Geochemistry of the Permian Kalatongke Mafic Intrusions, Northern Xinjiang, Northwest China: Implications for the Genesis of Magmatic Ni-Cu Sulfide Deposits

Abstract

The Kalatongke Cu-Ni sulfide deposit in northern Xinjiang, northwest China, is located on the southern side of the regional Irtysh fault zone, which is the boundary between the early Paleozoic Altai orogenic belt to the north and the late Paleozoic Junggar terrane to the south. In the Kalatongke region there are 11 mafic intrusions which were emplaced in Lower Carboniferous strata. Economic Ni-Cu sulfide ores are found within three of these intrusions, which are well differentiated, and compositionally zoned. Four rock types are recognized which, from top to base of the three mineralized intrusions, include biotite diorite, biotite-hornblende norite, biotite-hornblende-olivine norite, and biotite hornblende-dolerite. The biotite-hornblende olivine norites and biotite-hornblende norites are the most favorable host rocks for Ni-Cu mineralization. The initial ( 87 Sr/ 86 Sr)t (t = 280 Ma) ratios of the intrusions vary from 0.70375 to 0.70504, and εNd(t) from 6.3 to 8.2, implying that the magmas originated from depleted asthenospheric mantle. However, the strong enrichment of lithophile elements such as K, Rb, Th, U, and LREE, the negative Nb and Ta anomalies, and the high δ 18 O values of whole rocks (5.4-10.6‰) suggest significant crustal contamination. These patterns are present in almost all samples from the intrusions, indicating that the contamination took place before the magma was emplaced at its present level in the crust. Crustal contamination is interpreted to have driven the magma to S-saturation and brought orthopyroxene onto the liquidus. Convection, or perhaps flow differentiation of the crystal-bearing magma during ascent, caused the dense sulfide melt with entrained olivine and orthopyroxene crystals to become concentrated in the center of the intrusions, whereas the fractionated magmas formed other, less mafic intrusions, which intrude the nearby strata.

Petrogenesis and magmatic–hydrothermal evolution time limitation of Kelumute No. 112 pegmatite in Altay, Northwestern China: Evidence from zircon UPb and Hf isotopes

“…The Mesozoic Aral porphyritic granite has been dated at~251 Ma (Rb\Sr isochron, Liu, 1993; K\Ar isochron for biotite, Liu et al, 1997), 210-220 Ma (SHRIMP zircon U\Pb, Wang et al, 2007Wang et al, , 2008 and (Tong, 2006); Sedimentary rocks (Long et al, 2007) and this study. Some data (Tong, 2006;Zhang et al, 2009) are obtained by the formula: ε Hf = 1.36ε Nd + 2.95 (Vervoort et al, 1999). ~233 Ma (LA-ICPMS zircon U\Pb, Chen, 2011) in different ways.…”

A review of mineral systems and associated tectonic settings of northern Xinjiang, NW China

“…The boundaries between these zones are gradational. The geology, geochemistry and isotope systematics of the Kalatongke ores and their host rocks have been studied by Yan et al (2003) and Zhang et al (2009).…”

Zircon U–Pb geochronology, geochemistry, and Sr–Nd isotopes of the Ural–Alaskan type Tuerkubantao mafic–ultramafic intrusion in southern Altai orogen, China: Petrogenesis and tectonic implications

“…This suggests that the Shaerbulake terrane belongs to an active margin built on an old micro-continent but not the young intra-oceanic subduction systems (Wong et al, 2010). The Permian Kalatongke mafic intrusions hosting the Cu-Ni sulfide deposits were located in the east of the terrane and interpreted to be formed in the post-collision setting (Song and Li, 2009;Zhang et al, 2009). The Tuerkubantao mafic-ultramafic intrusion is situated in the east of the Kekesentao mafic-ultramafic intrusion area ( Fig.…”