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Metallogeny of the Lannigou Sedimentary Rock-hosted Disseminated Gold Deposit in Southwestern Guizhou Province,China

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Acta Geologica Sinica(English Edition) 2007年第1期81卷 121-134页

作者： BAO Zhiwei jayanta.guha Key Laboratory for MetaUogenic Dynamics Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou Guangdong 510640 China Earth Sciences/CERM University of Quebec at Chicoutimi Chicoutimi P.Q. G7H 2B1 Canada

The Lannigou deposit is a large-sized sedimentary rock-hosted disseminated gold （SRHDG） deposit located in the Youjiang Basin. It is hosted by the Middle Triassic turbidite. Wall rock alterations, including silicification, pyritization, arsenopyritization, carbonatization and argillization, commonly occur along fractures. PGE study demonstrates that either Permian basalts or Triassic ultrabasic intrnsives are unlikely to be the main source of gold mineralization. Coupled with the lack of other nmgmatic activity in the vicinity of the mining area, an amagmatic origin is proposed. Organic matter compositions and GC-MS analysis of the ores and host rocks show that the organics in the ores and the host rocks have a common source; the organic matter in the ores was mainly indigenous. The positive correlation between S2 and Au contents, along with the common occurrence of organic inclusions, suggest involvement of organic matter in the ore-forming process in terms of promoting Au leaching from the source rocks, making colloidal Au migration possible, as well as hydrocarbon reduction of sulphate. Geological and geochemical characteristics of the Lannigou deposit suggest that it was formed through circulation of meteoric water and probably less importantly organic bearing formation water driven by high geothermal gradient caused by late Yanshanian extension, which leached Au from the source bed, and then migrated as Au-bisnlfides and colloidal Au, culminating in deposition by reduction-adsorption and surface complexation of gold onto the growth surface of arsenlan pyrite.

关键词： sedimentary rock-hosted disseminated gold deposit metallogeny Lannigou Guizhou

Microstructural analysis of a subhorizontal gold-quartz vein deposit at Donalda,Abitibi greenstone belt,Canada:Implications for hydrodynamic regime and fluid-structural relationship

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Geoscience Frontiers 2011年第4期2卷 529-538页

作者： Guoxiang Chi jayanta.guha Department of Geology University of Regina Regina Saskatchewan Canada Sciences de la Terre/Centre d＇Etude sur les Ressources Minerales Universite du Quebec a Chicoutimi Chicoutimi Quebec Canada

The Donalda gold deposit in the southern part of the Archean Abitibi greenstone belt consists mainly of a subhonzontal gold-quartz vein perpendicular to subvertical shear *** 0.3—0.5 m thick vein is characterized by vein-parallel banding structures indicating multiple episodes of fracture opening and mineral *** of the c-axis of primary growth quartz indicates that quartz preferentially grew perpendicular to the fracture,suggesting open space filling and/or extensional nature of the *** of the orientations of microfractures,veinlets and fluid—inclusion planes（FIPs） crosscutting primary growth quartz indicates that the vein minerals were subject to a vertical maximum principal stress（σ_1）,which is inconsistent with the subhorizontalσ_1 inferred from the regional stress field with N—S *** apparent discrepancy is explained by invoking episodic fluid pressure fluctuation between supralithostatic and hydrostatic regimes accompanied by episodic opening and closing of the sub-horizontal *** fluid pressure was higher than the lithostatic value,the fracture was opened and primary growth minerals were precipitated,whereas when fluid pressure decreased toward the hydrostatic value,the hanging wall of the fracture collapsed,causing collision of protruding primary growth minerals from both sides of the fracture and resulting in formation of vein-parallel deformation *** columns where the two facing sides of the fracture collided were subject to higher-than-lithostatic stress due to the bridging effect and reduced support surface area,explaining the development of verticalσ_*** hypothesis is consistent the fault-valve model,and explains the flipping ofσ_1 without having to change the regional stress field.

关键词： Hydrodynamics Fluid-structural relationship Gold deposit Fluid inclusion planes Microstructural Subhorizontal veins

Tendency and Fractal Pattern of Migration of Trace Elements in Source Rocks During Thermal Event

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Science China Chemistry 1994年第6期37卷 744-757页

作者：周永章 Edward H. Chown jayanta.guha 卢焕章 Institute of Geochemistry Guangzhou Branch Academia Sinica Guangzhou 510640 PRC Sciences Appliqées Uniersityé du Qubec a ChicoutimiCanada G7H2B1

The reactivation of trace elements in source rocks is fundamental in the formation of many economic deposits. Although transport by fluid flow and infiltration is very effective along visible fractures, the migration of trace elements from the inner part of solid cells to the weaknesses is much less efficient, and so becomes the bottleneck in the migration of these elements from their initial positions in the source rock to the final deposition site in an ore body. Diffusion may play a key role in the reactivation of trace elements. The overall migration pattern of trace elements in source rocks is characterized by an embedded sink mosaic structure, which possesses the self-similarity of a fractal. There are two general migration tendencies of trace elements. One is from within solid cells, such as mineral grains, toward the sink, consisting of weaknesses in the source rock. The other is from high-temperature fields toward low-temperature ones. High temperature favors the realization of these two tendencies. Conjugate geochemical anomalies are the inevitable result of a closed system.

关键词： migration trace element fractal embedded sink mosaic structure.

Hydrogeochemistry of toxic metals in Au-As-Hg-Tl mineralized area in southwest Guizhou Province, China

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Chinese Science Bulletin 1999年第S2期44卷 171-172页

作者： Boyle Dan guha jayanta Mineral Resources Division Geological Survey of Canada Ottawa K1A OE8 Canada Science de la Terre Departement des Sciences Aplliquees Universite du Quebec a Chicoutimi Quebec G7H2B1 Canada

THE environmental geochemistry problems during the processes of mining activities are intensively considered by scientists worldwide, and the hydrogeochemistry presents an important implication of toxic metalcontamination related to mining activities. The hydrogeochemistry due to mining activities and naturalmineralized processes present some differences whose comparison can indicate a good understanding of theinfluence of mining on the environment. This ongoing study aims at the hydrogeochemistry of toxic metals in the Au-As-Hg-Tl metallogenicbelt of Huijiabao anticline in southwest Guizhou, China. The presently-mined Lanmuchang mercury-thallium deposit with a Hg-mining history of about 350 years containing one of the world’s highest concentration of thallium and the to-be-mined Yanshang gold deposit enriching high concentration of toxic metals have been chosen to study the hydrogeochemistry of toxic metals. The groundwater samples werecollected from the shallow aquifer in terms of spring, domestic well and karstic cave whereas the surfacewater was only sampled downside the surface drainage leaching the mine waste at Lanmuchang. All

关键词： toxic metals hydrogeochemistry Au-As-Hg-TI mineralized area southwest Guizhou Province.

Mathematical Invariant and Quantitative Estimation on Element Migration of Hydrothermal Wall-Rock Alteration--With an Example of Application in the Hetai Gold Field, Guangdong Province, China

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Chinese Science Bulletin 1994年第19期39卷 1638-1643页

作者：周永章涂光炽 Edward H. Chown jayanta.guha 卢焕章 Institute of Geochemistry Guangzhou Branch Academia Sinica Guangzhou 510640 PRC Universite du Quebec a Chicoutimi Canada G7H 2B1

Hydrothermal wall-rock alteration is the interaction of hydrothermal fluids with the wall rock, causing changes or redistribution of chemical compositions of initial wall *** study of hydrothermal alteration may enric... 详细信息

关键词： constant sum constraint conserved element balance estimation of mass element migration.

加拿大Abitibi绿岩带Donalda金矿近水平含金石英脉的显微构造分析及其对成矿流体动力学的指示

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地学前缘 2011年第5期18卷 43-54页

作者：池国祥 jayanta.guha 加拿大里贾纳大学地质系萨斯喀彻里贾纳S4S 0A2 加拿大魁北克大学希库蒂米分校魁北克希库蒂米

位于加拿大Abitibi绿岩带南部的Donalda金矿床主要由近水平的、与剪切带近垂直的含金石英脉组成,矿脉厚度0.3～0.5m,含大量与脉壁平行的条带,指示多期次裂隙扩张和矿物沉淀。原生石英c-轴方位测量显示石英生长方向垂直于脉壁,指示断裂... 详细信息

位于加拿大Abitibi绿岩带南部的Donalda金矿床主要由近水平的、与剪切带近垂直的含金石英脉组成,矿脉厚度0.3～0.5m,含大量与脉壁平行的条带,指示多期次裂隙扩张和矿物沉淀。原生石英c-轴方位测量显示石英生长方向垂直于脉壁,指示断裂属张性,矿物沉淀属空间充填。显微裂隙、细脉及流体包裹体面(FIPs)的方位测量指示原生矿物受到了近直立的最大主压应力(σ1)作用,与区域性的、近水平的南北向挤压应力不符。这一矛盾现象可用流体压力在超静岩和静水压力之间周期性变化及近水平断裂的周期性张开与闭合来解释。当流体压力大于静岩压力时,断裂张开,原生矿物沉淀,而当流体压力减小时,断裂上盘往下垮,两盘突出的矿物碰撞、碾压形成与脉壁平行的变形条带。由于断裂两盘岩石不是沿整条断裂都互相接触,两盘相顶部分承受的垂直应力大于水平方向的挤压应力,这就解释了为什么显微构造指示近直立的最大主压应力(σ1)。这个流体-构造模式支持断层阀模式,并且无须改变区域应力场就可解释脉体内局部主压应力的变化。

关键词：流体动力学流体-构造关系造山型金矿流体包裹体面显微构造

Nil Clean Graphs of Rings

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Algebra Colloquium 2017年第3期24卷 481-492页

作者： Dhiren Kumar Basnet jayanta Bhattacharyya Department of Mathematical Sciences Tezpur University Napaazn Tezpur-784028 Assam India

In this article, we define the nil clean graph of a ring R. The vertex set is the ring R, and two ring elements a and b are adjacent if and only if a ＋ b is nil clean in R. Graph theoretic properties like the girth, ... 详细信息

关键词： nil clean ring weak nil clean ring nil clean graph

Geochemical characteristics of Neogene sandstones of the East and West Siang Districts of Arunachal Pradesh,NE India:implications for source-area weathering,provenance,and tectonic setting

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Acta Geochimica 2022年第1期41卷 100-120页

作者： Roshmi Boruah jayanta Jivan Laskar Department of Geological Sciences Gauhati UniversityGuwahatiAssam 781014India

Sandstones from the Neogene Siwalik successions of the East and West Siang Districts of Arunachal Pradesh were analyzed to evaluate source-area weathering,provenance,and tectonic setting by using major,trace,and rare earth elements(REEs)as *** sandstones are classified as lithic arenite and wacke arenite based on their mineralogical *** values of different weathering indices such as Chemical Index of Alteration(CIA;60.93–89.86)and Chemical Index of Weathering(CIW;40–96.8)suggest moderate to intense weathering in the source *** plot of Th/Sc versus Zr/Sc indicates enrichment of zircon by sediment sorting and/or recycling from a weathered *** high positive correlation between Al2 O_(3) and K2 O points towards a strong influence of the constituent clay minerals on the major oxide composition of the *** analysis together with enriched LREE,flat HREE,negative Eu anomalies(Eu/Eu^(*)=0.47 to 0.90)in the chondrite-normalized diagrams,and the ratios of La/Sc,La/Co,Th/Sc,Th/Co,Cr/Th collectively suggests that the Neogene sediments were derived from felsic igneous and/or reworked sedimentary/metasedimentary sources in an upper continental crustal *** geochemical characteristics of the studied Neogene Siwalik sandstones indicate that the sediments were sourced from pre-Himalayan gneisses and granitoids together with metabasic rocks,which had formed in a passive margin tectonic setup.

关键词： Geochemistry Neogene sandstones Arunachal Pradesh Paleo-weathering Provenance Tectonic setting

Adjustable Mechanism for Walking Robots with Minimum Number of Actuators

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Chinese Journal of Mechanical Engineering 2011年第5期24卷 760-766页

作者： guha Anirban AMARNATH C Department of Mechanical Enginering Indian Institute of Technology Bombay

Recent literature on walking robots deals predominantly with multi-degrees-of-freedom leg mechanisms and machines capable of adopting several *** paper explores the other end of the spectrum suggesting mechanisms derived from a four bar coupler curve for a one degree of freedom walking *** of the walk indicates that body of the robot is able to move with low variation in *** best strategy for changing the gait to enable the robot to walk over obstacles and the effect of change in length of different links are explored to open up the possibility of a two degree of freedom walking robot with the capability of changing its gait,suitable as a low cost unit for several *** rugged units would permit the use of an IC engine as the primary source of power and could be of utility in installations where electronics may not be *** simple walking machines the foot of a leg is usually required to trace a D shaped curve with respect to the *** this paper we begin with a Hoecken mechanism capable of tracing such a *** foot is required to move parallel to itself and the same could be achieved using a six or eight link mechanism.A few such devices have been synthesized in this paper and their motion properties *** study also covers the possibility of providing adjustments to vary the step length and height of the foot＇s movement.

关键词： walking robot degree of freedom coupler curve gait