南扬子地块与华夏地块并合：蛇绿岩地球化学证据

摘要 扬子地块东南缘新元古代蛇绿岩记录了华南构造演化。∼1.0 Ga Xiwan 蛇绿岩和约。830 Ma 富川蛇绿岩表明扬子地块和华夏地块在新元古代长期聚集。来自西湾蛇绿岩的橄榄岩显示出高 Al2O3 (1.24–2.67 wt%) 和低 MgO 含量 (39.61–44.26 wt%)，类似于深海和弧后橄榄岩经历了低程度的部分熔融。它们的 U 形 REE 模式和 HFSE 富集表明熔体交代作用较弱。全岩 187Re/188Os (0.09–0.29) 和 187Os/188Os 比值 (0.11526–0.12193) 产生的熔体提取年龄为 1.8–2.1 Ga。 然而，富川蛇绿岩橄榄岩的耐火度更高。 wt%) 和高 MgO 含量 (43.99–48.24 wt%)，类似于经历了高度熔融提取的弧前橄榄岩。它们的 187Re/188Os (0.01–1.08) 和 187Os/188Os (0.11852–0.12867) 变化可能是由俯冲相关流体引起的熔融熔融引起的。橄榄岩与上覆的镁铁质洋壳岩相结合，表明西湾和富川蛇绿岩是SSZ型蛇绿岩，分别形成于弧后和弧前环境，随后是扬子地块和华夏地块的碰撞。 . 830 马。表明西湾和富川蛇绿岩是 SSZ 型蛇绿岩，分别形成于弧后和弧前环境，随后在约 830 马。表明西湾和富川蛇绿岩是 SSZ 型蛇绿岩，分别形成于弧后和弧前环境，随后在约 830 马。