Prediction of Hidden Granites in the Luziyuan Area of Yunnan Province and the Prospecting Direction

The Fe-Pb-Zn-Cu polymetallic deposits in the Luziyuan area, are of a sedimentary-reformed type related with magmatic hydrothermalism. Previous researches have suggested that the mineralization is closely related to the hidden granites, but little is known about these granites including their burial depth and scale, which has limited the establishment of prospecting models and the optimization of prospecting targets. Geophysical methods have a great exploration depth, and have played a unique role in the prediction of hidden granites. It is shown that granites have low density and high resistivity,

Types of uranium deposits in central Zhuguang Mountains in Hunan Province,South China and their metallogenic regularity and prospecting directions

The central Zhuguang Mountains in Hunan Province is located at the junction of the three provinces,namely Hunan,Jiangxi,and Guangdong,where the famous Lujing uranium ore field lies.The uranium deposits occurring in this area are all granite-related and they can be divided into three types,namely endogranitic ones,perigranitic ones,and contact zone types.The endogranitic uranium deposits are mainly controlled by the structural alteration zones developing within granites,with fragmentation,hematitization,and alkali metasomatism as their main mineralization characteristics.The perigranitic uranium deposits are mainly produced in the carbonaceous,siliceous,and argillaceous composite layers of epimetamorphic rocks and are controlled by fractured zones formed due to interlayer compression.The contact zone type uranium deposits mainly occur in the contact parts between the granites and favorable horizons.They have developed in favorable sections where multiple sets of structures are combined and intersected.The main metallogenic regularities of uranium in the central Zhuguang Mountains are as follows.The basic conditions for the uranium mineralization in this area include the framework consisting of regional deep large faults and their associated multi-set multi-direction favorable metallogenic structures,multi-cycle and multi-stage uranium-rich rock masses,and uranium-rich folded basement.Meanwhile,the uranium deposits in this area are closely related to granites in terms of genesis and space and they are formed in different structural parts subject to the same metallization.Furthermore,based on the summary of the characteristics and regularities of uranium mineralization in this area,the controlling factors of different types of uranium deposits in the area were explored and six metallogenic target areas were predicted.All these will provide references for the exploration of uranium deposits in this area.

Indo–Chinese Magmatic Activity in the Duobaoshan District of Heilongjiang Province and Its Geological Significance

The Duobaoshan ore concentration area, located in Nenjiang County of Heilongjiang Province, is an important porphyry Cu-Mo ore concentration area in China, which is characterized by complex magmatic activities and multi-phase overprinting metallogenesis. On the basis of field geological observation, systematic sampling, in-lab analysis and the metallogenic regularity in the Xiang＇an- Mongolian metallogenic belt, this work carried out high-precision dating and geochemical analysis on the Yuejin, 173-kilometer and Wolihedingzi rock bodies. These rock bodies are renamed monzonitic granite and their consistent age （238 Ma） show that they were formed not in Variscan but in Indosinian. Therefore, it is inferred that the ore spots formed in the potassium silicate and sericite alteration zones of the rock mass also belong to Indosinian. In addition, we collected granodiorite from the Tongshan mining pit, and its zircon age is 223.1＋2.8 Ma and the Cu content of the sample is high. The Tongshan mineralization is inferred to undergo the superimposition of Indosinian diagenetic mineralization. The age of the granodiorite porphyry related to copper-molybdenum mineralization in the Xiaoduobaoshan area is 222.1~5.5 Ma, and the earlier age of granodiorite is 471.8^-7.4 Ma, indicating that the initial magmatic activities belong to the Duobaoshan porphyry system in the Caledonian period. The geochemical characteristics of the Indosinian rock samples show continental arc features, with reference to tectonic-magmatic activities of the whole Daxing＇anling area. We consider that the magmatic activities and mineralization of the Indosinian period are affected by the southward subduction of Okhotsk Ocean since Late Permian. By combining the mineralization rules of Daxinganling area and the structural systems of Duobaoshan ore concentration area, we divide two rock-mineralization belts in this area including the Yuejin-Duobaoshan-Tongshan belt and 173-kilometer-Xiaoduobaoshan-Wolihedingzi belt, which are distributed nearly parallel along the NW-trending fractures and show similar geotectonic settings and the timing of the magmatic activities. It is favorable for discovering porphyry Cu-Mo deposits in these two metallogenic belts, especially in the Yuejin, 173-kilometer and Wolihedingzi areas where less research work has been made.

Deep Mineralization Background and Metallogenic Regularity of the Tongling Ore District

Based on the geological conditions and characteristics of mineralization present,three-dimensional geological modelling is used in conjunction with previous deep research results,in order to discuss the process of deep mineralization in the Tongling ore district.The structural analysis shows that surface deformation is strong,deep deformation is weak,the surface has mainly experienced brittle deformation,with the possibility of a large number of deep ductile deformations.There is a thrust nappe between the Tongling uplift and the Nanling basin,that is the boundary of the Tongling block,which has resulted in the southwest uplift of the Tongling block.Combined with the deep exploration data,the threedimensional shape of the main rock masses is interpreted,with three-layer structures in the deep magma chamber.The spatial distribution of magmatic rocks is mainly controlled by the structure.The movement of magmatic hydrothermal fluid is dominated by mesoscale seepage in the deep part and'dike'type upwelling in the shallow part.There is a certain coupling relationship between the ore-forming rock mass and the surrounding rock.The ore-forming age is dominated by the Yanshanian period.Based on the distribution,types and metallogenic characteristics of the deposits,the metallogenic model of'layer coupling'in the Tongling ore district is summarized,with the'one body,two belts and a multilayer metallogenic system'is established,which is significant for the future direction of deep prospecting in the Tongling area.

Classification,metallogenesis and exploration of silver deposits in Daxing’anling of Inner Mongolia and its adjacent areas

By the end of 2020,83 silver deposits(or ore occurrences),including four super-large-scale deposits,nine large-scale deposits,33 medium-scale deposits and 37 small-scale deposits or ore occurrences,have been proved.The amount of silver metal exceeds 86000 t with average grade of 100 g/t,which makes Daxing’anling region one of the the most important silver ore belt in China.However,the metallogenic characteristics and metallogenesis need to be clarified.The silver deposits in the study area are classified into three main types,which are magmatic hydrothermal vein type,continental volcano-subvolcanic type and skarn type,respectively.The supergiant deposits include the Shuangjianzishan deposit(silver metal amount of 15214 t with average grade of 138 g/t),the Baiyinchagandongshan deposit(silver metal amount of 9446 t with average grade of 187 g/t),the Huaobaote deposit(silver metal amount of 6852 t with average grade of 170 g/t),and the Fuxingtun deposit(silver metal amount of 5240 t with average grade of 196 g/t).The silver deposits are mainly distributed in the central and south of the Daxing’anling area,and mainly formed in the Yanshanian period.The silver polymetallic deposits in the Daxinganling area are significantly controlled by regional faults and the junction zone of volcanic rock basins and their margins.The north-east trending deep faults are the most important ore-controlling structures in this area.The distribution of silver polymetallic deposits along the main faults is obvious,and the intersection area of multiple groups of faults often form important mine catchments.The Permian is the most important ore-bearing formation in this area,but some important silver polymetallic deposits occur in Mesozoic volcanic basins or pre-Mesozoic strata.The magmatic rocks related to mineralization are mainly intermediate acidic or acidic intrusions,intermediate acidic lavas,pyroclastic rocks,and small intrusions of ultra-shallow or shallow facies of the Yanshanian Period.The mineralization element combination is mainly determined by the elemental geochemical background of surrounding rocks or source layers.In addition,the type of deposit,the distance from the mineralization center,and the degree of differentiation of ore-forming rock mass are also important influence factors.The article analyzes the prospecting prospects of each silver deposit type in the study area,discusses the relationship between mineralization center and deep prospecting,and proposes that porphyry silver deposits should be paid attention to.In the prospecting and exploration of silver deposits,comprehensive evaluation and multi-target prospecting need to be strengthened because silver can coexist or be associated with a variety of metals.

The genesis and resource potential of gold deposits in the Liaodong Peninsula

Plenty of gold deposits related to Late Mesozoic craton destruction are widely distributed in eastern North China Craton. However, significant differences in research degrees, ore-forming characteristics, and proven reserves exist among different regions in the North China Craton. The Liaodong Peninsula has similar regional geological characteristics to those of the Jiaodong Peninsula, with both experiencing craton destruction during Late Mesozoic, but the two areas have substantial differences in terms of gold mineralization and the proven gold resources. Based on regional geology, Mesozoic magmatictectonic evolution and ore geology, combined with integrated geophysical exploration and big data AI resource prediction, in this paper, we propose that the ore-forming materials of Late Mesozoic gold deposits in Liaodong were mainly originated from mantle-derived melts and/or fluids induced by craton destruction. The gold deposits were primarily controlled by NE-NNEtrending faults, mainly classified as fracture-controlled altered rock-type and sulfide-bearing quartz vein-type. Moreover, our study predicts that the Yalu River fault zone and its related secondary faults, as well as the periphery and deeper parts of known goldfields, are the important regions for future gold resource exploration. The Yalu River metallogenic belt has an enormous potential for gold resources, and the Liaodong Peninsula has a potential to add thousands of tons of gold resources.