镁铝对烧结矿中铁酸钙的矿物学特性影响

铁酸钙是高碱度烧结矿中的主要黏结相矿物,它的含量、结晶形态、化学成分及晶体结构等矿物学特性对烧结矿质量起着关键性作用,而烧结原料中各组分的含量直接影响着铁酸钙的生成。以Fe₃O₄、SiO₂、CaO、MgO、Al₂O₃的化学纯试剂为原料,在实验室进行微型烧结实验,运用XRD、偏光显微镜、电子探针等手段,定量分析研究了原料组分中MgO、Al₂O₃对烧结矿中铁酸钙的生成及其矿物学特性的影响。原料中MgO含量的增加对铁酸钙的生成有一定抑制作用,尤其在MgO含量为2.0%~3.0%时,烧结矿中铁酸钙含量明显减少,其晶体形态也从以板柱状和针状为主逐渐过渡为它形不规则状;原料中Al₂O₃的增加,对烧结矿中铁酸钙的形成具有促进作用,即随着Al₂O₃的增加铁酸钙含量呈明显增加趋势,且铁酸钙的形态也由以柱状和针状为主向板柱状变化。电子探针成分分析及矿物化学式计算结果表明,铁酸钙是由Fe₂O₃、CaO、SiO₂、Al₂O₃及MgO组成的复杂结晶体,其化学通式为Ca_2.60Mg_0.44Si_1.07Al_0.96Fe_8.92O₂₀。原料中MgO、Al₂O₃含量的变化,对铁酸钙的化学成分中Fe₂O₃/CaO摩尔分数比影响不大,均接近3∶2。上述研究结果对于深刻理解烧结工艺条件下铁酸钙晶相的晶体化学特征及其对烧结矿质量的影响具有重要指导意义。     

用同位素方法研究额济纳盆地承压含水层地下水的补给

本文通过环境同位素、温度、电导率和人工示踪等方法研究了黑河下游古日乃和额济纳盆地深部承压水的补给源 ,初步揭示了额济纳盆地承压水来自于祁连山的降水 ,是部分祁连山西端雪水直接渗入山前的深大断裂 ,在玉门宽滩山一带注入与之相交的阿尔金断裂 ,然后继续向东补给至巴丹吉林沙漠 ,并顺着古日乃断层补给到额济纳盆地。通过蒸发量计算得到的补给量为 5× 10 8m3/a。黑河流域承压水中的 T(氚 )为 17.8～ 0 .1TU ,地下水的年龄与取样孔的位置有关 ,靠近强渗漏带附近的地下水的年龄只有 2 0～ 30 a。古日乃、拐子湖的湖泊、泉、沼泽等消失的主要原因是由于 5 0 a来温度升高、蒸发量增加和下游抽水量增大的原因。该项研究对于重新认识额济纳盆地、古日乃、巴丹吉林沙漠的地下水补给与黑河下游水资源调度、开发与利用具有十分重大的意义     

昆仑山北坡晚新生代含植物化石石灰华的孢粉组合及其古环境

本文根据孢粉分析,推测古石灰华沉积时期的植被,是以蒿、藜为主的山地草原,散布有柳、栎、榆、桦等组成的落叶阔叶林块;古气候比现今温暖湿润,年平均气温约10—13℃,属暖温带半干旱气候,当时的海拔高度约1500—2000m。     

Genesis of large siliceous stromatolites at Frying Pan Lake, Waimangu geothermal field, North Island, New Zealand

Lilypad stromatolites, up to 3 m long and 1·5 m wide, were found to be actively growing in the shallow marginal waters of Frying Pan Lake and its outflow channel. These stromatolites, composed of Phormidium (> 90%), Fischerella, and a variety of other microbes, develop through a series of distinct growth stages. Dark green microbial mats cover the floor of the outflow channel and give rise to columns of various sizes and shapes in the shallower marginal waters. Once the columns reach the water level, the mats spread laterally to form a lilypad stromatolite. The lilypads are characterized by a raised, dark green rim, 4–5 mm high, that encircles a flat interior covered with a distinctive orange-red mat. The microbes forming the columns and lilypad plate are being actively silicified. The stromatolites are formed of: (i) flat-lying Phormidium filaments (P-laminae), (ii) upright filaments of Phormidium that are commonly associated with Fischerella (U-laminae), and (iii) mucus, diatoms and pyrite framboids (M-laminae). P-laminae dominate most of the columns, with tripartite cycles of P-, U-, to M-laminae being found mostly in the upper parts of the stromatolites. The transition from the P- to U-laminae is marked by a change in the growth pattern of the Phormidium and branching of Fischerella, which was probably triggered by a change in environmental conditions. In the Frying Pan Lake outflow channel, this change may be related to fluctuations in water level and flow rates that are caused by periods of heavy rain, seasonal changes, long-term variations in rainfall, and/or the unique 40-day hydrological cycle that exists between Frying Pan Lake and Inferno Crater, which is a nearby hydrothermal crater lake.     

An unusual modern silica–carbonate sinter from Pavlova spring, Ngatamariki, New Zealand

ABSTRACT A silica–carbonate deposit is forming from the dilute alkali chloride waters of Pavlova spring, a small thermal pool and outflow channel (85 to <40 °C), situated at the northern extent of the South Orakonui area of the Ngatamariki geothermal field, Taupo Volcanic Zone (TVZ), New Zealand. It is one of a small but growing number of thermal spring features known to yield deposits of mixed mineralogy. At Pavlova, a distinctive, crustose, chalk‐white, meringue‐like sinter, comprising non‐crystalline opal‐A silica with subordinate calcite, is actively precipitating both around the margins of and as small islets within the spring, with an average accumulation rate of ≈ 2 mm year^?1. Both emergent and partly submerged substrates host the sinter, including fallen pine branches, twigs, needles and cones, gum leaves, grass blades, bracken fronds, pumice, sediment and microbial mats. The sinter is thin (25–35 mm thickness), finely laminated and contains three distinct types of stacked horizons. Submerged basal layers constitute stratiform to undulatory microstromatolites with pseudocolumns, which grew outwards and upwards on narrow twig nuclei. Emergent middle layers comprise discontinuous, spicular microstromatolites (to 10 mm height), with prostrate and erect microbial filaments, silica spheres and silicified mucus, overlain by silicified structures of probable fungal origin. In places, lower and middle sinter layers are capped by white, smooth, convex surfaces that coalesce into subdued, curved ridges, resembling laterally continuous peaks of egg‐white meringue. The meringue is internally laminated, with fossilized microbes preserved in thin horizons. Small lensoid masses of calcite crystals nestle between silica laminae throughout the sinter. The near‐neutral (pH ≈ 7·2) spring water is a dilute chloride‐carbonate type (HCO≈ 470 µg g^?1, Cl^–≈ 600 µg g^?1) with low (≈ 50 µg g^?1), typical of TVZ thermal fields where deep chloride fluid mixes with CO₂‐rich, steam‐heated shallow waters before discharge. The hot water changed little in composition from 1993 to 1999 and, despite dilution by meteoric waters, contains sufficient SiO₂ (≈ 220 µg g^?1) for opal‐A to deposit at the surface upon cooling. However, the concentration of Ca²⁺ (≈ 6 µg g^?1) is such that the precipitation of calcite is not expected without modification of spring waters. Precipitation occurs by evaporation of thin water films at exposed substrate surfaces, via meniscoid as well as capillary creep (wicking), through porous sinter horizons and across emergent vegetative surfaces in contact with spring water or steam. The height of the deposit above the water surface is restricted by the upper limit of moisture bathing these substrates. Splash and spray are not involved in the formation of Pavlova spicular microstromatolites, as is the case for other texturally similar deposits from hotsprings elsewhere. This young (< 15 years), mineralogically and morphologically complex hot‐spring deposit exhibits > 10 times lower accumulation rates than typical siliceous sinters in the TVZ, and deposition of both silica and calcite is controlled by microchemical conditions and local temperature gradients, rather than by bulk spring water chemistry.     

利用不溶性钾矿热法生产硅钾钙镁复合肥

以钾长石为原料和助剂白云石、氯化钠等在高温下生产硅钾钙镁肥的一种方法。并对生产原理做了进一步探讨,经过大量试验找到最佳反应条件。     

云南白水台泉华台地旅游业可持续发展浅析

从自然和人文两方面,阐述了滇西北高原上白水台发展旅游业的物质基础,评述了该旅游区旅游业发展中存在的问题。在分析了白水台泉华台地环境系统脆弱性特点的基础上,遵循可持续发展旅游业的内涵要求,提出在该旅游区适宜开展生态旅游,针对该旅游区存在的问题,为实现该区旅游业可持续发展,提出了修渠引水以增加泉华台面水流量及加强基础设施建设等建议。      

四川西部现代热泉沉积物地球化学特征及意义

西南三江地区现代热泉很发育,但以往对其成矿作用研究不够。笔者发现在四川西部义敦热坑和理塘热水塘两处热泉群产地普遍存在硅化和黄铁矿化现象。地表热泉沉积物主要是硅华和钙华及其过渡类型,大多数是硅华和钙华的混合堆积物。在地表泉华、断裂裂隙充填物及其蚀变围岩中存在金矿化,金质量分数从＜0.1×10^-6到1.89×10^-6。泉华和蚀变围岩中亲花岗岩元素Li、Be、Mo、Ga、Rb、Cd等含量高于地壳丰度值,可作为找矿指示元素。热泉沉积物的地球化学特点总体上与现代海底热泉沉积物比较接近,但成因不同。鉴于三江地区热泉广布,成矿条件有利,建议加强勘查和研究,以期找矿突破。     

西藏搭格架热泉型铯矿床年代学研究

西藏昂仁县搭格架地热田硅华中的铯达到超大型矿床规模,不同特征的热泉沉积或分布于冈底斯冰期冰碛物的外表或裂隙中,或覆于长马曲上游第5至第1级阶地及现代河床的不同部位.据热泉华野外分布的地貌部位和岩石学特征可将其分为6套.这6套泉华代表性样品的全溶法或等时线法U系测年结果表明：第1套泉华（钙华）形成于晚更新世晚期的末次冰期间冰阶晚期,相当于深海氧同位素第3阶段即MIS 3;第2套泉华（硅华）形成于中更新世晚期的倒数第二次冰期,相当于MIS 8～7;第3套泉华形成于晚更新世早期的末次间冰期,相当于MIS 5;第4套泉华（硅华）形成于晚更新世晚期的末次冰期间冰阶晚期至末次盛冰期早期,相当于MIS 3～2;第5套泉华（硅华）形成于晚更新世末期的末次盛冰期至全新世冰后期,相当于MIS 2～1;第6套泉华即现代硅华.参考前人的ESR年龄测定结果,可将搭格架热泉华的形成分为5个阶段：403～202ka BP,99ka BP左右,39～25ka BP,17～4ka BP与现代.在第3阶段硅华活动早期,有一次钙华活动.     

Exploring the dating of “dirty” speleothems and cave sinters using radiocarbon dating of preserved organic matter

Speleothems and other carbonate deposits such as tufa containing high proportions of detrital material can be difficult to chemically date due to detrital thorium levels causing a high level of error in conventional U-Th disequilibrium dating. Here we investigate the use of an alternative technique centring on radiocarbon dating of organic matter preserved within the detrital fraction. Non-acid soluble humic, particulate and detritally absorbed organic matter was recovered from eight samples from a flowstone sinter formed within a roman aqueduct at Trento in Italy with a maximum age of 100 CE (1850 cal yr BP), and two repeat samples from a dripstone formed within the 20th Century on a wire fence at Lilly-Pilly Cave, Buchan Caves Reserve in Victoria, Australia. In the aqueduct samples the median calibrated ¹⁴C ages ranged from 2232 to 2889 cal yr BP, with 95.4% probability age range in the youngest and oldest samples of 2153–2337 and 2342–3449 cal yr BP respectively. The median age of the more modern dripstone was 336 cal yr BP, with a 95.4% probability age range of 148–486 cal yr BP. These results provide very approximate ball-park estimates of the age of the sample, but are consistently too old when compared to the known maximum ages of formation. It is hypothesised that this offset is due to a combination of the nature of the organic carbon transported from the source organic matter pools, and reworking of both modern and old organic carbon by in situ microbial communities.