Impact of Montmorillonite and Calcite on Release and Adsorption of Cyanobacterial Fatty Acids at Ambient Temperature

Minerals might act as important sorbents of sedimentary organic matter and reduce biodegradation, which favors the formation of hydrocarbon source rocks in the earth's history. Since most organic matter is degraded during the sinking process, at ambient temperature, it is important to investigate the adsorption capacity of different minerals during this process, to assess the organic loss from primary productivity to sedimentary organic matter. In this study, montmorillonite and calcite have been selected to study the impact of different minerals on the release, adsorption, and deposition of cyanobacterial (Synechococcus elonpata) fatty acids (FAs) at ambient temperature. Gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS) have been utilized to detect the variation in fatty acids. Primary results suggest that minerals have a different impact on dissolved organic matter. Montmorillonite can specifically enhance the release of fatty acids from cyanobacterial cells by lowering the pH values of the solution. The adsorption of the dissolved organic matter by montmorillonite will also be enhanced under a lower pH value. Conjunction of fatty acids with montmorillonite to form a complex will favor the sinking and preservation of these organics. Selective adsorption is observed among fatty acids with different carbon numbers. In contrast, calcite does not show any impact on the release and adsorption of organic matter even though it is reportedly capable of acting as a catalyst during the transformation of organic matter at high temperature. The primary data bridge a link between primary productivity and sedimentary organic matter, suggesting the relative importance of claystones in the formation of hydrocarbon source rocks in the earth's history.     

Geochronology of the Xihuashan Tungsten Deposit in Southeastern China: Constraints from Re–Os and U–Pb Dating

Xihuashan tungsten deposit is one of the earliest explored tungsten deposits in southeastern China. It is a vein type deposit genetically associated with the Xihuashan granite pluton. Here we report new dating and zircon geochemistry results. Re–Os isotopic dating for molybdenite intergrowth with wolframite in the oldest generation of the Xihuashan pluton yielded an isochron age of 157.0 ± 2.5 Ma (2σ). Zircon U–Pb laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) dating shows that the pluton crystallized at 155.7 ± 2.2 Ma (2σ). This age is similar to the molybdenite Re–Os age for the ore deposit within error. This, together with published data, suggests that the major W(Mo)‐Sn mineralization occurred between 160–150 Ma in southeastern China. These deposits constitute a major part of the magmatic‐metallogenic belt of eastern Nanlin. The lower Re content in molybdenite of the Xihuashan tungsten deposit shows crustal origin for the ore‐forming material. The limited direct contributions from the subducting slab for the tungsten mineralization in the Nanling region suggest a change of the style of the paleo‐Pacific plate beneath southeastern China.     

Formation Environment of Main Brown Coal Seam in Xi-2 Minefield of Shengli Coalfield Based on Coal Ash Phase Analysis

The formation environment of the main coal seam in Shengli coal mine is analyzed, and the effect of coal ash parameters on the coal-forming environment is mainly discussed according to gray component parameters combined with other coal quality test analysis data. Results show that the hydrodynamic conditions of the main coal during coal accumulation have a general pattern of strong northeast and weak southwest, and lakeside swamp is generally in the retrograde process from south to north. The No.5 coal seam is a water entry cycle, and the No.5_lower coal is a water withdrawal cycle. The No.6 thick coal seam is formed in the peat swamp environment where the water is shallow and the groundwater activity is weak. The input of terrestrial debris material was most abundant in the formation period of No.5_lower coal, followed by No.5 coal, and that in No.6 coal is the least. Vertically, the peat swamp environment changed from weak reduction to weak oxidation to strong reducing environment. The ash yield was low to high to low from bottom to top. The organic sulfur is the main type of sulfur in the main coal seam. The weaker the hydrodynamic condition, the higher the organic sulfur content in the reduction environment, while lower organic sulfur content in the oxidation environment. The peat swamp water of No.5_lower coal is medium alkaline, and the peat swamp water of No.5 and No. 6 coals is weakly alkaline or acidic.     

页岩孔隙系统研究实验方法

基于页岩孔隙系统的特殊性,讨论了FESEM-QEMSCAN、FIB-FESEM、NANO-CT、氮气吸附法、小角中子散射等几种页岩孔隙系统研究方法的特点和适用范围。指出场发射扫描电镜以及与之结合的能谱和矿物定量评价系统(FESEM-QEMSCAN)是研究页岩纳米级孔隙类型、大小、形态以及矿物分布的基础手段;聚焦离子束扫描电镜、微纳米CT可刻画页岩孔隙系统在三维空间的展布特征,利用获得的三维数据体进行数值模拟,可进一步计算孔隙度、渗透率等物性参数;氮气吸附法可对小于100nm的极微孔隙的孔径、形态进行求算;小角中子散射则可利用孔隙中存在的气体分子,获得孔隙系统连通性等重要参数。最后从页岩岩石组构的角度,探讨了页岩孔隙控制因素,指出有机质含量与成熟度,黏土矿物类型、含量,碎屑颗粒的含量以及成岩强度是影响页岩孔隙系统的主要因素。     

红柱石微粉对高铝矾土熟料制品的补强作用

高铝矾土熟料制品是除粘土制品之外使用范围最广、用量最大的耐火材料,在各种工业窑炉中都有广泛应用。生产铝矾土熟料制品一般采用不同粒级的铝矾土熟料与塑性粘土为原料,用倒焰窑烧成时,烧成温度为１４３０～１４５０℃,保温４０ｈ;用隧道窑烧成时,烧成温度为１５５０～１５６０℃。其工艺关键是控制二次莫来石化产生的体积效应。当制品的Ａｌ２Ｏ３含量在７０％以下时,铝矾土熟料制品的高温性能取决于莫来石晶相与液相间的数量比例。Ａｌ２Ｏ３含量越高,制品中莫来石含量越高,玻璃相相应减少,制品的高温性能越好。在生产中提高…     

北极地区地质构造及主要构造事件

北极地区范围很广,北极圈面积达2 100×10⁴ km²,区域地质复杂。通过对北极地区区域地质编图,笔者认为前寒武纪主要由波罗的、劳伦和西伯利亚三大克拉通,以及其间的微板块或地块组成。主要造山带包括新元古代-早寒武世的贝加尔造山带、晚志留世-早石炭世的加里东造山带、晚古生代-早中生代的海西造山带、晚中生代的上扬斯克造山带、新西伯利亚造山带与楚科奇-布鲁克斯造山带。根据北极地区区域地质构造特征,显生宙以来经历的构造事件大致包括:新元古代-早寒武世的贝加尔运动,致使波罗的古陆与斯瓦尔巴-喀拉地块碰撞造山;晚泥盆世-早石炭世的加里东运动,在劳伦古陆周边形成规模巨大的加里东造山带;晚古生代的海西运动,波罗的古陆与西伯利亚古陆的碰撞造山形成海西造山带;北极阿拉斯加-楚科奇微板块裂离加拿大边缘,侏罗纪加拿大海盆开始张开;早白垩世,阿拉斯加-楚科奇微板块继续与西伯利亚碰撞,阿纽伊洋(Anyui Ocean)消亡,形成上扬斯克-布鲁克斯造山带。受北极调查程度影响,许多问题有待进一步研究。     

Geochemistry of the Jinman Vein—Type Copper Deposit,Western Yunnan Province,China——I.Element Geochemical Characteristics

The Jinman copper deposit,which is situated on the northern margin of the Lanping-Simao back-arc basin,western Yunnan Province,is a silver-bearing,high-grade vein-type copper deposit.Comprehensive element geochemical studies of the host rocks and hydrothermal minerals revealed the regularities in the distribution,mobilization and transport of elements from the host rocks to hydrothermal minerals.In conjunction with the fluid inclusion and isotope data,it is suggested that the ore-forming fluid was derived mainly from a deep source characterized by CO2 enrichment and reduction in nature.It is also suggested that the oreforming materials come largely from a deep source.although the contribution of the country rocks should not be ruled out.It is also found that some hydrothermal minerals are possessed of MREE-enrichment patterns.It is deduced that the REEs in the deep-source ore fluid were transported in the form of CO3^2- complexes and were deposited in a continental basin(or a hot-spring basin).     

Zircon U-Pb ages and Hf isotopic characteristics of the Dehe biotite monzonitic gneiss pluton in the North Qinling orogen and their geological significance

The Dehe granitic pluton intruded the Xiahe Group which is in the core complex of the North Qinling Orogenic Belt(NQOB).It shows gneissic bedding and possesses typical S-type granite minerals such as muscovite and garnet.LA-ICP-MS U-Pb isotopic dating of the Dehe granite yielded a weighted average age of 925±23 Ma which represents the emplacement age of the pluton.Most of the εHf(t) values are negative,and the two-stage model ages are consistent with the age of the Qinling Group.The isotope data show that the Dehe granite was formed in the following geological setting:in the syn-collision setting of the NQOB in the Neoproterozoic,crustal thickening induced partial melting of materials derived from the Qinling complex,and then the maga upwelled and intruded into the Xiahe Group.The formation of the Dehe S-type granite implied the occurrence of a convergent event in the QOB during the Neoproterozoic.     

喜马拉雅碰撞造山带不同类型部分熔融作用的时限及其构造动力学意义

喜马拉雅新生代淡色花岗岩,是世界上S型花岗岩的典例,主要分布于两条近平行排列的东西向构造带内,特提斯喜马拉雅带和高喜马拉雅带。实验岩石学和理论研究表明:这些淡色花岗岩是中—下地壳岩石进行不同性质的地壳深熔作用的产物,部分熔融类型与构造变形密切耦合。具体表现在:146~35 Ma,在增厚地壳条件下,以角闪岩部分熔融作用为主,形成了具有高Sr/Y比值的二云母花岗岩;228~9 Ma,减压条件下,俯冲物质快速折返,白云母发生脱水部分熔融,形成具有较高Rb/Sr比值的花岗岩;3其中,在21~16 Ma期间,与藏南裂谷系E—W向伸展作用开启密切相关,变泥质岩发生水致白云母部分熔融作用,形成Rb/Sr比值较低,Sr和Ba含量较高的花岗岩;4在25~27 Ma期间,局部地区发生高压水致部分熔融作用。     

Diagenesis impact on a deeply buried sandstone reservoir (Es1 Member) of the Shahejie Formation,Nanpu Sag,Bohai Bay Basin,East China

Diagenesis has a significant impact on reservoir quality in deeply buried formations. Sandstone units of the Shahejie Formation (Es₁ Member) of Nanpu Sag, Bohai Bay Basin, East China is a typical deeply buried sandstone with large hydrocarbon accumulations. The methodology includes core observations and thin section studies, using fluorescence, scanning electron microscope (SEM), cathodoluminescence (CL), fluid inclusion and isotope and electron probing analysis as well as the numerical determination of reservoir characteristics. The sandstones consist of medium to coarse-grained, slight to moderate sorted lithic arkose and feldspathic litharenite. Porosity and permeability values range from 0.5 to 30% and 0.006 to 7000 mD, respectively. The diagenetic history reveals mixed episodes of diagenesis and deep burial followed by uplift. The main diagenetic events include compaction, cementation alteration, dissolution of unstable minerals and grain fracturing. Compaction resulted in densification and significantly reduced the primary porosity. Quartz, calcite and clay are the dominant pore-occluding cement and occur as euhedral to subhedral crystals. Alteration and dissolution of volcanic lithic fragments and pressure solution of feldspar grains were the key sources of quartz cement whereas carbonate cement is derived from an external source. Clay minerals resulted from the alteration of feldspar and volcanic lithic fragments. Porosity and permeability data predict a good inverse relationship with cementation whereas leaching of metastable grains, dissolution of cement and in some places formation of pore-lining chlorite enhanced the reservoir quality. The best reservoir is thicker sandstone bodies that are medium to coarse-grained, well-sorted sandstone with low primary ductile grains with a minor amount of calcite cement. The present study shows several diagenetic stages in the Es₁ Member, but the overall reservoir quality is preserved.