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981.
新疆坡北镁铁-超镁铁质杂岩体由一个辉长岩体以及二十多个超镁铁质侵入体组成,其中坡一超镁铁质岩体稀有气体同位素组成揭示存在地幔柱的贡献。坡北杂岩体西端的坡一、坡四、坡十和坡十四等几个超镁铁质岩体的稀有气体同位素对比分析结果表明,岩浆矿物的3He/4He值（0.26~2.79Ra）分布于地壳与地幔值之间,较高的20Ne/22Ne和较低的21Ne/22Ne值分布于Ne质量分馏线（MFL）和L-K线之间,40Ar/36Ar=295~598。3He/4He与40Ar/36Ar比值揭示坡北杂岩体西端不同超镁铁质岩体形成过程中地幔（柱）、地壳和大气组分的贡献不同,岩体成因也可能不同。其中,坡一岩体具有地幔柱作用的贡献,其他三个岩体的岩石圈地幔及地壳流体组分的贡献较大。岩浆地幔源区由深部地幔柱物质叠加俯冲流体交代的岩石圈地幔物质所组成,大气与地壳物质组分可能由俯冲再循环洋壳带入到岩浆地幔源区以及围岩物质的混入。 相似文献
982.
环状杂岩体的岩相分带有多种成因模式。为了查明新疆阿拉塔格环状岩体的成因,本文特就其中暗色包体的成因及其岩浆演化进行探讨。包体分布极不均匀,在酸性岩单元的东南角集中发育,大部分呈浑圆状或次圆状,微细粒结构,部分包体中含有寄主岩石中的长石斑晶。通过对暗色包体主量、微量元素、Sr-Nd同位素及单颗粒锆石U-Pb年龄测试,认为该环状岩体中的暗色包体主要为闪长质-花岗闪长质岩浆包体,包体SiO_2(56.72%~61.80%)低,K_2O+Na_2O(8.12%~10.55%)高,具有高钾富碱的特征,属于高钾钙碱性岩石系列;里特曼指数(σ)为4.59~4.85,稀土元素富集。包体及寄主岩的主量和微量元素协变图呈不同程度的线性关系,而且两者稀土、微量元素曲线形态相近,显示出包体和寄主岩在地球化学特征上既有相似性,又有不同的特点。这种特征表明,环状花岗岩岩浆的形成至少与两种岩桨的混合有关。包体的(~(87)Sr/~(86)Sr)t较低(0.705204~0.705914)、ε_(Nd)(t)=1.65~2.57,全部为正值,揭示包体的原始岩浆为幔源玄武质岩浆。包体和寄主岩石的关系显示岩浆的混合方式为基性岩浆注入到已经开始结晶的酸性岩浆。本研究为环状杂岩体的多种成因过程提供了重要依据,认为其中的环状花岗岩单元为壳源酸性岩浆与幔源基性岩浆混合作用的产物。包体和寄主岩石的特征均反映在晚古生代中天山造山带发生过一定程度的后碰撞地壳垂向生长。 相似文献
983.
Shivesh Kishore Karan 《国际地球制图》2018,33(10):1084-1094
The main objective of this study was to improve the long-term land use change detection by improving classification accuracy of previous generation satellite image using a recent super-resolution technique. The study also analysed the change in land cover over a period of 41 years in a coal mining area. A dual-tree complex wavelet transform-based image super-resolution technique was used to enhance Landsat images of 1975 and 2016. Separating pixels with similar spectral response is an enigmatical task, especially when those pixel represent different ground features. Therefore, an advanced neural net supervised classifier was used to minimize classification errors. Accuracy of the classified images (both super-resolved and original) were measured using confusion matrices and kappa coefficients. A significant improvement of more than 10% was observed in the overall classification accuracy for the image of 1975, highlighting that the classification accuracy of earlier generation satellite data can be improved substantially. 相似文献
984.
Three stages of complex technological monitoring for the increase of high-temperature-permafrost soil bearing capacity are described. The feasibility of process monitoring to improve the targeted strength properties of subgrade bases on frozen soils is demonstrated. The rationale for the necessity of predictive modeling of freeze-thaw actions during the subgrade construction period is provided. 相似文献
985.
锡田印支-燕山期复式花岗质岩浆-热液活动时限和物质来源 总被引：2，自引：0，他引：2
锡田钨锡多金属矿田位于湘赣两省交界,南岭成矿带的北部。锡田花岗岩体是一个复式岩体。本文利用LA-MC-ICP MS技术对8个样品的锆石进行了原位微区U-Pb定年和Lu-Hf同位素测试,结果显示其中有4个为印支期(226~225Ma)、另外4个为燕山期(166~158Ma)。印支期花岗岩锆石的εHf(t)值为-4.6~-10.8,两阶段模式年龄TDM2值为2011~1534Ma,根据是否呈正态分布可分为7组;燕山期花岗岩锆石的εHf(t)值为-4.3~-10,TDM2值为1896~1429Ma,可分为5组。相似的Hf同位素组成表明两期花岗岩具有同源性,均源自古元古代晚期至中元古代早期地壳物质的部分熔融。而εHf(t)值变化范围较大且分成很多组可能更主要受控于源区Hf同位素的不均一性。此外,本文利用40 Ar-39 Ar定年方法测得花岗岩顶部石英脉和云英岩中4个白(金)云母的年龄为150~148Ma,这期与成矿有关的热液作用应该与最晚一期岩浆活动有关。通过本次获得的定年数据和对已有的成岩成矿定年数据的总结,本文认为锡田岩体可以分为三个期次,印支期(226~225Ma),燕山期第一阶段(166~158Ma)和燕山期第二阶段(151~141Ma)。 相似文献
986.
中国碱性杂岩的成因及其成矿作用 总被引：3，自引：0，他引：3
本文从碱性杂岩的产出和分布、地质特征、地球化学特征、成因、成矿作用几个方面综述了近年来对于我国碱性杂岩的研究成果与进展:(1)岩石学和同位素特征表明,硅不饱和的碱性杂岩类多属地幔低度部分熔融的原始岩浆为主侵位的产物;而硅饱和或过饱和碱性杂岩类多属深源岩浆与陆壳混染的产物。(2)地幔源区的低度部分熔融导致了稀土元素和大离子亲石元素等不相容元素的富集,同时富集的挥发份构成了矿化剂,对成矿具有重要控制作用。(3)深大断裂控制着碱性杂岩的产出,同时伴随着地质历史时期的重要地质事件,中国受深大断裂控制的碱性杂岩带主要有郯城-庐江碱性杂岩带、攀西碱性杂岩带和哀牢山-金沙江碱性杂岩带等9条。 相似文献
987.
AbstractThis paper presents a new integrated GIS modelling methodology for assessing groundwater contamination risk. Analytical and numerical tools within a GIS framework were used to define the raster maps of various factors interfering along the contaminant pathway from source to groundwater. In the proposed methodology, these factors were introduced into a unified GIS model for groundwater risk assessment that incorporates all the necessary information to improve the accuracy of the results. Fifteen factors were considered in order to estimate the spatial distribution of the groundwater contamination risk areas. Some of these factors, such as artificial drainage and seepage velocity, had not been used previously in GIS groundwater risk mapping. The study area, the island of Crete in Greece, was divided into five regions characterized by different degrees of groundwater risk ranging from very low to very high. A sensitivity analysis was performed and the developed methodology was validated for different contaminants that were detected in groundwater of the island of Crete.
Editor Z.W. Kundzewicz 相似文献
988.
The Yandong porphyry copper deposit, located in the Eastern Tianshan Mountains, Xinjiang, China, is part of the Central Asian Orogenic Belt. The Yandong deposit is hosted by a volcanic complex in the Early Carboniferous Qi’eshan Group and a felsic intrusion. The complex consists of andesite, basalt, diorite porphyry, and porphyritic quartz diorite. The felsic intrusion is a plagiogranite porphyry emplaced within the complex. The diorite porphyry and plagiogranite porphyry yield SIMS zircon U–Pb ages of 340.0 ± 3 and 332.2 ± 2.3 Ma, respectively. Element geochemistry shows that both the complex and plagiogranite porphyry formed in the Dananhu–Tousuquan island arc, a Carboniferous magmatic arc.The diorite porphyry and plagiogranite porphyry are host porphyries, but the plagiogranite porphyry is a productive porphyry. It caused the porphyry-style Cu mineralization and associated alteration. The alteration assemblages include early potassic and propylitic assemblages. These were overprinted by a chlorite–sericite assemblage, which in turn was overprinted by a late phyllic assemblage. The phyllic alteration is associated with the highest Cu grades. The mineralization is recognized to include three stages, from early to late: stage 1, a potassic alteration associated with a chalcopyrite + pyrite assemblage; stage 2, represented by chlorite–sericite alteration with a chalcopyrite + pyrite assemblage; and stage 3, the main-ore stage that is marked by phyllic alteration with chalcopyrite + pyrite ± molybdenite and producing more than 70% of the total copper production at Yandong. Yandong may represent a common scenario for Paleozoic porphyry Cu systems in the Central Asian Orogenic Belt. 相似文献
989.
The Katherina ring complex (KRC) in the central part of south Sinai, Egypt, is a typical ring complex of late Neoproterozoic age (605–580 Ma). It was developed during the final tectono-magmatic stage of the north Arabian–Nubian Shield (ANS) during evolution of the Pan-African crust. The KRC includes Katherina volcanics, subvolcanic bodies, ring dykes and Katherina granitic pluton. The Katherina volcanics represent the earliest stage of the KRC, which was subsequently followed by emplacement of the subvolcanic bodies and ring dykes. The Katherina granitic pluton depicts as the latest evolution stage of the KRC that intruded all the early formed rock units in the concerned area. The Katherina volcanics are essentially composed of rhyolites, ignimbrite, volcanic breccia and tuffs. Mineralogically, the peralkaline rhyolites contain sodic amphiboles and aegirine. The rhyolite whole rock chemistry has acmite-normative character. The subvolcanic bodies of the KRC are represented by peralkaline microgranite and porphyritic quartz syenite. The ring dykes are semicircular in shape and consist mainly of quartz syenite, quartz trachyte and trachybasalt rock types. The Katherina subvolcanic rocks, volcanic rocks as well as the ring dykes are alkaline or/and peralkaline in nature. The alkaline granitic pluton forms the inner core of the KRC, including the high mountainous areas of G. Abbas Pasha, G. Bab, G. Katherina and G. Musa. These mountains are made up of alkaline syenogranite and alkali feldspar granite. The mantle signature recorded in the KRC indicates a juvenile ANS crust partial melting process for the generation of this system. The evolution of the KRC rocks is mainly dominated by crystal fractionation and crustal contamination. Mineral geothermometry points to the high temperature character of the KRC, up to 700–1100 °C. 相似文献
990.