黑龙江省乌拉嘎金矿黄铁矿和白铁矿的矿物学特征

乌拉嘎金矿床的黄铁矿和白铁矿均可划分为三个世代,不同世代的黄铁矿与白铁矿在形态、成分和热电性上表现了不同的特点,与金矿化有不同的联系。形态上,粉末状和球粒状黄铁矿以及胶状白铁矿与金矿化关系密切;成分上,富硫贫铁和As/Sb值高的黄铁矿、白铁矿对金的富集有利,它们的热电系数值与矿石品位呈正相关。     

Palynoflora of Wulaga dinosaur site in Jiayin （ Zeya-Bureya Basin,China）

The palynological assemblage from Wulaga dinosaur site in Jiayin from southeastern Zeya-Bureya Basin was studied. The high content of pteridophytes spores is characteristic for this assemblage. The further characters are in decrease of abundance-tricolpate pollen, Ginkgocycadophytus, pollen of Taxodiaceae, Cupressaceae and Taxaceae （TCT） , bisaccate pollen of Pinaceae, and triporate pollen. The bone-bearing burials of Wulaga dinosaur site formed under conditions of vast swampy river valley covered by ferns and taxodialeans. Tricolpate pollen, produced by plants, close to those of Platanaceae, Fagaceae, Betulaceae, and Juglandaceae, counts in favor of valley river open canopy forests.     

Forecast of blind ore body in Zhangcaigou area around Wulaga gold deposit

By the study of metallogenetic conditions and ore-controlling factors, the metallogenetic indicators in geology, geochemistry and geophysics about Wulaga gold deposit have been obtained. Using the indicators the blind ore bodies have been forecasted in Zhangcaigou area. By drilling check, a gold-bearing ore body with 3 m thickness in an average tenor of 20.4×10-6 at the depth of 70 m has been found in the forecast area. It shows that the forecast method should be effective.     

黑龙江省乌拉嘎金矿外围土壤地球化学找矿信息评价

地质、土壤地球化学找矿信息、高精度磁测和γ能谱信息的分析表明,乌拉嘎金矿外围土壤地球化学找矿信息特征为Au、As、Sb、Cu、Ag、Mo元素的组合异常。采用综合地质累积指数对研究区内的元素组合异常进行评价,结果表明该方法可以有效地区分异常下限、划分异常等级。按照综合地质累积指数大于零的原则,圈定了研究区内A、B、C三处找矿靶区。     

Rb–Sr Dating of Gold‐bearing Pyrites from Wulaga Gold Deposit and its Geological Significance

Wulaga epithermal gold deposit is located in northeast China. Gold mineralization mainly occurs within the crypto‐explosive breccia belt of subvolcanic intrusion. Constraints on the precise timing of mineralization are of fundamental importance for understanding the ore genesis of the Wulaga gold deposit and its mineralization potential. Three hydrothermal stages have been identified: the early veiny quartz–euhedral pyrite stage; the fine pyrite–marcasite–gray or black chalcedony stage; and the late carbonate–pyrite stage. The Rb–Sr dating of gold‐bearing pyrites from the fine pyrite–marcasite–gray or black chalcedony stage is 113.8 ± 4.4 Ma with an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.706346 ± 0.000019. The age of the gold deposit is consistent with the age of ore‐bearing volcanic (109–113 Ma) and subvolcanic intrusion (103–112 Ma) within the error limits, and the pyrite initial ratio has an identical value of ⁸⁷Sr/⁸⁶Sr to subvolcanic intrusion (0.705547 ± 0.000012). These indicate that crystallization of the wall rock and epithermal gold mineralization was coeval and likely cogenetic. Moreover, a lot of epithermal gold deposits that formed in Early Cretaceous volcanic and subvolcanic intrusions have been discovered in recent years in Heilongjiang province. Combined with the studies of tectonic and magmatic activities, we propose that the formation of the Wulaga gold deposit might be caused by the heated circum‐flow water related to the volcanic–subvolcanic intrusive hydrothermal event triggered by the ancient subduction of the Izanagi plate in the Early Cretaceous.