Late Palaeozoic tectonic evolution of the southern North China Craton: Constraints from detrital zircon dating and Hf–O isotopic compositions of the Benxi Formation, Sanmenxia area, North China Craton

Abstract

This study presents new detrital zircon laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) U–Pb ages and in situ Hf–O isotopic data in order to constrain the depositional age and provenance of the Benxi Formation in the Sanmenxia area of the southern North China Craton (NCC). Detrital zircons in quartz sandstone drillcore from the Benxi Formation are euhedral–subhedral, oscillatory zoned, and have high Th/U ratios (0.03–1.60, generally greater than 0.3) that are indicative of a magmatic origin. Detrital zircons from samples 13H16A and 13H16B yield seven (2544, 1788, 1123, 955, 737, 441, and 344 Ma) and six main age populations (2440, 1583, 951, 759, 434, and 348 Ma), respectively. The εHf(t) values of the Neoarchean–Paleoproterozoic zircons range from −11.3 to +13.9, and these zircons have δ18O values that range from 5.68‰ to 8.83‰. The Neoproterozoic zircons have variable εHf(t) (−9.2 to +12.5) and δ18O (5.58‰ to 9.85‰) values, whereas the Palaeozoic zircons have εHf(t) values between −19.9 and +13.4 and δ18O values of 5.23‰–9.43‰. The Benxi Formation was deposited during the late Carboniferous and contains sediments derived from igneous rocks of the North Qinling Orogen combined with a small amount of material derived from Precambrian basement of the NCC. The northward subduction of the South Qinling Orogen caused the uplift and erosion of the North Qinling Orogen during the late Carboniferous.

Age, geochemistry, mineralization, and tectonic significance of felsic‐intermediate dikes in Shuangqishan Au deposit, Cathaysia block, South China

“…The initial 176 Hf/ 177 Hf ratio, εHf (t), 176 Hf/ 177 Hf ratio (0.282772) and 176 Lu/ 177 Hf ratio (0.0332) refer to the literature for a detailed description (Blichert-Toft & Albarède, 1997). The singlestage Hf model ages (T DM1 ) are calculated based on a depleted-mantle source with a 176 Hf/ 177 Hf ratio of 0.28325 and using a 176 Lu decay constant of 1.865 Â 10 À11 year À1 (Scherer et al, 2001), the parameters and detailed calculation process of two-stage Hf model ages (T DM2 ) see the paper (Griffin et al, 2000;Huang et al, 2016). F I G U R E 9 Cathode luminescence (CL) images of zircons from the granites of the Shuangqishan Au deposit.…”