蒙古查干苏布尔加(Tsagaan Suvarga)大型斑岩型铜钼矿床含矿蚀变岩常量、微量和稀土元素地球化学特征及意义

蒙古Tsagaan Suvarga大型斑岩型铜钼矿床围岩蚀变类型主要有网脉状硅化、泥化、石英-绢云母化、钾硅酸岩化和青盘岩化。从热液成矿中心向外的矿化蚀变分带特征为含铜网脉状硅化蚀变带→含铜泥化带→含铜钼石英-绢云母化带→含铜钼钾硅酸岩化带→青盘岩化带。早期为钾硅酸岩化带,中期为石英-绢云母化和硅化,晚期为泥化带和碳酸盐化(方解石)。含矿蚀变岩明显受不同级次构造-裂隙带控制,北东向和北西向裂隙带可能是斑岩成矿热液体系的运移通道。随着接近循环热液成矿体系的成矿中心和硅化不断增强,REE,LREE和HREE含量降低,轻和重稀土元素之间分异程度增强;轻和重稀土元素之间分异程度与硅化-钾硅酸盐化之间关系具有指数关系。随着(Na2O+K2O)含量逐渐增高,从负Eu异常→无Eu异常→正Eu异常→明显正Eu异常,说明Eu异常受循环热液成矿体系的碱交代程度控制明显,因此,正Eu异常、轻和重稀土元素之间分异程度明显及其相关围岩蚀变特征是寻找与蒙古Tsagaan Suvarga斑岩型铜钼矿床类似的找矿预测指标。

Geochemical Characteristics and Significance of Major Elements, Trace Elements and REE in Mineralized Altered Rocks of Large-Scale Tsagaan Suvarga Cu-Mo Porphyry Deposit in Mongolia

The alteration types of the large-scale Tsagaan Suvarga Cu-Mo porphyry deposit mostly comprise stockwork silicification, argillization, quartz-sericite alteration, K-silicate alteration, and propylitization. The mineralized and altered zones from hydrothermal metallogenic center to the outside successively are Cu-bearing stockwork silicification zone, Cu-beating argillized zone, Cu-Mo-bearing quartz-sericite alteration zone, Cu-Mo-bearing K-silicate alteration zone, and pro- pylitization zone. The K-silicate alteration occurred in the early phase, quartz-sericite alteration in the medium phase, and argillization and carbonatization （calcite） in the later phase. Ore-bearing-altered rocks are significantly controlled by the structure and fissure zones of different scales, and NE- and NW-trending fissure zones could probably be the migration pathways of the porphyry hydrothermal system. Results in this study indicated that the less the concentrations of REE, LREE, and HREE and the more the extensive fractionation between LREE and HREE, the closer it is to the center circulatory hydrothermal ore-forming and the more extensive silicification. The exponential relationship between the fractionation of LREE and HREE and the intensity of silicification and K-silicate alteration was found in the Cu-Mo deposit studied. The negative Eu anomaly, normal Eu, positive Eu anomaly and obviously positive Eu anomaly are coincident with the enhancement of Na2O and K2O concentrations gradually, which indicated that Eu anomaly would be significantly controlled by the alkaline metasomatism of the circulatory hydrothermal ore-forming system. Therefore, such characteristics as the positive Eu anomaly, the obvious fractionation between LREE and HREE and their related special alteration lithofacies are suggested to be metallogenic prognostic and exploration indications for Tsagaan Suvarga-style porphyry Cu-Mo deposits in Mongolia and China.

Morphodynamic development of the Terkhiin Tsagaan Lake Depression,Central Mongolia:Implications for the relationships of Faulting,Volcanic Activity,and Lake Depression Formation

Data on the origin and morphology of lake depressions caused by volcanism are scarce in Mongolia.Previous studies focused on climate change patterns based on Terkhiin Tsagaan Lake sediment.We present a result of existing reconstructions of lake depression development and changes in the hydrology system during the Khorgo volcanic activation and the Holocene environmental change.A depression of the Terkhiin Tsagaan Lake is formed by a lava flow barrier from the Khorgo volcano.However,the Khorgo volcanic eruption and the lake depression that could shape a large lake have arisen instead from a fault.The morphometric analysis and field measurements indicate that the derivation of the Terkhiin Tsagaan Lake depression and Khorgo volcano may have evolved from movement on a sinistral strike-slip fault,which is about 70 km long.The southern mountains and rivers were displaced from northwest to southeast along the Terkh Fault.The offset along Terkh Fault is 4.02-5.28 km in the depression of the Terkhiin Tsagaan Lake.After movement,a wide valley of the Terkh River developed in the present landscape.The active Khorgo Volcano formed along the Khorgo Fault.The Terkhiin Tsagaan Lake is formed by blocked water from the PaleoTerkh River after lava damming from the Khorgo Volcano.The initial paleo-lake area was about 195.7km^(2),which was three times larger than the modern lake.The current water volume of the Terkhiin Tsagaan Lake is 0.351 km^(3) while the volume of the paleo-lake was 2.248 km^(3).Based on this volume indicator the paleo-lake was 6.4 times larger than the current lake.Overflowing water from the lake depression formed the Suman River by a drying canyon through the lava plateau,but the canyon is along the Terkh Fault.Changes in the water volume of Terkhiin Tsagaan Lake and erosion of Suman River canyon are inversely related to each other.We present the morphometric relationships between the lava plateau of Khorgo Volcano and development of Terkhiin Tsagaan Lake depression.

蒙古国查干苏布尔加大型铜-钼矿床地质特征及成因

查干苏布尔加斑岩铜钼矿床位于西伯利亚板块南缘近东西向和北东向深大断裂所夹持的南蒙古构造岩浆带内,容矿围岩二长花岗斑岩与花岗闪长斑岩主量元素高SiO2(64.69×10-2~73.42×10-2),高Al2O3(15.33×10-2~18.35×10-2),贫MgO(0.13×10-2~0.56×10-2),微量元素Sr二长花岗斑岩略低(144×10-6~175×10-6),花岗闪长斑岩表现为高Sr(样品>300×10-6,476×10-6~720×10-6),二者均低Y(Y<18×10-6,2.21×10-6~10.20×10-6),低Yb(Yb<1.9×10-6,0.30×10-6~1.48×10-6),高Sr/Y(Sr/Y>20,21.8~63.52),稀土元素特征为亏损重稀土,无明显负铕异常,(87Sr/86Sr)i=0.70154~0.70397,(143Nd/144Nd)i=0.512290~0.512600,εNd(t)为+2.4^+8.5,二长花岗斑岩和花岗闪长斑岩均具有埃达克质岩特征,但二长花岗斑岩与花岗闪长斑岩主、微量和稀土元素又存在一定差别,它们可能是岩浆不同演化阶段的产物。通过年龄测定,获得辉钼矿Re-Os等时线年龄为(370.0±5.9)Ma,二长花岗斑岩锆石SHRIMPU-Pb加权平均年龄为(365.7±3.6)Ma,铜钼矿形成时代与二长花岗斑岩形成时代相近,均形成于晚泥盆世。铜钼矿床与二长花岗斑岩、花岗闪长斑岩紧密共生,矿区范围内二长花岗斑岩与花岗闪长斑岩多被蚀变并矿化,表明二长花岗斑岩、花岗闪长斑岩与铜钼矿化存在密切的时空关系,为铜钼成矿提供了主要成矿物质和流体来源。

蒙古国查干油田基本石油地质特征

通过对钻井、录井、岩心化验、试油等资料的研究,结合区域勘探成果,分析了查干油田的基本石油地质特征。研究表明,下宗巴音组下段发育200m左右的油泥岩和暗色泥岩,有机质类型为Ⅱ1型,镜质体反射率平均值为0.7%,生烃指标好,评价为优质烃源岩;查干油田处于"凹中隆"上,其西、北、东三面被生油洼陷环绕,成为捕捉油气最有利的场所。查干组和下宗巴音组发育扇三角洲前缘水下分流河道和席状砂微相,查1和查27断块油藏储层物性好,为中孔中渗透储层;查14断块油藏为中孔低渗透储层。通过成藏特征分析认为,中央断裂背斜带因近油源、纵向上输导条件好而成为油气聚集的有利构造带,并且与良好的储集相带相匹配,为查干油田的形成创造了条件。

内蒙古东乌旗巴润查干陶勒盖地区物化探异常特征及找矿远景

内蒙古东乌旗巴润查干陶勒盖地区位于二连-东乌旗成矿带东段,具有良好的成矿地质背景,晚华力西期花岗岩、石英二长斑岩侵入体及各类晚期脉岩伴随北东向断裂构造侵入安格尔音乌拉组地层中,具有十分有利的成矿地质条件。1:5万及1:1万土壤地球化学异常元素主要为Pb、Zn、Cd、Cu等,浓集中心明显,套合较好。1:5万航磁局部异常及1:1万地面高精度磁测异常均与北东向构造岩浆活动密切相关。1:1万地质测量圈定的地表矿化蚀变带与上述物化探异常形态基本一致。通过分析研究区的控矿地质条件及物化探异常特征,认为研究区热液型Pb、Zn多金属矿床具有良好的成矿远景,有进一步工作价值。

蒙古南戈壁欧玉陶勒盖铜(金)矿床地质特征及其对我国找矿勘查工作的启示

近二十年来,蒙古南戈壁成矿带在寻找大宗金属矿产方面取得丰硕成果,发现了欧玉陶勒盖和查干苏布尔加等与古亚洲洋晚泥盆世岛弧演化有关的大型斑岩型矿床。研究表明:1)欧玉陶勒盖—查干苏布尔加地区在法门期弧岩浆与矿化作用之后,经历了短暂的抬升和剥蚀过程,随后被石炭纪火山-沉积岩所覆盖。两个矿床皆被埋藏于法门期(D_3)—杜内期(C_1)不整合面之下;2)矿床现今出露于石炭纪—二叠纪岩体包围的"天窗"中,矿体能否保存与其上覆岩层遭受的剥蚀程度有关;3)近EW向展布的蒙古南戈壁成矿带在欧玉陶勒盖—查干苏布尔加地区受三叠纪—早白垩世准巴彦断裂左旋走滑运动的影响,局部转变为NE走向,向东可延伸至中国境内东乌旗一带。因此,在中国内蒙古东乌旗地区开展的找矿勘查工作应重点关注法门期(D_3)—杜内期(C_1)不整合之下的晚泥盆世侵入体及其围岩,并在成矿远景区进行相应的区域构造解析研究。

内蒙古塔拉查干花岗岩地质特征及形成时代

内蒙古塔拉查干地区出露着大面积的花岗岩,本文在研究塔拉查干花岗岩野外地质特征的基础上,对该区花岗岩锆石U-Pb同位素测年方面进行详细研究,总结研究区花岗岩的地质特征并确定花岗岩的形成时代。