Field analysis of metallogenic information and its application

Focusing on the issue to deal with inadequate extraction of metallogenic information especially geological information,a new method of extracting metallogenic information based on field model,i.e.the field analysis method of metallogenic information,was proposed.In addition,a case study by using the method of the extraction of metallogenic information from the west Guangxi and southeast Yunnan district as an example was performed.The representation method for the field models of metallogenic information,including the metallogenic influence field model and the metallogenic distance field model,was discussed by introducing the concept of the field theory,based on the characteristic analysis of the distance gradualness and the influence superposition of metallogenic information.According to the field theory superposition principle and the spatial distance analysis method,the mathematical models for the metallogenic influence field and the metallogenic distance field of point,line and area geological bodies were derived out by using parameter equation and calculus.Based on the metallogenic background analysis,the metallogenic information field models of synsedimentary faults and manganese sedimentary basins were built.The relationship between the metallogenic information fields and the manganese mineralization distribution was also investigated by using the method of metallogenic information field analysis.The instance study indicates that the proposed method of metallogenic information field analysis is valid and useful for extracting the ore-controlling information of synsedimentary faults and manganese sedimentary basins in the study area,with which the extraction results are significant both statistically and geologically.

Quantitative analysis of geological ore-controlling factors and stereoscopic quantitative prediction of concealed ore bodies

To address the issues for assessing and prospecting the replaceable resource of crisis mines, a geological ore-controlling field model and a mineralization distribution field model were proposed from the viewpoint of field analysis. By dint of solving the field models through transferring the continuous models into the discrete ones, the relationship between the geological ore-controlling effect field and the mineralization distribution field was analyzed, and the quantitative and located parameters were extracted for describing the geological factors controlling mineralization enrichment. The method was applied to the 3-dimensional localization and quantitative prediction for concealed ore bodies in the depths and margins of the Daehang mine in Guangxi, China, and the 3-dimensional distribution models of mineralization indexes and ore-controlling factors such as magmatic rocks, strata, faults, lithology and folds were built. With the methods of statistical analysis and the non-linear programming, the quantitative index set of the geological ore-controlling factors was obtained. In addition, the stereoscopic located and quantitative prediction models were set up by exploring the relationship between the mineralization indexes and the geological ore-controlling factors. So far, some concealed ore bodies with the resource volume of a medium-sized mineral deposit are found in the deep parts of the Dachang Mine by means of the deep prospecting drills following the prediction results, from which the effectiveness of the predication models and results is proved.

Geology and Geochemistry of the Shizitou Molybdenum Deposit, Jiangxi Province： Implications for Geodynamic Setting and Metallogenesis

The Shizitou molybdenum （Mo） deposit in Yongping, Jiangxi, is an important, recently discovered deposit in the eastern section of the Qin-Hang metallogenic belt. The Mo deposit is located in the outer contact zone behveen the porphyritic biotite granite and the Neoproterozoic migmatite, and present in the deep central part of the intrusion. Re-Os dating and S and Pb isotopic analysis have been conducted to assess the metallogenesis of the Shizitou Mo deposit. S, Pb and Re isotopes show that the ore-forming materials were derived from the porphyritic biotite granitic magma, which originated from the mixing of mantle and crust. Re-Os dating of molybdenite from the ores gives a model age from 156.9±2.2 to 158.5±2.4 Ma, with a weighted mean age of 158±1 Ma and an isochron age of 158.0±2.5 Ma. Geological and geochemical characteristics of the ore deposit and the related granitoids indicate that the Shizitou deposit is a Climax-type Mo deposit. Based on previous studies of the Qin-Hang metaliogenic belt, two metallogenic events are believed to have occurred during 172-145 Ma and 137-132 Ma. These two metallogenic periods are consistent with the timing of two metallogenic peaks during the middle to late Jurassic and the Cretaceous in South China. These events represent responses to the partial backarc extension associated with the subduction of the Izanagi plate beneath the Eurasian continent and the rapid northeastward movement of the subducting Izanagi plate.

Magnetotelluric signal-noise separation method based on SVM–CEEMDWT

To better retain useful weak low-frequency magnetotelluric(MT)signals with strong interference during MT data processing,we propose a SVM-CEEMDWT based MT data signal-noise separation method,which extracts the weak MT signal affected by strong interference.First,the approximate entropy,fuzzy entropy,sample entropy,and Lempel-Ziv(LZ)complexity are extracted from the magnetotelluric data.Then,four robust parameters are used as the inputs to the support vector machine(SVM)to train the sample library and build a model based on the different complexity of signals.Based on this model,we can only consider time series with strong interference when using the complementary ensemble empirical mode decomposition(CEEMD)and wavelet threshold(WT)for noise suppression.Simulation results suggest that the SVM based on the robust parameters can distinguish the time periods with strong interference well before noise suppression.Compared with the CEEMD WT,the proposed SVM-CEEMDWT method retains more low-frequency low-variability information,and the apparent resistivity curve is smoother and more continuous.Moreover,the results better reflect the deep electrical structure in the field.

The geology and geochemistry of the Shizitou molybdenum deposit, Jiangxi province, China: Implications for the geodynamic setting

1 Introduction The Qin-Hang suture zone is the most important polymetallic metallogenic zone in southern China[1-2]and has the greatest resource potential.In recent years,a group of molybdenum(Mo)deposits have been discovered in the northeastern part of the Qin-Hang belt[3].From Mar.2006to Dec.2014,the Jiangxi Copper Group Geological Exploration Engineering Co.,Ltd.conducted prospecting,

Ore-forming mechanism of Xiajinbao gold deposit in Pingquan, Hebei based on fluid inclusions and stable isotopes

The Xiajinbao gold deposit is located in Yong’an-Xiayingfang-Maojiagou polymetallic metallogenic belt,which is animportant metallogenic belt in North China block.In this paper,we present a detailed study on fluid inclusions and stable isotopes ofthe Xiajinbao gold deposit,Hebei Province,China,aiming at discussing the ore source,evolution of ore-forming fluid andore-forming mechanism of the deposit.The macroscopic geological characteristics,S and Pb isotopic analysis results show that thesource of ore-forming materials is mainly from granitic magma,and subordinately from country rocks.H and O isotopic compositionfeatures indicate that the ore-forming fluid is mainly derived from magmatic water.Fluid inclusion characteristics show that theore-forming fluid experienced boiling during the early mineralization stage,which led to the precipitation of gold.Fluid mixingdominated the precipitation of the ore-forming materials during the middle and late stages.The gold precipitation was caused bywater/rock reaction throughout the whole ore-forming process.

Petrogenesis of granite from Xiaofan Mo deposit, Dabie Orogen

The Mesozoic granitoids in the Dabie Orogen are of particular geological interest as indicators for Mesozoic lithospheric evolution because of their close association with porphyry Mo mineralization. Here, we present a study using petrogeochemistry data to constrain the petrogenesis of the Xiaofan granites in the Dabie Mo mineralization belt （DMB）, Henan Province, China. Field investigations show that the Xiaofan pluton mainly consists of porphyritic granite. The Xiaofan granites have high SiO2 contents of 74.29 wt%-76.07 wt% （average： 75.18 wt%）, A1203 contents of 11.66 wt%-12.83 wt% （average： 12.13 wt%）, and K20 contents of 5.37 wt%-7.90 wt% （average： 6.86 wt%） and low MgO （0.06 wt%-0.16 wt%）, TiO2 （0.09 wt%-0.10 wt%）, and P205 （0.047 wt%-0.103 wt%） contents. They are enriched in Rb, U, K and Hf but depleted in Ba, Nb, Ta, Sr and Ti. By geochemical and mineralogical features, we propose that the Xiaofan granites belong to A-type type granite and dominantly sourced from the crust. The granites from the Xiaofan Mo deposit may have formed in a post-collision extensional setting.