黔北栗园向斜北段铝土矿床地质特征及控矿条件研究

黔北栗园向斜北段铝土矿是产于早志留世韩家店群（S1Hj）泥页岩或晚石炭世黄龙组（C2h）粗晶灰岩之上的一水硬铝石型沉积型铝土矿床。铝土矿产出层位为晚石炭世大竹园组（C2d）。在阐述该铝土矿床的成矿地质背景和矿床地质特征的基础上,对矿床形成过程中的控矿条件进行了分析,认为主要有构造、古地理及古气候、地层、成矿物质来源四大控矿条件。鉴于区域内具备相似条件的向斜构造还有多个,如参照该矿床开展地质勘查工作,有望再找到多个中—大型铝土矿床。     

渝东南地区隐伏铝土矿物探勘查技术试验研究—以车盘矿区试验结果为例

全国矿产资源潜力评价研究表明渝东南地区有着丰富的铝土矿资源,在此开展隐伏铝土矿的物探勘查技术试验研究对今后勘查工作的展开具有重要的指导意义。文中首先在充分了解渝东南地区铝土矿的成矿规律及矿体特征的基础上,总结了该地区铝土矿的储存模式;然后根据其成矿规律和储存模式,结合前人的经验及区域物性差异,提出了使用电磁测深法来确定该区唯一含矿层位—梁山组地层的空间分布形态,以达到间接寻找隐伏铝土矿的方案。选取重庆武隆车盘矿区作为试验场地,在同一剖面上同时展开了可控源(人工场源)音频大地电磁测深法(CSAMT)和高频大地电磁测深法（EH4）两种方法的试验工作,介绍了数据采集及数据质量评价等,对两种电磁测深数据分别进行了人机交互的二维连续介质反演,并结合钻孔资料对两个反演的频率—视电阻率剖面进行了对比分析,最后结合区域地质构造背景勾画出物探成果推断图。     

遵义后槽铝土矿的矿物学特征

现已载入<中国矿床发现史·综合卷>内的贵州遵叉后槽铝土矿,是遵义铝土矿带中矿床规模较大、矿石质量较佳和露采条件良好的主要矿区之一.文章应用矿石薄片、重砂鉴定和扫描电镜、电子探针等多种测试成果,论述了铝土矿矿石的矿物成分、矿物学特征,包括其结晶形态、粒度大小、物理光学性质和产出特征等,同时阐明了主要矿物在不同类型矿石中的含量及其组合特征.进而研究表明,不同类型矿石的矿物组合有所差异,其中一水硬铝石的含量不同,其形态各异,这在一定程度上反映了铝土矿的形成条件.     

Mineralogical and geochemical evolution of the Bidgol bauxite deposit,Zagros Mountain Belt,Iran: Implications for ore genesis,rare earth elements fractionation and parental affinity

The present study focuses on the Late Cretaceous Bidgol bauxite deposit in the Zagros Simply Fold Belt, SW Iran. The orebody is located in the eroded major NW–SE trending Koh-e-Hosseyn anticline and hosted as discontinuous stratified layers and lenses within the upper member of the Cenomanian–Turonian Sarvak Formation. Detailed mineralogical analysis reveals that diaspore, hematite, goethite, anatase, clinochlore, chamosite, and calcite are the major mineral components accompanied by minor amounts of detrital and REE-bearing minerals such as rutile, zircon and parisite. The ore texture suggest that the bauxite material has an authigenic origin but in some parts it has been transported short distances from a primary in situ environment and redeposited in karstic depressions. The spheroidal pisolites of the Bidgol bauxite formed under conditions of low water activity, favouring the formation of large diaspore cores and a single dry-to-wet climatic fluctuation. The mass change calculations relative to the immobile element Ti show that elements such as Si, Fe, Mg, K, Na and Sr are leached out of the weathered system; Al, Ni, Zr, Ga, Cr and Ba are concentrated in the residual system; and Hf, Ta, Co, Rb, Cs, Be, and U are relatively immobile during the bauxitisation processes. The Nb, Th, Y, V, Sc, Sn and ΣREE are relatively immobile in the initial stage of bauxitisation processes in the bauxite ores, but were slightly mobile at the later stage of bauxitisation. Geochemical data reveal progressive enrichment of the REE and intense LREE/HREE fractionation toward the lower parts of the bauxite profile. Cerium behaves differently from the other REEs (especially LREE) and show positive anomalies in the upper horizons that gradually become negative in the deeper parts of the profile. The distribution and fractionation of trace elements and REEs during the bauxitisation process in the Bidgol deposit are mainly controlled by the presence of REE-bearing minerals, fluctuations in soil solution pH, REE ionization potential and the presence of bicarbonates or organic matter. Geochemical analyses confirm a protolith contribution from the bedrock argillaceous limestone and suggest that the source material for the Bidgol bauxite was provided from a siliciclastic material derived from a continental margin. The mid-Turonian uplift led to the formation of karstic topography, rubbly breccia and a layer of ferruginous–argillaceous debris that was affected by lateritic weathering under humid tropical climate. Subsequently, mobile elements are removed from the profiles, while Al, Fe and Ti are enriched, resulting in the formation of the pristine bauxite materials. When the platform subsided into the water again, the pristine bauxitic materials were partly converted to bauxite. During the exposure of bauxite orebodies on the limbs and crests of anticlines and subsequent eroding and accumulation in the karstic depressions during folding and faulting in Oligocene–Miocene, important factors such as intensity of the weathering, drainage and floating flow may have improved the qualities of the bauxite ores.     

Sodium affected subsoils,gypsum, and green-manure: Inter- actions and implications for amelioration of toxic red mud wastes

Experiments were carried out on two alkaline sodium affected sub-soils (15–30 cm) from Strathalbyn and Two Wells in South Australia, under glasshouse conditions in pots containing 1 kg of soil. The effect of green manure was examined with and without the addition of gypsum. Before flowering, the common vetch (Vicia sativa) was incorporated into the soil, and incubated at 80% field capacity. After 12 weeks, the improvements in hydraulic conductivity (K_sat) occurred in the following order of treatments: gypsum+green manure >gypsum >green manure >control. Green manure did not improve macroaggregation in sodic soils. However, stabilisation occurred at the microstructure level. The average size of dispersed materials in control soils was <5 m, whereas after green manuring, the average particle size increased up to 30 m. The products of decomposition of green manure were both organic compounds and the released Ca²⁺ from native lime which aggregated the clay particles and stabilized the domains. The results of this study promise the use of green manure as an ameliorant for sodic alkaline environments such as the red muds of bauxitic minespoils.     

云南砚山红舍克原生及堆积型铝土矿

红舍克铝土矿分为沉积和堆积型两类,受上二叠统(P2l)含矿层控制明显:沉积矿位于上段(P2l2)下部,堆积矿位于沉积铝土矿上覆层。     

Study of spectral signatures for exploration of Bauxite ore deposits in Panchpatmali,India

Spectral analysis technique has been utilized to identify the Bauxite mineral occurrences in Panchpatmali, Orissa, India. Spectral processing of Landsat ETM+ data has been carried out by converting the digital data from quantized and calibrated values to reflectance values. Minimum noise fraction transformation is used to determine the inherent dimensionality of reflected Landsat ETM+ data, to segregate noise in the data, and to reduce the computational requirements for subsequent processing and interactively to locate pure pixels within the data-set, projecting n-dimensional scatterplots. Spectral processing results are displayed in the form of images corresponding to each group of pixels (endmembers). Mixed tune matched filtering method has been applied on Landsat ETM+ images which gave three score (abundance) images for three different classes (endmembers) such as Bauxite, vegetation and soil. Further, mineralized zones are identified using image fusion of ERS-2 SAR and Landsat ETM+ data using intensity-hue-saturation technique.     

Towards an impact assessment of bauxite red mud waste on the knowledge of the structure and functions of bathyal ecosystems: The example of the Cassidaigne canyon (north-western Mediterranean Sea)

Since 1967, the alumina plants in the Marseilles area (Barasse and Gardanne) have been discharging the mineral residue (i.e., red mud) resulting from the alkaline processing of bauxite into the submarine Cassidaigne canyon (north-western Mediterranean Sea) through pipes situated at 320-330 m in depth. The Barasse pipe stopped being used in 1988. From 1987 to 1996, many decrees and regulations were promulgated by the French State to rule the conditions under which the Gardanne alumina refinery was authorized to dispose of the bauxite residue in the sea. The refinery was required: (i) to study the hydrodynamic circulation in the Cassidaigne canyon to evaluate the potential dispersion and transport of fine elements discharged into the water mass and their impact on the pelagic ecosystem; (ii) to survey the marine environment every five years to control the expansion and thickness of the red mud deposit and compare the evolution of the benthic macrofauna at representative sampling sites in the environment affected by the red mud discharge with that of reference sites outside of the red mud plume; (iii) to study the effect of the discharge on fishing activities; and (iv) to investigate the toxicity of the red mud, particularly its persistence, accumulation, interaction and effect on the marine ecosystem, paying special attention to the bio-accumulation of chromium and vanadium. A Scientific Committee was created to insure an independent evaluation of the studies promised by the manufacturer in response to the State’s regulations. Since the beginning of the 1960s, data have been accumulating on the structure and long-term functioning of the Cassidaigne bathyal ecosystem. This paper presents the collaborative efforts of the State-Manufacturer-Committee triplet and summarizes the main results obtained during the last period’s sea campaigns (1991-2007). This paper also illustrates how national regulations concerning manufacturers, such as Gardanne alumina refinery, have provided new knowledge about the structure and functioning of a bathyal ecosystem in the Cassidaigne canyon in the north-western Mediterranean Sea.     

Composition,environment, and economic value of the Permian to Cretaceous coated grains from Zagros and the Persian Gulf

Ooid grainstone/packstone carbonate facies of the Dalan, Kangan, and Arab formations are the main hydrocarbon reservoirs in the Persian Gulf. Based on detailed petrographic and petrophysical analyses,sedimentological and mineralogical features of the Permian to Late Cretaceous carbonate and iron-rich coated grains from Zagros and the Persian Gulf were investigated. Frequent ooids in these formations indicate a high-energy environment and a wave-dominated shallow carbonate platform. Because of wi...     

瓷坩埚代替铂坩埚测定铝土矿石中的烧减量

采用优质瓷坩埚代替铂坩埚,按YS/T575.19—2007测定铝土矿中烧减量,经国家标准管理样的对比测试,结果准确,重现性较好(RSD,n=6在0.30%~0.70%)。