粤北热水岩体SHRIMP锆石U-Pb年龄及地球化学特征研究     

邓平  凌洪飞  沈渭洲  孙立强  朱捌  黄国龙  谭正中 《地质学报》2011,85(8)

热水岩体位于贵东岩体中部南侧,SHRIMP锆石U-Pb定年结果为162.8±5.8 Ma(MSWD=4.2),属于燕山早期岩浆活动产物。该岩体具有富硅(SiO2平均为76.32%)、富铝(A/CNK值平均为1.14)、钾大于钠(K2O/Na2O值平均为1.32)和高的P2O5含量(平均为0.41%);大离子元素富集,Ba、Sr、Ti、Nb、Ta亏损,具有高的Rb/Sr(平均为28.5)和Rb/Nb值(平均为19.8);轻、重稀土之间分馏不明显,配分模式呈水平型,Eu亏损明显(δEu值平均为0.14);εNd(t)值低(平均为-10.2),Nd模式年龄古老(平均为1777 Ma);岩浆源区物质由泥质岩组成。这些特征表明,热水岩体属于典型的S型或壳源型花岗岩。热水岩体可能是在燕山早期太平洋板块俯冲导致先存的东西向大东山-贵东断裂带重新复活的构造背景下,由古—中元古代泥质变质岩低程度部分熔融的方式形成。  相似文献   

黔东留茶坡组硅质岩元素地球化学特征与形成环境   总被引：1，自引：0，他引：1  

杨恩林  陈恨水  陈焕  吴波  陈宇  杨友  罗建均 《矿物学报》2011,31(3):406-411

黔东晚震旦世一早寒武世留茶坡组硅质岩,具有展布广、层位稳、厚度大等特征,并具有热水沉积的岩石学证据。代表性剖面硅质岩主量元素分析结果显示,ｗ（SiO：）为93．41％一96．32％,均值95．23％,表示其为化学成分纯净的硅质岩;TFeO、MnO相对富集,A12O3、TiO2、MgO含量相对较低,与热水沉积物相似,表明具有热水沉积特征;研究区硅质岩的Ba／Sr和U／Th等比值均大于1,以及稀土总量偏低（∑REE为9．22×10^6～24．04X10^6）,Ce负异常（0．44～0．76）,重稀土富集等特征,表现出热水沉积岩的元素地球化学特征;而其At／（A1＋Fe＋Mn）、K2O／Na20、CaO／（CaO＋Fe）和MgO／A12O3等比值的均值分别为0．46,1．86,0．33和0．19,也暗示出研究区热水沉积硅质岩受到一定程度陆源物质的影响。综合研究表明,典型剖面硅质岩形成于大洋盆地向大陆边缘台地过渡环境。  相似文献   

吉林西部土壤有机碳含量与元素地球化学特征     

王冬艳  杨园园  李月芬  王孟  郭冬艳  靳克 《吉林大学学报(地球科学版)》2011,(Z1):333-338

针对土壤有机碳影响因素多且复杂而造成碳储量模拟模型中参数难以确定的问题,利用吉林西部167个典型土壤样点资料,通过统计分析对吉林西部表层土壤有机碳含量及元素地球化学进行了详细研究。结果表明:吉林西部土壤有机碳含量整体水平偏低,并存在着明显的区域分布特点,不同工作区的分异性不同;吉林西部土壤有机碳含量与Si含量、硅铝率、硅铝铁率和K含量之间存在着极显著的负相关,而与P、Al、Fe、Ca、Mg含量存在极显著的正相关;不同元素变异特征值可以解释土壤有机碳含量总变异的能力也不相同。通过研究土壤有机碳与元素含量的关系来定量研究土壤有机碳与土壤理化性质的关系是可行的,将二者量化关系与土壤有机碳储量模拟模型相结合,使得对土壤碳储量的认识更加科学。  相似文献   

星际尘埃研究现状与进展   总被引：3，自引：0，他引：3  

李墨萍  赵刚  李爱根 《天文学进展》2006,24(3):260-276

由于星际尘埃的广泛存在和其在恒星与行星系统的形成、星系以及整个宇宙演化中的重要作用,星际尘埃的研究成为当今天体物理领域的热点前沿课题。该文从尘埃与电磁场相互作用的观测证据出发,系统地介绍了星际消光(包括吸收和散射)、星际红外辐射、星际偏振等的研究现状,讨论了星际元素减损,以及行星际尘埃和陨石中的前太阳尘埃等问题。从相应的观测证据中,可以得到关于星际尘埃的丰度、化学组成、尺寸和形状的信息。该文还对当前比较流行的三种尘埃模型(硅酸盐-石墨-PAHs模型、硅酸盐核-碳有机耐熔质壳层模型和多孔尘埃模型)进行了讨论与比较,对该研究领域中待解决的问题也作了简要的概括。  相似文献   

沉积物中元素碳的提取、鉴定及其古气候环境意义   总被引：1，自引：0，他引：1  

周斌  沈承德  郑洪波  陈晋阳 《沉积学报》2007,25(5):745-752

通过化学氧化方法提取沉积物中元素碳物质,采用拉曼光谱对其进行分析鉴定,实验结果表明:元素碳是介于单晶石墨碳和无定形碳之间的一系列物质,是一种操作上的定义;化学氧化法提取沉积物中元素碳是可靠的,控制好氧化条件和时间,则能有效去除有机碳,保留元素碳成份。鉴于目前不同工作者由于不同的实验条件和方法下得到了不同结果,我们认为确定标准样及其浓度,统一实验方法是亟待解决的问题,进而统一这种碳微粒的名称,明确其定义,以利于相关研究的横向对比和深入。而在纵向研究方面,我们利用该实验流程提取灵台黄土剖面长时间序列黄土—古土壤样的元素碳,并进行元素碳含量的测定,结果表明元素碳记录能有效揭示古气候环境变化。在不同时间尺度上,元素碳记录有不同的气候指示意义,并且与其他气候环境指标能进行较好的对比,元素碳记录为古气候环境变化提供一新的指标。  相似文献   

综合物化探在河北某斑岩型铅锌矿床中的应用及找矿效果     

郑丽超  李玉堂  赵博  降雨薇  翟大兴 《物探与化探》2021,(2):281-291

河北某铅锌矿床作为燕山地区唯一具有中等规模的斑岩型铅锌矿床,被发现后多年的地质勘查工作无大的找矿突破。经综合整理研究历年物化探及地质资料,结合开展大功率的激电中梯扫面等系列工作,认为本区化探异常元素分带明显,激电异常发育,成矿系列完整,找矿潜力大。经钻探验证,于斑岩体外围及接触带发现了厚大的铅锌富矿体,于深部发现了铜钼矿体,形成了斑岩型矿床完整的成矿系列,实现了本区新的找矿突破,使其具有了成为大型铅锌矿床的潜力,进一步扩大了本区资源前景。  相似文献   

New constraints on elemental and Pb and Nd isotope compositions of South American and Southern African aerosol sources to the South Atlantic Ocean     

R. Khondoker  D. Weiss  T. van de Flierdt  M. Rehkämper  K. Kreissig  B.J. Coles  S. Strekopytov  E. Humphreys-Williams  S. Dong  A. Bory  V. Bout-Roumazeilles  P. Smichowski  P. Cid-Agüero  M. Babinski  R. Losno  F. Monna 《Chemie der Erde / Geochemistry》2018,78(3):372-384

Improving the geochemical database available for characterising potential natural and anthropogenic aerosol sources from South America and Southern Africa is a critical precondition for studies aimed at understanding trace metal controls on the marine biogeochemical cycles of the South Atlantic Ocean. We here present new elemental and isotopic data for a wide range of sample types from South America and Southern Africa that are potentially important aerosol sources. This includes road dust from Buenos Aires and lichen samples from Johannesburg, soil dust from Patagonia, volcanic ash from the Andean volcanic belt, and aerosol samples from São Paulo. All samples were investigated for major (Al, Ca, Fe, Mg, Na, K, Mn) and trace element (Cd, Co, Cr, Cu, Ni, Pb, REE, Sc, Th, Y, V, Zn) concentrations and Nd and Pb isotopic compositions. We show that diagrams of ²⁰⁸Pb/²⁰⁷Pb vs. ε_Nd, ²⁰⁸Pb/²⁰⁷Pb vs. Pb/Al, 1/[Pb], Zn/Al, Cd/Al, Cu/Al, and ε_Nd vs. Pb/Al, and 1/[Nd] are best suited to separate South American and South African source regions as well as natural and anthropogenic sources. A subset of samples from Patagonia and the Andes was additionally subjected to separation of a fine (<5?μm) fraction and compared to the composition of the bulk sample. We show that differences in the geochemical signature of bulk samples between individual regions and source types are significantly larger than between grain sizes. Jointly, these findings present an important step forward towards a quantitative assessment of aeolian trace metal inputs to the South Atlantic Ocean.  相似文献   

Geochemical tracers of northern Portuguese estuarine sediments on the shelf     

M. F. Araújo  J. -M. Jouanneau  P. Valrio  T. Barbosa  A. Gouveia  O. Weber  A. Oliveira  A. Rodrigues  J. M. A. Dias 《Progress in Oceanography》2002,52(2-4)

The northern Portuguese coastal zone is drained by large Iberian rivers, along which there is intensive industrial, agricultural and urban activity. Offshore of the two main river basins of the Douro and Minho, two fine-grained sedimentary formations can be characterised. A geochemical study of this sediment cover has been performed focussing in particular on the fine deposits and the adjacent estuaries. The chemical composition of superficial sediments collected from the northern Portuguese shelf and from the river basins of the Minho and Douro rivers was determined for major, minor and trace elements; the rare earth elements (REE) composition was also determined in selected samples. Statistical analyses of these data for the shelf sediments allow us to identify elements with similar behaviours and the different sediment types along the shelf, and to evaluate of their origins. Downcore profiles of the chemical composition of the fine sediments reveal no evidence for changes induced by recent human activities. To assess the influence of the rivers on the fine sedimentary formations, the elemental distribution patterns of selected sediments have been compared with the estuarine sediments. Lithogenic elements composition normalised to Al and the shale normalised REE distributions showed there are similarities between the Douro River sediments and the sediment composition of the Douro and Galicia mud patches. However, the Galicia mud field showed no relationship in its chemical composition to sediments derived from the Minho River. Nor was any evidence for heavy metal contamination originating from the Douro estuary detected in anthropogenic element/Al ratios in the shelf sediments. This may be because of processes associated with resuspension, complexation and bioturbation that occur during sediment transport and deposition. Nevertheless, the Douro River seems to be the main continental source of fine sediments being deposited on the northern Portuguese shelf.  相似文献   

Determination of Carbon,Hydrogen, Nitrogen and Sulfur in Geological Materials Using Elemental Analysers     

Maria F. Gazulla  Marta Rodrigo  Monica Orduña  Carmen M. Gómez 《Geostandards and Geoanalytical Research》2012,36(2):201-217

This article describes a series of methods developed for the determination of total carbon (C_Total), organic carbon (C_org), hydrogen, nitrogen and sulfur. The following elemental analysers were used: LECO model RC‐412 for the determination of organic carbon, total carbon and hydrogen; LECO model CS‐200 for the determination of total carbon and sulfur; LECO model TN‐400 for the determination of nitrogen; and LECO model TruSpec CHNS for the determination of organic carbon, total carbon, hydrogen, nitrogen and sulfur. Uncertainty and limits of detection and quantification were calculated for each method, as well as the running costs to define the most effective instrument for each material and each analyte. Accuracy was checked by the application of the Sutarno–Steger test. Finally, a compilation of the results obtained in the determination of C_Total, C_org, H, N and S in forty‐nine reference materials is presented.  相似文献   

2001-2010年生物地球化学研究进展与展望     

谢树成  罗根明  宋金明  李超  黄咸雨  杨欢  李一良  黄俊华  胡超涌 《矿物岩石地球化学通报》2012,(5):447-469

阐述了21世纪第一个十年生物地球化学领域的重要研究进展和未来可能的重点发展方向。在近代陆-海系统碳循环的库和通量上已经取得了重要进展,并发现了一些参与氮、硫循环新的微生物功能群。阐述了显生宙生物大灭绝期间碳循环异常的特点及其可能的原因,但对氮、硫循环的了解比较薄弱。地球早期的碳、硫循环与生命起源、大气和海洋水化学条件的关系已经取得重要认识。生物地球化学过程可以通过生态毒理,以及大气成分和海洋水化学条件的改变影响生命系统。微生物地球化学功能的微区、原位、痕量示踪等技术得到快速发展。未来将加强地质历史时期碳、氮、硫循环的定量分析以及空间变化的研究,各种元素循环之间的相互关系及其界面过程、极端环境的生物地球化学过程将进一步受到重视。生命科学领域重要技术的引入将提升生物地球化学过程的研究。  相似文献