A reappraisal of the high-Ti and low-Ti classification of basalts and petrogenetic linkage between basalts and mafic–ultramafic intrusions in the Emeishan Large Igneous Province, SW China     

Tong Hou  Zhaochong Zhang  Timothy Kusky  Yangsong Du  Junlai Liu  Zhidan Zhao 《Ore Geology Reviews》2011,41(1):133-143

Based on published data, we reappraise the classification of high-Ti and low-Ti basalt from the Emeishan large igneous province (ELIP) and the correlations between basalts and mafic–ultramafic intrusions. Because of the lack of clear spatial and temporal variations of different types of basalts, we suggest that the basalts in the ELIP cannot be classified into high-Ti and low-Ti groups, by TiO₂ contents and/or Ti/Y ratios. The distinctive characteristics of these high-Ti and low-Ti lavas probably result largely from the different fractionating assemblages. Whether or not fractional crystallization of the Fe–Ti oxides occurred probably is the key factor that controls the Ti abundances and Ti/Y ratios in the residual melts, e.g., lavas, although the nature of the mantle sources, variable degrees of partial melting of mantle and crustal contamination also influence the geochemical signatures of the lavas. Therefore, neither Ti abundance nor Ti/Y ratios in basalts can reflect the nature of their mantle source. Moreover, the different types of mafic–ultramafic intrusions in the ELIP cannot simply be attributed to be genetically related special types of basalts, either high-Ti or low-Ti basalts. It is likely that they are merely the cumulus phases, i.e. chamber or conduit of the basaltic lavas. Hence, caution should be exercised in the use of high-Ti or low-Ti basalts as prospecting vectors for ore deposits in the region. Potential implications are proposed that both the Fe–V–Ti oxide and Cu–Ni–(PGE) sulfide mineralization in the ELIP intrusions is largely due to the variable differentiation and crustal contamination during magmatic processes.  相似文献   

基于分形理论的1915—2000年渭河泾河口—潼关段河道演变研究     

潘威 《沉积学报》2011,29(5):946-952

渭河泾河口—潼关段是渭河平面形态中最活跃的部分。运用近百年来的多种地形资料,在调校民国地图测绘误差的基础上重建了1915—2000年本段渭河平面形态的空间矢量数据,使用盒维数法测算了其近百年来的分维D,发现D区间为[1.0432,1.0774]。1915—1958年是本段河型在相对天然环境下的发展过程,D呈现动态平衡态...  相似文献   

三塘湖油田低压低渗透砂岩油藏井网优化设计研究     

付宇  李凡华  于家义 《四川地质学报》2011,(3):306-308,311

三塘湖油田西山窑组为"低孔、低渗、低压、高粘"复合圈闭砂岩油藏,属于辫状河-三角洲前缘沉积,成南北向带状分布,储层非均质性强,开采难度较大。通过对该油田地质特征的分析,结合不同井网的实际生产情况、应用数值模拟技术合理优化井网类型,从而为新区开发提供了理论基础。  相似文献   

低固相泥浆在福建煤田钻探中的应用          下载免费PDF全文

李宏 《探矿工程》2011,38(9):18-20

通过对福建煤田地层特征及其对钻探影响的分析,阐述了在福建煤田钻探中所遇的主要问题,结合实践论述了低固相泥浆的主要性能和优点、以及低固相泥浆对预防处理水敏性地层的缩径和破碎、松散等不稳定地层的坍塌、掉块现象具有的效果,对保证施工的顺利进行、提高施工质量与效率的重要作用。  相似文献   

“黄石热点”对鄂东南地区金属矿床的制约          下载免费PDF全文

马光  宫丽  张桂平  杨学军 《地质找矿论丛》2011,26(1):8-11

鄂东南地区是我国铁、铜、金等多金属的重要成矿带。通过地球物理和地球化学等研究表明,多种类型矿床均与黄石地区存在的上达上地壳的地幔热柱密切相关,并以＂热点＂（＂黄石热点＂）的形式表现出来,这种新认识对指导鄂东南地区的地质和找矿工作具有重要意义。  相似文献   

GFAAS法测定地质样品中痕量银   总被引：2，自引：0，他引：2  

刘红毅  罗大芳  鲍爱华 《云南地质》2011,30(3):348-352

采用石墨炉原子吸收光谱法测定化探样品中痕量银。选择仪器最佳温度程序,采用四酸溶样,硝酸介质,硫脲、铱盐为基体改进剂,国家一级标准样品绘制工作曲线。在取样0．1000g,定容10mL情况下,方法检出限为0．01ug／g,经用国家标准物质验证,测定准确度和精密度比较满意。  相似文献   

川东南涪陵地区石炭系黄龙组地震异常特征及其意义     

施泽进  夏文谦  王长城  张良六 《物探化探计算技术》2011,33(3):231-236,225

涪陵地区位于川东南探区北部,通过该区石炭系黄龙组地震剖面测线逐条解释,识别出了四种典型异常反射结构：①地震同相轴波峰、波谷均表现为中振幅～弱振幅;②地震同相轴下拉波峰振幅有强有弱,上部波谷反射呈现强振幅～中振幅;③地震反射同相轴明显下拉,同时下拉同相轴上部反射呈现中振幅～弱振幅、下部反射振幅减弱;④地震同相轴反射为弱振幅,近空白反射或弱波谷反射。基于岩溶单元发育理论模型及该区沉积特征,对四种典型地震剖面反射异常地质成因解释进行了地球物理正演模拟,结果显示了与实际典型地震反射结构相吻合的地震剖面特征。其分别代表了岩溶高地峰丛与浅洼发育;被泥质充填或半充填的溶洞或孔隙性非常高的储层发育;高泥质含量充填物,或低速度、未被完全充填的缝洞体发育;7 m～9 m及以下的黄龙组地层。同时,基于特殊剖面结构研究成果,对该区可能发育的新型储层类型进行了预测,有效地指导了该区下部油气有利储层的寻找。  相似文献   

西藏扎西康铅锌锑多金属矿地质特征及矿床成因探讨   总被引：2，自引：0，他引：2  

王晓曼  李及秋  张学良  赵延朋 《矿产与地质》2011,25(4):273-279

扎西康铅锌锑多金属矿已发现规模较大的四个矿体,控制资源量达100万吨以上.矿体均分布在NNW或NNE张扭性断裂破碎带内,受断裂破碎带控制,矿体与围岩界线明显.铅同位素位组成显示成矿物质主要来源于上地壳,包裹体研究成矿流体为中低温-低盐度成矿,氢、氧、硅同位素组成显示成矿流体主要为大气降水下渗循环构成的地热水.硫同位素特...  相似文献   

低影响发展的雨洪资源调控措施研究现状与展望   总被引：8，自引：0，他引：8       下载免费PDF全文

孙艳伟  魏晓妹  POMEROY C A 《水科学进展》2011,22(2):287-293

低影响发展(Low Impact Development,LID)作为新兴的雨洪资源调控设计策略,对城市雨水资源化利用及生态环境保护具有重要的作用.系统论述了LID的定义、产生背景、设计目标及理念;分析了LID在主要技术措施、设计方法、效果监测、模型模拟等方面的研究进展,归纳总结了LID的优点及局限性;在此基础上,分析了LID的推广及应用前景,指出实地监测、介质试验、模型模拟及其与区域可持续发展的融合研究是目前LID研究的关键问题.国外LID的雨洪资源调控技术和方法对中国城市雨水资源化利用和生态环境保护具有借鉴意义.  相似文献   

Nutrients in an oligotrophic boundary current: Evidence of a new role for the Leeuwin Current   总被引：1，自引：0，他引：1  

P.A. Thompson  K. Wild-Allen  M. Lourey  C. Rousseaux  A.M. Waite  M. Feng  L.E. Beckley 《Progress in Oceanography》2011,91(4):345-359

New observations along the continental shelf of Western Australia provide a novel explanation for the established ∼60 years relationship between Leeuwin Current (LC) strength and greater winter nitrate concentrations at 32°S plus the inter-annual variation in the magnitude of the annual, shelf-scale, phytoplankton bloom. The potential source of dissolved nitrogen to support the annual shelf scale phytoplankton bloom was identified as thin layers of an unprecedented areal extent, nitrate concentration and shallow nature that were observed off the northwest of Australia. We propose that the dissolved inorganic nitrogen (DIN) in these layers enters the LC at depth and then enters the euphotic zone via by three mechanisms: instability that results in a warm core eddy, cooling that deepens the surface mixed layer and shallowing of the thin layer. During the onset of the annual phytoplankton bloom along the west coast of Australia from 22°S to 34°S the poleward flowing LC was clearly evident as a surface intensified ocean boundary current transporting warmer, lower-salinity, greater-silicate waters in a shallow mixed layer rapidly southward. Between 24 and 26°S the core of the LC was present as a 50–100 m deep layer over one or more thin layers, 15–50 m thick, with high nitrate and low dissolved oxygen (DO). These layers were of lower salinity, cooler water with markedly reduced DO, high nitrate concentrations and distinct nitrate:silicate (NO₃:Si(OH)₄) nutrient ratios. As the LC flowed south it cooled and deepened thereby entraining the thin layers of high nitrate water into the euphotic zone. The LC also formed large (greater than 100 km diameter) warm core eddies with a deep surface mixed layer that also entrained nitrate from these thin layers. In some locations as far south as 32°S the LC was still present with the thin layer of high nitrate intact but now within the euphotic zone. Thus, the available evidence suggests the LC arises under conditions that favour rapid and shallow nitrification. This nitrification fuels a shelf-scale bloom on a downwelling favourable coast. Depending upon the rate of nitrification the source of the particular organic matter may be local or delivered from the tropics via horizontal advection in a subsurface layer of the LC.  相似文献