Depositional age and genesis of the host strata of the Shuangjianzishan Ag–Pb–Zn deposit: Implications for the Late Carboniferous magmatic–hydrothermal activities and tectonic evolution of the eastern central Asia orogenic belt

Geological characteristics and genesis of the Late Carboniferous extremely thick slate in the Shuangjianzishan Ag-Pb-Zn district, southern Great Xing’an Range, NE China: constraints on metallogenesis and tectonic setting

“…Previous studies on the zircon oxygen isotope composition of the interlayer tuff indicate wide variations in δ 18 O values, mostly lower than the mantle value (5.3‰ ± 0.3‰; Valley et al, 2005). This may be attributed to the remelting of hydrothermally altered rocks in the continental rift (Gong et al, 2021). The lithosphere stretching caused by the continental rift setting enhances the subterranean heat and provides enough heat for the magmawallrock reaction so that the surface water can penetrate the depth of at least 10-15 km, and then a notable high-temperature water-rock reaction occurs (Bindeman, 2008;Watts et al, 2011;Drew et al, 2013).…”

“…Normalized values of the North American shale were cited from Gromet et al (1984). The whole-rock major and trace element data of the drilling cores ZK12 were cited from Gong et al (2021).…”

“…An Eu-positive anomaly in marine sediments is generally attributed to two conditions: the addition of calcium-rich volcanic ash during deposition or the influence of high-temperature-reducing hydrothermal fluids rich in Eu 2+ during deposition (Douville et al, 1999). In the slate samples from the Shuangjianzishan basin, interlayer tuff has been identified (Gong et al, 2021), suggesting that the Eu-positive anomaly may be related to the addition of calcium-rich volcanic ash and hydrothermal activity. It is proposed that the slate was formed in seawater under the influence of magmatic-hydrothermal fluids (Owen et al, 1999).…”

“…Petrographic observations reveal that the primary mineral particle sizes are all within 50 μm, making it challenging to distinguish mineral assemblages and cement types under a polarizing microscope. Through zircon U-Pb dating and Monte Carlo simulation, Gong et al (2021) have constrained the maximum duration of the 2030 m thick strata in the Shuangjianzishan basin to 6.9 Ma. They have also determined that the minimum sedimentation rate of the slate is 294 m/Myr, equivalent to the lacustrine sedimentation rate observed in the East African Rift Zone (Bourrouilh, 1987;Eberli and Ginsburg, 1987;Einsele, 2000) and much higher than that of forearc basins (Doubleday et al, 1993;Vannucchi et al, 2003;Butterworth, 2009;Rains et al, 2012).…”

“…The Dashizhai Formation, widely distributed in the Shuangjianzishan basin, is identified as the host rock of the Shuangjianzishan Ag-Pb-Zn deposit, primarily comprising slate, siltstone, and intermediate volcanic rock. The formation age remains controversial, with the volcanic rock being attributed to the Early Permian (Yu et al, 2017;Zhang et al, 2018), while the interlayer tuff of the slate has been dated to the Late Carboniferous (Gong et al, 2021). Therefore, we temporarily define the Dashizhai Formation as a diachronic stratum, with the formation age between the Late Carboniferous and the Early Permian.…”