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31.
Xiao-Long Huang Yi-Gang Xu Ching-Hua Lo Ru-Cheng Wang Chuan-Yong Lin 《Contributions to Mineralogy and Petrology》2007,154(6):691-705
Petrographic investigations and electron microprobe analyses have been performed on a rare aggregate of clinopyroxene megacrysts
collected from Cenozoic basalts in Yinfengling, Leizhou Peninsula of South China. The aggregate, composed of several clinopyroxene
megacrysts, shows abundant exsolution lamellae of garnet (Grt) and orthopyroxene (Opx), and granular texture. Cr- and Ti-poor
spinels are also present in this sample. They occur predominantly as Sp–Opx–Grt clusters (Cr# = 0.025–0.034) at the interspace
between different megacrysts, and subordinately as bleb-shaped (Cr# = 0.025–0.034) or thin-lamella crystals (Cr# = 0.006–0.021)
in clinopyroxene. Three different assemblages of exsolution are identified, namely (1) Sp (high Cr/Al) and Opx; (2) Grt–Opx;
(3) Sp (low Cr/Al) and Opx. In addition, some garnets were likely developed as response to breakdown of the high-Cr/Al Sp.
The homogeneous compositions in all constituent minerals and the good agreement between calculated Cpx/Grt partition coefficients
(K
d’s) for trace elements and reference data strongly suggest a chemical equilibrium among coexisting minerals, probably attained
by diffusion after the exsolution. Thermobarometric calculation based on exsolved assemblage yields a temperature of 900 ± 30°C
and a pressure of 12 ± 2.2 kbar, corresponding to the present-day thermal gradient in the region. Much higher P–T estimates
(T = 1,210 ± 30°C, P = 16.2 ± 3.5 kbar) are obtained for the reconstructed composition of cpx prior to exsolution. The contrast in thermal state
before and after the exsolution might reflect the thermal evolution of the lithosphere beneath South China during the Cenozoic.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
32.
第六次国际耦合模式比较计划（CMIP6）评述 总被引：4，自引：0，他引：4
世界气候研究计划（WCRP）发起了新一轮的国际耦合模式比较计划（CMIP6),目的是回答当前气候变化领域面临的新的科学问题,为实现WCRP“大挑战”计划所确立的科学目标提供数据支撑。文中回顾了CMIP的发展历程,介绍了CMIP6的组织思路,阐述了CMIP6核心试验及23个模式比较子计划（MIPs）的科学关注点,总结了参与CMIP6的全球模式概况以及中国的贡献。最后,从继承性和创新性等角度对CMIP6进行了评述,指出了CMIP6组织和实施中存在的问题,并对CMIP未来的发展进行了展望。 相似文献
33.
三维地质建模是实现深部矿产勘查突破的重要途径,其通过控矿地质体的三维建模,直观刻画控矿要素之间的空间、成因和演化关系,帮助理解成矿系统,开展深部找矿预测。当前三维建模主要采用地质资料构建,在缺少钻孔等已知资料的情况下,难于构建出可靠的三维地质模型。为了克服常规三维地质建模方法可信度低、精度差的缺点,本文将重磁电交互反演技术引入到三维地质建模中,提出了基于先验信息约束,通过重磁二度半剖面交互反演、电法反演、三维物性反演联合修正的三维地质模型方法。本文采用该方法建立了彭山穹隆的三维地质模型,并在此基础上对彭山穹隆的成因进行了讨论。 相似文献
34.
35.
旅游目的地区域(TDD)及其空间结构研究——以西安为例 总被引：23，自引：1，他引：22
在对国内外相关研究进行综述的基础上,以西安为例,对旅游目的地区域(TDD)进行了界定。以"一日游"旅游行为基准给出了西安旅游目的地区域范围,即以250 km为半径,相当于单程旅行2.5小时的通达范围。并发现西安TDD对周边地区旅游客源产生了明显的截流效应。分析了主要旅游景点(3A以上)的空间分布特征,认为呈现集聚分布,有利于旅游资源组团式开发。运用洛仑兹曲线,发现西安市出行的5条主要旅游路径利用强度存在严重不均衡。文章结论主要包括:TDD的核心表现为旅游区、旅游节(景)点和旅游路径三种空间要素,其中对旅游目的地区域发展影响较大的两个要素是高级别景区与旅游路径,二者决定了区域旅游产业的规模、空间分布和旅游流向。随着区域旅游一体化的推进,客观上要求以西安为中心的关中旅游热点地区要逐步打破地区壁垒,共同开拓市场,优化旅游景点组合,打造旅游精品群,以促进旅游业的持续发展。 相似文献
36.
This paper studies the exciton-longitudinal-optical-phonon coupling in InGaN/GaN single quantum wells with various cap layer thicknesses by low temperature photoluminescence (PL) measurements. With increasing cap layer thickness, the PL peak energy shifts to lower energy and the coupling strength between the exciton and longitudinal-optical (LO) phonon, described by Huang-Rhys factor, increases remarkably due to an enhancement of the internal electric field. With increasing excitation intensity, the zero-phonon peak shows a blueshift and the Huang-Rhys factor decreases. These results reveal that there is a large built-in electric field in the well layer and the exciton-LO-phonon coupling is strongly affected by the thickness of the cap layer. 相似文献
37.
2012年南海西北陆架冬季水文特征的观测分析 总被引：1，自引：0，他引：1
本文基于2012年12月南海西北部陆架海区的温盐和流速实测资料,分析了粤西和琼东陆架海区冬季三维温、盐结构和流场特征,给出沿陆架和跨陆架方向的水体和热盐通量。结果表明：（1）在50m以浅,粤西和琼东海区温度均由近岸向外海递增,深层则相反;冬季近岸海区混合层较深,外海密度跃层位于60—120m深度且层结较强,浮力频率大于10–2/s;（2）海流大致沿等深线向西南流动,30m以深流速大小在0.03—0.40m/s之间,且随着深度增加而略有减小;琼东海区100m等深线附近在60m以浅水层观测到水体辐聚并有明显温度锋面存在;（3）沿陆架方向的水体和热盐输送均大于跨陆架方向,其中粤西单位面积沿/跨陆架水体通量平均值为0.13×10–6/0.03×10–6Sv/m2,低于琼东海区的0.91×10–6/0.56×10–6Sv/m2。 相似文献
38.
后弯管式波力发电装置作为一种漂浮式振荡水柱式装置,具有可靠性强、安装维护方便、工作地点灵活的特点。本文在前人研究基础上,以10kW级后弯管式漂浮型发电装置为研究对象,以装置的水动力学性能为主要研究内容,以气室内相对波高作为主要表征参数,通过断面水槽水工物理模型试验,考察了气室内水柱振荡幅度与入射波波高和入射波周期之间的关系,分析了气室完全开敞、输气管添加负载以及弯管横管长度对气室内水柱振荡的影响,为进一步的大功率装置设计与试验提供了理论依据。 相似文献
39.
外源性硫化物可通过抑制或阻断线粒体电子传递经典途径而对生物体产生损伤甚至致死,交替氧化酶(Alternative Oxidase,AOX)是线粒体硫化物氧化电子传递分支途径中的1个关键酶。为了研究硫化物环境中单环刺螠的生存对策,本文利用间接竞争性ELISA和酶活性分析等技术检测了单环刺螠在硫化物应激前后中肠和后肠中AOX的蛋白含量以及活性的变化。结果显示:在未处理的单环刺螠中,后肠的AOX蛋白含量和酶活性均高于中肠。当单环刺螠暴露在硫化物(50和150μmol·L-1)环境中时,2个器官的AOX含量和酶活性水平均随着硫化物浓度的提高和暴露时间的延长而提高,并且150μmol·L-1硫化物处理组的单环刺螠2个器官AOX蛋白含量和酶活性普遍高于相同处理时间下的50μmol·L-1组。结合已报道的单环刺螠硫化物应激下细胞色素c氧化酶活性的变化,提出单环刺螠体内存在线粒体电子传递分支途径;提高组织线粒体中AOX活性是其应对环境硫化物毒性的对策之一。 相似文献
40.
Yi?Gang?XuEmail author Xiao-Long?Huang Jin-Long?Ma Yan-Bin?Wang Yoshiyuki?Iizuka Ji-Feng?Xu Qiang?Wang Xiang-Yang?Wu 《Contributions to Mineralogy and Petrology》2004,147(6):750-767
Chronological, geochemical and Sr–Nd–Pb isotopic analyses have been carried out on the Mesozoic plutons in western Shandong with the aim of characterizing crustal–mantle evolution during the tectono-thermal reactivation of the craton. Detailed SHRIMP zircon U–Pb dating reveals two main periods of Mesozoic activity with contrasting compositions. The older magmatic pulse is manifested by monzonites and monzodiorites from Tongshi for which zircon rims yield a concordant age of 177±4 Ma and the cores have a discordant age of ca. 2.5 Ga. Low MgO and Cr, high Na2O contents and especially their isotopic compositions (87Sr/86Sr < 0.7042, 206Pb/204Pb < 16.8 and Nd ~ –12) are consistent with derivation from late Archean–Paleoproterozoic lower crust. Relatively high HREE contents in these Jurassic plutons indicate a garnet-free source (<32 km), in contrast to the garnet-bearing source (>40 km) of the late Mesozoic high Sr and low Y granitoids from the same region. Distinctively different depths of crustal melting suggest dynamic thickening of the crust by magmatic underplating during the Jurassic and Cretaceous. The younger dioritic plutons from Laiwu and Yinan were emplaced at 132–126 Ma and show relatively high MgO and Cr contents and large isotopic variability. They were likely derived from enriched lithospheric mantle source and were subjected to crustal contamination during magma evolution. Early Cretaceous mantle melting is coeval with the widespread late Yanshanian granitic magmatism in North China. Early Cretaceous time may correspond to a critical period when a temperature increase due to lithospheric thinning allowed the intersection of the local geotherm and the wet peridotite solidus. While some mantle-derived magmas were erupted, most were trapped at variable crustal depths, triggering large-scale concomitant melting of the crust. Lithospheric thinning must have continued until the late Cretaceous because of the change in the source of mafic magmas from lithospheric to asthenospheric at that time. It is proposed that removal of the lithospheric keel beneath the North China craton may have been initiated as early as the Jurassic, but with the most intense period in the Cretaceous between 130–75 Ma. Such a relatively long timescale (~100 Ma) emphasizes the role of thermomechanical erosion by convective mantle in lithospheric thinning beneath this region. 相似文献