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排序方式: 共有543条查询结果,搜索用时 13 毫秒
161.
<正>The technology of applying the scale-space theory for processing digital elevation models(DEMs)is developed to single out and analyse relief structures and to solve geologic problems.Analysis of families of signals often involves the task 相似文献
162.
CHENG Yuqi LIU Dunyi I.S. WILLIAMS JIAN Ping ZHUANG Yuxun GAO Tianshan Institute of Geology Chinese Academy of Geological Sciences Barwanzhuang Rd. Beijing China Research School of Earth Sciences Australian National University G.P.O Box Canberr A.C.T. Australia Anhui Geological Survey Changjiangdong Rd. Hefei Anhui China 《《地质学报》英文版》2000,74(4):748-765
The paper reports SHRIMP U-Pb zircon data of a dark eclogite and a post-eclogite garnet-bearing gneissic granitic rock from the Bixiling area, Yuexi County, Anhui Province, in the eastern Dabie Mountains. The eclogite, which is metamorphosed basic tuff, contains very scarce zircons in omphacite or garnet, but more zircons in quartz. They usually exhibit a double-layered texture, as shown clearly in cathodoluminescence images. Their inner main parts give a 206Pb/238U age of 757±7 Ma, representing the approximate age of the high-pressure (HP)- ultrahigh-pressure (UHP) metamorphic event during which the eclogite was formed. The outer peripheral parts of the zircons, which have been modified by late-stage fluids, give an age of 223±3 Ma. The granitic rock contains more zircons of anatectic origin found mostly in feldspar and quartz and usually also showing a similar composite texture. The inner main parts of the anatectic zircons with oscillatory zoning give a 206Pb/238U age of 727±15 Ma for the approxim 相似文献
163.
Luis F.O.Silva Ismael L.Schneider Paulo Artaxo Yuleisy Núñez-Blanco Diana Pinto Érico M.M.Flores Leandro Gómez-Plata Omar Ramírez Guilherme L.Dotto 《地学前缘(英文版)》2022,(1):376-387
Air pollution has become an important issue,especially in Caribbean urban areas,and,particulate matter(PM)emitted by different natural and anthropogenic sources causes environmental and health issues.In this work,we studied the concentrations of PM10 and PM2.5 sources in an industrial and port urban area in the Caribbean region of Colombia.PM samples were collected within 48-h periods between April and October 2018 by using a Partisol 2000 i-D sampler.Elemental geochemical characterization was performed by X-ray fluorescence(XRF)analysis.Further,ionic species and black carbon(BC)were quantified by ion chromatography and reflectance spectroscopy,respectively.Using the Positive Matrix Factorization(PMF)receptor model,the contributions of PM sources were quantified.The average concentration of PM10 was 46.6±16.2μg/m3,with high concentrations of Cl and Ca.For PM2.5,the average concentration was 12.0±3.2μg/m3,and the most abundant components were BC,S,and Cl.The receptor model identified five sources for PM10 and PM2.5.For both fractions,the contributions of marine sea spray,re-suspended soil,and vehicular traffic were observed.In addition,PM2.5 included two mixed sources were found to be fuel oil combustion with fertilizer industry emissions,and secondary aerosol sources with building construction emissions.Further,PM10 was found to also include building construction emissions with re-suspended soil,and metallurgical industry emissions.These obtained geochemical atmospheric results are important for the implementation of strategies for the continuous improvement of the air quality of the Caribbean region. 相似文献
164.
CHEN Junren WAN Ling Guangzhou Marine Geological Survey MGMR P. O. Box Guangzhou 《《地质学报》英文版》1999,73(2):216-224
Experimental examinations and analyses have been made of the sediments from drill holes in the Zhuhai area, Guangdong Province. The studies show that there occurred four transgressions in this area over the historical times. The first transgression occurred at 7500 a B.P., with the maxium sea level up to about 1 m above the present level. The second transgression occurred at 5750 a B.P., with the sea level possibly 4 m higher than the present. The third and fourth transgressions took place at 4650 a B.P. and 2600 a B.P. respectively, which lasted for a long time with multiple fluctuations. The fifth transgression is in process. It could be predicted that the sea level at Zhuhai would rise by 15-20 cm in the coming 50 years. 相似文献
165.
1.IntroductionTheShan--Thai-MalayBlock(STMB)isadonorcontinentalfragmentintheSWborderregionofChinaandSoutheastAsia.IthaslongbeenrecognizedasablockdisplacedfromGondwanaintheLatePaleozoic(Mitchell,1981;Cao,1986).ThePaleozoicmarinesequenceandfossilassemblagesaremarkedlydifferentfromthoseofotherChineseblockssuchasYangtze,NorthChinaandTarim,aswellaseasternChineseblocks.Instead,specificsedimentaryfactessuchasEarlyPenmanglaciomarinedeposits,Carboniferouscool-coldwaterfaunaandPenmanGlossopt… 相似文献
166.
Karlo L. QUEA?O Carla B. DIMALANTA Graciano P. YUMUL JR. Decibel V. FAUSTINO-ESLAVA Edanjarlo J. MARQUEZ Noelynna T. RAMOS Keisuke ISHIDA Shigeyuki SUZUKI Ricky C. SALAPARE Michael Peter M. SANCHEZ Juan Miguel R. GUOTANA Rose Ann B. CONCEPCION 《地球学报》2012,33(S1):58-58
A number of geological studies have already been conducted on the Zambales Ophiolite Complex (ZOC), a north-south trending complete ophiolite sequence exposed in the western portion of Central Luzon, Philippines. Previous works recognized the ZOC as being made up of two blocks, the Acoje and the Coto, acting as an arc-back arc pair sometime during the Eocene. 相似文献
167.
雷州英峰岭玄武岩中单斜辉石巨晶的地球化学和地幔交代作用 总被引:5,自引:1,他引:5
雷州半岛英峰岭火山岩中单斜辉石巨晶以低Mg^#值(0.62—0.47)、贫重稀土(HREE)和富Al2O3、TiO2、Na2O和中稀土(MREE)为特征,并具有明显的成分变化。随着Mg^#降低,单斜辉石的Al:O,(11.58~6.97%,)、TiO,(2.28~1.06%)和HREE逐渐降低。这种变化特征不同于世界上大多数辉石巨晶的变化规律。随着演化辉石巨晶的大多数不相容元素,如Nb、Sr、Zr、Hf和LREE—MREE逐渐增加。低的Mg^#值和Ni、Co、Cr含量指示巨晶母岩浆是一种强烈演化的残余岩浆(Mg^#=0.27~0.35)。分离结晶模拟表明本研究最富镁的巨晶(Lz-54)的母岩浆很可能是由拉斑玄武质岩浆经70~80%,以单斜辉石为主的结晶分异后形成。而本研究的其它辉石巨晶是该母岩浆在不同演化阶段(25~80%)分离结晶的产物。分离矿物中除了单斜辉石还包含了大量的石榴子石、斜长石和钛铁矿。温压计算表明英峰岭巨晶是高温岩浆在56~60km深的上地幔的结晶产物(r=1290℃~1130℃,P=1.73~1.83GPa),这一深度有利于石榴子石结晶。对比不同地区辉石巨晶的成分特征和形成条件,作者指出不同地区单斜辉石巨晶各种元素的不同变化规律主要受母岩浆成分和结晶条件控制。巨晶母岩浆在地幔结晶时对围岩橄榄岩进行了不同程度的交代作用。早期贫流体的岩浆对橄榄岩的交代作用较弱,只有Sr,La等强活动性元素被明显改变;晚期富流体(F,P,H2O)岩浆对橄榄岩的交代作用强烈,大多数元素被明显改变。因此,可以推断交代熔体中流体的含量是影响地幔橄榄岩交代作用的关键。 相似文献
168.
Baruch Spiro Dominik J. Weiss Valery Udachin Ben J. Williamson O. William Purvis Richard M Herrington Svetlana Tessalina 《中国地球化学学报》2006,25(B08):7-7
The isotopic composition of lead has proven a powerful tool for the characterization of the types of its sources, and with other information on their identity. Lead is dispersed in the environment through water courses or airborne particulates, and has serious impact on the natural and human environments. Lake sediments record deposition derived mainly from its catchment while lichen represents the fine-grained atmospheric deposition of the site. The records of deposition differ in the scales of grain size, time and space. This investigation aims at comparing and contrasting these two types of records in an area affected essentially by a single visible emission source, and to improve the understanding of the controls on the formation of these records. The visible source is a Cu smelter complex with mining installations within the town of Karabash, in the southern Ural Mountains of Russia and considered one of the most heavily polluted areas in the world. 相似文献
169.
170.
ZHANG Qiuying Bureau of Geology China National Nuclear Corporation P.O. Box Beijing 《《地质学报》英文版》2000,74(3):602-604
: Black shales are marine sediments with argillaceous, silty and siliceous compositions and high contents of organic materials, disseminated pyrite and uranium. Uraniferous black shale has uranium content of more than 20 ppm.Black shales are widely distributed in 17 provinces or autonomous regions in northwestern and southern-central China. Their sedimentary ages are from the Sinian to the Tertiary and uraniferous black shales are mainly exposed in Yunnan, Guizhou, Sichuan, Hunan, Hubei, Jiangxi, and Zhejiang provinces and Guangxi Zhuang Autonomous Region and the economically significant uranium deposits associated with black shale occur in Hunan and Jiangxi provinces and Guangxi Zhuang Autonomous Region.Uranium mineralization associated with black shale has the following main features: (1) forming stratabound deposits; (2) controlled by structures such as interlayer and intersected faults and fractures; (3) associated with different ore-forming processes such as leaching and hydrothermal reworking; (4) 相似文献