四元体系Na~ ∥Cl~-,CO_3~(2-),B_4O_7~(2-)-H_2O 273K介稳相平衡研究

采用等温蒸发法研究简单四元体系Na ∥Cl-,CO32-,B4O72--H2O273K时的介稳相平衡,并测定该体系273K平衡液相中各组分的溶解度及密度,该体系的介稳相图和密度组成图显示:该四元体系在273K时的相图由3条溶解度单变量线、3个结晶区及1个共饱和点组成。体系属简单共饱型,无复盐或固溶体形成,3个结晶区分别对应单盐Na2CO3·10H2O,NaCl和Na2B4O7·10H2O。共饱点E处于Na2CO3·10H2O,NaCl及Na2B4O7·10H2O3盐共饱和,所对应的平衡液相组成为w(Na2CO3)=6.81%,w(NaCl)=21.69%,w(Na2B4O7)=0.65%,w(H2O)=70.85%。研究体系在273K下,Na2CO3·10H2O是碳酸钠盐的唯一析出形式,且硼酸钠对碳酸钠有盐析作用。     

华北地台中元古代碳酸盐岩中的微生物成因构造及其生烃潜力

华北地台中元古界主要由环潮坪石英砂岩、浅海碳酸盐岩和浅海—泻湖相暗色页岩3种沉积相组合构成,以陆表海浅水碳酸盐岩占主导。碳酸盐岩中除含有丰富的微古植物、宏观藻类和微生物建隆外,还发育大量的微生物成因构造(MISS)和微生物诱发的碳酸盐沉淀(MMCP)。微生物席和MISS构造在高于庄组上部(约1.6 Ga)和雾迷山组下部(约1.45 Ga)碳酸盐岩中尤为发育,表明活跃的微生物活动和高有机质产量。在石化微生物席中,发现有丝状、球状细菌化石和草莓状黄铁矿;围岩中发现有针状文石、花瓣状重晶石、放射状菱铁矿、铁白云石和葡萄状碳酸盐胶结物等多种自生碳酸盐矿物,指示甲烷厌氧氧化(AOM)导致的自生碳酸盐沉淀。中元古代的温暖气候和海洋分层、缺氧、硫化条件有利于微生物的高生产量和高有机质埋藏率。气隆构造和核形石状碳酸盐结核反映浅埋藏条件下活跃的成烷作用和甲烷排放,围岩和MMCP中富沥青质。华北地台中元古界富微生物席碳酸盐岩有良好的生烃潜力,有可能形成重要的烃源岩。据微生物席、MISS构造及MMCP的研究,初步估算华北地台中元古代碳酸盐岩的概略生烃潜力约为10×108t石油当量。     

Carbon and oxygen isotopic composition of car- bonate cements of different phases in terrigenous siliciclastic reservoirs and significance for their origin： A case study from sandstones of the Triassic Yanchang Formation, southwestern Ordos Basin, China

Early carbonate cements in the Yanchang Formation sandstones are composed mainly of calcite with relatively heavier carbon isotope （their δ^18O values range from -0.3‰- -0.1‰） and lighter oxygen isotope （their δ^18O values range from -22.1‰- -19.5‰）. Generally, they are closely related to the direct precipitation of oversaturated calcium carbonate from alkaline lake water. This kind of cementation plays an important role in enhancing the anti-compaction ability of sandstones, preserving intragranular volume and providing the mass basis for later disso- lution caused by acidic fluid flow to produce secondary porosity. Ferriferous calcites are characterized by relatively light carbon isotope with δ^13C values ranging from -8.02‰ to -3.23‰, and lighter oxygen isotope with δ^18O values ranging from -22.9‰ to -19.7‰, which is obviously related to the decarboxylation of organic matter during the late period of early diagenesis to the early period of late diagenesis. As the mid-late diagenetic products, ferriferous cal- cites in the study area are considered as the characteristic authigenic minerals for indicating large-scaled hydrocarbon influx and migration within the clastic reservoir. The late ankerite is relatively heavy in carbon isotope with δ^13C values ranging from -1.92‰ to -0.84‰, and shows a wide range of variations in oxygen isotopic composition, with δ^18O values ranging from -20.5‰ to -12.6‰. They are believed to have nothing to do with decarboxylation, but the previously formed marine carbonate rock fragments may serve as the chief carbon source for their precipitation, and the alkaline diagenetic environment at the mid-late stage would promote this process.     

δ^13C-δ^18O Covariance： An Effective Indicator of Hydrological Closure for Lakes？

The correlation between theδ~(13)C andδ~(18)O in primary carbonates is affected by several factors such as hydrological balance,total CO_2 concentrations,climatic condition and lake productivity. The influence of these factors on theδ~(13)C-δ~(18)O correlation may be different on different time scales.In this paper,two different-type lakes in southwestern China,Lake Erhai and Lake Chenghai,are selected to investigate the influence of climatic pattern on theδ~(13)C-δ~(18)O correlation and to evaluate the reliability of theδ~(13)C-δ~(18)O covariance as an indicator of hydrological closure.The results show that there exists good correlation between theδ~(13)C andδ~(18)O in Lake Erhai (overflowing open lake) and in Lake Chenghai (closed lake).This suggests that theδ~(13)C-δ~(18)O covariance may be not an effective indicator of hydrological closure for lakes,especially on short time scales.On the one hand,a hydrologically open lake may display covariantδ~(13)C andδ~(18)O as a result of climatic influence.The particular alternate warm-dry and cold-wet climatic pattern in southwestern China may be the principal cause of theδ~(13)C-δ~(18)O covariance in Lake Erhai and Lake Chenghai.On the other hand,a hydrologically closed lake unnecessarily displays covariant trends betweenδ~(13)C andδ~(18)O because of the buffering effect of high CO_2 concentration on theδ~(13)C shift in byper-alkaline lakes.We should be prudent when we use the covariance betweenδ~(13)C andδ~(18)O to judge the hydrological closure of lake.     

<Superscript>40</Superscript>Ar-<Superscript>39</Superscript>Ar dating of lamprophyre dykes in the Baimazhai nickel deposit,Yunnan Province,China, and its geological significance

The Baimazhai nickel deposit, Yunnan Province, China, is located in the southern part of the Sanjiang （Tri-river） alkali-rich intrusive rock belt （Sanjiang ARIR）. In this paper was conducted ^40Ar-^39Ar dating of two phlogopites in lamprophyres which are, as dikes, widely distributed in the orefield, and two plateau ages were acquired, i.e., 32.46±0.62 Ma and 32.01±0.60 Ma, respectively （averaging 32.23±0.60 Ma）. The ages are obviously younger than those of the ore-hosted complex and mineralization of the Baimazhai nickel deposit. In combination with the characteristics, it is indicated that lamprophyres in the orefield and those in the Sanjiang ARIR are similar in tectonic setting, mineral assemblage and geochemistry. It is considered that lamprophyres in the orefield are the important component of the Sanjiang ARIR, and the lamprophyres and ore-hosted complex in the orefield represent the products of two times of different magmatic activity from different mantle sources. On the other hand, the age of lamprophyres in the orefield is older than that of the strike-slip shearing of the Ailaoshan-Honghe fault belt, suggesting that the strike-slip shearing of the Ailaoshan-Honghe fault belt is not the factor leading to magmatic activity of lamprophyres in the orefield, while it is more possible that magmatic activity of the Sanjiang ARIR promoted strike-slip shearing of the fault belt.     

基于ArcGIS的动态路径诱导系统研究

在分析中心式动态路径诱导系统、ArcGIS、Web服务和GIS Web服务等关键技术的基础上,设计了基于ArcGIS的动态路径诱导系统方案和仿真系统的总体框架,并对系统采用的方法、技术进行分析和研究。     

碳酸盐型磷矿的反浮选工艺研究

针对某碳酸盐型磷矿,采用反浮选工艺流程进行试验研究,获得了低镁优质磷精矿。反浮选工艺具有药剂种类少,分选效率高,选矿技术指标先进,操作控制容易等优点,是选别碳酸盐型磷矿的先进浮选工艺。     

滇西沘江流域水体中重金属元素的地球化学特征

通过测定流经兰坪金顸铅锌矿区的沘江水体中Pb、Zn、Cd、As的含量和底泥中重金属元素的化学形态的含量,分析了重金属元素的分布和化学形态的变化。结果表明,沘江水遭到了Cd污染,底泥已经成为重金属元素的蓄积库,以国家土壤环境质量标准（Ⅲ级）衡量,Pb、Zn、Cd和舡分别超标3．4倍、15．8倍、106倍和2．6倍。沘江水中重金属元素含量的峰值在矿山附近的下游,而底泥中重金属元素的峰值在矿山下游30-50km的地方,矿业活动、水流变缓、pH等水体环境条件的变化都能影响水和底泥中重金属元素的含量。底泥中的Pb以碳酸盐结合态为主,Zn和Cd以铁锰氧化物结合态为主,而As以残渣态为主。Pb、Cd、Zn三种元素的环境有效态含量比较高,对沘江流域生态环境具有潜在的巨大的危害。     

紫金牛生长土壤微生物和养分特性

研究了自然坡地坡上、坡中和坡下三种不同部位上紫金牛生长土壤的微生物特性和养分特性。结果表明，紫金牛只生长在坡下，紫金牛生长的坡下土壤中细菌比例最高、真菌比例最低，土壤全氮和有机质含量均高于对照的坡中和坡上。     

The chromite deposits associated with ophiolite complexes, Southeastern Desert, Egypt： Petrological and geochemical characteristics and mineralization

1 Introduction The association of massive Fe-Ni-Cu sulfides andchromite is a very unusual feature of podiformchromitites occurring in mantle tectonites of ophioliticcomplexes. It has only been described in theSoutheastern Desert, Egypt, where sulfides a…