四川康定母猪笼沟泥石流形成特征与物源定量计算

母猪笼泥石流的形成条件、受控因素和变化发展趋势在康定地区及周边具有代表性。通过调查,母猪笼沟形成区两岸滑坡体较大,主要为6个滑坡体和3个沼泽淤积土,边坡稳定性较差,在强降雨、饱水以及地震情况下,失稳可能性较大。综合分析,母猪笼沟松散物总储量达268050 m3,强活动物源(一次泥石流最大可能提供的物源量)储量达22550 m3。从水源、地形、物源补给、人工活动方面上,母猪笼沟泥石流处于活跃阶段,发生泥石流的可能性较大。     

山东平邑盆地古近系湖相微生物碳酸盐岩形成机理*

微生物碳酸盐岩是当前沉积学的研究热点之一,但关于古近系湖相微生物碳酸盐岩的报道还非常少。为探讨山东平邑盆地古近系官庄组中段湖相微生物碳酸盐岩的形成机理,笔者进行了野外实测以及室内偏光显微镜和扫描电镜观察。研究结果认为：（1）研究区微生物碳酸盐岩主要有核形石、叠层石和凝块石;（2）在核形石、叠层石和凝块石内部均发现了球状微生物化石、席状体和凝块状泥晶等微生物成因的显微组构,表明了它们形成过程中共同的生长、粘结和钙化等微生物作用;（3）微生物作用对环境变化比较敏感,水体较小、变化频繁的湖泊环境,对微生物碳酸盐岩结构和形态的发育有很大影响;核形石、叠层石和凝块石的形成环境大致呈现出水动力依次减弱、陆源碎屑物质依次减少、水深依次加大的规律;（4）提出了研究区微生物碳酸盐岩的成因模式,认为这3种微生物碳酸盐岩正是以微生物活动为共同基础,在不同的环境条件下形成的。     

豫西南湍源银多金属矿集区典型矿床(点) ——来自地质、流体特征及锆石U-Pb年龄的证据

豫西南湍源银多金属矿集区位于秦岭造山带中部,分布有板厂铜多金属矿床、银洞沟银多金属矿床、许窑沟金矿床、银虎曼铅锌矿,以及万人洞沟、铁罗沟、万沟等金银矿点。流体包裹体研究表明,与含矿有关的石英脉流体包裹体组成复杂,特别是富气包裹体十分发育,而不含矿的石英包裹体类型简单,多为水盐包裹体。获得研究区内与成矿关系比较密切的卢家坪岩体和五龙潭岩体的锆石206Pb/238U年龄分别为446Ma±7Ma和424.6Ma±4.9Ma,据此认为该区成矿时间最早可延伸至加里东期。系统总结了矿集区矿床矿点的成矿作用过程,认为湍源银多金属异常区典型矿床可以分为以下几类：①与地层有关的火山喷流沉积及后期热液叠加改造的块状硫化物矿床(VMS-SEDEX),火山作用提供成矿物质,后期热液改造形成矿床,代表性矿床为银虎曼铅-锌矿床; ②与构造有关的蚀变岩-石英脉型金、银多金属矿床,成矿物质来源于深部和围岩,朱-夏断裂带次级构造提供容矿空间,代表性矿床为银洞沟银多金属矿床、许窑沟金矿; ③与中酸性侵入岩有关的斑岩型-矽卡岩型矿床,成矿物质来源于深部和围岩,朱阳关-夏馆断裂带提供容矿空间,代表性矿床为板厂铜多金属矿床 。     

Discussion on the concepts in paleoenvironmental reconstruction from coal macerals and petrographic indices

Organic facies analyses quantify the coal constituents and plot various associations to discriminate the paleoenvironment for coal bearing successions. This allows the relation of coal composition to mire ecosystems or environments. Coal petrographic models are used extensively to reconstruct the nature of ancient peat forming environments. Many authors proposed relations between specific maceral assemblages and/or micro-lithotypes and peat forming environments. The key controlling factors which affect peat environment include hydrogeology, redox, pH, vegetation type, clastic influx, sedimentation and peat accumulation rate etc. Recent advancements in coal maceral study and organic petrology reveal the pros and cons of the available indices and models. The main reasons for the failure of the petrographic models are – oversimplification of the effects of humification on tissue preservation vs. destruction, the use of post-diagenetic processes (e.g. geochemical gelification) in determining depositional environments, changes in petrographic composition related to floral evolution, geological age, rank increase and compaction, lack of distinction between different inertinite maceral in some models. Here the widely used petrographic indices and models are reviewed based on the observations of several workers and the applicability and concepts of paleo-environmental reconstruction are discussed. A multi-disciplinary approach including petrography, palynology, chemistry etc. has been recommended, which is more logical and scientific than the exclusive use of petrographic composition for paleoenvironmental interpretation.     

Characteristics of Ore-forming Fluid of the Gaoshan Gold-Silver Deposit in the Longquan Area,Zhejiang Province and its Implications for the Ore Genesis

The Gaoshan gold-silver deposit, located between the Yuyao-Lishui Fault and JiangshanShaoxing fault in Longquan Area, occurs in the Suichang-Longquan gold-silver polymetallic metallogenic belt. This study conducted an investigation for ore-forming fluids using microthermometry, D-O isotope and trace element. The results show that two types of fluid inclusions involved into the formation of the deposit are pure liquid phase and gas-liquid phase aqueous inclusions. The homogenization temperature and salinity of major mineralization phase ranges from 156°C to 236°C(average 200°C) and 0.35% to 8.68%(NaCleqv)(average 3.68%), respectively, indicating that the ore-forming fluid is characteristic of low temperature and low salinity. The oreforming pressure ranges between in 118.02 to 232.13'105 pa, and it is estabmiated that the oreforming depth ranges from 0.39 to 0.77 km, indicating it is a hypabyssal deposit in genesis. The low rare earth elements content in pyrites, widely developed fluorite in late ore-forming stage and lack of chlorargyrite(Ag Cl), indicates that the ore-forming fluid is rich in F rather than Cl. The ratios of Y/Ho, Zr/Hf and Nb/Ta of between different samples have little difference, indicating that the later hydrothermal activities had no effects on the former hydrothermal fluid. The chondrite-normalized REE patterns of pyrites from country rocks and ore veins are basically identical, with the characteristics of light REE enrichment and negative Eu anomalies, implying that the ore-forming fluid was oxidative and derived partly from the country rocks. The δD and δ18O of fluid inclusions in quartz formed during the main metallogenic stage range from -105‰ to -69 ‰ and -6.01‰ to -3.81‰, respectively. The D-O isotopic diagram shows that the metallogenic fluid is characterized by the mixing of formation water and meteoric water, without involvement of magmatic water. The geological and geochemical characteristics of the Gaoshan gold-silver deposit are similar to those of continental volcanic hydrothermal deposit, and could be assigned to the continental volcanic hydrothermal gold-silver deposit type.     

黔中隆起及周缘下寒武统牛蹄塘组页岩气勘探前景

文章基于黔中隆起及周缘地区下寒武统牛蹄塘组黑色页岩的野外露头,并与周边钻井资料类比,通过野外地质观测、样品显微薄片等多项实验测试,以地层沉积、岩石学、有机地球化学和泥页岩含气性等为重点,对其下寒武统牛蹄塘组页岩气形成的成藏条件与勘探前景进行了分析。结果表明黔中隆起及其周缘地区下寒武统牛蹄塘组主要发育以盆地相—深水陆棚沉积环境控制的富有机质泥页岩,富有机质泥页岩厚度大(80~160 m),有机质丰度高(平均TOC含量3.63%),有机质类型好(Ⅰ-Ⅱ1型),热演化程度高成熟―过成熟(Ro1.55%),石英等脆性矿物含量丰富(平均46%),泥页岩中发育微米至纳米级微孔隙和微裂缝,且有较好的保存条件,有利于页岩气的形成与富集,具有较好的勘探前景。     

塔里木北缘库鲁克塔格地块大金沟金矿流体包裹体特征:对矿床成因的启示

在成矿地质背景和矿床地质特征研究基础上,对大金沟金矿主矿体中含矿石英脉流体包裹体开展了系统的岩相观察和显微测温工作。结果表明:大金沟金矿含矿石英脉中主要发育富液相的气液两相包裹体,偶见纯液相或气相包裹体。这些包裹体可分为低温高盐度(75℃~121℃,16.71 wt%NaCl~19.68 wt%NaCl)、低温低盐度(100℃~172℃,0.7 wt%NaCl~5.71 wt%NaCl)、中低温中低盐度(75℃~253℃,6.16 wt%NaCl~12.51 wt%NaCl)和高温中低盐度(331℃~420℃,4.96 wt%NaCl~12.51 wt%NaCl)等4类。大金沟金矿主成矿期流体包裹体的均一温度(75℃~253℃)和盐度(0.7 wt%NaCl~19.68 wt%NaCl)变化较大,且两者的相关性不明显,属典型的中低盐度流体体系,与造山过程相关的变质流体类似,表明该矿床可能为造山型金矿床。     

内蒙古拜仁达坝铅锌矿矿集区土壤中成矿元素分布及其赋存形态研究

对拜仁达坝铅锌矿矿集区3个多金属矿区的3个土壤粒级样品中Zn、Pb、Cu、Ag 4种主要成矿元素的7种赋存形式(水溶态、离子交换态、碳酸盐结合态、有机质结合态、铁锰氧化物结合态、硫化物结合态和残渣态)进行了测定。研究结果表明:1银都矿区土壤中Zn、Pb和Ag浓度最高,而道伦达坝矿区土壤中Cu的浓度最高;2拜仁达坝矿集区土壤中Zn、Pb和Cu主要以残渣态形式赋存,而Ag主要以铁锰氧化物结合态和硫化物结合态形式赋存;3拜仁达坝矿集区Zn、Pb和Cu元素在3个土壤粒级中的各个赋存形式所占的比例略有差别,但总体上大致相同,而Ag元素的赋存状态在3个土壤粒级的差异较大;4 3个矿区土壤中水溶态、离子交换态、碳酸盐结合态和有机质结合态的Zn和Pb差别不大;铁锰氧化物结合态、硫化物结合态和残渣态的Zn和Pb,以及Cu和Ag的7个赋存状态在3个矿区的差别较大。     

鄂尔多斯盆地南部砂岩型铀矿成矿预测

鄂尔多斯盆地是我国北方重要的产铀盆地之一,但其南部地区的铀矿地质工作相对比较薄弱。笔者从铀源、构造、沉积建造、沉积相、层间氧化作用及物化遥等方面总结了鄂尔多斯盆地南部地区的铀矿预测要素特征,在GIS平台上采用MRAS软件和特征分析法,圈定并优选出Ⅰ、Ⅱ级远景区各1处;认为店头-瑶曲地段、彬县-旬邑地段是盆地南部砂岩型铀矿找矿的有利地区。     

桃山大布铀矿床绿泥石特征及其形成环境

花岗岩型铀矿中,绿泥石化作为热液蚀变的重要类型之一,其种类多样,据此可以推断其形成环境。笔者在岩石薄片观察的基础上,通过对绿泥石进行电子探针成分分析,认为桃山大布铀矿床的绿泥石主要为铁绿泥石、蠕绿泥石,其形成于中低温酸性热液作用环境。