Age of theYongxin Audeposit in theLesser Xing'an Range: Implications for anEarly Cretaceousgeodynamic setting for gold mineralization inNE China

Abstract

The newly discovered Yongxin Au deposit in the Lesser Xing'an Range of north‐eastern Heilongjiang Province, NE China, has a resource of ~20 t with a grade of 4.1 g/t Au. The deposit is hosted by Carboniferous syenogranite and mylonite, and Cretaceous diorite porphyry and granite porphyry. The syenogranite has a LA‐ICP‐MS 206Pb/238U zircon age of 316 ± 2 Ma, and both the granite porphyry and diorite porphyry yield an age of 119 ± 1 Ma. The Rb–Sr isochron age of Au‐bearing pyrite from hydrothermal breccia‐type ore is 107 ± 4 Ma, and this is interpreted as the mineralization age of the Yongxin deposit. In combination with published geochronological data, we argue that epithermal Au mineralization in NE China formed during the period ca. 124 to 107 Ma and was produced during rollback of Palaeo‐Pacific oceanic slab. The Cretaceous epithermal Au deposits are distributed in the Erguna Massif, Lesser Xing'an Range, Zhangguangcai Range, and Jiamusi and Nadanhada terranes. In combination with the coeval porphyry Mo deposits present in these areas, we propose that the Erguna Massif, Lesser Xing'an Range, north‐eastern Great Xing'an Range, and eastern Jiamusi and Nadanhada terranes, where only epithermal gold deposits were discovered up to date, might be prospective for concealed porphyry Cu or Mo deposits.

Zircon U–Pb geochronology and Sr–Nd–Pb–Hf isotopic constraints on the timing and origin of the Early Cretaceous igneous rocks in the Yongxin gold deposit in the Lesser Xing'an Range, NE China

“…The U–Pb dating spots are denoted by blue circles while the Lu–Hf analysis spots by dashed yellow circles. Note that the zircon U–Pb ages of the diorite porphyry (165‐25) and granite porphyry (170‐7) are from Z. H. Zhao et al () [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…The Yongxin gold deposit is located at ~115 km southwest of Heihe City, Heilongjiang Province and has a reserve of more than 20 tons of gold with an average Au grade of 4.1 g/t (Z. H. Zhao et al, , ). Early Carboniferous syenogranite and mylonitic granite are widespread in the ore district and are covered by Early Cretaceous volcanic rocks of the Longjiang Formation at the bottom and the Guanghua Formation at the top of the Longjiang Formation.…”

“…Visible gold often occurs in quartz and pyrite as microfracture and inclusion gold (Figure f), whereas invisible gold mainly occurs as nanometre‐sized particles and solid solution in the pyrite. Fine‐grained pyrite has the best gold‐bearing properties among all kinds of pyrite (Yuan et al, ; Z. H. Zhao et al, , b).…”

“…The Yongxin gold deposit is located at~115 km southwest of Heihe City, Heilongjiang Province and has a reserve of more than 20 tons of gold with an average Au grade of 4.1 g/t (Z. H. Zhao et al, 2018aZhao et al, , 2018b. Early Carboniferous syenogranite and mylonitic gran- Hydrothermal alterations include silicification, sericitization, and potassic alteration, of which silicification alteration is closely related to gold mineralization at Yongxin (Figure 2a; Yuan, Zeng, Li, Li, & Li, 2017).…”

Petrogenesis of the Early Cretaceous Aolunhua Adakitic Monzogranite Porphyries, Southern Great Xing’an Range, NE China: Implication for Geodynamic Setting of Mo Mineralization

“…132-142 Ma), such as the Aolunhua, Banlashan, Haisugou, Shabutai, Yangchang, and Huanggang plutons in the Xilamulun district (see Figure 1b) [13,15,17,[23][24][25]. [26]). (b) A simplified geological map of the Xilamulun district in the southern Great Xing'an Range, NE China (after Wu et al [12]), and (c) simplified geological map of the Aolunhua region (after Ma et al [13]).…”