Early Paleoproterozoic Post-Collisional Basaltic Magmatism in Quanji Massif: Implications for Precambrian Plate Tectonic Regime in NW China
Hassan Abdelslam Mustafa, Fanxi Liao, Nengsong Chen, Zhendong You, Meshaal Abdelgadir Salih, Lu Wang, Lu Zhang
Journal of Earth Science ›› 2022, Vol. 33 ›› Issue (3) : 706-718.
Early Paleoproterozoic Post-Collisional Basaltic Magmatism in Quanji Massif: Implications for Precambrian Plate Tectonic Regime in NW China
Basaltic magmas can provide important information about mantle source nature, tectonic settings and tectonic evolution for a given terrain. This paper reports geology, petrography and geochemistry of whole-rock major and trace elements and Nd−Sr isotopes for a suite of garnet amphibolites from southeastern Wulan (Ulan), Quanji Massif, northwestern China. The garnet amphibolites were likely generated from basaltic lavas, associated with both paragneisses and orthogneisses of the lower Delingha Group. The basaltic protolith of these amphibolites can be broadly constrained to be formed at ∼2.33 Ga in an extensional setting post-collision. The geochemistry of amphibolites shows subalkaline and highly evolved characteristics. They display high-Fe low-Ti characteristics, with TFeO of 13.1 wt.%–17.9 wt.% and TiO2 of 1.42 wt.%–3.09 wt.% (in most samples TiO2 ⩽2.5 wt.%). The chondrite-normalized REE patterns show enrichment of LREE and LILE and the primitive-mantle-normalized incompatible element patterns display negative P, Ti, Nb−Ta and Zr−Hf anomalies. The (87Sr/86Sr), values of 0.697 8–0.712 3 and ε Nd(t) values of −2.81–5.08 respond to depleted mantle model ages (T DM) of 2.33–3.30 Ga. These suggest that the precursor magmas of the protolith of the garnet amphibolites were probably derived from the Early Paleoproterozoic depleted sub-continental lithospheric mantle that had been metasomatized by subduction-induced fluids and melts. The precursor basaltic magmas were contaminated by the older crustal components during magma ascending. This post-collisional basaltic magmatic event at ∼2.33 Ga in Quanji Massif thus enhanced the subduction shutdown or slowdown tectonic regime both in NW China and coevally with those plate tectonics in some important domains worldwide during the Early Paleoproterozoic.
amphibolite / geochemistry / NW China / post-collisional magmatism / Precambrian tectonic evolution
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Ernst, R. E., Buchan, K. L., 2001. Large Mafic Magmatic Events Through Time and Links to Mantle Plume Heads. In: Ernst, R. E., Buchan, K. L., eds., Mantle Plumes: Their Identification through Time. Special Paper Geological Society of America, 352: 483–575. https://doi.org/10.1130/0-8137-2352-3.483
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Pearce, J. A., 1982. Trace Element Characteristics of Lavas from Destructive Plate Boundaries. In: Thorpe R. S., ed., Andesites: Orogenic Andesites and Related Rocks. John Wiley and Sons. 525–547
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Pearce, J. A., 1996. A User’s Guide to Basalt Discrimination Diagrams. In: Wyman, D. A., ed., Trace Element Geochemistry of Volcanic Rocks: Applications for Massive Sulfide Exploration. Geological Association of Canada, 12: 79–113
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