| Jianchaling gold and nickel ore field, which has the unique tectonic structure position, is located in the combining site between the Yangtze plate and Qinling orogenic belt. Jianchaling is just a small place where gathers many kinds of minerals, such as gold minerals, nickel minerals, iron minerals, asbestos minerals, magnesite, serpentine nanotubes and other materials of metal and non-metallic minerals. Jianchaling nickel deposit has been exploiting, gold minerals has been prospecting external at present. The research of the tectonic deformation in this area not only provides the most directly and basically geological material to restore the tectonic evolution regularity of Yangtze plate and Qinling orogenic belt, but also analyzes the ore-controlling rule of the gold and nickel ore in ore field, which can be used to guide further exploration. Therefore, the research of the structure in Jianchaling gold and nickel ore field has great theoretical and practical significance.Using structural analysis methods, with the structure characteristics of Jianchaling gold and nickel ore field as the research center and focusing on the rock-controlling and ore-controlling structure, based on the theory of regional tectonic rule, structural geology, structural petrology, geochemistry, isotope chronology, the mineral deposit geology and other subjects, structure characteristics and evolution regularity of ore field, ore-controlling structure characteristics, rock-controlling and ore-controlling structure are studied systematically, and then discuss how to find other minerals. The main achievements and conclusions of this paper are as follows:(1) The multi-episodic deformation of Mesoproterozoic metamorphic basement in Jieguanting Formation is analysed:In the early Mesoproterozoic, after the intermediate-basic volcanic rocks, medium acid volcanic rocks and cinerite were formed, a small amount of clastic rocks and carbonaceous mudstone are deposited in Jieguanting Formation; in the later of Mesoproterozoic, the first-phase fold occured in the Jieguanting Formation, the north wing of the fold is normal and the south wing is reversed, axial surface occurrence is S1≈216°(?)45°, hinge of fold isβ1≈215°(?) 50°, late fold overlied on the early fold make early axial surface curve to form an antiform anticlinal fold, which axial surface occurrence is 165°(?)75°, hinge of fold isβ2≈70°(?)20°. In the early Caledonian, because of the tectonic movement, overlying strata formed a series of nearly east-westward folds, such as Duantouya syncline, Jiudaoguai syncline, Guandiliang syncline, Xiqugou anticline and so on. Jiudaoguai syncline and Duantouya syncline are box-like folds, pitching angle is 20°-30°; Xiqugou anticline is linear anticline fold, the occurrence of axis surface is 115°-120°; Guandiliang syncline is a short axis fold. The stratums are controlled by the folds in this area.(2) Two area ductile shear belt in Jianchaling ore field are determined:NWW area ductile shear belt and NE area ductile shear belt(NWW ductile shear belt and NE ductile shear belt for short below). Based on the methods of field geological survey, ultramicrostructural and microstructural observation in laboratory, the kinematics and kinetics characteristics of two ductile shear belts are studied systematically. It is also found that the formation and evolution of the two ductile shear belts are not only strict controlling role, but also an important ore-controlling factors to Jianchaling ultrabasic rocks, granite porphyry and albitophyre.The characteristics of two ductile shear belts in the ore field are as follows:NWW ductile shear belt and NE ductile shear belt are conjugate, and both have the three activitie stages:At the late of Mesoproterozoic, NWW ductile shear belt is compressive and shear, surname cut; NE ductile shear belt is compressive and shear, sinistral cut,σ1≈282°(?)24°, paleostress value is about 59.1MPa, dynamometamorphism reached high greenschist-facies, both of which are flat-type strain; In Caledonian-Hercynian, NWW ductile shear belt is tension-shear, surname cut; NE ductile shear belt is tension-shear, sinistral cut,σ1≈344°(?)78°, paleostress value about 86.5MPa, dynamometamorphism reached middle greenschist-facies; in the Indo-Chinese epoch, with the degree of brittle further increasing, NWW shear ductile belt is compressive and shear, sinistral cut, NE ductile shear belt is compressive and shear, surname cut,σ1≈120°(?)20°, paleostress value is about 116.3MPa, dynamometamorphism reached low greenschist-facies, both are the flattening strain. the total draft of NWW ductile shear belt is about 0.259%, the total displacement of the first and second phases is about 0.98km, the sinistral displacement of the third phase is about 1.65km, and the difference between both is 0.67km.(3) By the preliminary study of Jianchaling ultrabasic rocks and granite-porphyry structures, the emplacement mechanism of Jianchaling ultrabasic rocks and granite-porphyry are proposed. During the medium-term activity of NWW ductile shear belt and NE ductile shear belt, ultrabasic rocks intruded into two ductile shear belts by the way of dike propagation, and then the shear transformated formed serpentinite mylonite, mylonitization magnesite and other dynamic metamorphism rocks; during the third phase of activities of two ductile shear belts, the granite-porphyry emplaced like a expandable balloon. According to the contact relation between rock mass and the surrounding rocks, a new understanding of the ultrabasic rocks formation period is proposed. Because some intrusive relation and many xenoliths are found in the rock mass and Sinian dolomite or the carbonaceous schist, the formation of ultrabasic rocks should be later than the Sinian; according to the activity issue of two ductile shear belts, it is formed in Caledonian.(4) According to the research of ore-controlling factors and geological features of mineral deposits, "three factors and one orebody" ore-forming mechanism, which is the ductile shear belts-ultrabasic rocks-acid-instrusions(veins), is proposed. Jianchaling gold and nickel deposits have the similar ore-controlling factors and mineralization, they are in a unified metallogenic system, but in the different physical and chemical conditions and formed at same time.(5) The crystallization age of the Jianchaling granite-porphyry is 216±4Ma, and it is belong to the Triassic (Indosinian), by the comprehensive study, the granite-porphyry and gold and nickel deposits are close connection with time, space and cause of formation, So Jianchaling gold nickel mineralization era is Indosinian, and the third activity of ductile-brittle shear occurred in Indosinian too.(6) The characteristics and ore-controlling disciplines of the ore-controlling ductile-brittle shear belts in the Jianchaling gold and nickel ore field are summarized. Gold ore-controlling structure is in ductile-brittle shear zone which is near contact zone between the structural alteration ultrabasic rocks and dolomitic mylonites contact zone, the general tendency is 10°-50°, the local tendency is east, obliquity changes are between 50°and 85°, both along the strike and the tendency show the wave-like. The dynamic metamorphic rock mainly consisted of ductile deformation, using transmission electron microscopy, and gold-related quartz veins formed a lot of dislocation arches, dislocation loops, dislocation lines, dislocation walls, dislocation nets, second grain structure and so on. Ore bodies are around the ultrabasic rocks and form the "gold necklace" ore-controlling pattern. Nickel ore-controlling structures are the ductile-brittle shear belts among the granite porphyry northwest and southeast direction trailing position, which the core of "a-type rotating porphyroclasts system" is granite porphyry. The occurrence of Ore-controlling structures is 170°-200°(?) 56°-80°, both along the strike and the tendency show the wave-like, the dynamic metamorphic rock is mainly ductile deformation, S-C surface is visible in the tectonic foliation, also the rotating porphyroclasts system, sub-particles, kink band. Currently, most of nickel ore bodies are found in the north-western "tail" of "rotating porphyroclasts system", the south-east "tail" is also a very good nickel mineralization with excellent mineralization conditions.(7) According to the research of this paper, the tectonic evolution of Jianchaling gold nickel ore field should be:①At the end of the late Archean, Yudongzi Group has a strong transformation of deformation and metamorphism to generate granitic gneiss, leucoleptite, granulite, magnetite-quartzite and so on, and folds were formed simultaneously, metamorphism was (low) amphibolite facies. Subsequently, the district is in the uplift denudation phase.②At the late Mesoproterozoic, a ductile shear deformation occured in the ore field after Jieguanting Formation generated, formed the NWW and NE direction ductile shear belts. Series of heavy oblique folds were formed in Jieguanting Formation, because of extrusion, the strata folded and uplifted, at the same time in Yudingzi Group, these folds superposed those earlier inclined and oblique folds.③At the end of Late Proterozoic, the studying area along with the Yangtze plate went to the evolution stage of stably passive continental margin, the Lower Sinian Duantouya Formation and the Jiudaoguai Formation are deposited extensively, and the Duantouya Formation and the Middle Proterozoic Jieguanting Formation emerged a clear angle unconformity.④During the Caledonian, a strong compressive folds and nappe structure occurred in the studying area, and the deformation of the intersection between NWW direction and the NE ductile shear was stronger, and produced some weak areas and extended downwards, which provided the good invasion channel for ultrabasic magma, and the ultrabasic rocks were formed, with the last shearing activities. The strong plastic deformation of the ultrabasic rocks has taken place. As the crust uplifting, the Cambrian-Devonian stratas are worn away.⑤In the Indo-China period, tectonic active took place in the region again, and caused the third shear of the NWW direction and NE ductile shear belts, the granite-porphyry, diabase dikes, and albite porphyry invaded.⑥After Indo-China movement (Yanshan-Himalayan), triangle area and the Yangtz plate subducted to the Qinling, and formed Qinling orogenic belt, which resulted differnet degree erosion between north strata and south strata, In the north of F18, Jiudaoguai Formation and the majority of the Carboniferous Lueyang Formation were denudated greater than the south significantly.(8) According to the " three factors and one orebody " principle, four gold and nickel mineralization prospect areas are pointed out. They are gold mineralization prospective areas in southeast structure altered ultrabasic rocks, nickel mineralization prospective areas in the southeast and northwest of graniteporphyry, gold and nickel mineralization prospective areas in Jiudaoguai. What is new?Firstly, two area ductile shear belts are determined in Jianchaling ore field:NWW ductile shear belt and NE ductile shear belt, the author studies the characteristics of geometry, kinematics,kinetics detailedly, and correlation between the two ductile shear belts, metamorphic facies, phase of deformation and structure stress field. And the author further discussed their control action to ultrabasic rocks, granite porphyry, albitophyre and gold and nickel deposits in the ore field.Secondly, the characteristics of ductile brittle shear belts and ore-controlling regulation in Jianchaling gold and nickel ore field are summed up. The gold-controling structure is the ductile brittle shear belts, which is near contact zone between the altered ultrabasic rocks and dolomitic mylonites, and formed the ore-controlling pattern like " gold necklace" around the ultrabasic rocks. Nickel ore-controlling structures are the ductile-brittle shear belts among the granite porphyry northwest and southeast direction trailing position, which the core of "a-type rotating porphyroclasts system" is granitic porphyry. At present, the main nickel ore bodies were found in the the northwestern "tail" of "rotating porphyroclasts system", the southeast "tail" was also found a very good nickel mineralization, with excellent mineralization conditions.
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