The Kiloton Class Jiaojia Gold Deposit in Eastern Shandong Province and Its Genesis

The recent deep prospecting results in the Jiaojia area of Eastern Shandong Province indicate that the Jiaojia ore field composed of several individual gold deposits as previously suggested is actually an ultra-large gold deposit.This deposit covers an area of ～40 km2,and shows a structural control by the Jiaojia fault and its secondary faults.Gold orebodies generally occur along the same mineralization-alteration belt,and the main orebodies intersect with each other or exhibit a parallel or overlapping distribution.This deposit＇s reserves are estimated to be 1,200t of gold,being the first gold deposit of more than 1000t gold reserves in China.The No.Ⅰ-1 orebody in the Shaling-deep Sizhuang ore blocks holds gold reserves greater than 350 t,or 29 percent of the total reserves,followed by the No.Ⅰ orebody in Matang-Jiaojia ore blocks with exceeding 150t gold reserves.This deposit mainly occurs in the footwall of the Jiaojia fault,and presents zoned patterns in mineralization,alteration and structures.The strongly mineralized zones agree with strongly altered and tectonically fractured zones.These orebodies display strataform-like,veinlike or lenticular shapes,and generally show characteristics of pinching out and reappearing,branching and converging,expanding and shrinking.The orebodies commonly occur along positions where the fault strike changes and in gentle locations with dips changing from steep to gentle.The main orebodies are parallel to the main plane of the orecontrolling fault,and tend to be gentle from the surface to the deep.The orebodies mainly plunge to the southwest,with plunge angle of 45°-606° Orebodies near the main plane of the ore-controlling fault have more gold resource than those away from main fault zone.The slant depth of orebodies is generally larger than the length along its strike direction; orebodies become thick and gold grades become low from the shallow area to the deep area.Ore-forming fluids are H2O-CO2-NaCl±CH4 type with medium-temperature and moderate to low salinity.Sulfur isotopic values （δ34SCDT） for gold ores range between 11.08‰ and 12.58‰,indicating mixed sulfur sources; hydrogen isotopic values （δDVSMOW） range from-83.68‰ to-116.95‰ and oxygen isotopic values （δ18OV-SMOW） range between 12.04‰ and 16.28‰.The hydrogen and oxygen isotopes suggest that ore-forming fluids originated from primary magma,and mixing with a large amount of atmospheric water during the late stage.The Eastern Shandong Province gold deposits are associated with magmatic activities which have mantle crust-mixed source,and also share some similarities with orgenic and epithermal hydrothermal golddeposits.Because Eastern Shandong Province gold deposits with unique metailogenic features and formation setting which are different from other gold deposit types in the world,we call it the Jiaojiatype gold deposits.The kiloton class Jiaojia gold deposit is related to fluid activities,extension and detachment resulted from thermal upweiling of magmas.The strong magmatic activities in the middle to late stage of early Cretaceous in Eastern Shandong Province lead to active fluids,and provided abundant ore-forming materials for gold depsoits.Moreover,many extensional structures resulting from crustal extension provided favourable space for orebody positioning.

Geophysical-Geological Interpretation and Deep-Seated Gold Deposit Prospecting in Sanshandong-Jiaojia Area, Eastern Shandong Province, China

Integrated gravitational, electrical-magnetic surveys and data processing carried out in the Sanshandao-Jiaojia area, Eastern Shandong Province, northeast China, aim to illuminate the geological characteristics of this shallow-covered area and delineate deep-seated gold prospecting targets. In this region, altogether 12 faults exert critical control on distribution of three types of Early Precambrian metamorphic rock series, i.e. those in the metamorphic rock area, in the granitic rock area underlying the metamorphic rock, and in the remnant metamorphic rock area in granites, respectively. Additionally, the faults have major effects on distribution of four Mesozoic Linglong rock bodies of granite, i.e. the Cangshang, Liangguo, Zhuqiao-Miaojia and Jincheng granites. The Sanshandao and Jiaojia Faults are two well-known regional ore-controlling faults; they have opposite dip direction, and intersect at a depth of 4500 m. Fracture alteration zones have striking geophysical differences relative to the surrounding county rocks. The two faults extend down along dip direction in a gentle wave form, and appear at some steps with different dips. These steps comprise favorable gold prospecting areas, consistent with a step metallogenic model. Six deep-seated gold-prospecting targets are delineated, i.e. Jincheng-Qianchenjia, Xiaoxizhuang-Zhaoxian, Xiyou-Wujiazhuangzi, Xiangyangling-Xinlicun, Panjiawuzi and Miaojia-Pinglidian.

Metamorphic Rock-hosted Disseminated Gold Deposits——A Case Study of the Xiaotongjiapuzi Gold Depositof Eastern Liaoning

The Xiaotongjiapuzi gold deposit occurs in a Palaeoproterozoic rift accretionary terrane in eastern Liaoning and is hosted by a carbonate formation of the Dashiqiao Formation, Liaohe Group. The metamorphic grade of the host rock is low amphibolite-high greenschist facies. Gold, which is mainly invisible, is distributed in pyrite and arsenopyrite. The grains of Au-bearing sulphide minerals are fine, ranging from 0.0 n to 1 mm. The wall-rock alterations are characterized by low-temperature silification, hydro-sericitization, sericitization and carbonatization. The homogenization temperatures of the fluid inclusions in quartz closely associated with gold mineralization range from 140 to 240°C. The metallogenic age represented by the Ar-Ar isotopic age of sericite is 167 Ma. Comparisons and studies show that the Xiaotongjiapuzi gold deposit can be classified as the submicron-sized disseminated deposit (analogous to the Carlin-type) hosted in metamorphic rocks.

Remote Sensing Technology for Identification of Alteration Information of Gold Deposits in the Eastern Tianshan Area, Xinjiang

Based on specific well-exposed rocks useful for high-quality remote sensing interpretation in the gold-prospecting area in the eastern Tianshan, this paper gives a detailed description of a remote sensing model for metallogenic prediction. The model reveals that multi-spectral remote sensing data are integrated with high-resolution remote sensing data, and enhanced extraction and visual description of weak remote sensing information are used for prospecting. This model has tested in the given gold deposit, and used successfully in Au-Cu prospecting in the Kalatage area.

Study on fluid inclusions of Shawang gold deposit in Haiyang of Shandong

Shawang gold deposit is a large gold deposit, located in the NE margin of the Jiaolai basin, which is part of Muping-Jimo metallogenic belt in eastern Shandong. It was controlled by the footwall of Guocheng fault zone and secondary faults zone. Aiming to the fluid inclusions in Shawang gold deposit, the authors carry on petrographic, microthermometric and Raman spectroscopic component analyses. The results show that there are four-type fluid inclusions： single phase inclusions, gas-liquid two-phase inclusions, pure CO2 inclusions and three-phase inclusions containing CO2. Ore-forming fluid is characterized by low salinity （4.3%-12.6% NaC1. eqv）, low density （0.64-0.97 g/cm3 ）, medium-high temperature （280℃-320℃）, metallogenic pressure with 81-94 MPa, and metallogenic depth as 7.39-7.98 kin. The fluid experienced immiscibility of CO2-NaCl- H2O system during the metallogenic process. In combination with the analysis of hydrogen and oxygen isotopes in fluid inclusions, it is determined that the Shawang gold deposit is mesothermal vein-type, with participation of mantle-derived water and magmatic water for its genesis.

Chronology and Geochemistry of the Berezitovoe Polymetallic Gold Deposit in Eastern Siberia, Russia and its Geological Significance

The Berezitovoe deposit is a large-sized Au-Ag-Zn-Pb deposit in the east of the SelengaStanovoi superterrane, Russia. Au-Ag orebodies are hosted by tourmaline-garnet-quartz-muscovite metasomatic rocks; Zn-Pb orebodies are hosted by granodiorites, porphyritic granites and tourmalinegarnet-quartz-muscovite metasomatic rocks. These orebodies are surrounded by wall rocks dominated by the Tukuringra Complex granodiorites, porphyritic granites, and gneissic granodiorites. The alteration includes silicification and garnet, sericitization chloritization, carbonatization and kaollinization. LA-ICP-MS U-Pb zircon dating indicates that the gold mineralization can be divided into two stages in the Berezitovoe polymetallic gold deposit（at 363.5 ± 1.5 Ma, and133.4± 0.5）.Hornblende-plagioclase gneisses of the Mogocha Group in the study area underwent Paleoproterozoic metamorphism（at 1870 ± 7.8 and 2400 ± 13 Ma）, gneissic granodiorite of the Tukuringra Complex yields a late Paleozoic magmatic age（at 379.2 ± 1.1 Ma）,and subalkaline porphyritic granitoid of the Amudzhikan Complex yield late Mesozoic magmatic ages（133-139 and 150-163 Ma）. Granodiorites of the Tukuringra Complex in the study area have high concentrations of SiO_2（average of 60.9 wt%）, are aluminum-oversaturated（average A/CNK of 1.49）, are enriched in the large ion lithophile elements（e.g.,K, Rb, and Ba）, U, Th, and Pb, are depleted in high field strength elements（e.g., Ta, Nb, and Ti）, and have slightly negative Eu and no Ce anomalies in chondrite-normalized rare earth element diagrams.Fluid inclusions from quartz veins include three types： aqueous two-phase, CO2-bearing three-phase,and pure CO2. Aqueous two-phase inclusions homogenize at 167℃-249℃ and have salinities of 4.32%-9.47% NaCl equivalent, densities of 0.86-0.95 g/cm^3, and formed at depths of 0.52-0.94 km. In comparison, the CO2-bearing three-phase inclusions have homogenization temperatures of 265℃-346℃,salinities of 7.14%-11.57% NaCl equivalent, and total densities of 0.62-0.67 g/cm^3. The geochemical and zircon U-Pb data and the regional tectonic evolution of the study area, show that the Berezitovoe polymetallic gold deposit formed in an island arc or active continental margin setting, most probably related to late Paleozoic subduction of Okhotsk Ocean crust beneath the Siberian Plate.

Analysis of Ore-Controlling Structures of the Xincheng-Hexi Gold Deposit,Shandong Province,China

Based on quantitative and semi-quantitative mathematical and mechanical analysis of the shape, motion, structural factors, stress field and deformation field of the ore-hosting faults in the Xincheng-Hexi gold deposit, the ore-controlling features of faults and mineralization mechanism are discussed. It is concluded that the mineralization is controlled by the main faults, subsidiary fractures, joint density, mechanical features and deformation of the faults. The ore bodies are mainly located in the lower part of the convex crest and upper part of the concave trough of the main undulating fault surface. Mineralization is positively correlated to the development of subsidiary fractures and joints, which correspond to zones of low internal stress and high body strain and shear strain. They are favourable positions for mineralization and alteration.

Geochemistry of fluid inclusions from Linglong gold deposit in Shandong,China

By means of microscopy and laser Raman spectroscopy, the authors studied the fluid inclusions in petrography. The results show that there exist three-phase CO2-bearing and two-phase aqueous inclusions in gold ore; the fluid of NaC1-H2O-CO2 system went through immiscibility in ore-forming process. Ore-forming fluids were of low salinity （0. 82%- 5.40% NaCleqv）, low density （0. 54-0.93 g/cm3 ） ; mineralization temperature were concentrated in 320℃-340℃ , with ore-forming pressure in 62-126 MPa and mineralization depth in 6.34-9.35 kin. The fluid inclusions in quartz are generally characterized by a small amount of CO2 and Na. Combined with recent results of the isotopic analysis for fluid inclusions and dating data, it was indicated that the main ore-forming fluids derived mainly from source of mantle-derived fluids with a small amount of magmatic fluid and meteoric water. The genetic type was mesothermal gold deposits involved by mantle-derived fluids.

Origin of Gold-Bearing Fluid and Its Initiative Localization Mechanism in Xiadian Gold Deposit,Shandong Province

The composition of quartz inclusions and trace elements in ore indicate that gold\|bearing fluid in the Xiadian gold deposit, Shandong Province, stemmed from both mantle and magma, belonging to a composite origin. Based on theoretical analysis and high temperature and high pressure experimental studies, gold\|bearing fluid initiative localization mechanism and the forming environment of ore\|host rocks are discussed in the present paper. The composite fluid extracted gold from rocks because of its expanding and injecting forces and flew through ore\|conducive structures, leading to the breakup of rocks. The generation of ore\|host faults and the precipitation of gold\|bearing fluid occurred almost simultaneously. This study provides further information about the relationships between gold ore veins and basic\|ultrabasic vein rocks and intermediate vein rocks, the spatial distribution of gold ore veins and the rules governing the migration of ore fluids.

Rb-Sr Isotopic Chronology of the Au-Bearing Quartz Veins in Gold Deposits in the Eastern Part of North China Platform

In the eastern part of China there had occurred large\|scale gold mineralization during the Mesozoic, resulting in a large number of important gold ore\|concentrated areas. In this paper we have selected some isotope data (including four gold deposits previously studied and two gold deposits in this work) of Au\|bearing quartz veins of the representative gold deposits in six important gold ore\|concentrated areas in the periphery of the North China Platform and calculated their metallogenic ages using the method of Ludwig (2.90 version). The results show that the representative gold deposits in the six gold ore\|concentrated areas were formed during the Mesozoic.

Genesis and Geological-Geochemical Characters of the Rushan Gold Deposit, Shandong, China

The Rushan gold deposit, explored in recent years in the Jiaodong area, Shandong Province is a quartz vein-type gold deposit hosted in granite. The temperature of its major mineralization episode is between 220℃ and 280℃. The salinity of the ore-forming fluid is 5 % to 9% NaCl equivalent, with H2O and CO2 as the dominant gas constituents. The fluid is rich in Na+, Ca+ and Cl-, but relatively impoverished in K+ and F-, characterized by either Ca2+ >Na+ >K+ (in three samples) or Na+ > Ca2+ > K+ (in six samples). Hydrogen and oxygen isotopes in the ore-forming fluid are highly variable with δ18 OH2O ranging between -7. 70‰ and 5. 97‰ and δDH2O between - 128‰ and - 71‰. The possibility of lamprophyre serving as the source of gold can be excluded in view of its low gold content on the order of 2. 5 × 10 -9. Rb-Sr isochron ages of the deposit and the host Kunyushan granite are (104. 8±1. 5) Ma and 134. 6 Ma respectively with the respective initial Sr ratios of 0. 71307 and 0. 7096. It is considered that the emplacement of the lamprophyre under a tensile environment had provided sufficient heat energy to facilitate deep circulation of meteoric water by which ore metals were extracted from the Kunyushan granite through long-term water-rock reaction.

Genesis and Geological and Geochemical Characteristics of Qixia Gold Deposit, Shandong, China

The Qixia gold deposit is one of the important quartz vein-type deposits hosted inmetamorphic rocks in the east of Shandong, China. Compositionally the wolframite which isassociated with gold mineralization in the deposit is rich in iron, but poor in manganese, showing that this mineral crystallized from hydrothermal solution at low temperature. The temperatures at the main metallogenic stage of the Qixia gold deposit are Within the range of 160 -270t. The gaseous phases in fluid inclusions are dominated by H2O and CO2, while Na+,Ca2+ and Cl- are the major species in the fluid phase with K+ and F- present in relativelysmall amounts. The salinities of fluids are 4. 2 wt% - 8. 0 wt% NaCl equiv. Meanwhile, thefluid is characterized by either Ca2+ > Na+ > K+ (in five samples) or Na+ > Ca2 + > K+ (in twosamples), quite similar to the composition of ore-forming fluid derived from meteoric water.Primary data on the hydrogen and oxygen isotopic compositions of the ore-forming fluid fallwithin a wide range: δ%H2o = - 56‰-95‰ and δ18OH2O=- 3.6‰-4. 5‰ relative toSMOW. These isotopic values fully reflect the distribution features of meteoric water which hasexchanged with the metamorphic rocks of the Jiaodong Group at different temperatures and W/R ratios, and the metallogenic process is characterized by low W/R ratios. The Rb-Sr isochronage of the Qixia gold deposit is 125. 8 ± 1. 7 Ma, with (87Sr/86Sr) being 0. 7168, and the timeinterval between the gold deposit and its country rocks (granite or metamoprhic rocks) is verylarge. The formation Of the Qiaxia gold deposit is directly related to the evolution of geologicalhistory in eastern Shandong, and a genetic model in which the deep convective circulating meteoric water reacts with the country rocks can be used to explain the metallogenic mechanism ofthe deposit.

Ore Mineralogical and Geochemical Studies on El-Daghbag-I Gold Deposit, Central Eastern Desert, Egypt

El-Daghbag-I gold mineralization is a part of El-Daghbag gold deposit, Central Eastern Desert, Egypt. It is represented by several NW-trending quartz veins cutting across highly sheared granodiorite rocks along NW-trending shear zone. The recorded ore mineral assemblage is magnetite, ilmenite, native gold, pyrite, chalcopyrite, sphalerite and galena. Bornite, covellite and goethite are the secondary ore minerals. Statistical parameters, Clark of Concentration, linear productivity, contrast coefficient, zonality index and zoning coefficient were calculated to investigate the geochemical association and whether there are factors controlling distribution of its members. The geochemical primary distribution patterns of gold and the elements properly forming the mineralization revealed that the gold associated elements are (Cu, As, Zn, Ni, Co, Ag and Pb). These elements occur as proper ore sulfide-minerals. The recorded lateral zoning sequence of deposition along the NW-SE extension of the main quartz vein is (Ag-Co-Ni-Cr-Cu-As-Zn-Pb). The lateral zoning sequence along the SW-NE trend crossing the quartz vein exhibits variable depositional sequence is (Ag-Co-Cr-Ni-Cu-As-Pb-Zn). With regard to position of the ore metals in the general sequence of zoning, the gold potential of the central and southeastern parts, due to its probable accumulation at deeper levels of the mineralization, are expected to be promising. Drilling is recommended for studying the vertical zoning of these elements to reveal the site of gold accumulation.

Paleoproterozoic Sediment-hosted Gold Deposits in Eastern Liaoning,Northeast China: Implications for Gold Exploration

Gold deposits in eastern Liaoning, northeast China are hosted in the middle and upper parts of a Paleoproterozoic volcanic-sedimentary succession, which consists of interlayered carbonates and fine-grained clastics. This paper discusses the geological features of ore-bearing formations, ore-controlling structures and metallogenetic characteristics. Analysis of ore-controlling factors suggested that the schists from the Gaixian formatyion, syngenetic faults and ductile shear zones are principal ore controls over mineralization and thereafter indicators for gold exploration.

Geology and mineralization of the Dayin’gezhuang supergiant gold deposit(180 t)in the Jiaodong Peninsula,China:A review

The Dayin’gezhuang gold deposit is located in the central part of the Zhaoping Fault metallogenic belt in the Jiaodong gold province-the world’s third-largest gold metallogenic area.It is a typical successful case of prospecting at a depth of 500-2000 m in recent years,with cumulative proven gold resources exceeding 180 t.The main orebodies(No.1 and No.2 orebody)generally have a pitch direction of NNE and a plunge direction of NEE.As the ore-controlling fault,the Zhaoping Fault is a shovel-shaped stepped fault,with its dip angle presenting stepped high-to-low transitions at the elevation of -2000-0 m.The gold mineralization enrichment area is mainly distributed in the step parts where the fault plane changes from steeply to gently,forming a stepped metallogenic pattern from shallow to deep.It can be concluded from previous studies that the gold mineralization of the Dayin’gezhuang gold deposit occurred at about 120 Ma.The ore-forming fluids were H_(2)O-CO_(2)-NaCl-type hydrothermal solutions with a medium-low temperature and medium-low salinity.The H-O isotopic characteristics indicate that the fluids in the early ore-forming stage were possibly magmatic water or mantle water and that meteoric water gradually entered the ore-forming fluids in the late ore-forming stage.The S and Pb isotopes indicate that the ore-forming materials mainly originate from the lower crust and contain a small quantity of mantle-derived components.The comprehensive analysis shows that the Dayin’gezhuang gold deposit was formed by thermal uplifting-extensional tectonism.The strong crust-mantle interactions,large-scale magmatism,and the material exchange arising from the transformation from adakitic granites to arc granites and from the ancient lower crust to the juvenile lower crust during the Early Cretaceous provided abundant fluids and material sources for mineralization.Moreover,the detachment faults formed by the rapid magmatic uplift and the extensional tectonism created favorable temperature and pressure conditions and space for fluid accumulation and gold precipitation and mineralization.

TECTONIC EVOLUTION OF THE GARZE—LITANG PLATE JUNCTION, WITH PARTICULAR REFERENCE TO THE GOLD DEPOSITS

Garez—Litang plate junction lies in the eastern margin of the Nujiang—Lancangjiang—Jinshajiang area, NW\|trendingly and antisigmoidally extending for more than 800km from Zhidoi ,Qinghai through Garze and Litang to Muli ,Sichuan ,with a width of 5～35km .The junction is located in the arcuate turning part of the Alpine—Himalayan—Indosinian Tethyan tectonic domain ,which lies in the structural transition position between the Yangtze plate and the Yidun area . The plate junction represents an important tectonic belt ,which is a composed of a gold mineralization belt in the east Tethyan tectonic domain.(1) Garze—Litang plate junction may be divided into the following structural units:ductile shear zone and fracture system, Paleozoic nappes ,ophiolite \|tectonic blocks,flysch formation in passive continental margin (Triassic Xikang group ),forearc sedimentary formation in active margin (Triassic Yidun group),and such boundary geological bodies as granitoids ,faulted basins and Tertiary nappes.

Fission Track Thermochronology Evidence for Multiple Periods of Mineralization in the Wulonggou Gold Deposits, Eastern Kunlun Mountains, Qinghai Province

It is a puzzle to determine metallogenetic ages in the world. This article uses zircon fission track （FT） dating to probe the mineralizing epochs of Wulonggou （五龙沟） gold ore deposits in eastern Kunlun （昆仑） Mountains. Total of six zircon FT ages have been obtained and can be divided into groups of 235-216 and 197-181 Ma, as well as 162 and 124 Ma, revealing multiple epochs of metalloge- netic processes took place in Wulonggou area, mainly first two age groups. The mineralizing ages be- come lower from northeast Yanjingou （岩金沟） to southwest Hongqigon （红旗沟）. The second epoch of 197-181 Ma is first achieved by this work. It is shown that the FT ages consist with other isotopic data and reflect different regional thermotectonic events.

A step metallogenetic model for gold deposits in the northwestern Shandong Peninsula, China

Based on our study of the nature and variation of mineralization-controlling faults in their deep extension and the spatial distribution of gold orebodies in the northwestern Shandong Peninsula (NSP), here we propose that the gold deposits in the Jiaojia gold belt are controlled by listric faults and the gold deposits in the NSP are controlled by extensional fault system. We also suggest that there is a multiple mineralization space in the deep part of the NSP gold belt. As steps or benches occur along the deep extention of the listric fault where its dipping angle changes from steep to gentle, a number of gold deposits are correspondingly distributed as a steplike pattern, which is named as a step metallogenetic model for gold deposits in the NSP. The gold deposits in Shandong Peninsula were formed in the Cretaceous when the crust in the region experienced extention and thinning following the strong collision between North China Plate and Yangtze Plate during the Triassic. Crust anataxis, fluid remobilization, and extention-detachement of the crust are the leading factors for the gold mineralization.

Metallogeny of Shoshonite-Hosted Copper-Gold Deposits in Middle-South Parts of Tancheng-Lujiang Deep Fault Zone and Its Vicinity, Eastern China

The middle south parts of Tancheng Lujiang deep fault zone and its vicinity are an important locality of Cu Au deposits related to Mesozoic volcanic subvolcanic magmatism in eastern China. According to their metallogenic features and ore forming conditions, copper gold deposits in this district are ascribed to two groups: the epithermal group which can be further divided into tellurium gold type, quartz adularia type and quartz manganoansiderite type; the magmatic hydrothermal group which includes porphyry Cu Au deposit, breccia pipe porphyry type Au Cu deposit and skarn type Au Cu deposit. In this paper, characteristics of six typical shoshonite hosted Cu Au deposits are outlined. Additionally, the factors that control the metallogenesis and distribution of these Cu Au deposits are discussed preliminarily.