罗布泊盐湖巨量钙芒硝沉积及其成钾效应分析

罗布泊盐湖位于新疆塔里木盆地东部,盐湖沉积的主要盐类矿物是钙芒硝,其资源量巨大,卤水钾矿赋存于钙芒硝岩晶间孔隙中,显然,钾盐的聚集与钙芒硝沉积有着密切的联系。文章通过对罗布泊盐湖的钙芒硝沉积特征研究,探讨了钾盐矿床的形成与钙芒硝的沉积关系。研究显示钙芒硝沉积时期,古气候具有“热”的特点,有利于钙芒硝沉积;盐湖物质来源有“富硫酸根”的地表水,也可能存在富钙水的补给。结晶试验显示,罗布泊现代卤水与含氯化钙水掺合后,蒸发析出石膏和水钙芒硝;同时,早期沉积的石膏被交代成为钙芒硝,这两种方式是钙芒硝形成的主要机制。罗布泊钙芒硝的成钾效应主要表现于3个方面:钙芒硝具有菱板状结构,在沉积和成岩过程中钙芒硝岩发育大量孔隙;钙芒硝孔隙储集了富钾卤水;大量钙芒硝的析出导致卤水中钾离子相对富集。研究认为,罗布泊盐湖巨量钙芒硝的沉积控制了钾盐的形成和分布,钙芒硝岩成储钾盐的认识在实践上推进了罗布泊盐湖的找钾工作。     

鄂尔多斯盆地陇东地区延长组砂岩储层孔隙成因类型及其控制因素

陇东地区延长组砂岩储层属于典型的低孔低渗储层,分析孔隙成因类型及其控制因素,对于寻找相对高孔渗储层具有重要指导意义。通过大量孔隙铸体薄片鉴定认为,陇东地区延长组砂岩发育原生与次生两大类孔隙类型,其中原生孔隙包括压实剩余原生粒间孔和胶结剩余原生粒间孔;次生孔隙包括粒间杂基及胶结物溶孔、长石和岩屑粒内溶孔及铸模孔、粒间高岭石绿泥石胶结物晶间孔;另外还存在少量构造成因的微裂缝。现今孔隙多为部分原生与部分次生组成的混合孔隙。孔隙成因类型受沉积条件和成岩作用双重因素控制,沉积条件决定了砂岩沉积时的水动力条件,从而决定了砂岩的岩石学特征和原生粒间孔的发育程度,压实作用决定了压实剩余粒间孔的大小与多少,胶结作用决定了胶结剩余粒间孔的多少,溶蚀作用控制了各种溶蚀孔隙的类型及发育程度,如粒间杂基和碳酸盐胶结物溶孔、长石及岩屑粒缘与粒内溶蚀孔隙的发育程度。原生孔隙在长8、长9、长4+5粒度较粗的层段中较明显,次生孔隙在长6、长7粒度细层段和顶部不整合面附近的长1-3中占的比例较多。系统运用大量薄片和物性资料首次明确指出陇东地区延长组砂岩储层孔隙为混合成因,且次生孔隙特征明显,原生孔隙由于压实和胶结作用大量损失。     

罗布泊盐湖钙芒硝巨量堆积对富钾卤水形成的控制——来自流体包裹体组成的约束

<正>罗布泊盐湖位于新疆塔里木盆地东端,为我国最大的硫酸盐型卤水钾盐成矿区,富钾卤水主要赋存于巨量钙芒硝岩晶间孔隙中。一般海水和陆相盐湖需经历石盐沉积之后,才出现钾元素富集和钾盐矿物沉积,晶间卤水通常赋存于石盐晶间孔隙中。海水蒸发至石盐析出时卤水中KCl含量约0.52%(瓦里亚什科,1965)。然而,罗布泊盐湖在石膏沉积之后出现巨量钙芒硝沉积,石盐析出时间相对很晚,沉积量也相对很小。钙芒硝大量沉积后,晶间卤水钾元素出现超前富集,卤水KCl平均含量达1.40%,     

南华北盆地谭庄凹陷下白垩统储层类型及次生孔隙成因

通过岩心观察、岩心物性统计和薄片鉴定等方法,对谭庄凹陷下白垩统碎屑岩储层类型及次生孔隙成因进行了研究。结果表明：谭庄凹陷下白垩统埋藏经历了早、中成岩阶段,目前处于中成岩A阶段。下白垩统砂岩储层类型主要有原生和次生孔隙,经历了由原生到次生的演化过程;不同井区成岩阶段不同,原生到次生孔隙的演化程度也存在差异。铸体薄片、扫描电镜的研究结果表明：谭庄凹陷下白垩统砂岩储层存在3个次生孔隙带,并且每口井的次生孔隙发育程度存在差别。次生孔隙的形成与长石、岩屑、石英的溶蚀,粘土矿物的脱水以及油气的充注密切相关;不同探井、不同井段砂岩次生孔隙的形成原因具有差异,长石、岩屑的溶蚀占主导地位,石英和粒间粘土杂基的溶蚀作用次之。     

阿克苏地区寒武系肖尔布拉克组不同白云岩的孔隙特征、成因及演化

根据阿克苏地区两条典型野外剖面（肖西沟剖面、苏盖特布拉克剖面）的细测及大量薄片资料分析,认为肖尔布拉克组发育凝块石云岩、残余颗粒云岩及晶粒云岩等3种类型白云岩,主要孔隙类型有晶间孔、晶间溶孔、粒间溶孔、凝块内溶孔等4种。凝块石云岩中孔隙面孔率与胶结物含量及单个凝块大小呈反比,孔隙的连通性与单个凝块大小、堆积疏松程度、胶结物含量、凝块含量呈正比。残余砂屑云岩孔隙面孔率与残余颗粒含量呈正比、与胶结物含量呈反比。根据沉积—成岩作用影响的差异,建立3种不同白云岩孔隙演化发育模式:在凝块石云岩中,同生—准同生期大气淡水溶蚀作用是形成孔隙的关键,埋藏期溶蚀作用使得孔隙进一步改善,最终形成以凝块内溶孔（占比72%）为主的孔隙类型;在残余颗粒云岩中,同生—准同生期的溶蚀作用是形成孔隙的基础,埋藏期溶蚀作用是增加有效孔隙的关键因素,最终形成以粒间溶孔（占比51%）为主的孔隙类型;在晶粒云岩中,早期的溶蚀改造作用对晶粒云岩孔隙发育影响较小,而埋藏期的扩大溶蚀作用是有效孔隙发育的关键因素,使其形成以晶间溶孔（占比62%）为主的孔隙类型。     

浅海微孔泥晶碳酸盐岩储层研究进展

微孔泥晶灰岩储层是一种重要的油气储层类型,尤其是对于中东地区白垩系碳酸盐岩储层,这明显不同于典型碳酸盐岩储层—古风化壳型岩溶储层、礁滩相储层及层状白云岩储层等三大类型。泥晶基质具有致密镶嵌结构和白垩质结构两种结构类型。泥晶晶体具有微菱形、圆形和它形三种晶体形态,以圆形泥晶储层物性最好,微菱形泥晶储层其次,它形泥晶为致密储层。微孔（直径小于10 μm）是泥晶基质中孔隙的主体,除此还发育铸模孔、海绵状基质溶孔和溶蚀沟道等。微孔的形成主要受原始矿物组分和成岩条件的共同制约:低镁方解石灰泥是微孔泥晶灰岩形成的先决原始矿物条件,相对矿物学稳定性可促进原始组构包括原生晶间微孔的保存。特殊的成岩环境是微孔泥晶灰岩发育的必要改造条件,泥晶灰岩中孔隙的形成是早期浅层埋藏下大气淡水淋滤及埋藏成岩期间有机酸溶蚀作用等两期溶蚀叠加的结果。在浅埋藏淡水透镜体内,方解石次生加大（奥斯特瓦尔德成熟过程）形成了沉积物早期胶结,防止压实的同时部分保留了原始结构和晶间微孔网络,还通过消除小晶体提高了渗透性;淡水选择性淋滤也形成了较广泛发育的铸模孔。在埋藏成岩过程中,有机酸性流体溶蚀作用形成海绵状基质溶孔及溶蚀沟道,也导致了圆形泥晶晶体的形成。     

达县—宣汉地区长兴组礁滩白云岩成岩过程中的孔隙演化

川东北达县—宣汉长兴组礁滩白云岩具有良好的油气储集潜力。作者通过大量岩石常规薄片、铸体薄片观察研究,发现该礁滩白云岩储层储集空间主要为次生成因的晶间孔、晶间溶孔、粒间粒内溶孔、生物体腔内溶孔和生物格架间溶孔。这些孔隙的形成和演化除了受沉积作用、构造作用和有机质热演化史的影响外,还受成岩作用的控制。首先在海底-暴露-浅埋藏环境下,压实及胶结使原生孔隙基本消失;而准同生混合水白云石化及早期暴露溶蚀作用改变了沉积物内部结构,形成众多微小孔隙的网络及溶孔,为后期形成大量孔隙创造了条件。其次在中—深埋藏环境下,强烈的重结晶作用和溶蚀作用使得岩石形成大量的次生孔隙,大大提高了礁滩白云岩的储集性能。     

鄂尔多斯盆地上古生界层序格架内的成岩作用

鄂尔多斯盆地上古生界主要发育石英砂岩、岩屑砂岩、杂砂岩、“牛毛毡砂岩”、黑色石英砂岩等五种砂岩类型。这些砂岩具有成份成熟度较高、结构成熟度中—低、以正粒序为主、粒级普遍为中粗粒、储层填隙物类型多、含量变化大的特点。经历了三个重要成岩阶段:早成岩压实期—原生孔隙大量破坏损失期，中成岩A期—有机酸溶蚀—次生孔隙发育期，中成岩B期—埋藏压溶再胶结成岩期。在SQ8主要发育压溶、高岭石溶蚀、石英次生加大等成岩作用。SQ11主要发育硅质胶结、碳酸盐胶结成岩作用。成岩相可分为三级五类，即Ⅰ强压溶—石英加大相；Ⅱ压溶—碳酸盐溶蚀—高岭石交代相及溶蚀—弱杂基充填—高岭石交代相；Ⅲ强压实—粘土胶结相及强压实—碳酸盐胶结、交代相。区内储层整体为低孔低渗的致密砂岩储层，以发育次生孔隙为主，包括粒间溶孔、粒内溶孔和高岭石晶间孔，原生孔隙较少保留。通过对沉积砂体展布、储层成岩相类型及储集性能的综合分析，对有利的储层分布区带进行了预测。     

桩海地区下古生界潜山内新一类储层:硅化岩储层的发现及特征

通过对研究区下古生界取心井的岩心描述、镜下(包括偏光显微镜和扫描电镜)观察,并对目的层段声波时差、密度、自然伽马等测井参数进行分析,发现研究区下古生界硅岩段与原生硅岩的岩-电特征明显不同,本文称之为“硅化岩”,并总结了硅化岩段的特征.研究区下古生界硅化岩之原岩残留结构清晰、硅岩晶粒自形程度高;硅化岩段常出现热水矿物萤石、重晶石、黄铁矿、铁方解石、石英等的共生组合,且次生热水矿物的再次溶蚀特征显著;硅岩段孔隙极为发育,不但有角砾间溶洞、溶缝,次生矿物溶蚀也形成溶洞、裂缝等有效储集空间,另外,自形石英晶簇的晶间微孔隙也十分发育;与碳酸盐岩相比硅化岩段具有极低速度、较低密度特点,且其分布具有“穿层性”.通过与下古生界原生硅岩特征进行对比,认为桩海地区下古生界硅化岩为次生成因,其形成是埋藏溶蚀作用的结果.次生硅化岩为下古生界潜山中一种新的储层类型.这种新储层类型的发现不但对中国东部陆相盆地高成熟探区的油气挖潜具有重要的实际意义,而且对于进一步丰富硅岩理论、推动硅岩研究进展也具有一定的学术价值.      

准东下侏罗统三工河组砂岩成岩作用及其对孔隙的影响

准噶尔盆地东部下侏罗统三工河组孔隙类型：主要有剩余原生粒间孔和次生孔隙。剩余原生粒间孔是成岩早期淀粘主石英加在形成的,它们围绕屑边部分布。本地区,在剩余原生粒间孔发育的茂盛上、发生溶蚀作用,形成一些原生扩大孔,超大孔、粒内溶孔等。成岩早期胶结作用形成剩余原生粒间孔,晚期的溶蚀作用形成次生孔隙。     

高压微波消解法测定醋酸纤维过滤器采集的微尘粒子中的砷镉钴铬铜铁锰镍铅钒锌

最新的流行病学研究表明,空气中较高浓度的悬浮细颗粒可能对人类的健康有不利的影响。根据该项研究显示,由于心脏病、慢性呼吸问题和肺功能指标恶化而导致死亡率的升高与细尘粒子有关。这些研究结果已经促使欧盟于1999年4月出台了限制空气中二氧化硫、二氧化氮、氧化氮、铅和颗粒物含量的法案(1999/30/EC),对各项指标包括对可吸入PM10颗粒的浓度提出了新的限制性指标。PM10颗粒是指可以通过预分级器分离采集的气体动力学直径小于10μm的细颗粒。目前研究的兴趣重点逐步偏向PM2.5这些更细微颗粒物,PM2.5这种颗粒物对健康有明显的不利影响。在欧盟指令2008/50/EC中,对PM10和PM2.5都提     

Analysis of F, Al, Mn, Zn, Fe, Cu, Ca and Mg concentrations in brick teas from main producing areas in China

Brick-tea-type fluorosis is a peculiar endemic disease in China, which had been discovered in minority areas of western China since 1980, and distributed mainly in Tibet, Inner Mongolia, Gansu, Xinjiang, Qinghai and parts of Sichuan Province. The prevalence rate of fluorosis in Tibetan and Mongolian nationality people was higher. Epidemiological investigation showed that fluorosis morbidity and degrees were different in different brick-tea drinking areas, and it was probably caused by drinking various kinds of brick tea from different regions. Therefore, we collected 33 samples of brick tea from six provinces where minority nationalities were accustomed to drinking a large quantity of brick tea. F concentrations were determined by the combustion hydrolysis-ion selective electrode method. The results showed that among the brick teas, the F concentrations ranged from the minimum 74.1 mg/kg in Yunnan Province to the maximum 991.2 mg/kg in Sichuan Province. Besides, there was a great difference among the various kinds of brick tea, and F concentrations decreased in the order of Kang brick tea, Green brick tea, Black brick tea, Mi brick tea, Fu brick tea, Chitsu ping tea, Puerh tea, and Tuo tea. The average F concentration in brick teas was 431.92 mg/kg.     

贵州安顺地区岩腊片区水淹坝岩溶内涝成因分析

水淹坝岩溶内涝是安顺市西秀区发育最大范围的岩溶内涝,严重制约了当地经济发展。本文以岩溶地下水系统为单元,通过开展1:10000水文地质调查、地球物理勘探、水文地质钻探等手段,查明内涝所在区的岩溶发育特征、水文地质条件。在此基础上分析得出,水力坡度小、岩层倾角缓造成地下河管道淤塞;人类工程活动使有水落水洞口堵塞,加之广阔的集雨面积和连续的强降雨是造成水淹坝岩溶内涝的主要原因。通过对水淹坝内涝成因分析,为岩溶内涝灾害综合整治提供参考依据。     

等离子体质谱法测定岩石中的锆、铪、铌、钽

本文建立了用HF、HNO3 在高压釜内溶解样品 ,准确测定花岗岩样品中Nb、Ta、Zr、Hf的ICP MS分析方法。分析结果与推荐值的偏差在 5 %以内。该方法具有简单、准确、测定元素多的特点。本文还对高压釜酸溶和碱熔方法进行了对比实验。     

Chemical characteristics of groundwater in parts of mountainous region, Alvand, Hamadan, Iran

Eighty-seven groundwater samples have been collected from a mountainous region (Alvand, Iran) for hydrochemical investigations to understand the sources of dissolved ions and assess the chemical quality of the groundwater. Most water quality parameters are within World Health Organization acceptable limits set for drinking water. The least mineralized water is found closest to the main recharge zones and the salinity of water increased towards the north of the basin. The most prevalent water type is Ca–HCO₃ followed by water types Ca–NO₃, Ca–Cl, Ca–SO₄ and Mg–HCO₃. The Ca–NO₃ water type is associated with high nitrate pollution. Agricultural and industrial activities were associated with elevated level of NO₃⁻. Mineral dissolution/weathering of evaporites dominates the major element hydrochemistry of the area. Chemical properties of groundwater in Alvand region are controlled both by natural geochemical processes and anthropogenic activities.     

湖北宜昌王家湾五峰组顶部Chondrites的发现及其环境意义

本文报道了湖北宜昌王家湾剖面五峰组笔石页岩段观音桥层发现的遗迹化石Chondrites的分布及其生态特点。结合生物相和同期上扬子海盆相对海平面的变化,分析了盆地水体底域在缺氧一富氧转折时期的古氧相变化特征：指出五峰组笔石页岩段上部地层沉积底域为典型的缺氧环境,在其与上覆观音桥段之间的沉积转换面附近发生了从无氧到有氧的转变,观音桥段中Hirnantia动物群繁盛于富氧的海底环境。     

Alteration of Chalcocite in Tamoshan,Siujen,Kuangsi

It is the purpose of this paper to state briefly the alteration of chalcociteand its products.The specimens were collected by W.Y.Chang' fromTamoshan~2,about 675 m above sea-level.The exact locality of occurrence ison the west slope of the Yao Mountain~(?),12 km SE of Chichenchieh~4,15 kmNE of Tungmu~(?),and 48 km SW of the Siujen~(?) City.     

ICP-MS测定土壤中的As、Cr、Pb、Se、Cu和Zn

本文用电感耦合等离子质谱法(ICP-MS)测定了土壤的As、Cr、Pb、Se、Cu和Zn6种微量元素的质量分数,以In作为内标进行基体效应的补偿,方法快速灵敏,回收率为92.4%～106.8%,相对标准偏差小于5.0%,结果达到国家标准要求。     

西藏东喜马拉雅错那地区亚马荣淡色花岗岩的年代学、地球化学与岩石成因

本文通过对东喜马拉雅错那地区亚马荣岩体的地球化学、锆石U-Pb年代学和Hf同位素研究,试图探索亚马荣岩体的形成机制,解释地壳深熔作用过程。锆石U-Pb定年获得两期年龄,分别为14.4Ma和17Ma,结合前人已有结果,本文认为错那地区的深熔作用至少持续5Myr时间。亚马荣岩体具有较高Si O2(71.85%~72.91%)、Al2O3(15.30%~15.67%)含量,较低的Fe2O3T(0.58%~0.90%)、Ca O(0.72%~1.05%)含量,铝饱和指数(A/CNK)为1.08~1.22;锆石Ti温度计、εHf(t)的变化以及大离子亲石元素Rb/Sr比值和Ba含量之间的协变关系都说明,错那淡色花岗岩形成过程中存在多种熔融方式,经历了脱水熔融和水致熔融的转变,发生熔融反应的转变可能与藏南东-西向伸展构造的启动有关。     

Roles of xenomelts,xenoliths, xenocrysts,xenovolatiles, residues,and skarns in the genesis,transport, and localization of magmatic Fe-Ni-Cu-PGE sulfides and chromite

Most sulfide-rich magmatic Ni-Cu-(PGE) deposits form in dynamic magmatic systems by partial melting S-bearing wall rocks with variable degrees of assimilation of miscible silicate and volatile components, and generation of barren to weakly-mineralized immiscible Fe sulfide xenomelts into which Ni-Cu-Co-PGE partition from the magma. Some exceptionally-thick magmatic Cr deposits may form by partial melting oxide-bearing wall rocks with variable degrees of assimilation of the miscible silicate and volatile components, and generation of barren Fe ± Ti oxide xenocrysts into which Cr-Mg-V ± Ti partition from the magma. The products of these processes are variably preserved as skarns, residues, xenoliths, xenocrysts, xenomelts, and xenovolatiles, which play important to critical roles in ore genesis, transport, localization, and/or modification. Incorporation of barren xenoliths/autoliths may induce small amounts of sulfide/chromite to segregate, but incorporation of sulfide xenomelts or oxide xenocrysts with dynamic upgrading of metal tenors (PGE > Cu > Ni > Co and Cr > V > Ti, respectively) is required to make significant ore deposits. Silicate xenomelts are only rarely preserved, but will be variably depleted in chalcophile and ferrous metals. Less dense felsic xenoliths may aid upward sulfide transport by increasing the effective viscosity and decreasing the bulk density of the magma. Denser mafic or metamorphosed xenoliths may also increase the effective viscosity of the magma, but may aid downward sulfide transport by increasing the bulk density of the magma. Sulfide wets olivine, so olivine xenocrysts may act as filter beds to collect advected finely dispersed sulfide droplets, but other silicates and xenoliths may not be wetted by sulfides. Xenovolatiles may retard settling of – or in some cases float – dense sulfide droplets. Reactions of sulfide melts with felsic country rocks may generate Fe-rich skarns that may allow sulfide melts to fractionate to more extreme Cu-Ni-rich compositions. Xenoliths, xenocrysts, xenomelts, and xenovolatiles are more likely to be preserved in cooler basaltic magmas than in hotter komatiitic magmas, and are more likely to be preserved in less dynamic (less turbulent) systems/domain/phases than in more dynamic (more turbulent) systems/domains/phases. Massive to semi-massive Ni-Cu-PGE and Cr mineralization and xenoliths are often localized within footwall embayments, dilations/jogs in dikes, throats of magma conduits, and the horizontal segments of dike-chonolith and dike-sill complexes, which represent fluid dynamic traps for both ascending and descending sulfides/oxides. If skarns, residues, xenoliths, xenocrysts, xenomelts, and/or xenovolatiles are present, they provide important constraints on ore genesis and they are valuable exploration indicators, but they must be included in elemental and isotopic mass balance calculations.