冲绳海槽西南端中全新世以来的沉积特征及其物源与环境意义

作为大陆向大洋的过渡带，由于享有得天独厚的沉积环境，具有独特的构造特征以及与黑潮主流之间的密切关系，一直以来，冲绳海槽都是中外学者研究的重点靶区。2005年5月，由我国与法国联合主持的IMAGES 航次在台湾东北海域获取MD05-2908柱状岩芯（24º48.04′N,122 º29.35′E,水深为1275米），该柱状岩芯为一34.17米长高质量的连续沉积记录，岩性以深灰色粘土质粉砂为主，含水量较高，粘性、可塑性强，含有数层厚度不等的夹层。岩芯年龄模式依据17个AMS 14C定年数据建立，岩芯底部年代约6.8ka，为中全新世以来的沉积。在实验室对样品按照2cm的间隔进行分割后分别进行了粒度分析、粘土矿物提取与测试、碎屑矿物提取与鉴定、常微量元素和稀土元素分析等实验。 粒度分析结果显示，MD05-2908岩芯沉积物粒度垂向上总体比较均一，以细颗粒的粘土与粉砂质为主，但不同层位也稍有差别，表现为底部层位粒度较粗，含砂量较高，说明底部沉积环境比较复杂。粘土粒级（<2µm）矿物主要由四种粘土矿物和少量石英、长石碎屑组成。其中，粘土矿物相对含量变化中，伊利石（～68％）与绿泥石（～17%）构成主要成分，含有蒙皂石（～10％）和高岭石（～5％）。结合台湾东北外海表层沉积物的研究，利用粘土矿物伊利石/蒙皂石和绿泥石/高岭石比值得出岩芯粘土矿物主要为陆源碎屑粘土矿物，其源岩主要为台湾中央山脉的变质岩与台湾东部的沉积岩。重矿物分析共选取了41个层位，对63~250μm粒级的样品在实体镜和偏光显微镜下进行鉴定，结果显示，岩芯重矿物主要由绿泥石（29%）、普通角闪石（22%）、白云石（10%）、黑云母（8%）、绿帘石（7%）、白云母（7%）、褐铁矿（5%）等组成。稳定矿物少，矿物成熟度低。碎屑矿物风化程度低，磨蚀不明显，分选较差，表明沉积物来自于近源，后期改造作用不明显。常量元素分析结果表明，SiO2 、Al2O3和Fe2O3是岩芯沉积物中的最主要组分，这三种组分占沉积物总量的82%左右。 整个岩芯自下而上各常量组分变化不大，其平均值与东海陆架沉积物基本接近。微量元素变化比较明显， Ba、Cr、Cu、Zn元素的含量比东海陆架沉积物中的含量要高，而Sr的含量明显低于东海陆架。对常微量元素的R型因子分析表明，常量元素SiO2、Al2O3、Fe2O3、MgO和K2O，微量元素Cr、Cu、Ni、Zn、Pb、Rb和Mn可代表陆源物质；常量元素CaO和微量元素Sr、Ba可代表生物源物质。岩芯沉积物以陆源物质为主，生源物质的贡献起次要作用。岩芯沉积物中稀土元素总量平均为169.87×10-6，并且轻稀土含量均高于重稀土，LREE/HREE平均值为10.14，表明了轻稀土对稀土总量的贡献远高于重稀土，沉积物富集轻稀土，反映了沉积物的陆源特征。 岩芯MD05-2908中全新世以来平均5m/ka的高沉积速率主要源于丰富的物质供应和适宜的沉积环境。岩芯细粒级沉积物中，地球化学特征表明沉积物主要来源于陆源碎屑物质，粘土矿物特征与台湾东部陆源物质相同；粗粒级沉积物中，重矿物含量及矿物特征也表明岩芯沉积物粗颗粒组分主要来自于近源沉积。台湾宜兰境内的兰阳溪每年携带约一千万吨冲积物入海成为研究区重要的物质来源。由于受到黑潮的强烈影响，逆时针涡流及底层反向流的存在是岩芯高沉积速率重要控制因素。因此，利用动力分选的粉砂组分可以用来示踪古洋流强度，结果显示，6.8ka以来黑潮的强弱波动频繁，并表现出一定的旋回性变化，频谱分析表明，其具有的千年尺度周期（1500a）、百年尺度周期（604a、242a、192a、153a、133a）与十年尺度周期（22a）的周期性变化均与太阳辐射量变化有密切关系，因此，黑潮的强弱变化在大背景上是由太阳活动所控制的。 根据测年资料可以识别出岩芯存在5期快速堆积事件，这与区域性降水增加有关，降雨量增加导致陆源物质输入的增加。另外，岩芯位于大陆斜坡区，附近存在有三支海底峡谷，并且地震活动频繁，沉积在宜兰陆架及东海陆架处的浅海沉积物由于受到地震、风暴等活动的影响而受扰动崩塌、因重力作用而向低处输送，产生二次侵蚀并经由海底峡谷搬运到冲绳海槽南段堆积,使得沉积环境更为复杂，但同时也为冲绳海槽提供了丰富的物质供应。

中国北方中新世风尘物质来源及古气候的地球化学指示

The most prominent tectonic and environmental events during the Cenozoic in Asia are the uplift of the Himalaya-Tibetan plateau, aridification in the Asian interior, and onset of the Asian monsoons. These caused more humid conditions in southeastern China and the formation of inland deserts in northwestern China. The 22 Ma eolian deposits in northern China provide an excellent terrestrial record relative to the above environmental events. Up to date, many studies have focused on the geochemical characters of the late Mio-Pleistocene eolian deposits, however, the geochemical characteristics of the Miocene loess and soils is still much less known. In this study, the elemental and Sr-Nd isotopic compositions of the eolian deposits from the Qinan (from 22.0 to 6.2 Ma) and the Xifeng (from 3.5 Ma until now) loess-soil sections were analyzed to examine the grain size effects on the element concentrations and the implications about the dust origin and climate. The main results are as follows: 1. The contents of Si, Na, Zr and Sr are higher in the coarser fractions while Ti and Nb have the highest contents in the 2-8 μm fractions. Al, Fe, Mg, K, Mn, Rb, Cu, Ga, Zn, V, Cr, Ni, LOI have clear relationships with grain-size, more abundant in the fine fraction while non significant relationship is observed for Y. Based on these features, we suggest that K2O/Al2O3 ratio can be used to address the dust provenance, and that VR (Vogt ratio = (Al2O3+K2O)/(MgO+CaO+Na2O)) can be used as a chemical weathering proxy for the Miocene eolian deposits because of their relative independence on the grain size. Meanwhile, SiO2/Al2O3 molar ratio is a best geochemical indicator of original eolian grain size, as suggested in earlier studies. 2. Analyses on the Sr and Nd isotope composition of the last glacial loess samples (L1) and comparison with the data from the deserts in northern China suggest that that Taklimakan desert is unlikely to be the main source region of the eolian dust. In contrast, these data suggest greater contributions of the Tengger, Badain Jaran and Qaidam deserts to the eolian dust during the last glacial cycle. Since the geochemical compositions (major, trace, REE and Sr, Nd isotope) of loess samples for the past 22 Ma are broadly similar with the samples from L1, these data trend to suggest relatively stable and insignificant changes of dust sources over the past 22 Ma. 3. Chemical weathering is stronger for Miocene paleosol samples than for the Plio-Pleistocene ones, showing warmer/more humid climatic conditions with a stronger summer monsoon in the Miocene. However, chemical weathering is typical of Ca-Na removal stage, suggesting a climate range from semiarid to subhumid conditions. These support the notion about the formation of a semi-arid to semi-humid monsoonal regime by the early Miocene, as is consistent with earlier studies.

湘黔地区早寒武世黑色岩系沉积学及地球化学研究

中国南方古生代广泛分布富有机质的黑色页岩，分布层位较多(如下寒武统牛蹄塘组底部的黑色页岩、奥陶系五峰组页岩、志留系龙马溪组黑色页岩、泥盆系深水台间盆地的黑色碳质、硅质页岩，以及二叠系的黑色页岩、硅质岩等），并伴有Mo、Ni、PGE、V、Au、Ag等贵重金属元素富集层，尤其是湘黔地区下寒武统牛蹄塘组底部的黑色页岩，作为瞬时灾变沉积物，可与全球大洋缺氧事件对比。贵州省遵义地区黄家湾和湖南张家界地区柑子坪剖面为该地区较典型的剖面，前人已进行了大量的岩石地层、生物地层、元素地球化学研究工作，但沉积学方面尚缺乏系统性与较深入研究，特别是关于以黄家湾剖面为代表的浅水沉积体系与柑子坪剖面为代表的深水相黑色页岩沉积体系之间的时空关系缺乏统一的认识，且有机地球化学研究涉及甚少。因此，本文从沉积学和地球化学两方面，特别是有机地球化学方面，探讨了湘黔地区下寒武统底部牛蹄塘组黑色岩系的成因以及相应的灾变事件－大洋缺氧事件，取得如下认识： (1)本文对研究区下寒武统地层进行了较全面的清理，重新厘定了研究区下寒武统地层系统。下寒武统自下而上划分为牛蹄塘组、明心寺组、金顶山组和清虚洞组，其时代经历了梅树村阶、筇竹寺阶、沧浪铺阶和龙王庙阶，与西伯利亚地区同期沉积相比，分别对应晚Tommotian、Atdabanian、Botonian和Toyonian期。 (2)确定了研究区下寒武统岩石类型有碳酸盐岩、泥质岩和碎屑岩三大类。下寒武统下、中部泥质岩、粉砂岩及砂岩发育，且以泥质岩为主，少有碳酸盐岩发育，而上部清虚洞组灰岩(白云岩)发育。下寒武统牛蹄塘组黑色岩系主要由黑色页岩、石煤、硅质页岩、硅岩、粉砂岩、磷块岩、重晶石岩等组成，主要矿物组合为石英、伊利石和黄铁矿以及少量重晶石、磷灰石和方解石。从生物地层、岩石地层、年代地层来看，牛蹄塘组底部黑色页岩与南亚、西亚、欧洲、北美等地Tommotian期广泛分布的黑色页岩有很好的可对比性。 (3)基于对地层清理、古生物以及岩石学特征的详细研究，研究区下寒武统可划分为碎屑岩海相和碳酸盐岩海相两个沉积体系组。碎屑岩海相又分为滨岸、内陆棚、外陆棚、斜坡亚相；碳酸盐岩海相主要为开阔台地亚相。从时空上看，地层由老到新，粒度逐渐变粗，水体逐渐变浅，从外陆棚-斜坡、内陆棚到滨海，最后为开阔台地相；从西向东，由浅水相区的滨岸到内陆棚，最后到深水相区的外陆棚到斜坡。 (4)晚震旦世灯影组灰白色粉晶白云岩样品的SiO2含量比较低，MgO、CaO、CO2含量较高。牛蹄塘组黑色碳质泥岩、碳质页岩以SiO2含量为主，其次为Al2O3和Fe2O3。微量元素含量具有如下特征：地层由老到新，从灯影组白云岩→牛蹄塘组磷块岩/硅质岩→多金属富集层，呈现出增加趋势，此后至黑色页岩又有回落。特征微量元素(如Mo、Ni、V、U等)及其比值(如V/(V+Ni)、V/Cr、Ni/Co、U/Th、δU等)显示这套富含有机质黑色页岩为热水沉积，其沉积环境为含氧量逐渐减少的贫氧-缺氧的还原环境。 (5)稀土元素总量(∑REE)从6.67ppm变化到481ppm，平均含量为123ppm，轻稀土相对比较富集。经PAAS标准化的稀土配分模式曲线具有近于水平或略显右倾特征。灯影组Ce异常值均小于-0.10，代表当时海水处于氧化阶段。而牛蹄塘组底部和上部Ce异常值大于-0.10，接近0，代表弱的缺氧沉积环境。对于牛蹄塘组中部，其值小于-0.10，说明缺氧环境持续了一段时间后，海洋出现了一个短暂的充氧期。根据Ce异常和参考海平面，研究区晚震旦世-早寒武世可识别出3个主要海平面升降旋回。而Eu异常为0.002-1.16，大多数样品显示负Eu异常，表明其沉积环境为缺氧的还原环境。 (6)所有样品均含丰富的正构烷烃、类异戊二烯烃、萜类化合物以及甾类化合物，尤其是具有重要价值的甲基三环萜烷系列、25-降藿烷系列以及甲基甾烷。在GC谱图上，正构烷烃显示明显的单峰型分布特征，碳数分布范围为nC14-nC31，主峰碳为nC18、nC19或nC20，无明显的奇偶碳数优势分布。类异戊二烯烃、萜类化合物以及甾类化合物等的特点也表明，早寒武世黑色岩系不同层位中有机质的先质均来源于菌藻类生物，有机质类型属于腐泥型，沉积环境为强还原到弱还原环境。有机质成熟度指标显示了研究区有机质热演化程度高，一般已经达到生油门限或高成熟阶段，其中以黑色页岩的演变程度最高，但仍未达到演变的最终阶段。 (7)在地层剖面上，有机碳含量为0.05-12.31％，平均为4.97%；有机碳同位素组成(δ13Corg)从-29.49－-34.41‰（PDB），发生负偏移，偏移量达到4.3‰，而δ13Ｃcarb值从晚震旦世的-4.6‰下降至早寒武世的-10.6‰，具有6.0‰的负偏移，δ18Ocarb值在-13.7－-2.3‰(PDB)之间。δ13Corg与δ13Ｃcarb变化具有一致性，表明其偏移与有机质组分无关。在Tommotian晚期，海平面持续上升，海洋循环引起海洋的含氧量减少，可能是引起δ13Ｃ负偏移的一个原因。另外，加上海洋条件急剧恶化，底层水缺氧更严重。因此可确定研究区Tommotian期缺氧事件的存在。 上述研究表明，湘黔地区早寒武世黑色岩系的形成和Tommotian期缺氧事件的发生既与区域背景有关，又与有机质遭受细菌降解、生物爆发致使生物生产率的提高有关，还与海平面升降有关。扬子地台在晚震旦世-早寒武世处于全球海平面上升阶段，底层洋流活跃，大量营养物质被上升流周期性地带到表层水中使生物大量繁殖，生物生产率增加，底层水含氧量减少。在这种背景下，氧化作用缓慢，海进期间歇性的上升洋流把富有机质的缺氧水带到相对深水区，导致黑色页岩广泛分布。由于表层浮游生物大量死亡，腐烂分解吸收大量溶解氧，再加上上升洋流也分解有机质，因此底层水迅速变成“无氧状态”，导致沉积物中海洋生物死亡，有机质突然急增而大量保存下来，加强了缺氧环境。

个旧岩浆杂岩地质地球化学及成因研究

燕山中晚期，个旧岩浆活动强烈，并形成基性、中性、酸性及碱性杂岩体。对此前人已做过很多工作，但对其成因机制并未做详细探讨。本文以神仙水花岗岩、卡房花岗岩及贾沙辉长-二长岩为研究对象采用XRF、ICP-MS、EMPA-1600等分析测试方法，对个旧岩浆杂岩体的元素地球化学特征做了详细的分析和总结，并初步得出以下结论： 1、贾沙辉长-二长岩富集LILE、LREE，相对亏损HREE，并具有富碱特征和Eu的弱负异常，说明其为富集地幔来源；但与OIB相比，具有Nb、Ta、Ti等元素的亏损，说明其受到地壳混染作用。 2、个旧花岗岩普遍具有高硅、高铝、富碱（尤其富钾）等特征。随着SiO2含量的增加，Al2O3、Fe2O3T、MgO、CaO、TiO2、P2O5的含量呈线性降低；当SiO2含量大于70%时，Na2O和K2O含量变化不大。 3、岩石类型上，个旧各花岗岩体的铝质系数A/CNK值为0.92～1.08，属于I型花岗岩；构造环境上，个旧花岗岩形成于大陆碰撞环境，为碰撞晚期或后碰撞构造环境；其主要成分来源于地壳，并有基性成分和酸性成分的混合特征。 4、初步研究表明，个旧花岗岩形成于与玄武质岩浆底侵有关的下部大陆壳重熔作用。

大麻坪地区二辉橄榄岩的部分熔融实验研究

本文以大麻坪地区二辉橄榄岩为初始物料，在压力为1.0~3.0GPa、温度为1350~1550℃条件下进行了部分熔融实验，对实验产物的岩石化学成分进行了相应的分析和研究，查明了二辉橄榄岩发生部分熔融和结晶分异的条件，揭示了熔融过程中主量元素迁移的趋势，实验中还发现了实验产物的产出形态与压力的关系及成分的变化。本次研究根据大麻坪二辉橄榄岩的部分熔融所得的熔体与该区玄武岩之间的关系，并利用这些关系来初步探讨汉诺坝玄武岩的成因。本次实验得出大麻坪地区二辉橄榄岩部分熔融实验产物的一些规律：MgO的含量随着熔融程度的增加而增加，在熔体中MgO含量较低情况下，特别压力为0.5~1.0GPa的条件下，MgO和SiO2的含量呈负相关函数；初始物料中的Mg#明显地控制着部分熔融产物FeO的含量；随着部分熔融程度增高，部分熔融熔体成分中的CaO/Al2O3值随之增加。大麻坪玄武岩具有单斜辉石分异趋势，而本次利用二辉橄榄岩部分熔融实验的反演也有类似的趋势，这暗示着如果本区玄武岩的原岩为二辉橄榄岩，那么可能存在橄榄玄武岩→玄武岩的演化趋势。

热带亚热带季风气候条件下表生成矿地球化学－以个旧和老挝Nameung、Boloven地区为例

在前人对热带亚热带季风型气候条件下云南个旧砂矿、老挝Xaymomboun特区Ban Nameung铜多金属矿和Champasak省Boloven高原玄武岩等研究成果基础上，采用典型表生矿床实证解剖思路，选择个旧白云岩风化剖面、锡铅砂矿、锰结核、砂矿重选流程、Ban Nameung硫化氧化矿和Boloven玄武岩风化壳等对象，通过岩矿鉴定、主量微量元素地球化学、稀土元素地球化学、人工重砂、化学物相和微区分析等研究手段，研究这些矿床表生成矿物质来源、成矿机理、矿床地球化学特征和矿物工业可利用性等内容，并探索热带亚热带季风型气候条件下典型矿床表生成矿三个问题：（1）Sn、Pb、Mn、Ag、REE、Nb、Ta、Ga和Cd等元素表生富集成矿（矿化）规律；（2）上述元素成矿机理和工业利用可能性；（3）典型矿床其他20几种元素表生贫化与富集规律。研究获得如下主要认识： 1. 个旧地区燕山期以来持续抬升和亚热带季雨林的表生环境，使个旧地区大面积出露的碳酸盐岩风化形成强烈岩溶地貌，碳酸盐岩风化过程中CaO和MgO大量淋失，为砂矿提供了巨大容矿空间，同时碳酸盐地区碱性环境有利于原生硫化矿分解。含矿或不含矿白云岩、花岗岩、玄武岩、夕卡岩和原生硫化矿石等风化形成粘土矿物和铁锰氧化物，释放出Sn、Pb、Mn、Ga、Cd、Ag、In、Cu和Zn等元素，难风化重矿物如锡石表生残留富集，而粘土矿物和铁锰氧化物对成矿元素吸附是砂矿表生成因机理之一。 2. 个旧地区岩溶型砂矿形成机理为：（1）原生重矿物残留富集成矿，如锡石、磁铁矿。（2）金属硫化物残留成矿，如砂矿中残存大量方铅矿、黄铜矿、黄铁矿，是原生硫化物残留结果。（3）表生矿物富集成矿，如白铅矿、孔雀石、自然铅和自然铜等富集。（4）铁锰氧化物吸附和包裹成矿，如铁锰氧化物吸附Pb和Ga等元素，包裹含Pb和Zn微粒矿物。（5）锰结核吸附包裹成矿，锰结核吸附和包裹Sn、Pb和Cu等元素和微粒矿物。（6）类质同象成矿，如Ga和Al类质同象，Cd和Zn等类质同象成矿。（7）岩溶作用成矿，岩溶落水洞或溶洞内水流冲刷使锡石等重矿物富集成矿。元素表生成矿不仅是单一成矿作用结果，而是综合作用结果，如Pb有表生矿物富集成矿，也有铁锰氧化物吸附成矿。 3. 砂矿中锰结核是锰铁结核，主要成分为Fe2O3 、Al2O3、SiO2和MnO等，包裹了赤铁矿、方解石、云母、石英、蒙脱石、高岭石、白云石、钾长石等和锡石、白铅矿等矿物。锰结核中Mn、Sn、Pb、Ag、Ga、Cd和In富集成矿，Cu和Zn富集矿化，锰结核比砂矿更富集Mn、Pb和REE，其成矿机理应是吸附和包裹成矿元素或矿物使其富集成矿。 4. 个旧表生砂矿共生伴生组分复杂，有用矿物有锡石、方铅矿、白铅矿、黄铜矿、自然铅、自然铜、孔雀石、软锰矿、白钨矿、磁铁矿和褐铁矿等。模拟岩溶作用自然过程中砂矿矿物流向的源兴采选车间砂矿重选流程结果表明，锡铅精矿中Pb、Ga、Mo、Cd、In、Cu和Zn等金属总实收率仅为3.03％～6.44％，绝大部分金属留在了尾矿中。一段床和矿泥床分析中，Ag和Mn回收率低于0.66％～0.29％，Ag富集在硫化物态中，没有富集在铁锰氧化物态中；Mn富集在碳酸盐态中，没有铁锰氧化物态中。整个流程中Pb、Mn、Cu和Zn等富集在碳酸盐态矿物中，没有富集在硫化物态中。选矿流程没有利用具有潜在利用价值矿物如磁铁矿。重选流程解释了岩溶过程能富集Pb、Mn、Cu和Zn的碳酸盐矿物，不能富集这些元素的硫化矿物。 5. 老挝Ban Nameung硫化矿氧化初期，风化产物中Ag、Pb、Zn和Cu淋失，SiO2、K2O和CaO富集，风化后期Ag、Fe和Mn富集。硫化矿风化过程中，Au硫化物态部分变为有机态和铁锰氧化物态；Ag硫化物态部分变为铁锰氧化物态和有机态；Cu硫化物态部分变为铁锰氧化物态和碳酸盐态；Pb硫化物态、吸附态、碳酸盐态和铁锰氧化物态部分变为铁锰氧化物态、碳酸盐态和有机态；Zn硫化物态变为部分铁锰氧化物态、有机态、碳酸盐态和吸附态矿物。随着风化作用加强，上述几种相态比例还会改变。 6. 老挝Boloven新生代亚碱性玄武岩富Nb、Ta和Ga等微量元素，风化壳中REE、Nb、Ta和Ga已富集成矿，∑REE最高775×10-6～1003×10-6，（Nb2O5＋Ta2O5）最高642×10-6~656×10-6，Ga最高81.6 ×10-6。风化壳中达到边界品位的（Nb2O5＋Ta2O5）厚度有2m以上。REE可能存在于含P和Ti矿物中，也可能形成REE独立矿物。Nb、Ta和Ga应赋存在Ti、U、Zr和Th矿物中，其成矿应是重矿物表生残留富集结果，与粘土矿物吸附和三水铝石关系不紧密。

Alkaline-earth aluminosilicate-based glass and glass-ceramic sealants for functional applications

The planar design of solid oxide fuel cell (SOFC) is the most promising one due to its easier fabrication, improved performance and relatively high power density. In planar SOFCs and other solid-electrolyte devices, gas-tight seals must be formed along the edges of each cell and between the stack and gas manifolds. Glass and glass-ceramic (GC), in particular alkaline-earth alumino silicate based glasses and GCs, are becoming the most promising materials for gas-tight sealing applications in SOFCs. Besides the development of new glass-based materials, new additional concepts are required to overcome the challenges being faced by the currently existing sealant technology. The present work deals with the development of glasses- and GCs-based materials to be used as a sealants for SOFCs and other electrochemical functional applications. In this pursuit, various glasses and GCs in the field of diopside crystalline materials have been synthesized and characterized by a wide array of techniques. All the glasses were prepared by melt-quenching technique while GCs were produced by sintering of glass powder compacts at the temperature ranges from 800−900 ºC for 1−1000 h. Furthermore, the influence of various ionic substitutions, especially SrO for CaO, and Ln2O3 (Ln=La, Nd, Gd, and Yb), for MgO + SiO2 in Al-containing diopside on the structure, sintering and crystallization behaviour of glasses and properties of resultant GCs has been investigated, in relevance with final application as sealants in SOFC. From the results obtained in the study of diopside-based glasses, a bilayered concept of GC sealant is proposed to overcome the challenges being faced by (SOFCs). The systems designated as Gd−0.3 (in mol%: 20.62MgO−18.05CaO−7.74SrO−46.40SiO2−1.29Al2O3 − 2.04 B2O3−3.87Gd2O3) and Sr−0.3 (in mol%: 24.54 MgO−14.73 CaO−7.36 SrO−0.55 BaO−47.73 SiO2−1.23 Al2O3−1.23 La2O3−1.79 B2O3−0.84 NiO) have been utilized to realize the bi-layer concept. Both GCs exhibit similar thermal properties, while differing in their amorphous fractions, revealed excellent thermal stability along a period of 1,000 h. They also bonded well to the metallic interconnect (Crofer22APU) and 8 mol% yttrium stabilized zirconium (8YSZ) ceramic electrolyte without forming undesirable interfacial layers at the joints of SOFC components and GC. Two separated layers composed of glasses (Gd−0.3 and Sr−0.3) were prepared and deposited onto interconnect materials using a tape casting approach. The bi-layered GC showed good wetting and bonding ability to Crofer22APU plate, suitable thermal expansion coefficient (9.7–11.1 × 10–6 K−1), mechanical reliability, high electrical resistivity, and strong adhesion to the SOFC componets. All these features confirm the good suitability of the investigated bi-layered sealant system for SOFC applications.

Condutividade térmica de rochas: uma aplicação para granitos ornamentais

This dissertation focuses on rock thermal conductivity and its correlations with petrographic, textural, and geochemical aspects, especially in granite rocks. It aims at demonstrating the relations of these variables in an attempt to enlighten the behavior of thermal effect on rocks. Results can be useful for several applications, such as understanding and conferring regional thermal flow results, predicting the behavior of thermal effect on rocks based upon macroscopic evaluation (texture and mineralogy), in the building construction field in order to provide more precise information on data refinement on thermal properties emphasizing a rocky material thermal conductivity, and especially in the dimension stone industry in order to open a discussion on the use of these variables as a new technological parameter directly related to thermal comfort. Thermal conductivity data were obtained by using Anter Corporation s QuicklineTM -30 a thermal property measuring equipment. Measurements were conducted at temperatures ranging between 25 to 38 OC in samples with 2cm in length and an area of at least 6cm of diameter. As to petrography data, results demonstrated good correlations with quartz and mafics. Linear correlation between mineralogy and thermal conductivity revealed a positive relation of a quartz percentage increase in relation to a thermal conductivity increase and its decrease with mafic minerals increase. As to feldspates (K-feldspate and plagioclase) they show dispersion. Quartz relation gets more evident when compared to sample sets with >20% and <20%. Sets with more than 20% quartz (sienogranites, monzogranites, granodiorites, etc.), exhibit to a great extent conductivity values which vary from 2,5 W/mK and the set with less than 20% (sienites, monzonites, gabbros, diorites, etc.) have an average thermal conductivity below 2,5 W/mK. As to textures it has been verified that rocks considered thick/porphyry demonstrated in general better correlations when compared to rocks considered thin/medium. In the case of quartz, thick rocks/porphyry showed greater correlation factors when compared to the thin/medium ones. As to feldspates (K-feldspate and plagioclase) again there was dispersion. As to mafics, both thick/porphyry and thin/medium showed negative correlations with correlation factor smaller than those obtained in relation to the quartz. As to rocks related to the Streckeisen s QAP diagram (1976), they tend to fall from alcali-feldspates granites to tonalites, and from sienites to gabbros, diorites, etc. Thermal conductivity data correlation with geochemistry confirmed to a great extent mineralogy results. It has been seen that correlation is linear if there is any. Such behavior could be seen especially with the SiO2. In this case similar correlation can be observed with the quartz, that is, thermal conductivity increases as SiO2 is incremented. Another aspect observed is that basic to intermediate rocks presented values always below 2,5 W/mK, a similar behavior to that observed in rocks with quartz <20%. Acid rocks presented values above 2,5 W/mK, a similar behavior to that observed in rocks with quartz >20% (granites). For all the other cases, correlation factors are always low and present opposite behavior to Fe2O3, CaO, MgO, and TiO2. As to Al2O3, K2O, and Na2O results are not conclusive and are statistically disperse. Thermal property knowledge especially thermal conductivity and its application in the building construction field appeared to be very satisfactory for it involves both technological and thermal comfort aspects, which favored in all cases fast, cheap, and precise results. The relation between thermal conductivity and linear thermal dilatation have also shown satisfactory results especially when it comes to the quartz role as a common, determining phase between the two variables. Thermal conductivity studies together with rocky material density can function as an additional tool for choosing materials when considering structural calculation aspects and thermal comfort, for in the dimension stone case there is a small density variation in relation to a thermal conductivity considerable variation

Geochemical and radioactivity characterization of rocks from the Rio Preto (Go) Project

The Rio Preto Project, developed by the extinct Brazilian nuclear state company, Nuclebrás, during the late 70s and early 80s, consisted of basic geological mapping and radiometric characterization by aerogeophysical gamma-ray spectrometry, without channel discrimination, of a surface area of 650 km2 located to the west of the Chapada dos Veadeiros National Park on the northeastern of Goiás State, Brazil, including the confluence area of Claro and Preto Rivers. Additionally, the natural radioelements U, Th and 40K were determined by gamma-ray spectrometry in 300 rock samples from cores of the Rio Preto Project area. The tests were conducted at LABIDRO-Isotopes and Hydrochemistry Laboratory of the Departament of Petrology and Metallogeny (DPM) of the Institute of Geosciences and Exact Sciences, UNESP, in Rio Claro, SP, Brazil. This paper reports the results of petrographic characterization and chemical analyses of major oxides (SiO2, TiO2, Al2O3, Fe2O3, MgO, MnO, K2O, Na2O, CaO and P2O5) for all samples used to determine the natural radioelements present in the region. The organic matter content results obtained by colorimetry are also reported for selected cores of different lithotypes in order to investigate the possible relationship between graphite and the radioelements uranium and thorium. Finally, uranium content and 234U/238U activity ratio data for selected samples of schists and gneisses of the Lower Member of the Ticunzal Formation suggest the influence of weathering processes in the area. © 2012 Sociedade Brasileira de Geofísica.

Radioelementos naturais na área do Projeto Rio Preto (GO)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Desenvolvimento de cerâmicas de mulita a partir de alumina, ácido silícico e aerosil

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A comparative evaluation of the CF:CS and CRS models in Pb-210 chronological studies applied to hydrographic basins in Brazil

The Constant Flux: Constant Sedimentation (CF:CS) and Constant Rate of Supply (CRS) of unsupported/excess Pb-210 models have been applied to a Pb-210 data set providing of eighteen sediments profiles sampled at four riverine systems occurring in Brazil, South America: Corumbatai River basin (S1=Site 1, Sao Paulo State), Atibaia River basin (S2=Site 2, Sao Paulo State), Ribeirao dos Bagres basin (S3=Site 3, Sao Paulo State) and Amazon River mouth. (S4=Site 4, Amapa State). These sites were chosen for a comparative evaluation of the performance of the CF:CS and CRS models due to their pronounced differences on the geographical location, geological context, soil composition, biodiversity, climate, rainfall, and water flow regime, among other variable aspects. However, all sediments cores exhibited a common denominator consisting on a database built from the use of the same techniques for acquiring the sediments major chemical composition (SiO2, Al2O3, Na2O, K2O, CaO, MgO, Fe2O3, MnO, P2O5, TiO2 and LOI-Loss on Ignition) and unsupported/excess 210Pb activity data. In terms of sedimentation rates, the performance of the CRS model was better than that of the CF:CS model as it yielded values more compatible with those expected from field evidences. Under the chronological point of view, the CRS model always provided ages within the permitted range of the Pb-210-method in the studied sites, whereas the CF:CS model predicted some values above 150 years. The SiO2 content decreased in accordance with the LOI increase in all cores analyzed and such inverse relationship was also tracked in the SiO2-LOI curves of historical trends. The SiO2-LOI concentration fluctuations in sites S1 and S3 also coincided with some Cu and Cr inputs in the drainage systems. (C) 2014 Elsevier Ltd. All rights reserved.

Chemistry of gabbroic rocks of ODP Hole 118-735B

We present results of a microprobe investigation of fresh and least-deformed and metamorphosed gabbroic rocks from Leg 118, Hole 735B, drilled on the east side of the Atlantis II Fracture Zone, Southwest Indian Ridge. This rock collection comprises cumulates ranging from troctolites to olivine-gabbro and olivine-gabbronorite to ilmenite-rich ferrogabbros and ferrogabbronorites. As expected, the mineral chemistry is variable and considerably expands the usual oceanic reference spectrum. Olivine, plagioclase, and clinopyroxene are present in all the studied samples. Orthopyroxene and ilmenite, although not rare, are not ubiquitous. Olivine compositions range from Fo85 to Fo30, while plagioclase compositions vary from An70 to An27. Mg/(Mg + Fe2+) of clinopyroxene (mostly diopside to augite) varies from 0.88 to 0.54. Mg/(Mg + Fe2+) of orthopyroxene varies from 0.84 to 0.50. These minerals are not significantly zoned. All mineralogical data indicate that fractional crystallization is an important factor for the formation of cumulates. However, sharp contacts, interpreted as layering boundaries or intrusion margins, suggest polycyclic fractionation of several magma batches of limited volumes. Calculated compositions of magmas in equilibrium with the most magnesian mineral samples at the bottom of the hole represent fractionated liquids through separation of olivine, plagioclase, and clinopyroxene at moderate to low pressures (less than 9 kb). Crystallization of orthopyroxene and ilmenite occurs in the most differentiated liquids. Mixing of magmas having various compositions before entering the cumulate zone is another mechanism necessary to explain extremely differentiated iron-rich gabbros formed in this slow-spreading ridge environment.

Igneous geochemistry of OP Leg 126 samples

Major element, trace element, and radiogenic isotope compositions of samples collected from Ocean Drilling Program Leg 126 in the Izu-Bonin forearc basin are presented. Lavas from the center of the basin (Site 793) are high-MgO, low-Ti, two-pyroxene basaltic andesites, and represent the products of synrift volcanism in the forearc region. These synrift lavas share many of the geochemical and petrographic characteristics of boninites. In terms of their element abundances, ratios, and isotope systematics they are intermediate between low-Ti arc tholeiites from the active arc and boninites of the outer-arc high. These features suggest a systematic geochemical gradation between volcanics related to trench distance and a variably depleted source. A basement high drilled on the western flank of the basin (Site 792) comprises a series of plagioclase-rich two-pyroxene andesites with calc-alkaline affinities. These lavas are similar to calc-alkaline volcanics from Japan, but have lower contents of Ti, Zr, and low-field-strength elements (LFSE). Lavas from Site 793 show inter-element variations between Zr, Ti, Sr, Ni, and Cr that are consistent with those predicted during crystallization and melting processes. In comparison, concentrations of P, Y, LFSE, and the rare-earth elements (REE) are anomalous. These elements have been redistributed within the lava pile, concentrating particularly in sections of massive and pillowed flows. Relative movement of these two-element groupings can be related to the alteration of interstitial basaltic andesite glass to a clay mineral assemblage by a post-eruptive process. Fluid-rock interaction has produced similar effects in the basement lavas of Site 792. In this sequence, andesites and dacites have undergone a volume change related to silica mobility. As a result of this process, some lithologies have the major element characteristics of basaltic andesite and rhyolite, but can be related to andesitic or dacitic precursors by silica removal or addition.

Geochemistry at DSDP Hole 57-439

Acidic to intermediate volcanic rocks were obtained as boulders, pebbles, and clasts with intercalated matrix sediments near the Japan Trench. A 47.5-meter conglomerate bed unconformably overlies acoustic basement consisting of Upper Cretaceous siltstone and is overlain in turn by massive coarse-sandstone and siltstone beds with many fossil mollusks. The volcanic cobbles and boulders in the conglomerate show pronounced porphyritic texture. Their phenocrysts are plagioclase, hornblende, and biotite; the groundmass consists of plagioclase, K-feldspar, quartz, iron oxide, and altered interstitial glass. The Plagioclase content of these volcanic rocks is very high, whereas iron oxide minerals are rare. The chemical composition of these volcanic rocks was analyzed to determine the rock series. Matrix sediments were also analyzed chemically, and their chemical composition was found to be similar to that of volcanic rocks, except for a lower CaO content. SiO2 content of the volcanic rocks ranges from 60.23 to 73.90, corresponding to that of andesite to rhyolite. All the samples show extremely high Al2O3 content, which reflects the high amounts of modal plagioclase. These volcanic rocks belong to both the calc-alkalic and tholeiitic rock series, and the differentiation trend is controlled by fractional crystallization, mainly of plagioclase, K-feldspar, and hornblende. The assemblage of calc-alkalic and tholeiitic rock series is frequently observed in island arcs and active continental margins. These volcanic rocks are derived from the Oyashio ancient landmass, which is a slightly matured island arc.