广西大厂超大型锡矿的形成条件与成矿模式   总被引：3，自引：0，他引：3       下载免费PDF全文

何海洲 《地质找矿论丛》2008,23(3):187-190

超大型矿床的形成条件有其特殊性.大厂超大型锡矿产出于南丹-昆仑关基底性深大断裂带上,经过多旋回构造-岩浆活动使矿质继承叠加,最后聚积于燕山晚期的岩浆热液中.大厂超大型锡矿床是各种成矿因素良好匹配,并经长时期的多重富集综合作用的结果.  相似文献   

Benthic nutrient fluxes in the intertidal flat within the Changjiang （Yangtze River） Estuary   总被引：1，自引：0，他引：1  

GAO Lei    LI Daoji  WANG Yanming  YU Lihua  KONG Dingjiang  LI Mei  LI Yun  and FANG Tao State Key Laboratory of Marine Geology  Tongji University  Shanghai  China State Key Laboratory of Estuarine  Coastal Research  East China Normal University  Shanghai  China 《中国地球化学学报》2008,27(1):58-71

In an annual cycle from March 2005 to February 2006, benthic nutrient fluxes were measured monthly in the Dongtan intertidal flat within the Changjiang （Yangtze River） Estuary. Except for NH4^＋, there always showed high fluxes from overlying water into sediment for other four nutrients. Sediments in the high and middle marshes, covered with halophyte and consisting of macrofauna, demonstrated more capabilities of assimilating nutrients from overlying water than the low marsh. Sampling seasons and nutrient concentrations in the overlying water could both exert significant effects on these fluxes. Additionally, according to the model provided by previous study, denitrification rates, that utilizing NO3- transported from overlying water （Dw） in Dongtan sediments, were estimated to be from -16 to 193 μmol·h^-1·m^-2 with an average value of 63 μmol·h^-1·m^-2 （n=18）. These estimated values are still underestimates of the in-situ rates owing to the lack of consideration of DN, i.e., denitrification supported by the local NO3^- production via nitrification.  相似文献   

Changes in nutrient uptake of phytoplankton under the interaction between sunlight and phosphate in the Changjiang （Yangtze） River Estuary     

FANG Tao LI Daoji YU Lihua LI Yun 《中国地球化学学报》2008,27(2):161-170

We conducted ship-board incubation experiments to investigate changes in nutrient uptake of phytoplankton under different phosphate concentrations and irradiances in the Changjiang River Estuary and its adjacent waters in China. Under 100% natural irradiance the uptake rates of phosphate, silicate, and nitrate were accelerated at high phosphate levels （1.84 μM）, while under low irradiance （about 50% natural irradiance） their uptake rates were restrained at the high but stimulated greatly at the intermediate phosphate concentrations （1.26 μM）, as the growth of phytoplankton, changes in nitrite and ammonium uptake didn＇t follow an obvious pattern. Our results also showed that there were linear relationships between nitrate, silicate and phosphate uptake at different phosphate concentrations under low and high irradiances, and the growth period of phytoplankton was prolonged both at the high phosphate concentrations under high irradiance and at the intermediate concentrations under low irradiance, suggesting that the limitation of phytoplankton growth mainly reflected changes in its growth period, and because no such environment （low irradiance and low phosphate concentrations） actually existed in a high turbidity zone, phytoplankton blooms hardly occurred there. In the absence of irradiance, denitrification occurred readily and phytoplankton was kept decreasing, which resulted in phosphate regeneration.  相似文献   

<Superscript>40</Superscript>Ar-<Superscript>39</Superscript>Ar dating of lamprophyre dykes in the Baimazhai nickel deposit,Yunnan Province,China, and its geological significance     

Bo Li  Zhilong Huang  Tao Guan  Wei Ding 《中国地球化学学报》2008,27(4):351-355

The Baimazhai nickel deposit, Yunnan Province, China, is located in the southern part of the Sanjiang （Tri-river） alkali-rich intrusive rock belt （Sanjiang ARIR）. In this paper was conducted ^40Ar-^39Ar dating of two phlogopites in lamprophyres which are, as dikes, widely distributed in the orefield, and two plateau ages were acquired, i.e., 32.46±0.62 Ma and 32.01±0.60 Ma, respectively （averaging 32.23±0.60 Ma）. The ages are obviously younger than those of the ore-hosted complex and mineralization of the Baimazhai nickel deposit. In combination with the characteristics, it is indicated that lamprophyres in the orefield and those in the Sanjiang ARIR are similar in tectonic setting, mineral assemblage and geochemistry. It is considered that lamprophyres in the orefield are the important component of the Sanjiang ARIR, and the lamprophyres and ore-hosted complex in the orefield represent the products of two times of different magmatic activity from different mantle sources. On the other hand, the age of lamprophyres in the orefield is older than that of the strike-slip shearing of the Ailaoshan-Honghe fault belt, suggesting that the strike-slip shearing of the Ailaoshan-Honghe fault belt is not the factor leading to magmatic activity of lamprophyres in the orefield, while it is more possible that magmatic activity of the Sanjiang ARIR promoted strike-slip shearing of the fault belt.  相似文献   

地震瞬时属性分析技术在岩溶勘查中的应用   总被引：3，自引：1，他引：2  

钟韬  肖宏跃  雷宛 《物探化探计算技术》2008,30(1):30-33

介绍地震瞬时属性分析技术的原理及处理方法,分别对岩溶在地震剖面、瞬时振幅剖面、瞬时频率剖面、瞬时相位剖面上的表现特征作了说明.并结合实际资料进行多参数解释,进而确定地下岩溶的发育情况、分布范围和规模,同时对异常进行钻井验证,结果表明,地震瞬时属性分析技术比常规地震处理方法能更好地排除干扰,确定岩溶异常.  相似文献   

天山公路地质灾害决策支持地理信息系统的设计研究   总被引：1，自引：0，他引：1  

尹江涛  何政伟  杨斌  张东辉  张俊峰  张峰  袁明 《物探化探计算技术》2008,30(6)

天山公路由于其特殊复杂地形、地质条件及受降雨、地下水等因素,严重影响其正常通行,同时天山公路还经常受到泥石流、滑坡、崩塌、溜砂坡等地质灾害的危害,这对该公路稳定性和沿线居民的安全性都具有一定的威胁。因此,运用先进的技术手段,建立一套适应于天山公路的地质灾害决策支持信息系统就显得尤其重要。该系统的建立,对天山公路的建设改造和管理提供了强有力的支持。天山公路地质灾害决策支持地理信息系统利用强大的ArcEngine开发组件,针对新疆天山公路实际,引入RS、GIS的相关理论、方法和技术分析手段,采用相应的数学分析评价模型,对提高天山公路地质灾害防治管理水平和地质灾害的有效防治,以及评价决策等方面,都具有重要的意义。  相似文献   

基于权重与混合模型的遥感图像分类方法研究     

何海清  李发斌  李何超  王勇 《国土资源遥感》2008,(2):18-21

提出了一种基于权重与混合像元模型的遥感图像分类方法。该方法在现有光谱混合模型的基础上,根据实际应用需要确定地类权重,通过地类丰度与权重因子加权平均确定像元的隶属类型,从而实现遥感图像分类。以SPOT-5土地覆盖遥感分类为例,对权重与混合像元模型结合的图像分类方法进行了验证,结果表明,该方法提高了遥感图像分类精度,在一定条件下更具实际意义。  相似文献   

Ore-forming geological anomalies and delimitation of favorable target areas for prospecting of Guangxi Mn deposits     

LEI Ying-ping  HE Hai-zhou 《矿产与地质》2008,22(5)

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Developing ecological mining and ensuring sustainable utilization of bauxite resources, Guizhou Province     

YANG Tao  WU Yin-qian 《矿产与地质》2008,22(6)

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以铜山测区为例谈大比例尺航测数字化成图质量控制          下载免费PDF全文

马忠卫  杨礼平  何朝津 《江苏地质》2008,32(4):305-307

为了适应城市发展的需要,全数字摄影测量系统获取城市基础地理信息是目前大比例尺城市测绘的主要手段,如何保证航测法获取基础测绘数字产品的质量尤为重要。结合生产实践,阐明了进行大比例尺航测数字化地形图生产的质量控制及质量检查中应注意的细节问题。  相似文献