塔里木盆地早、中志留世沉积序列及其对构造一海平面变化的响应:以柯坪露头区为例

志留纪是晚加里东运动对塔里木盆地古地理和古构造格局产生重要影响的构造变格阶段,以全盆地规模的不整合面为界,前志留纪以海相碳酸盐岩沉积为主的古环境转变为志留纪以海相碎屑岩沉积为主的古环境.开展志留纪沉积充填序列及岩矿特征研究,有助于进一步认识塔里木盆地该变格阶段构造运动特征及其沉积充填响应.为此,精选柯坪露头区志留系出露连续、完整的大湾沟及四石场剖面,进行了露头精细沉积学观察采样及室内分析测试工作,描述和重建了早、中志留世沉积环境、沉积序列及其所反映的海平面变化,在此基础上划分了层序地层单元.下、中志留统可识别出陆棚、三角洲和潮汐影响的海岸等沉积体系类型,大型三角洲的存在则是柯坪露头区的特色.通过砂岩碎屑组分构成研究,并与Dickinson的砂岩组构大地构造背景模式图解对比,揭示该区早、中志留世砂岩沉积物主要来自碰撞造山带和前陆隆起区以及大陆块的物源区,该结果反映了志留纪早期,受晚加里东运动影响,塔里木周缘发生汇聚碰撞,并由此造成塔里木地块南部和北部构造抬升并形成剥蚀区的背景.综合分析揭示早、中志留世沉积序列对构造和海平面变化响应特征.受晚加里东运动影响,早期(柯坪塔格组沉积期)构造活动较强,海平面波动明显,在陆棚基础上发育有大型三角洲沉积.其砂岩岩屑含量高、成分成熟度低,总体反映了构造活动期快速抬升导致大量物源注入的特点;后期(柯坪塔格组上部-依木干他乌组沉积期)构造活动逐渐减弱并趋于稳定,海平面低幅度波动,主要以潮坪、潮道、小型三角洲和泻湖沉积为主,砂岩成分成熟度高,细粒沉积物比例加大.总体上,早、中志留世沉积序列反映了构造活动由强逐渐减弱并对凹陷区逐渐填平补齐的演化特征.     

湘西北龙山地区中志留世沉积岩稀土元素地球化学特征及意义

湘西北龙山地区中志留世沉积岩的稀土元素地球化学特征显示,其轻、重稀土元素分异明显,轻稀土元素富集,重稀土元素呈平坦型,Eu具弱负异常,Ce基本正常。通过分析认为,研究区中志留世的古环境为缺氧的弱还原环境,其沉积速率整体较快,物源来自于沉积岩和大陆拉斑玄武岩的混合区。     

P-T事件后特提斯洋从停滞到动荡的岩石学证据

上扬子地区下三叠统飞仙关组下部薄层状、纹层状微晶灰岩、泥质灰岩之上普遍发育与风暴作用有关的角砾状灰岩、"错时相"扁平砾屑灰岩、丘状交错层理颗粒灰岩或粉砂岩,这一现象在南阿尔卑斯、伊朗、克什米尔等地的早三叠世早期地层中也广泛存在,其等时性有待深入研究.从薄层状、纹层状灰岩到砾屑灰岩的岩性转换表明,特提斯洋沿岸陆架地区的古海洋水动力条件在早三叠世早期经历了从停滞到动荡的显著变化.岩石学特征显示纹层状、薄层状灰岩泥质含量较高且普遍缺乏反映浅水暴露的沉积构造标志,表明其形成水体相对较深,为低能环境的产物,指示了当时静止、停滞的海洋环境;角砾状灰岩、扁平砾屑灰岩中丘状交错层理以及"菊花状"构造的大量出现则表明其形成是风暴引起的高度搅动的水体对弱固结的碳酸盐沉积物进行打碎、撕裂、搬运等再改造作用的结果,代表了动荡的海洋环境.薄层灰岩、纹层灰岩中生物扰动较弱,反映了P-T事件后萧条的海洋生态系统对底栖生物垂直钻孔作用的限制,生物扰动作用的缺乏有利于薄层、纹层灰岩的发育和保存;而触发大范围砾屑沉积的风暴活动则可能与当时全球CO2增多导致的全球交暖、海水温度升高,特提斯洋所处的古地理位置以及当时盛行的巨型季风气候等多种因素有关.     

鄂西晚泥盆世含磷鲕状铁矿石中磷的赋存状态与形成

广泛分布于我国南方泥盆纪地层的"宁乡式"铁矿储量巨大,然而含磷高严重制约了该类型铁矿的开发利用.铁矿石中磷的赋存状态是设计该类型铁矿"提铁降磷"方案的理论基础,是开发该铁矿首先要了解的问题.充分利用湿化学全岩分析、电感耦合等离子体质谱分析等全岩元素分析,扫描电子显微镜、X射线衍射等物相分析,电子探针微分析、激光剥蚀电感耦合等离子体质谱分析等微区分析技术,对鄂西晚泥盆世含磷鲕状铁矿石中磷的赋存状态、物质来源与磷矿物形成过程进行了初步探讨.铁矿石中的含磷矿物主要为碳氟磷灰石,分别以短柱状磷灰石晶体颗粒(65%以上粒径小于20 μm)、磷灰石内碎屑(粗砂至极粗砂级,集中形成透镜状或带状层理)以及鲕粒中与赤铁矿相互包裹的凝胶状磷灰石(层厚度10～50μm)3种形式存在.磷灰石晶体是在孔隙水中重结晶而生成,磷质可能来源于晚震旦世地层的磷块岩;磷灰石内碎屑是古海水体中原位化学沉积的产物,磷质可能来源于古海周边的大陆;鲕粒中凝胶状磷灰石也是原位化学沉积的产物,但与铁质沉积位置相同,并与富铁的鲕绿泥石混合或相互包裹形成鲕粒.     

内蒙古自治区额济纳旗梧桐井西磁铁矿点成因类型分析

内蒙古额济纳旗梧桐井西磁铁矿点产于早志留世中细粒黑云石英闪长岩、中细粒含黑云二长花岗岩和古元古代北山岩群第二岩组的接触带内。笔者通过内蒙古自治区额济纳旗梧桐井等六幅1∶5万区域矿产地质调查,对该磁铁矿点地质特征、磁异常特征、矿化特征、矿体特征进行了调查研究,对该矿点的控矿因素、成因类型等进行了分析和总结,认为古元古界北山群第二岩组角闪岩、蛇纹石化大理岩、透辉橄榄岩、透辉阳起岩是形成该磁铁矿点的赋矿层,而早志留世侵入岩的侵入活动为成矿元素的活化、萃取、运移提供了热源和载体,最终形成了矽卡岩型磁铁矿。     

银根-额济纳旗及邻区石炭-二叠纪碳酸盐岩的沉积特征及其地质意义

从碳酸盐岩的岩石学、建造特征的分析入手,研究了区内石炭-二叠纪碳酸盐岩的沉积特征及其地质意义.野外凋查表明,本区域石炭-二叠纪碳酸盐岩以砾屑灰岩、海百合灰岩和微晶灰岩为主,块状构造和粒序层理常见,作为碳酸盐岩建造底座及夹层的火山岩或火山碎屑岩发育,显示了本区域石炭-二叠纪期间张裂频繁、火山作用强烈、地形较陡和覆水较深的浅海古地理背景.本区域石炭一二叠纪碳酸盐岩建造发育于火山岩或火山碎屑岩、辫状三角洲或扇三角洲砂砾岩、海岸泥岩和陆架泥岩等底座之上,分别形成了火山抬高型(VEF)、二角洲垫高型(DEF)、海岸/降起沉没型(CSF/USF)和陆架变浅型(SSF)4种碳酸盐岩建造.不同类型的碳酸盐岩建造,是区域构造和海平面升降联合作用的产物,但其形成机制有别,其中,火山垫高型建造最普遍,含火山岩或火山碎屑岩夹层,系区域海平面长期上升的背景下,构造张裂引发的火山喷发引起相对海平面下降的产物;三角洲垫高型建造分布也较广,含砂砾岩夹层,为区域海平面长期上升的背景下,构造抬升造成辫状三角洲或扇三角洲进积导致相对海平面下降形成;海岸/隆起淹没型和陆架变浅型建造为纯灰岩建造,相对较少,则是在区域构造稳定的构造背景下,短期相对海平面变化驱动的结果.然而,不同类型碳酸盐岩建造的沉积特征,则受沉积环境制约.同时,针对这4种不同的碳酸盐岩建造,分别建立了火山垫高型碳酸盐台地(VEP)、三角洲垫高型碳酸盐台地(DEP)、海岸/隆起淹没型碳酸盐缓坡(CSR,USR)和陆架变浅碳酸盐缓坡(SSR)4种沉积模式,不同的沉积模式形成了沉积特征有别的碳酸盐岩建造.该时期浅海陆棚的古地理背景,不仅为区内海相烃源岩的发育创造了良好的古地理条件,也使得这一时期的碳酸盐岩、底座火山岩或火山碎屑岩、辫状三角洲或扇三角洲砂砾岩,以及碳酸盐岩建造中的火山岩、火山碎屑岩和砂砾岩夹层,成为本区域石炭一二叠纪的潜在油气储层.     

国外鲕状铁矿石选矿研究现状

前言在铁矿选矿领域中,鲕状铁矿石的研究一直是引人关注的。近六十年来世界各国的试验和生产实践表明,鲕状铁矿石难选的主要原因在于:①有价铁矿物嵌布粒度极细,如要使其环带解离或鲕核单体解离,则必须磨至30微米以下或者几个微米;②此类矿石绝大部分属于沉积型铁矿床,一般伴生有大量的粘土,硬度低,在碎矿过程中易形成含铁较高的矿泥,严重影响随后之选别作业;③矿物本身构造复杂,有以赤铁矿或褐铁矿,也有以石英或绿泥石为鲕核的多种类型;④一般伴生有较高的有害杂质磷矿物,而且有些以胶状物与鲕铁粒致密连生;⑤原铁矿品位低,大多在30％左右。     

广西那坡县中里沉积型铝土矿成矿机理及找矿标志

中里铝土矿区紧挨孟麻街大型堆积铝土矿区西侧,同属于南华活动带右江成矿带南坡-靖西弧形褶皱带。该带具有利的沉积型铝土矿成矿条件及堆积铝土矿次生富集条件,已发现多个大型堆积型铝土矿矿床。本文通过对矿区地质特征及矿体特征进行综合研究,浅析矿区沉积型铝土矿成矿机理:本区在晚二叠世吴家坪期古陆抬升遭受风化剥蚀,造成沉积间断,形成碳酸盐岩古风化壳,丰富铝土矿物质来源;然后在长兴期海侵接受沉积,在温暖潮湿气候条件下,海水加速基岩中Al2O3的析出并形成悬浮物和胶体,后被搬运至低流速的古岩溶盆地;最后在较稳定的弱还原沉积环境,沉积Al2O3悬浮物和胶体并形成沉积型铝土矿矿床。     

江西省萍乡桐子坪及铅山双门早二叠世地层中火山碎屑岩的发现

以往对江西省早二叠世的火山碎屑岩了解不够,资料甚少。通过研究宜春幅及上饶幅区测资料,在萍乡市桐子坪、铅山县双门石一带发现火山碎屑岩,从剖面的古生物群面貌及地层层序,将此套地层归属于晚二叠世晚期火山活动的产物,在浅海环境中沉积而成。本次发现对解释江西省内早二叠世的古地理及火山活动提供可靠地佐证。     

库牙克北部四连岩体锆石U-Pb定年及地球化学特征

沿库牙克断裂侵入的四连岩体,通过锆石LA-MC-ICP-MS U-Pb测年对其年龄进行测定,共获得5组处于晚奥陶世-早志留世之间。岩石类型主要为花岗闪长岩及黑云母花岗岩,岩石为钙碱性岩石,通过构造图解显示岩石类型为碰撞造山型中酸性岩浆岩。     

Heeding warnings ... from the canary, the whale, and the Jnuit, Part Two

There is a tension between traditional and modern definitions of reproductive risk and normalcy. These experts describe that tension as it plays out among the Inuit of Northern Canada from the perspective of a community midwife who has worked with the Inuit. She presents an analytical framework which classifies and illuminates the types of logic that compete in most birth settings around the world--a framework useful for showing how some types of logic can be supervalued while others, such as cultural or intuitive logic, are devalued or simply ignored, often at great cost. Part One presented political, scientific, clinical and cultural logic, and the influence of time. We now go on to look at professionalization and training and describe legal, personal, intuitive and economic logic. The author describes how the Inuit settlement of Povungnituk (POV) attempts to re-integrate the authoritative knowledge of the community by allowing Inuit midwives at The Maternity to choose their own criteria for balancing the imperatives of each kind of logic in decision-making for birth.     

ICP—AES法测定金属铬中铁、铝、硅、磷、铜的含量

提出采用ICP—AES法直接测定金属铬中的Fe、Al、Si、P、Cu的含量,测定结果的精密度、准确度满足分析要求,该测试方法满足该产品的检测要求。     

Proceedings of the American Psychological Association for the Legislative Year 2004: Minutes of the Annual Meeting of the Council of Representatives, February 20-22, 2004, Washington, DC, and July 28 and 30, 2004, Honolulu, Hawaii, and Minutes of the February, April, June, August, October, and December 2004 Meetings of the Board of Directors.

The minutes presented in this article are the official record of the actions of the Association taken during the year by both the Board of Directors (Board) and the Council of Representatives (Council). The minutes consist of: Elections, Awards, Membership, and Human Resources; Ethics; Board of Directors; Divisions and State, Provincial, and Territorial Associations; Organization of the APA; Publications and Communications; Convention Affairs; Educational, Professional, Ethnic Minority, International, Financial, and Scientific Affairs; Public Interest; and Central Office. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychology, ideology, utopia, and the commons.

Argues that the failure of social scientists to seriously question their own ideological and methodological assumptions contributes to the complex interrelationship between global ecological and individual psychological problems. Much of the literature (e.g., G. Hardin, 1968) on the tragedy of the commons focuses on saving the global commons through increased centralization and regulation, at the expense of the individual's autonomy and psychological sense of community. It is suggested that utopian speculation in general and anarchist political analysis in particular are necessary correctives to misplaced attempts to rearrange the elements of the status quo rather than to alter it in a direction more in keeping with both survival and human dignity. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attribution, the attractiveness stereotype, and the elderly.

The applicability of the physical attractiveness stereotype to perceptions of the elderly was tested in two studies. In the first study, college age and old observers rated the physical attractiveness of faces of elderly people (age 60–93). On the basis of these ratings, faces at three distinct levels of attractiveness were selected for use in the second study. In the second study, 72 young adult and 72 old volunteers viewed the selected faces and rated them in three areas of perceived social characteristics: personality factors, success in life experiences, and occupational achievements. The typical physical attractiveness stereotype was found for both groups of observers and in each of three areas of judgment. Multivariate analyses of variance for linear trends showed higher favorability of perceived social characteristics for faces with high perceived physical attractiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)