宽甸群中的层控矿床

宽甸群是中朝准地台东北部的一个很重要的含矿层位,其中含有一种独特的含硼建造,产有硼矿和硼镁铁矿-磁铁矿类型的矿床。     

辽宁小砬子沟硼矿区矿床地质特征及成因探讨

根据小砬子沟硼矿的赋矿地质条件和物化探异常特征,阐述了该矿床硼矿的成矿地质条件.小砬子沟硼矿区硼矿床的成因为层控火山沉积变质再造式矿床,严格受辽河群里尔峪岩组一段含硼蛇纹岩的控制,并受褶皱构造的影响.野外地质和物化探工作表明,该矿区具有成矿的层控性和再造性等特征.     

Comparison of the Typical Metallogenic Systems in the North Slope of the Tongbai‐East Qinling Mountains and its Geologic Implications

The Tongbai-East Qinling Mountains, an important part of the Central orogenic belt, is one of the most important metallogenic belts in China and contains lots of orogenic-type and VMS-type (Volcanogenic Massive Sulfide type) metallogenic systems. The Dahe and Shuidongling VMS-type Cu-Zn deposits, located in the Erlangping Group in Tongbai and East Qinling Mountains, respectively, show similar geological and geochemical features. The Huoshenmiao Formation in the East Qinling region and the Liushanyan Formation in the Tongbai region are spilite-keratophyre sequences occurring in the western and eastern sides of the Nanyang Basin, respectively, and are interpreted to be equivalent to each other. The orogenic-type Au-Ag deposits can be subdivided into two styles; namely, fault- or structure-controlled (e.g. Yindonggou) and stratabound (e.g. Poshan). The Poshan and Yindongpo orogenic-type Au-Ag deposits, whose ore bodies are strictly hosted in carbonaceous strata in the Tongbai Mountains, show obvious stratabound characteristics. Their ore-fluids are enriched in K+ and SO42? and are regarded as K+-SO42? types. The Pb-isotope ratios of sulfides of the ores are extremely uniform and significantly different from those of the tectonostratigraphic terranes of the Qinling orogens except for the ore-hosting strata of the Waitoushan Formation. The Yindonggou and Xuyaogou orogenic Au-Ag deposits in the East Qinling Mountains, whose ore bodies are hosted in the faults cutting the hosting strata or granite body, show fault-controlled characteristics. Their ore-fluids belong to the Na+-Cl? type. The Pb-isotope ratios of sulfides of ores are similar to those of the northern Qinling orogenic belt. The Waitoushan Formation, dominated by carbonaceous sericite-rich schists and only occurring in Tongbai region, should be detached from the Erlangping Group, which occurs both in the western and eastern sides of the Nanyang Basin. Future ore exploration in the Tongbai-East Qinling Mountains should focus on fault-controlled Au-Ag lodes.     

河南围山城金银成矿带铅同位素地球化学及矿床成因

桐柏山区的围山城金银成矿带包括破山特大型银矿、银洞坡大型金矿、银洞岭大型银多金属矿床及一些矿点,所有矿床赋存于上元古界歪头山组地层,并具有层控特征。矿石矿物的铅同位素组成为²⁰⁶Pb/²⁰⁴Pb=16.753~17.216,²⁰⁷Pb/²⁰⁴Pb=15.417~15.638,²⁰⁸Pb/²⁰⁴Pb=38.251~39.050;与歪头山组地层的铅同位素组成一致,而与桐柏地区的其他地层、岩体差别较大,表明成矿物质来自赋矿地层歪头山组。围山城成矿带应属于典型的层控造山型金银成矿系统,它形成于中生代扬子与华北板块的陆陆碰撞造山过程,碰撞造山期间的下插板片变质脱水诱发了矿带内流体成矿系统的发育,强烈的流体-岩石相互作用使歪头山组内的成矿物质被萃取、迁移、聚集到碳质绢云片岩层。     

Tourmalinites from the Eastern Sierras Pampeanas, Argentina

In the eastern Sierras Pampeanas, Central Argentina, tourmalinites and coticules are found in close association with stratabound scheelite deposits in metamorphic terranes. In Sierra Grande (Agua de Ramón and Ambul districts) and Sierra de Altautina, tourmalinites are associated with stratabound scheelite deposits related to orthoamphibolites. In the Pampa del Tamboreo area, tourmalinites are located in biotite schists stratigraphically related to acid to intermediate metavolcanic rocks and scheelite-bearing quartzites.The mineral chemistry and boron isotopic compositions of tourmalinite-hosted and vein-hosted tourmalines are investigated. Overall, the tourmalines belong to the dravite-schorl series and are generally aluminous; Fe/(Fe+Mg) ranges from 0.33 to 0.85, Al/(Al+Fe+Mg) from 0.66 to 0.76 and the amount of X-site vacancy (0.12–0.48) indicates significant foitite components. Their boron isotopic compositions (δ¹¹B) are from −24.0‰ to−15.0‰.Similar mineral chemistries and boron isotopic values for tourmaline in tourmalinites related to stratabound scheelite mineralisation and in tungsten-bearing quartz veins suggest a common source for the boron and probably the tungsten. The field, chemical and isotopic relationships are consistent with tungsten and boron in quartz-vein deposits being remobilised from stratabound scheelite and tourmalinite, dominantly by liquid-state transfer associated with regional shear zones. Tungsten and boron in the original sedimentary sequence (now meta-exhalites) are ascribed to volcanogenic exhalations.     

南秦岭柞山地区铜矿成矿类型、成矿规律及找矿预测

[摘 要]南秦岭柞山地区位于陕西省东南部,其西起柞水县,东到山阳县,面积约3000km²。其地处南秦岭海西-印支褶皱带东段,主体夹持于商丹缝合带与凤镇-山阳大断裂之间。作者总结了区域成矿地质背景,对热卤水喷流沉积型铜(银铅)矿、沉积-改造层控型铜矿、热液脉型铜(镍)矿、矽卡岩型铜(铁)矿、震裂岩型铜矿、斑岩型铜(钼、金)矿等6 种铜矿成矿类型的特征进行了探讨,在此基础上阐述了柞山地区铜矿的成矿规律,指出热水喷流型铜矿、斑岩型铜矿、沉积-改造层控型铜矿最具找矿潜力。目前已知的矿床(点)均受具导浆、导热、导流、导矿功能的区域性凤镇-山阳大断裂控制,并沿其两侧展布。未来一段时期,柞山地区铜矿找矿主攻类型为热水喷流型铜矿、斑岩型铜矿、沉积-改造层控型铜矿。找矿靶区首推柞水县银洞子矿床深部、山阳县池沟铜矿点、柞水县冷水沟铜矿点,次为柞水县张家坪铜矿点、山阳县色河铺铜矿点。通过进一步勘查有望取得铜矿找矿的重大突破。     

Palaeogene Sediment-hosted Pb–Zn deposits in SE Asia: the Uragen example

The strata-bound Pb–Zn deposits in western China share many similarities and are controversial in genesis. The large Uragen Pb–Zn deposit is located in the northwestern part of the Kashgar sag, southwest of Tarim Basin, Xinjiang, NW China. With the 980.9 Mt tons of Pb–Zn ores at 0.45%Pb and 2.61%Zn, it is the third largest known Pb–Zn deposits in China. The orebodies are stratiform and stratabound and are predominantly controlled by the Uragen syncline that has an E–W axial trend. Mineralization mostly occurs in sandstones and conglomerates of the Lower Cretaceous Kezilesu Group (K₁kz), with a small amount in the Palaeocene limestone. The main ore types consist predominantly of disseminated ore with minor massive ore, veined ore, and breccia ore. The primary metal minerals are composed of sphalerite, galena, pyrite, and minor arsenopyrite and chalcopyrite, and the supergene metal minerals include smithsonite, cegamite, beudantite, jarosite, limonite, and minor hemimorphite. The gangue minerals are composed of dolomite, calcite, quartz, celestite, and gypsium. Our new Rb–Sr isotopic analyses on the separated sphalerite, galena yielded an isochron age of 55.1 ± 1.6 Ma, coeval to an isochron age of 55.4 ± 2.2 Ma by Sm–Nd isotopic data. This age is much younger than the youngest ore-bearing strata (E₁¹, 65.5–61.7 Ma), arguing for an epigenetic origin. The calculated initial ⁸⁷Sr/⁸⁶Sr ratio of sulphides is 0.710322, which is much lower than those of basement formation, regional bituminous sandstone, and even the ore-bearing strata, but higher than the regional mantle-derived, alkaline volcanic rocks and marine carbonate. The calculated initial ¹⁴³Nd/¹⁴⁴Nd ratio of calcite and galena is 0.512081. These data suggest that the metals may be chiefly derived from crust, possibly from the minor contribution of mantle materials. Our new-age data, in combination with the previous data, suggest that there probably is a huge medium-low-temperature epigenetic stratabound Pb–Zn belt, which is possibly correlated to the India–Asia collision event.     

辽宁后仙峪硼矿区混合花岗岩成因探讨与成矿特征

后仙峪硼矿区地表分布的岩石主要为混合花岗岩.前人研究认为该岩石为岩浆岩,其下不可能存在层控硼矿床.通过对该区地质资料及混合花岗岩的分析研究,结合多年野外勘查工作,得出该岩石为正常地层,经钻探验证在数百米厚混合花岗岩层下发现了隐伏硼矿体,取得了找矿突破,扩大了该区找矿前景.     

辽东地区硼矿床成因探讨与硼矿远景区预测

辽东地区硼矿赋存于以"含硼岩系"而著称的辽河群里尔峪(岩)组中,表现出明显的地层岩性控矿性.在广泛搜集前人有关硼矿研究成果的基础上,结合丹东市1/25万区调,对本区硼矿成因进行了较深入的研究,认为本区硼矿是混合岩化成矿-构造再次富集的层控型矿床.进而对硼矿成矿远景区进行了预测,共划分A、B、C三级预测区,A级1处,B级3处,C级3处,为今后硼矿找寻、立项提供了科学的依据.     

辽宁省凤城市四道门沟铁矿床地质特征及成因分析

辽宁省凤城市四道门沟铁矿床位于辽东铁、硼成矿带内。以下元古界辽河群变质岩系最为发育,褶皱构造是直接控制本区变质层控铁硼矿的重要控矿条件,其控制着矿体的产出空间位置,并控制着区内铁矿体的展布特征。该区的铁矿属于火山沉积变质-超变质热液迭生层控矿床,矿石自然类型为磁铁矿-透闪石型,局部有磁铁矿-蛇纹石型和磁铁矿-硼镁铁矿型。