The petrogenesis of the two-stage A-type granites from the Niujuan silver deposit in the northern margin of North China Craton and their tectonic implications

Yan, Xiang; Chen, Bin; Wang, Zhi–Qiang; Duan, Xiaoxia

doi:10.18654/1000-0569/2019.02.18

Cited by 3 publications

(1 citation statement)

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“…Along the Jiangnan Orogen, a number of 850–820 Ma S‐type granites intruded into the folded basement, including the Jiuling pluton in Jiangxi Province (Sun et al, 2017; Zhong et al, 2005), the Xucun, Shexian and Xiuning plutons in Anhui Province (Wu et al, 2006; Xue et al, 2010; Zheng et al, 2008), and the Sanfang, Bengdong, Yuanbaoshan and Motianling plutons in Guangxi and Guizhou provinces (Li et al, 2003; Ma et al, 2016; Wang et al, 2006).…”

Section: Geological Background and Samplingmentioning

confidence: 99%

Geochronology and geochemistry of basalts from the Yingchuan Formation, eastern Jiangnan Orogen: Implications for the Neoproterozoic tectonic evolution of the South China Block

Chen

Wang

et al. 2023

Geological Journal

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The Neoproterozoic magmatism along the Jiangnan Orogen preserves significant information for understanding the tectonic evolution of the South China Block (SCB). We conducted a systematic zircon U–Pb geochronological and whole‐rock geochemical study on the basalts from the Yingchuan Formation in the eastern Jiangnan Orogen, SCB. The basalts yielded a weighted mean 206Pb/238U age of 817 ± 13 Ma, enriched in Rb, Th, U, LREE and HFSE (e.g., Zr and Ti). The basalts have positive εNd(t) (+1.9 to +2.1) and high (87Sr/86Sr)i (0.69853–0.70737), indicating a slightly depleted mantle source. The high La/Nb (2.14–2.35) and La/Ta (28.6–33.3) ratios indicate a lithospheric mantle source for the basalts. Their high Ba/Yb (7.85–44.3) and Th/Yb (0.59–0.74) ratios and high absolute Nb contents (7.64–11.6 ug/g) indicate that the lithospheric mantle source has been metasomatized by melts and fluids derived from a subducted slab. The basalts are characterized by (La/Yb) N ratios (3.0–3.5) and Sm/Nd ratios (0.24–0.26), comparable to intra‐continental back arc basin basalts (BABBs). Their Ta/Yb (0.14–0.16) and Th/Yb (0.59–0.74) ratios are similar to those of Okinawa Trough basalts and contemporary mafic rocks formed in the back‐arc basin in the Jiangnan Orogen. Combined with their source features, we propose that the basalts were formed in a back‐arc basin setting. The identification of BABBs from the Yingchuan Formation shows that there were Neoproterozoic back‐arc basins in the south‐eastern Yangtze Block, indicating that the final assembly between the Yangtze and Cathaysia blocks did not occur before ca. 817 Ma.

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