Petrogenesis of Early Paleozoic lamprophyre in North Qinling Orogenic Belt and their implications
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GMGDA 2019
Petrogenesis of Early Paleozoic lamprophyre in North Qinling Orogenic Belt and their implications Jiangbo Wang 1,2 & Weihong Li 2 & Youdong Zhao 2 & Liang Zhang 2 & Lulu Wan 2 Received: 17 March 2020 / Accepted: 30 July 2020 # Saudi Society for Geosciences 2020
Abstract Early Paleozoic tectonic evolution of Qinling Orogenic Belt and Shangdan Ocean remains an argument because of the different understandings of Early Paleozoic geological records, including the petrogenesis of magmatic and metamorphic rocks and formation setting of Liuling Groups. In this paper, we present zircon U–Pb data and geochemical and isotopic compositions of the lamprophyres in the southern part of North Qinling Orogenic Belt. The lamprophyres yield zircon U–Pb ages of ca. 470 Ma and are coeval with the Early Paleozoic potassium–rich mafic rocks (Fushui complex). The lamprophyres belong to calc-alkaline series and are characterized by enrichment in large-ion lithophile elements and light rare earth elements and depletion in high field strength elements. Lamprophyre and mafic rocks, etc, the crust-like geochemical signatures represent a source feature. The lamprophyres also have high initial Sr ratios of 0.706859 to 0.713288 and enrich Nd isotopic composition with εNd(t) values of − 6.8 to − 8.3, implying that they are derived from the enriched subcontinental lithospheric mantle. In addition, the lamprophyres intrude into the supracrustal Luohansi Formation, representing their shallow intrusive level, and cross through the crust and carry the key information. In the lamprophyres, there are many Neoproterozoic zircon xenocrysts with ages of 813.3 to 825.6 Ma, which is affinity with South Qinling Orogenic Belt. This is an implication of the closure of Shangdan Ocean and collision between North Qinling Orogenic Belt and South Qinling Orogenic Belt during the formation of lamprophyre. Keywords Qinling Orogenic belt . Early Paleozoic . Lamprophyre . Tectonic evolution
Introduction Lamprophyres are common in Orogenic zone and are subdivided into four types, such as calc-alkaline, alkaline, ultramafic lamprophyre, and lamproite, which are considered to be related to an enriched mantle-derived melt (Rock 1987). The lamprophyres are generally associated with the alkaline igneous rocks and characterized by volatile-rich and dominated hydrous mafic mineralogy (Rock 1987). The different types of lamprophyre could loosely imply different tectonic settings, such as alkaline lamprophyre occurring at the This article is part of the Topical Collection on Geological Modeling and Geospatial Data Analysis * Jiangbo Wang [email protected] 1
State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, China
2
Research Institute No. 203, CNNC, Xianyang, Shanxi, China
divergent margin or continental intraplate setting (Batki et al. 2014; Lu et al. 2015) and calc-alkaline lamprophyre forming at the convergent settings (Owen 2008; Ma et al. 2014; Karsli et al. 2014). Although the lamprophyres are small
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