The Erbutu Ni-Cu Deposit in the Central Asian Orogenic Belt: A Permian Magmatic Sulfide Deposit Related to Boninitic Magmatism in An Arc Setting

Abstract

The Erbutu Ni-Cu sulfide deposit is hosted in a small ultramafic intrusion located at the southern margin of the Central Asian orogenic belt, Inner Mongolia. This deposit is the first case of a magmatic sulfide deposit related to boninitic magmatism in an arc setting. The host intrusion is composed of orthopyroxenite and olivine orthopyroxenite. More than three quarters of the intrusion contains economic, disseminated sulfide mineralization. SHRIMP U-Pb dating of zircons from the intrusion gives a crystallization age of 294.2 ± 2.7 Ma, similar to the age of the Permian Tarim plume in northwest China. Olivine orthopyroxenite is characterized by olivine crystals with relatively high Fo contents (85−88 mol %) and extremely low Ca contents (<250 ppm). Coexisting orthopyroxene crystals have clinoenstatite composition with enstatite from 86 to 88 mol %. Whole-rock data show characteristic enrichments of light REE relative to heavy REE, pronounced negative Nb-Ta anomalies, and moderately positive Hf anomaly. The d 34 S values of sulfide separates are 4 to 5‰, significantly higher than the typical mantle value (0 ± 2‰). The eHf values of zircons are from -4 to -9. These data indicate that the parental magma was a boninite. Crustal contamination was involved during magma evolution and ore formation.

Geochronology and Petrology of the Beiligaimiao Magmatic Sulfide Deposit in the Northern Margin of North China Craton, Inner Mongolia

“…1a, the southern part of the Central Asian Orogenic Belt contains magmatic sulfide deposits formed in a subduction setting such as the Beiligaimiao deposit (this study) and the Erbutu deposit (Peng et al, 2013) in the central region, and post-subduction setting such as the Huangshandong deposit in the western region (Mao et al, 2014) and the Hongqiling No.7 deposit in the eastern region (Wei et al, 2013).…”

Geochemistry and zircon U–Pb–Hf isotopes of the granitoids of Qianjinchang pluton in the Xi Ujimqi, Inner Mongolia: Implications for petrogenesis and geodynamic setting

“…Shi et al () suggested that the continuous subduction of the Paleo‐Asian Ocean along the northern margin of the North China Craton occurs in the late Paleozoic. Recent studies suggested (Jian et al, ; Peng et al, ; Shang, ; Wang & Fan, ; Chu et al, ; Eizenhöfer et al 2014, 2015a, b; Li et al , b, c) the existence of oceanic basins during the late Carboniferous to the Permian. However, several papers have reported the regional unconformity between the late Paleozoic strata and ophiolites or Precambrian basements.…”

“…These granitoids are probably formed by a hybridization process between basaltic magma and old continental components. Chondrite-normalized and primitive mantle-normalized values are from Boynton (1984) and Sun and McDonough (1989), respectively [Colour figure can be viewed at wileyonlinelibrary.com] (Jian et al, 2010;Peng et al, 2013;Shang, 2004;Wang & Fan, 1997;Chu et al, 2013;Eizenhöfer et al 2014Eizenhöfer et al , 2015aLi et al 2016a, b, c) FIGURE 10 CIPW-normative Qz-Ab-Or diagram with lowtemperature melt compositions at 1, 5, and 10 kb (Johannes & Holtz, 1996) [Colour figure can be viewed at wileyonlinelibrary.com] 2007; Sylvester, 1989Sylvester, , 1998 and references therein), backarc extension (Collins & Richards, 2008), ridge subduction (Cai et al, 2011), and mantle plume-related setting (Li et al, 2003). In this study, the biotite granodiorite (monzogranite) has features of high-K content with high silica, Rb, U, Th, low HFSE, and belongs to high-K calc-alkaline series, which are similar to those of collision-related granites (Chen et al, 2000;Shi et al, 2004aa, 2004b.…”

“…The timing of ocean closure varied from the late Devonian to the early Mesozoic (Chen et al, 2000;Xiao et al, 2003;Xu et al, 2013;Domeier & Torsvik, 2014;Zhang et al, 2015). Lots of papers (Xiao et al, 2003;Jian et al, 2010 ;Peng, Zhai, Li, & Ripley, 2013;Shang, 2004;Wang & Fan, 1997;Chu, Wei, Wang, & Ren, 2013;Li et al, 2014Li et al, , 2016aEizenhöfer et al, 2014Eizenhöfer et al, , 2015aEizenhöfer et al, , 2015bLi et al 2016a) have garnered support for the existence of oceanic basins during the late Carboniferous to the Permian and suggest a late Paleozoic to early-middle Triassic closure of the Paleo-Asian Ocean. However, based on the late Devonian unconformity and different deformation styles below and above the unconformity, Xu et al (2013) proposed that the Paleo-Asian Ocean closed during the late Devonian, followed by the Carboniferous-early Permian postcollisional thermal event, which led to the emplacement of bimodal volcanic rocks, alkaline granites, and gabbros (Tang et al, 2011a;Chen et al, 2012;Li et al, 2014;Tong et al, 2015;Zhao et al, 2016), and the continuous extension gave rise to the opening of a newly-born oceanic basins (Chen et al 2012;Zhang et al 2014a).…”

Geological Characteristics and Metallogenic Setting of Representative Magmatic Cu‐Ni Deposits in the Tianshan‐Xingmeng Orogenic Belt, Central Asia

“…Magmatic Cu-Ni sulfide deposits are known to occur in the TXOB, in associated with either subduction-related or postorogenic magmatism. For example, those at Erbutu and Kalatongke probably are related to subduction-related, bonibitic magmatism (Peng et al, 2013;Li CS et al, 2012), whereas those at Huangshan and many others might be related to extensionrelated, basaltic magmatism (Zhou et al, 2004;Song and Li, 2009). Recently, we propose that the mafic-ultramafic in TXOB are most likely to have formed in a tectonic setting analogous to the Alaska-type zoned ultramafic complexes .…”