TY - JOUR
T1 - Neoproterozoic ultramafic-mafic-carbonatite complex and grantoids in Quruqtagh of northeastern Tarim Block, western China: Geochronology, geochemistry and tectonic implications
AU - Zhang, C-L.
AU - Li, X-H.
AU - Li, Zheng-Xiang
AU - Lu, S-N.
AU - Ye, H-M.
AU - Li, H-M.
PY - 2007
Y1 - 2007
N2 - U-Pb zircon and baddeleyite ages, and geochemical and Nd isotopic data, are reported for a ultramafic-mafic-carbonatite complex and granites in Quruqtagh of northeastern Tarim Block, NW China. The carbonatite and plagioclase-bearing pyroxenite from the Qiganbulake matic-ultramatic-carbonatite ring complex (QMC), the Xingdi granodiorite and the Taiyangdao granite were emplaced at 810 +/- 6, 818 11, 820 +/- 10 and 795 +/- 10 Ma (95% confidence level), respectively. The QMC is composed of dunite, apatite-and/or feldspar-bearing pyroxenite, pyroxenite, phlogopitelite and carbonatite. Petrography, geochemistry and mineral chemistry suggest that the QMC rocks were generated by partial melting of a CO2-metasomatized mantle in a rifting environment. The Xingdi and Taiyangdao granitoids possess high LREE, Na2O/K2O, Sr/Y, (La/Yb)(N) ratios and low HREE and HFSE contents, similar to modem adakites. However, they have lower MgO (or Mg-#), Cr and Ni contents and unradiogenic Nd isotopes (pronounced negative epsilon Nd(t) value of - 12.7 to - 17.3 and Neoarchaean Nd model ages) than slab-derived adakites. Thus, they were likely formed by partial melting of Neoarchaean mafic protoliths in the lower crust, leaving behind a granulite residue. The QMC and the granitoids in Quruqtagh constitute a bimodal intrusive suite in a Neoproterozoic, continental rift setting, possibly related to mantle plume activities beneath the Rodinian supercontinent. (c) 2006 Elsevier B.V. All rights reserved.
AB - U-Pb zircon and baddeleyite ages, and geochemical and Nd isotopic data, are reported for a ultramafic-mafic-carbonatite complex and granites in Quruqtagh of northeastern Tarim Block, NW China. The carbonatite and plagioclase-bearing pyroxenite from the Qiganbulake matic-ultramatic-carbonatite ring complex (QMC), the Xingdi granodiorite and the Taiyangdao granite were emplaced at 810 +/- 6, 818 11, 820 +/- 10 and 795 +/- 10 Ma (95% confidence level), respectively. The QMC is composed of dunite, apatite-and/or feldspar-bearing pyroxenite, pyroxenite, phlogopitelite and carbonatite. Petrography, geochemistry and mineral chemistry suggest that the QMC rocks were generated by partial melting of a CO2-metasomatized mantle in a rifting environment. The Xingdi and Taiyangdao granitoids possess high LREE, Na2O/K2O, Sr/Y, (La/Yb)(N) ratios and low HREE and HFSE contents, similar to modem adakites. However, they have lower MgO (or Mg-#), Cr and Ni contents and unradiogenic Nd isotopes (pronounced negative epsilon Nd(t) value of - 12.7 to - 17.3 and Neoarchaean Nd model ages) than slab-derived adakites. Thus, they were likely formed by partial melting of Neoarchaean mafic protoliths in the lower crust, leaving behind a granulite residue. The QMC and the granitoids in Quruqtagh constitute a bimodal intrusive suite in a Neoproterozoic, continental rift setting, possibly related to mantle plume activities beneath the Rodinian supercontinent. (c) 2006 Elsevier B.V. All rights reserved.
U2 - 10.1016/j.precamres.2006.11.003
DO - 10.1016/j.precamres.2006.11.003
M3 - Article
SN - 0301-9268
VL - 152
SP - 149
EP - 169
JO - Precambrian Research
JF - Precambrian Research
IS - 3-4
ER -