Mineral photoelectrons and their implications for the origin and early evolution of life on Earth

Energy is the key issue of all life activities.The energy source and energy yielding pathway are the key scientific issues of the origin and early evolution of life on Earth.Current researches indicate that the utilization of solar energy in large scale by life was an important breaking point of the early evolution of life on Earth and afterwards life gradually developed and flourished.However,in the widespread biochemical electron transfer of life activities,it is still not clear whether the electron source is sun or how electrons originated from sun.For billions of years,the ubiquitous semiconducting minerals in epigeosphere absorb solar energy,forming photoelectrons and photoholes.In reductive and weak acidic environment of early Earth,when photoholes were easily scavenged by reducing matters,photoelectrons were separated.Photoelectrons could effectively reduce carbon dioxide to organic matters,possibly providing organic matter foundation for the origin of life.Photoelectrons participated in photoelectron transfer chains driven by potential difference and transfer into primitive cells to maintain metabolisms.Semiconducting minerals,by absorbing ultraviolet,also protected primitive cells from being damaged by ultraviolet in the origin of life.Due to the continuous photoelectrons generation in semiconducting minerals and utilization by primitive cells,photoelectrons from semiconducting minerals’photocatalysis played multiple roles in the origin of life on early Earth,such as organic synthesis,cell protection,and energy supply.This mechanism still plays important roles in modern Earth surface systems.     

修武盆地下寒武统黑色岩系铀矿物赋存特征及富集机理

通过野外地质调查、岩相学、地球化学和电子探针等分析方法,初步查明了修武盆地下寒武统黑色岩系中的铀矿物主要为磷钙铀矿和含磷钙钛铀矿,且多数以独立矿物形式存在,矿物颗粒微小,约1~3μm,少量与钛矿物共生;黑色岩系沉积受海底热液影响,其物源来自陆地和海底热水沉积物,由两者混合组成,且以陆源为主;铀的富集与碳、磷等元素关系密切。     

潮白河顺义段再生水补给区包气带理化参数相关性分析

土壤阳离子交换容量(CEC)、总有机碳(TOC)、粘土矿物总量和粘粒含量是影响再生水入渗过程中污染物在包气带及地下水含水层介质中迁移转化的四项重要指标,是反映包气带对污染物吸附性及生物作用的主要参数。本文选取北京市潮白河顺义段再生水补给区包气带作为对象,对CEC、TOC、粘土矿物总量及粘粒含量4项指标进行了两两相关性分析及函数拟合。结果表明,上述四项指标的大小均与埋深无关,只与介质本身特性有关,且两两之间存在着显著的相关性,相关系数均大于0.8。     

广东省天堂铜铅锌多金属矿床矽卡岩矿物学特征及其地质意义

天堂矿床是粤西地区以泥盆系上统天子岭组灰岩为围岩的大型矽卡岩型铜铅锌多金属矿床,矿体呈似层状、层状、透镜状、不规则状等产出在矽卡岩和矽卡岩化大理岩中,矿区发育石榴子石、透辉石、绿帘石、硅灰石、绿泥石等蚀变矿物,金属矿物主要包括黄铜矿、黄铁矿、方铅矿和闪锌矿等。本文以主要矽卡岩矿物为研究对象,利用电子探针技术对其矿物学特征进行研究。电子探针分析结果表明:天堂铜铅锌多金属矿床矽卡岩属于交代矽卡岩中典型的钙矽卡岩。石榴子石以钙铝榴石-钙铁榴石系列为主,从早到晚具有从钙铝榴石为主到钙铁榴石为主的演化趋势,说明成矿流体由酸性向碱性演化。辉石以透辉石为主,石榴子石和辉石的矿物组分分别为Adr4.60~96.47Grs2.10~94.28(Prp+Sps)0.41~3.88和Di88.51~95.09Hd3.31~9.76Jo0.28~3.98,其较大的成分变化特征反映出矽卡岩不是在一个完全封闭的平衡条件下形成的。帘石主要为绿帘石,含有少量的黝帘石。矿物成分分析表明辉石的Mn/Fe比值和矿化金属元素存在一定的联系。通过矽卡岩矿物学特征分析,进一步证实天堂铜铅锌多金属矿床是花岗岩类岩浆交代灰岩而形成的典型矽卡岩型矿床。     

Clay‐coat diversity in marginal marine sediments

The specific mineralogy of clay grain coats controls the ability of the coat to inhibit quartz cementation in sandstones during prolonged burial and heating. How and why clay‐coat mineralogy varies across marginal marine systems is poorly understood, even though these eogenetic phenomena strongly influence subsequent mesodiagenesis and reservoir quality. The novel development of the ability to predict the distribution of clay‐coat mineralogy would represent an important development for sandstone reservoir quality prediction. In marginal marine sediments, clay minerals occur as grain‐coats, floccules, mud intraclasts, clay‐rich rock fragments or as dispersed material. However, the relationships between clay mineralogy, the amount of clay, and its distribution is poorly understood. This study focused on the Ravenglass Estuary, UK. The key aim was to develop and apply a novel methodology utilising scanning electron microscope – energy dispersive spectrometry, for the first time, on grain coats in modern sediments, to differentiate the clay‐coat mineral signature from that of the bulk sediment, and reveal the distribution of clay minerals across marginal marine sediments. The study showed that marginal marine sediments principally have their clay mineral assemblage present as clay‐coats on sand grains. These clay‐coats have a mixed clay mineralogy and are spatially heterogeneous across the range of marginal‐marine depositional environments. The study further showed that clay‐coat mineralogy is governed initially by the hydrologically‐controlled segregation of the clay minerals within inner estuarine depositional environments, and subsequently by the selective abrasive removal of specific clay mineral types during reworking and transport into the outer estuary and the marine environment. The highest relative abundance of grain‐coating chlorite was in sand‐flat and tidal‐bar depositional environments. The availability of an analogue data set, and an understanding of the controlling processes of clay‐coat mineralogy, offer crucial steps in building a predictive capability for clay‐coat derived elevated reservoir quality in deeply buried sandstones.     

中国含油气盆地粘土矿物的某些矿物学特征

本文总结归纳了２０多个含油气盆地粘土矿物的类型，讨论了８种较常见的、６种较少见的和３种极少见的粘土矿物的Ｘ射线衍射特征及其成分、形态和分布等方面的矿物学特征．     

镇旬铅锌矿田矿物包裹体研究

镇旬铅锌矿田矿物包裹体研究表明，本区铅锌矿床最初形成于中一体温、弱－中等还原环境，成矿介质属低盐度，酸性条件下的Cl^--SO4^2--F^-/K^ -Na^ -Ca^2 (Mg^2 )热卤水流体，成因以沉积为主；经多期改造后的矿床出现中偏高温的成矿，加之沉积围岩的盐类组分不断及时地加入到成矿热液中，致使原喷流热流体类型逐渐演变为CI^---F^-(SO4^2-)/Na^ (K^ )-Mg^2 (Ca^2 )型。     

核-幔物质晶体化学、矿物学及矿床学初探

大量的高温、高压实验表明随着温度和压力的增加 ,地幔氧化物及硅酸盐的晶体结构会发生与其温度和压力相适应的多型转变 ,并导致元素金属性的增加 ,即氧离子半径的缩小以及硅和其他阳离子半径的增大。来自地核部分物质的晶体化学及晶体物理目前还很少涉及 ,根据其物质组成 ,可能具有金属及金属互化物的性质 ,即原子呈等大球最紧密堆积 ,具有高熔点、难溶性等特征。在地球形成时作为地核物质是最先凝聚的 ,并由于重力分异沉入地核 ,上升至浅部时不与其他元素化合 ,保持了零价状态 ;等大球最紧密堆积使其在地球各层圈中晶体结构保持恒定。地幔热柱使核、幔物质上升至地球浅部成为可能 ,并形成矿物及矿床。以西藏罗布莎铬铁矿床为例 ,已经发现了多达 5 0种的铂族元素矿物、铁族元素矿物及其金属互化物 ,包括成分复杂多变的Os Ir ,Os Ir Ru ,Pt Fe ,Ir Fe Ni,Fe Ni Cr及Fe Co等矿物 ,它们还与来自核幔边界的Si,Fe ,FexSiy,FeO和SiO2 矿物共生 ,其中铂属矿物及其金属互化物矿物应视为来自E层的地核矿物 ;探讨了该区矿物与陨石矿物在共生组合方面的相似性 ,地核矿物的聚集可能会形成新型的金属元素矿床     

刚果（布）主要矿产及地质特征

在结合刚果（布）1／100万区域矿产地质调查资料的基础上,对该国的主要矿产及地质特征进行了分析．结合区域地质矿产概况将该国的金属矿产分为12个矿带,归为3大类：结晶基底和绿岩带中的铁矿、金矿、钨锡铌钽及稀土矿,碳酸盐岩地层中的低温热液铜铅锌矿,构造、岩体、地层共同控制的多金属矿。根据分析结果对成矿规律进行了初步总结：绿岩带和重熔花岗岩及其相互作用形成了铁矿、金矿及钨锡铌钽等相关矿产;中生代的构造活动形成了碳酸盐岩地层中的低温热液铜铅锌矿;中元古代岩浆活动及中生代的构造活动促使了南部构造、岩体、地层共同控制的多金属矿带的形成。在对成矿规律认识的基础上对找矿潜力作了分析,认为该国所有金属矿产绝大部分为风化矿产和冲积砂矿,矿点多,但原生矿少,寻找原生矿的空间大;勘探和开采程度极低,矿业开发前景巨大．总的说来,以该国作为长期的矿业开发基地,具有战略意义。     

塔里木南缘浅变质岩系变质矿物特征及变质条件

在塔里木盆地南缘和田地区的阿其克、皮牙曼、杜瓦、康开依、桑株水库一带断续出露一套浅变质岩地层,主要岩石类型有变质杂砂岩、变质钙质砂岩、细粒片岩及少量千枚岩、变质砾岩、大理岩等.岩石中主要变质矿物为绿泥石、白云母、石英、方解石和少量黑云母、钠长石.本文着重就岩石中片状变质矿物绿泥石、白云母、黑云母的发育特点、化学成分特征、变质矿物组合以及它们的晶体化学成分所反映的变质温、压条件进行了研究,并在此基础上推断出该套变质岩属于由区域低温动力变质作用引起的低绿片岩相变质产物.