| Haigou gold deposit is located in Liangjiang town, Antu country of JilinProvince. It is in the transitional tectonic area between the northern margin of theNorth China Plate and the Xing’an-Mongolia orogenic belt （Jilin-Heilongjiangportion）. The study area is in a tectonic region where the Mesozoic Pacific tectonicdomain superposed on Hercynian Paleo-Asian Ocean tectonic domain. The Haigougold deposit exsits in the place where NW trending Jinyinbie-Qingchaguan Faultcrosscuts with NE trending Liangjiang Fault.The strata exposed in the region mainly include Ji’an Group and Seluohe Groupmetamorphic rock series, Qingbaikou System sedimentary strata of Proterozoic, andvolcanic-sedimentary rock series of Mesozoic-Cenozoic. NE trending and NWtrending faults are seen in and nearby the Haigou mine, for example, the LiangjiangFault and the Haigou-Huanggou Fault. The regional magmatic activities were alsostrong in the area and the intrusions are mainly Late Hercynian intermediate-acidgranitoids, and Mesozoic granitic and dioritic intrusions. The intermediate-basicvolcanic rocks of Mesozoic-Cenozoic are locally developped in the area.Haigou gold deposit contains more than50ore veins, and the28th,38thand43thvein are the main vein groups of them. The veins are mainly controlled by NE-NNEtrending structure belts in monzonite and monzogranite, a few in Seluohe complex.The mineralization type are auriferous quartz veins principally, and a few altered rocktype. The ore minerals are native gold, pyrite, galena, chalcopyrite, molybdenite,sphalerite and hematite etc, and the gangue minerals are mainly quartz, calcite, barite,kaolin, etc. There are many types of ore structures, mainly include crystallinestructure, replacement texture, cataclastic structure etc. Ore textures mainly includevein, reticulate vein texture, in addition to developing massive texture, disseminated texture and scattered texture, etc. In accordance with formation orders, themineralization of Haigou gold deposit can be divided into five phases:Ⅰ.quartzvein-hematite-pitchblende stage,Ⅱ. white quartz vein stage, Ⅲ. gold-gray quartzvein-pyrite stage, Ⅳ. gold-polymetallic sulfide stage, and Ⅴ.calcite stage. Amongthem the stage Ⅲ, Ⅳ are the principal mineralization stages. The types of wall-rockalteration include alteration to K-feldspar, pyrite, and silicification etc.The types of fluid inclusions can be divided into two phases: gas-liquidtwo-phase inclusions and gas-rich（mainly CO2） inclusions, whose size ranges from2to8μm. The components of ore-forming fluid are CO2-H2O-CH4system, which ischaracterized by CO2-rich and salinity-low, similar to the fluid composition of typicalorogenic gold deposits. The temperature of the main mineralization stage（Ⅲ,Ⅳ）focused on200300℃. The results of carbon-hydrogen-oxygen isotopes researchindicate that the ore-forming fluids are mostly magmatic water, a little meteoric waterand a few mantle-derived fluids in addition. Sulfur and lead isotopes research revealthat the ore-forming material resources mainly come from Seluohe group of LateProterozoic and Archean Strata, with crust-mantle mixing characteristics.The Haigou intrusion consists mainly of central monzogranite, and marginalmonzonite. Study on major elements shows that Haigou intrusive rocks are alkali-richand aluminum-rich shoshonite-serieshigh-K calc-alkaline series granitic rocks,characterized by enrichment in LREE(71.36×10-6220.97×10-6) and depletion inHREE(9.05×10-635.7×10-6), unconspicuous anomalies of Eu（δEu=0.811.26,averaged at1.01）. The rocks are characterized by the enrichment of LILE（Ba, Sr） andHFSE（Th, U, Pb），depletion of Pand Ti, etc.According to the CL image analysis and LA-ICP-MS U-Pb age of testing ofzircon in adamellite（HG11）, monzonite（HG12）, the petrogenic age of Haigouintrusion is Hercynian period（322.4-326.1Ma）, with inherited zircon of Archeanera（2802±37Ma） and Proterozoic era（2320±32Ma,2305±32Ma）. Combining the REEs,trace elements, and Sr, Nd, Hf isotopes research, the paper suggests that the sources ofHaigou intrusion are mainly derived from crust source, with a great amount of mantlematerial, its tectonic environment belongs a continental margin setting related toPaleo-Asian Ocean plate subduction..The geologic age of syn-mineralization granodiorite porphyry is132.4Ma.Considering the former studies about metallogenic epoch of the Haigou gold deposit, its mineralization time should be limited to142.3128Ma, mainly130Ma.The metallogenic model of the deposit is suggested as the followings:In142.3128Ma, the area was in the period of conversion of tectonic regimes.The ancient mantle lithospheric delamination and extension, asthenosphere upwelling,caused the lower crust partial melting, provided the initial heat source and highsalinity magmatic hydrothermal for mineralization. And with the occurrence anddevelopment of underplating, the CO2-rich mantle fluids and the basic magma intrudeupwards along the deep-large fault, carrying partial mantle-derived ore-formingmaterial and caused the formation of the Dahaigou gabbro-diorite stock and largenumber of intermediate-basic dikes in the mine. During the mantle-derived fluidsascending, they extracted the ore-forming materials from the crust and formedore-bearing hydrothermal fluids. Gold was deposited in the NE-NEE extending faultsin the Haigou intrusion where favorable physicochemical conditions （for instance, P, T,Ph, Eh） are met. |
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