1998 Vol. 4, No. 2

Display Method:
1998, 4(2): 1-4.
Abstract (96) PDF (144KB)(15)
Abstract:
STUDY OF THE TECTONO-PHYSICAL PROCESS OF THE SUBVOLCANIC GOLD DEPOSIT,JINCHANGGOULIANG, INNER MONGOLIA
Wang Jiaping, Meng Xianggang, Yang Yudong, Qu Wei, Tian Xiaojuan, Jia Hongjie, Liu Zhibin
1998, 4(2): 5-13.
Abstract (219) PDF (399KB)(11)
Abstract:
The Jinchanggouliang gold deposit located in the northern margin of the North China Block occurs where the Late Archean gneiss was invaded by the hypabyssal-subhypabyssal porphyritic granite stock during 126.3-121.5Ma.Vein golds were formed when magmatic hydrothermal liquids injected into the radial and conjugate fractures around the stock during 121.7-100.02Ma.On the background of the mineral-deposit geology and geochemistry,the tectonic style and the tectonic stress field during the gold mineralization are studied,and based on the Acoustic Emission stress measurements,the tectono-physical model is set up.It is suggested that the uplift-denudation process of the basement rock of the ore deposit from the depth of 9.1km to the surface and the emplacement of the small stocks at the depth of 3.4km are closely related with the Meso-Cenozoic tectonic movement of the East Asia-Peri-Pacific tectonic mineralization domain.
CHARACTERISTICS OF THE DAHEISHAN GOLD DEPOSIT IN-AOHAN QI,INNER MONGOLIA,AND THE STRUCTURAL-CONTROL OF MINERALIZATION
Meng Xiangang, Qu Wei, Shi Lei, Yang Yudong, Tian Xiaojuan, Jia Hongjie, Liu Zhibin
1998, 4(2): 14-20.
Abstract (235) PDF (330KB)(26)
Abstract:
The Daheishan gold deposit located in the Nuluerhu uplift belt in the northern margin of the North China Platform developed in the Archean high-grade metamorphic complex.The origin of the gold deposit is closely related to the Yanshanian Daheishan granitic intrusion.The gold deposit belonging to fragmentation-alteration type and or alteration-quartz vein type is regarded as a mesothermal ore deposit since its mineralization temperature ranges from 235℃ to 300℃,W18O from 2.89‰ to 14.74‰,and W34S from-1.30‰ to 4.27‰.The nearly W-E-trending faults,which are the major fractures that control industrial ore bodies,and NE-and NW-trending ones with weak mineralization developed widely in the mining area.The pay shoot,however,was usually formed where the W-E-trending faults join the NW-and NE-trending ones.Detailed study in the field suggests that the gold mineralization is mainly controlled by the brittle faults formed at shallow and medium depth,rather than by a ductile-shear zone formed at a deep level.
FAULT SYSTEMS IN THE QIFENGCHAN-DETIANGOU GOLD FIELD OF HUAIROU,BEIJING,AND ITS CONTROL OF GOLD MINERALIZATION
Li Zhongjian, Chen Bailin, Dong Faxian, Wang Ping'an, Wang Shifa, Li Huaiyong
1998, 4(2): 21-29.
Abstract (246) PDF (499KB)(20)
Abstract:
In the Qifengcha-Detiangou gold field,the N-S-trending and E-W-trending fault zones are the major ore-bearing structural zones,which are characterized by ductile-brittle deformation.Mineralization of gold is closely related to mylonites and quartz veins.Gold bodies are confined to part of fault zones where occur stronger deformation and facies changes of rock and minerals.
REE GEOCHEMICAL FEATURES OF THE QIFENGCHA-DETIANGOU GOLD FIELD,HUAIROU,BEIJING
Wang Ping'an, Li Zhongjian, Dong Faxian, Chen Bailin, Xu Gang, Wang Shifa
1998, 4(2): 30-38.
Abstract (174) PDF (418KB)(10)
Abstract:
The Qifengcha-Detiangou gold field in Huairou county,Beijing,is one of those that constitute the huge E-W-trending gold mineralization belt at the north margin of the North China Block and is located in the southwestern flank of the Miyun-Huairou uplift.The orefield is composed of the Qifengcha and the Detiangou gold deposits,and a group of discrete gold occurrences and Au-mineralized spots.The gold bodies and Au-mineralized bodies are mainly in veins or in lenses and are controlled mainly by faults,fractures and ductile-shear zones,associated with hydrothermal alterations such as silicification, chloritization, sericitization, pyritization and carbornatization.They mainly occur as native gold,and tellurides (calaverite and petzite),or as very fine grains and colloids within the crystal lattice of pyrite,pyrrhotite,chalcopyrite,galena and sphalerite.Quartz vein type and rock alteration type are two types of gold mineralization in this orefield,indicating a hydrothermal mineralization process.
In this paper,REE composition of sulfides,gold-bearing quartz veins,altered rocks,Mesozoic intrusive rocks and Archean metamorphic rocks in and around the orefield is studied.The main results are as follows:
(1) Fractionation of light and heavy REE of relatively earlier and larger acid or alkali acid magmatic bodies is usually higher than that of the later and smaller veins.
(2) The fact that the ΣCe/ΣY,La/Sm,(La/Sm)N,Gd/Yb,(Gd/Yb)N,La/Yb,(La/Yb)N and Sm/Nd ratios of sulfides are higher than those of Au-bearing quartz veins,indicates a higher light REE and higher LREE/HREE fractionation in sulfides than in-quartz veins.
(3) The syenite porphyry veins and syenite in this orefield are products of magmatism of the same source,with the former evolved from the latter at a late stage.REE geochemistry of syenite porphyry veins,such as ΣREE,ΣCe/ΣY,La/Sm,(La/Sm)N and Sm/Nd is more similar to that of the Au-bearing veins compared with the syenite masses.
(4) Acid intrusive rocks especially the beschtauite and granite porphyry veins are similar to syenite and syenite porphyry veins in REE geochemical features in many aspects such as the WEu,ΣCe/ΣY,La/Sm and (La/Sm)N ratios.The beschtauite veins are more similar to the Au-bearing quartz veins compared with the other acid rocks.
(5) Relationship between the Archean metamorphic rocks (such as plagioclase amphibolite,biotite granulite,biotite hornblende plagioclase gneiss and migmatite) and the Au-bearing quartz veins in REE composition is not very clearly recognized.Rocks derived from hydrothermal alteration of metamorphic rocks are similar to the acid or alkali acid magmatic veins in their Chondrite-normalized REE patterns.
We come to the conclusion that the present gold deposits are of hydrothermal origin associated with the Yanshanian alkali and acid magmatism.This knowledge will be helpful for a better understanding of the spatial distribution of the gold deposits and the ore bodies in the Qifengcha-Detiangou gold field,and for the further prognosis of gold deposits in this area.It may also provide an example for the study of gold deposits of similar origin occurring in areas of old metamorphic rocks using REE geochemistry.
ORE-BEARING STRUCTURES OF THE DABEIWU OREFIELD,JIANGXI PROVINCE AND THEIR CONTROL OF GOLD DEPOSIT
Dong Faxian, Chen Bailin, Liu Jianmin, Wang Ping'an
1998, 4(2): 39-44.
Abstract (170) PDF (283KB)(5)
Abstract:
In the Dabeiwu gold field occurs aλ-type structure composed of the NE-trending major shear fault and the NEE-trending splay compressive fracture zones,which developed in the regional ductile-shear zone,constituting the main ore-bearing structures.The growth and evolution and the difference in deformation and facies of the NEE-trending fracture zones controlled the localization of gold enrichment,the mineralization stages,as well as the state in which the gold exists.
STRUCTURES OF KANGGUER GOLD DEPOSIT IN THE-EASTERN TIANSHAN MOUNTAINS,XINJIANG
Ma Tianlin, Sun Liqian, Xu Xingwang
1998, 4(2): 45-52.
Abstract (228) PDF (354KB)(8)
Abstract:
Kangguer gold-polymetallic deposit with associated copper,lead,zinc and silver,lying south of the Tu-Ha basin in the eastern Tianshan Mountains,occur in the gigantic Qiugemintashi-Huangshan ductile compressional belt.The formation of the deposit is closely related to the evolution of this ductile compression belt and the deposit is considered as a hydrothermal altered rock-type gold deposit under the control of the ductile deformation belt.
The gold deposit occurs in the intermediate-acid rift volcanic rocks,was confined to the ductile compressional belt and the syntectonic pluton which formed during the orogeny as a result of the closing of the rift.The metallogenesis was synchronous with the tectono magmatic activity.
A trio model comprising volcanic rocks,syntectonic pluton and normal brittle-ductile-shear zone in one area is proposed for the ore deposit.Volcanic rock series provided most of metallogenic material,and syntectonic pluton supplied hydrothermal fluid,thermal energy and also part of metallogenic material while the normal brittle-ductile-shear zone formed the ore trapping structures."Three in one" is the necessary condition for the formation of ore deposit.
The normal brittle-ductile-shear zone,as a late product of ductile deformation is the main target for the prospecting of ore deposits.
RELATION BETWEEN THE FAULTING AND GOLD-MINERALIZATION IN THE JIAOJIA GOLD DEPOSIT, EASTERN SHANDONG PROVINCE
Xu Gang, Zheng Daxing, Wen Changshun
1998, 4(2): 53-58.
Abstract (144) PDF (255KB)(8)
Abstract:
The gold ores were found to be distributed along the faults occurring in the Jiaojia goldfield,Eastern Shandong.The faults had undergone at least 3 stages of acitivyt,the first two being characterized by compresso-shearing, the thrid by tenso-shearing.Each individual of the ores can be correlated to one of the 3 stages.
STUDY ON GEOCHEMISTRY OF MAIN MICROELEMENTS OF ORE-BEARING STRUCTURAL BELT OF DABEIWU GOLD DEPOSIT,JIANGXI PROVINCE
Liu Jianmin, Chen Bailin, Dong Faxian, Wang Ping'an, Zhu Yongyu
1998, 4(2): 59-66.
Abstract (173) PDF (361KB)(14)
Abstract:
The Dabeiwu gold deposit located in the Fuliang county,Jiangxi province is controlled by the ore-bearing strata and the brittle-ductile shear zone.It lies in the south-west section of the brittle-ductile shear zone in which the tectonic deformation of rocks is the strongest.The variation of the content of the main microelements in rocks and ores along the ore-bearingtectonic belt indicates that the process of tectonic deformation and facies change of rocks and ores was synchronous with the mineralization and concentration of gold.The steady increase of the contents of the main trace-elecments and their pair ratios in different ore belts with depth may suggest a possible presence of a promising deposit at some depth.
TECTONIC-LITHOFACIES FEATURES OF GOLD DEPOSIT OF METAMORPHIC ROCK TYPE IN EASTERN SHANDONG AND ITS ORE-CONTROLLING
Zhu Dagang, Lü Guxian, Guo Chusun, Deng Jun, Lu Anhuai, Zhang Zhenjiang
1998, 4(2): 67-74.
Abstract (222) PDF (377KB)(11)
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The tectonic-lithofacies features of gold deposit of metamorphic rock type in the Eastern Shandong are described in this paper.A comprehensive study of the control of ore deposits by tectonic systems and their compounding,the control of mineralization type and alteration by faulst size and their mechanical properties,the control of mineralization zoning and orebody assemblage by tectonic-lithofacies patterns is made.As a result the control of ore and rock by tectonic-lithofacies patterns is analyzed.The tectonic-lithofacies metallogenic series of the gold deposit of metamorphic rock-types in the Eastern Shandong as well as a model of its formation is also discussed.
STUDY ON THE STRUCTURES OF THE ZONGSHUBAN AREA, CHENXIAN,HUNAN PROVINCE AND ORE CONTROLLING CONDITIONS
Chen Bailin, Li Yusheng, Dong Faxian, Liu Jianmin, Liu Youxun, Zhang Yijun, Xu Shunshan, Li Jianzhong
1998, 4(2): 75-82.
Abstract (167) PDF (389KB)(15)
Abstract:
Zongshuban Pb-Zn deposit occurs in the eastern part of Chenxian where the E-W-trending Shanhe anticlinorium meets with the S-N-trending Xishan anticlinorium.The country rocks of the deposit is Sinian epimetamorphic detrital rocks.The NE-trending compresso-shear faults are the important ore-controlling structures.There develop some ore shoots in the strong kataclastic rocks in the fault zone.Individual ore shoot is lenticular,with the major/minor axis ratio of 2 to 1,and the major axis pitching to southwest at an angle of 50°-60°.Ore shoots are often en echelon arranged,one overlapping the other in longitudinal section from northeast to southwest along the mineralization zone.The metallogenic elements are derived mainly from the Mosozonic Qianlishan granite as indicated by the data of REE,microelements,sulfur isotope and lead isotope.The metallogenic temperature is determined as 168-224℃ and metallogenic period as 155-170 Ma.It is therefore a postmagmatic meso and epithermal deposit,one of the magmatic metallogenic sequence of the Qianlishan granite (Dongpo polymetallic orefield).The granite porphyry emplaced into the NE-trending faults is younger than the Pb-Zn metallogenesis and was found to cut and disrupt the ore veins.Thus the area around the early Yanshanian granite stock (or a buried granite at a depth of 3-5km) is most favorable for further exploration.
STRUCTURAL FEATURES OF THE XIAOREQUANZI COPPER-DEPOSIT,XINJIANG
Sun Liqian, Shang Ling
1998, 4(2): 83-90.
Abstract (175) PDF (392KB)(7)
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The major structure in the mine district is NW-SE-trending disharmonic brachy anticlinorium superimposed by later N-S-trending second-order fold.NW trending minor faults as branch faults of E-W-trending major faults are well developed.The main ore deposit (No.1) is characterized by a duplex mineralization.The deposit is considered as a mesothermal filling-replacement copper deposit.
MODELING OF STRESS FIELD OF FENGHUANGSHAN OREFIELD DURING MINERALIZATION
Zhang Da, Li Dongxu
1998, 4(2): 91-96.
Abstract (132) PDF (317KB)(9)
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This paper analyses the characteristics of structural compounding of Fenghuangshan orefield,and brings to light that the deformations during D4 and D5 phases are main structures controlling mineralization.The information obtained by analysis of the compounding of structural systems together with the data of regional geology and geophysics indicates that NNE-trending sinistral ductile-shear zones which lie on the east and west sides of the pluton may provide the main dynamic source for structural control of mineralization.From the above,the synmineralization stress field of Fenghuangshan orefield is modeled by means of finite element method.The results indicate that anomalously concentrated stress and strain are located along the contrat zone between the pluton and country rock and the outer ductile-shear zones.Low stresses occur where different systems of structures meet.Such places are favorable for the formation of deposits.