Abstract
Abstract As a result of the evolution of Meso-Tethys, Early Cretaceous granitoids are widespread in the eastern Tengchong terrane, SW China, which is considered as the southern extension of the Tibetan Plateau. These igneous rocks are therefore very important for understanding the tectonic setting of Meso-Tethys and the formation of the Tibetan Plateau. In this paper, we present new zircon U-Pb dating, whole-rock elemental, and Nd isotopic data of granitoids obtained from the eastern Tengchong terrane. Our results show that these granitoids are composed of monzogranites and granodiorites and formed at ca. 124 Ma in the Early Cretaceous. Mineralogically and geochemically, these granitoids display metaluminous nature and affinity to I-type granites, which are derived from preexisting intracrustal igneous source rocks. The predominantly negative whole-rock εNd(t) values (−10.86 to −8.64) for all samples indicate that they are derived mainly from the partial melting of the Mesoproterozoic metabasic rocks in the lower crust. Integrating previous studies with the data presented in this contribution, we propose that the Early Cretaceous granitic rocks (135–110 Ma) also belong to I-type granites with minor high fractionation. Furthermore, in discriminant diagrams for source, granitoids are mainly derived from the partial melting of metaigneous rocks with minor sediments in the lower crust. The new identification of the Myitkyina Meso-Tethys ophiolitic suite in eastern Myanmar and mafic enclaves indicate that these Cretaceous igneous rocks were the products of the tectonic evolution of the Myitkyina Tethys Ocean, which was related to post-collisional slab rollback. Moreover, the Tengchong terrane is probably the southern extension of the South Qiangtang terrane.
Highlights
Granites, as results of tectono-thermal events, display great diversity due to the variety of their sources, evolution processes, and emplacement within different tectonic regimes and geodynamic environments (Barbarin, 1999)
The Early Cretaceous granitoids widespread in the Tengchong terrane, SW China, are prime records for understanding their tectonic environments and Sn mineralization related to synchronous magmatism (Cong et al, 2011a, 2011b; Qi et al, 2011; Luo et al, 2012; Xu et al, 2012; Cao et al, 2014; Zhu et al, 2015; Xie et al, 2016; Fang et al, 2018; Zhang et al, 2018; Qi et al, 2019)
In this study we present new zircon laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) U-Pb dating data, whole-rock geochemical, and Nd isotopic results for Early Cretaceous granites (124 Ma) from the Tengchong terrane
Summary
As results of tectono-thermal events, display great diversity due to the variety of their sources, evolution processes, and emplacement within different tectonic regimes and geodynamic environments (Barbarin, 1999). The Early Cretaceous granitoids widespread in the Tengchong terrane, SW China, are prime records for understanding their tectonic environments and Sn mineralization related to synchronous magmatism (Cong et al, 2011a, 2011b; Qi et al, 2011; Luo et al, 2012; Xu et al, 2012; Cao et al, 2014; Zhu et al, 2015; Xie et al, 2016; Fang et al, 2018; Zhang et al, 2018; Qi et al, 2019). In this study we present new zircon laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) U-Pb dating data, whole-rock geochemical, and Nd isotopic results for Early Cretaceous granites (124 Ma) from the Tengchong terrane. Combined with previous data of granitoids and mafic enclaves in this area, we provide new insights into their petrogenesis, and the dynamic setting of the Early Cretaceous
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