Provenance of Late Carboniferous bauxite deposits in the North China Craton: New constraints on marginal arc construction and accretion processes |
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| Institution: | 1. Department of Sciences, University of Basilicata, viale dell''Ateneo Lucano 10, 85100 Potenza, Italy;2. CNR — Istituto di Metodologie per l''Analisi Ambientale, c/da S. Loya, 85050, Tito Scalo, Italy;3. CNR — Istituto di Geoscienze e Georisorse, via Ferrara 1, 27100 Pavia, Italy;1. Key Laboratory of Metallogenic Prediction of Nonferrous Metals and Geological Environment Monitoring, Ministry of Education, Central South University, Changsha 410083, China;2. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China;3. Department of Geology, University of Regina, Saskatchewan, S4S 0A2, Canada;4. Chengdu University of Technology, Chengdu, 610059, China |
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| Abstract: | The North China Craton (NCC) is bounded by two Paleozoic accretionary arc terranes: the North Qinling terrane to the south and the Bainaimiao terrane to the north. The timing of arc accretion to the NCC and the architecture of the Bainaimiao arc remain unclear. During the building and accretion of the arcs along its margins, the NCC experienced a long sedimentary hiatus since the Ordovician, which ended with the deposition of bauxite-bearing sediments in the Late Carboniferous. In this paper we report the U–Pb and Hf isotopes of detrital zircons from the Late Carboniferous bauxite layer and use these data to constrain the tectonic evolution of the margin of the NCC. The detrital zircons yield a minimum U–Pb age of ca. 310 Ma and a prominent age peak at ca. 450 Ma. Zircon crystals with ages of ca. 330 Ma and ca. 1900 Ma are more common in the bauxite samples from the northern part of the NCC than in those from the central part. The εHf(t) values of the ca. 450 Ma detrital zircon crystals of the bauxite samples from the NCC are similar to those of the contemporaneous detrital zircon crystals from the North Qinling arc terrane to the south, but different from those of the contemporaneous detrital zircon crystals from the Bainaimiao arc terrane to the north. The ca. 450 Ma detrital zircon crystals in the ca. 310 Ma bauxite deposits are therefore interpreted to have been derived from the North Qinling arc terrane. The source of the ca. 330 Ma detrital zircon crystals of the bauxite deposits is interpreted to be the northern margin of the NCC, where intermediate-felsic plutons formed at ca. 330 Ma are common. The results from this study support the interpretation that the Paleozoic continental arc terranes and their concomitant back-arc basins were developed along the margins of the NCC before ca. 450 Ma, and the arc complexes were subsequently accreted to the craton in the Late Carboniferous. This was then followed by the formation of a walled continental basin within the NCC. |
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