Geochemical and Isotopic Study of the Xiong’er Volcanic Rocks at the Southern Margin of the North China Craton: Petrogenesis and Tectonic Implications

Abstract

Abstract The Xiong’er volcanic rocks constitute a large Paleo-Mesoproterozoic volcanic belt along the southern margin of the North China Craton. The volcanic rocks can be petrographically and geochemically classified into the basaltic andesite–andesite and dacite-rhyolite series, with the former being the dominant component of the Xiong’er volcanic rocks. The volcanic rocks of the dacite-rhyolite series have been derived from the wet and low-temperature differentiation of the basaltic andesite–andesite series at shallow depth, suggested by regional geological, lithological, and geochemical studies. In addition, crustal assimilation was involved in the magmas to form volcanic rocks of the dacite-rhyolite series, as suggested by low ϵNd(t) values (−8.09 to ∼−9.99) and high Th/Yb ratios (1.7–2.7). Some of volcanic rocks from the basaltic andesite–andesite series show features of high-Mg andesites (HMA), being characterized by high MgO contents and Mg numbers, representing the most primitive end-member of the...