Geochemistry and geochronology of Carboniferous volcanic rocks in the eastern Junggar terrane, NW China: Implication for a tectonic transition

Tectonic framework of the northern Junggar Basin part I: The eastern Luliang Uplift and its link with the East Junggar terrane

“…Their TiO 2 contents range from 1.52 to 3.76%, Al 2 O 3 from 13.46 to 17.20%, and MgO from 2.45 to 10.95%, TFe 2 O 3 from 9.42 to 15.06% and P 2 O 5 from 0.26 to 1.07%. The Su et al (2010Su et al ( , 2012. Data for the Karamaili ophiolites are from Ma (2007) and Liu et al (2007), and the enriched mantle EMI and EMII members (Hart, 1988) are shown for comparison.…”

“…All the initial 87 Sr/ 86 Sr ratios and ε Nd (t) values were calculated using the new age of 308.6 Ma reported in this study. The Sr-Nd isotope data are plotted in terms of ε Nd (t) values versus initial 87 Sr/ 86 Sr ratios and compared with the reported compositional fields of Karamaili ophiolites and Carboniferous basalts in the East Junggar terrane Ma, 2007;Su et al, 2012). The Late Carboniferous basalts in the eastern Luliang Uplift show a wide variation of Sr-Nd isotopic compositions, with ( 87 Sr/ 86 Sr) i = 0.703571-0.705122, ε Nd (t) = 5.5-8.6 and young Nd model ages (T DM ) of 405-858 Ma.…”

Geochemistry, zircon U–Pb ages and Lu–Hf isotopes of early Paleozoic plutons in the northwestern Chinese Tianshan: Petrogenesis and geological implications

“…8), suggesting an origin from a depleted mantle source. These mafic rocks exhibit negative Ta, Nb, Ti anomalies, which are distinct from those of depleted asthenosphere-derived magmas (N-MORB) and oceanic island basalts (OIB) since such basic rocks generally have very low primitive mantle-normalized (Th/Nb) PM ratios of b1 (Saunders et al, 1992;Su et al, 2012). However, the early Paleozoic mafic rocks in this study have much higher (Th/Nb) PM ratios (0.74-7.16), suggesting a magma source different from N-MORB.…”

“…It is suggested that mantle-derived components or juvenile crust have played an important role in the generation of these granitoids in Central Asia Jahn et al, 2000Jahn et al, , 2004Sengör et al, 1993;Windley et al, 2007). Based on recent Hf and Nb isotopic studies, several important crustal growth events were proposed to have occurred in various parts of the CAOB during the Phanerozoic, namely at 280-306 Ma, 315-306 Ma and 345-463 Ma (Cai et al, , 2011Geng et al, 2009;Lei et al, 2011;Su et al, 2012;Sun et al, 2008;Tang et al, 2010bTang et al, , 2012aWang et al, 2011b;Xu et al, 2010;Yin et al, 2010Yin et al, , 2013Yuan et al, 2007;Zhang et al, 2012;and this study).…”

Organofacies and paleoenvironment of lower Carboniferous mudstones (Dishuiquan Formation) in Eastern Junggar, NW China

“…1b). Using U-Pb methods, the Zhaheba-Aermantai ophiolite belt was dated to 489 ± 4-503 ± 7 Ma (Jian et al, 2003;Tang et al, 2007;Xiao et al, 2006;Zhang and Guo, 2010), whereas the Karamaili ophiolite belt has an early Devonian to early Carboniferous age based on SHRIMP zircon U-Pb methods (Su et al, 2012). The geochemical characteristics of the lower Carboniferous volcanic rocks reveal that early Carboniferous volcanism occurred in an island-arc setting related to the subduction of the Paleo-Junggar Ocean (Su et al, 2012;Xiao and Santosh, 2014;Yang et al, 2012a,b).…”