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1.
JianPing Yang 《寒旱区科学》2019,11(3)
The source regions of the Yangtze and Yellow Rivers are important in the field of eco-environmental change research in China because of its distinct alpine ecosystem and cryosphere environment. At present, there are three different concepts on the extent of source areas of the Yangtze and Yellow Rivers: hydrological, geographical, and eco-environmental. Over the past decades, annual average air temperature has warmed significantly; moreover, the temperature rise rate increases notably with increase of time of the data series. Annual precipitation has no obvious increase or decrease trend, and the climate has become warm and dry in the source regions. As a result, the cryosphere in the regions has shrunk significantly since 1960 s. A warm and dry climate and changing cryosphere together induced a substantial declination of alpine wetlands, marked decrease in river runoff, significant degradation of alpine grassland, and a reduction of engineering stability.The ecological environment, however, has a tendency for restoration in the regions because the climate has become gradually warm and wet since 2000. Thus, studies on eco-environmental change is transforming from a single element to multidisciplinary integration. Climate change-cryopshere change-physical and socioeconomic impacts/risk-adaptation constitute a chain of multidisciplinary integration research. 相似文献
2.
利用NASA行星数据系统提供Apollo计划登月点采样线路影像数据,通过与嫦娥二号CCD数据、印度M~3数据空间校正获得采样路线坐标。开展嫦娥二号CCD数据与印度M~3数据MAP(后验概率)融合并选择Apollo 15、Apollo 16-62231的LSCC测得的标准岩石双向反射率光谱与M~3、嫦娥二号进行交叉定标。本文采用月球岩石光谱谱型全特征分析方法,选取涵盖Apollo计划登月获取的36个基站主要岩性87种、285件岩石样品,利用校正后的M~3数据分析月球典型岩石各阶吸收反射特征,建立月球典型岩石标准遥感影像光谱库,此后应用Apollo 623个岩石样品进行对比得到很好结果,同时完成Apollo 16登月点周围领域岩性分布图,并讨论了研究区的岩石成因,Apollo 16区域形成于高地大撞击,在早期的研究中已经被用于划分月球年代,本文方法对于月球岩石类别研究与理解月球的岩浆演化具有重要的研究价值。 相似文献
3.
撞击坑是月球表面广泛分布的重要构造形态,占据了月球表面的大部分面积。撞击坑的直径差别很大,从几微米到数百千米,其退化程度与形成年代具有密切关系。为了研究不同地质年代形成的撞击坑直径大小及其演化规律,需采用量化分级方法对大小不同的撞击坑进行定量分级和统计分析。本文在月表撞击坑数据库LU60645GT和Lunar_Impact_Crater_Database(2011)的基础上,结合数据库中撞击坑的直径、深度和年代信息,利用最优分割分级法对撞击坑直径进行定量化分级,并根据分级结果,综合分析撞击坑几何形态特征及其演化规律。研究结果表明,撞击坑形态特征的演化与年代有密切的关系。在相同级别、相同地体下,撞击坑形成的年代越早,其形态特征的精细结构退化程度越明显,只保留了大体的几何形状;而在不同级别、相同地体、相同年代下的撞击坑形态特征则由简单逐渐变为复杂,坑物质也逐渐变得复杂。 相似文献
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巴西大坎波斯盆地下白垩统湖相碳酸盐岩油气资源丰富,但是硅化碳酸盐岩的出现不仅使原始碳酸盐岩沉积微相类型和沉积模式有待系统研究,还给深水油气勘探开发带来了挑战。基于古地貌、壁芯薄片、测井响应等数据,分析了坎波斯盆地东部下白垩统硅化碳酸盐岩原始沉积的古水介质、湖平面变化及沉积微相,厘清了湖相碳酸盐岩发育的主控因素,建立起相应的沉积模式。借助Fischer曲线可将硅化碳酸盐岩发育段划分为一个可容空间由大减小再增大的三级旋回,湖平面表现为先下降后上升;湖盆中央古隆起周缘类似远端变陡缓坡,发育了灰泥坪、藻礁、颗粒滩、滩前前积体和滑塌体等5种沉积微相;古地貌决定了藻礁和颗粒滩发育在构造高部位的相对深水区,同时受湖平面变化而发生垂向互层叠置;该段碳酸盐岩沉积时期,湖平面至少出现过两次下降、三次上升,可以划分为高位湖退、低位湖退、低位湖侵、高位湖侵四个演化阶段。研究成果为湖相碳酸盐岩硅化成因分析、硅化作用过程研究及硅化碳酸盐岩中有利储层的寻找奠定了基础。 相似文献
5.
苏北榴辉岩中金红石的微量元素地球化学特征 总被引：5，自引：7，他引：5
本文利用电子探针分析了苏北地区三类榴辉岩中金红石的Nb、Cr和Zr含量，在Zaek et al．（2002）的金红石Nb-Cr图解中，三类榴辉岩的原岩均为镁铁质岩，但它们具有不同的地球化学特征，即（1）小焦G类金红石榴辉岩中金红石的Nb含量最低，平均值为68ppm，而其它两类榴辉岩中金红石的Nb含量较高，平均值介于192～255ppm；（2）蓝晶石榴辉岩具有极高Cr含量，均值6106ppm，而许沟P类榴辉岩中金红石的Cr含量也较高，均值1233ppm，金红石榴辉岩中金红石Cr含量最低，均值为183ppm。利用Zaek et al．（2004）提出的金红石地质温度计，计算得出许沟P类榴辉岩的金红石形成温度介于600～751℃，平均温度689℃；演马厂M类榴辉岩的金红石温度介于507～641℃，平均温度557℃；小焦G类金红石榴辉岩金红石的形成温度介于541～673℃，平均温度613℃；新扬昌G类蓝晶石榴辉岩的金红石形成温度介于541～655℃，平均温度603℃。一种可能的解释是，榴辉岩在拆返过程中退变质作用明显，流体活动强烈，导致金红石中Zr扩散丢失，金红石中Zr含量不同程度地受到角闪岩相退变质过程中再平衡作用的影响，致使计算的温度偏低。 相似文献
6.
Helium and argon isotopes of the Tertiary basic igneous rocks from Shandong Peninsula and implications for the magma origin 总被引：2，自引：0，他引：2
TANG HuaYun ZHENG JianPing? CHEN HongHan & YE XianRen State Key Laboratory of Geological Processes Mineral Resources Faculty of Earth Sciences China University of Geosciences Wuhan China Faculty of Earth Resources China University of Geosciences Wuhan China State Key Laboratory of Gas Geochemistry Institute of Geology Geophysics Chinese Academy of Sciences Lanzhou China 《中国科学D辑(英文版)》2007,50(7):1021-1032
Helium (He) and Argon (Ar) isotopic compositions of the Tertiary basic igneous rocks were determined by the high temperature melting extraction method. The selected samples for the studies included al-kaline basalts and diabases from the Jiyang basin,and the surrounding Shanwang and Qixia outcrops in the Shandong Peninsula,eastern China. The results show that the Paleogene basalts and diabases from the Jiyang basin yielded a wide range of P4 PHe abundance of (73.70-804.16)×10 P-8 Pcm P3 P STP·g P-1 P,with P3 PHe/ P4 PHe ratios of 0.374-2.959 Ra,which was lower than the MORB but evidently higher than the con-tinental crust value. The Neogene alkaline basalts from the Jiyang basin,Shanwang and Qixia outcrops have variable P4 PHe abundances ((42.34-286.72)×10-8 Pcm P3 P STP·g-1 P),and "continental crust-like" P3 PHe/ P4 PHe ratios (0.013-0.074 Ra). All of them contain atmospheric-like P40 PAr/ P36 PAr ratio (395.4-1312.7),reflecting the mantle sources with air components. Their low P3 PHe/ P4 PHe ratios are interpreted as the enrichment of the radiogenic P4 PHe mainly inherited from the mantle. He and Ar systematics show the mixing of MORB-type,air and a P4 PHe enriched member in the mantle source,suggesting that these igneous rocks originated from the depleted asthenospheric mantle mixed with an EMI component. Therefore,the present He and Ar isotopes do not support the viewpoints that the Cenozoic igneous rocks of Eastern North China were the products of mantle plume(s) activities. 相似文献
7.
High-pressure granulite from Western Kunlun,northwestern China: Its metamorphic evolution,zircon SHRIMP U-Pb ages and tectonic implication 总被引：1，自引：0，他引：1
QU JunFeng ZHANG LiFei AI YongLiang L Zeng WANG JianPing ZHOU Hui & WANG ShiYan MOE Key Laboratory of Orogenic Belts Crustal Evolution School of Earth Space Science Peking University Beijing China Henan Polytechnic University Jiaozuo China Geological Survey of Henan Province Zhengzhou China 《中国科学D辑(英文版)》2007,50(7):961-971
High-pressure mafic granulites occurring as lenticular bodies within garnet-amphibolites in Kangxiwar Fault have been first reported in this paper. The P-T conditions of two metamorphic stages were ob-tained using calibrated geothermal barometers and ThermoCalc Program. The peak metamorphic con-dition of these high-pressure granulites is about 760―820℃,1.0―1.2 GPa and the retrograde meta-morphic condition is about 620―720℃,0.7―0.8 GPa. The petrological studies show that they have a near-isobaric cooling P-T... 相似文献
9.
渤中西环古近系东营组物源转换与沉积充填响应 总被引：1，自引：0，他引：1
通过砂岩中碎屑锆石U-Pb年龄分析、火山碎屑组分含量变化、地震多属性分析、层序地层格架与沉积充填特征综合分析,认为东二段沉积时期渤中西环的物源供给方式、层序地层格架及沉积充填特征发生明显的变化.东二下段沉积期前,湖盆处于强烈裂陷期,中-深湖相泥岩发育,物源主要为盆地内部的中生代火成岩基底,沉积层序明显受盆内低凸起控制,在盆内低凸起四周发育一系列近源的扇三角洲朵体;东二下段沉积期后,湖盆处于断-坳过渡期,盆内低凸起四周的断裂活动减弱,沉积层序逐渐向盆内低凸起超覆,盆外太古代-元古代变质岩物源供给不断加强,近源的扇三角洲砂体逐渐向远源的辫状河三角洲砂体转化,同时发育宽广的滨浅湖环境.渤中西环古近纪沉积充填过程中,地层样式、沉积模式与物源供给方式的一致性变化,体现了裂陷湖盆充填演化的内在规律,为我国东部裂陷盆地演化及裂陷旋回划分提供了新的线索. 相似文献
10.
城市化引起的气温上升是土地覆盖变化影响区域气候的重要体现.本文采用“观测资料减去再分析”(Observation Minus Reanalysis,OMR)的方法估计四川盆地和周边地区下垫面城市化改变对夏季地面2 m气温变化趋势的影响.设计了不同城市化下垫面扩展变化的WRF模拟试验,对1998—2012年四川盆地及周边区域夏季逐日平均温度和日最高最低气温进行模拟.在检验模式模拟性能的基础上,利用OMR方法类似的思路定量探讨城市化下垫面对地面气温变化趋势的可能影响.结果显示,(1)基于站点观测资料的OMR分布表明成都、重庆地区的城市下垫面对夏季升温的影响可达0.1℃·a^-1;(2)WRF试验模拟的结果与实际观测接近,能较合理刻画出该地区夏季温度的平均分布及时间变化特征,可以用于该地区城市化区域气候效应的研究;(3)不同城市化进程的模式模拟试验中气温变化趋势的差值与基于站点观测的OMR方法计算得到的结果类似,都证明了重庆和成都的城市下垫面对地面2 m温度的升高具有显著影响,其中在日内低温的表现尤为突出. 相似文献