High-mass star forming regions: An ALMA view     

R. Cesaroni 《Astrophysics and Space Science》2008,313(1-3):23-28

The advent of ALMA is bound to improve our knowledge of OB star formation dramatically. Here, we present an overview of this topic outlining how high angular resolution and sensitivity may contribute to shed light on the structure of high-mass star forming regions and hence on the process itself of massive star formation. The impact of this new generation instrument will range from establishing the mass function of pre-stellar cores inside IR-dark clouds, to investigating the kinematics of the gas from which OB stars are built up, to assessing or ruling out the existence of circumstellar accretion disks in these objects.  相似文献   

中东地区阿普特阶Shuaiba组碳酸盐岩沉积体系特征及模式探究     

罗贝维  张庆春  段海岗  吕明胜  贾民强  杨沛广  林腾飞  杨超 《岩石学报》2019,35(4):1291-1301

中东地区主力产油层系Shuaiba组的勘探及研究逐渐以地层岩性圈闭为主,笔者通过总结Bab盆地阿普特阶Shuaiba组沉积相类型,多油田地层格架及空间展布特征的对比,为系统恢复Shuaiba组沉积演化过程及模式提供地质依据。研究表明,阿普特阶Shuaiba组共发育开阔台地、台地边缘、台缘斜坡及盆地相4种沉积相单元和6种亚相类型,各相带单元受控于四个三级层序且沿Bab盆地周缘呈带状展布。开阔台地一侧,主要沉积了第二个三级层序对应的Lower Shuaiba地层;台地边缘往Bab台内盆地区域,则以第三和第四个三级层序对应的Upper Shuaiba地层为主。Shuaiba组生物礁、滩建造集中发育在第二个三级层序的高位域阶段,滩间海、缓坡及盆地相受控于海进和低位体系域。阿普特阶Shuaiba台地边缘生物建隆、台内浅滩在空间上相互叠置并成带展布,符合弱镶边型缓坡台地沉积模式,该类型台地具备深水陆棚性质的非常宽缓的斜坡,且缓坡往盆地一侧发育一个镶边台地边缘。  相似文献   

Alteration and mineralization styles of the orogenic disseminated Zhenyuan gold deposit,southeastern Tibet: Contrast with carlin gold deposit   总被引：1，自引：0，他引：1  

Huajian Li  Qingfei Wang  Jun Deng  Lin Yang  Chaoyi Dong  Huazhi Yu 《地学前缘(英文版)》2019,10(5):1849-1862

Orogenic disseminated and Carlin gold deposits share much similarity in alteration and mineralization.The disseminated orogenic Zhenyuan Au deposit along the Ailaoshan shear zone,southeastern Tibet,was selected to clarify their difference.The alteration and mineralization from the different lithologies,including meta-quartz sandstone,carbonaceous slate,meta-(ultra)mafic rock,quartz porphyry and lamprophyre were researched.According to the mineral assemblage and replacement relationship in all types of host rocks,two reactions show general control on gold deposition:(1)replacement of earlier magnetite by pyrite and carbonaceous material;(2)alteration of biotite and phlogopite phenocrysts in quartz porphyry and lamprophyre into dolomite/ankerite and sericite.Despite the lamprophyre is volumetrically minor and much less fractured than other host rocks,it contains a large portion of Au reserve,indicating that the chemically active lithology has played a more important role in gold precipitation compared to structure.LA-ICP-MS analysis shows that Au mainly occurs as invisible gold in fine-grained pyrite disseminated in the host rocks,with Au content reaching to 258.95 ppm.The diagenetic core of pyrite in meta-quartz sandstone enriched in Co,Ni,Mo,Ag and Hg is wrapped by hydrothermal pyrite enriched in Cu,As,Sb,Au,Tl,Pb and Bi.Different host rock lithology has much impact on the alteration and mineralization features.Carbonate and sericite in altered lamprophyre show they have higher Mg than those developed in other of host rocks denoting that the carbonate and sericite incorporated Mg from phlogopite phenocrysts in the primary lamprophyre during alteration.The ore fluid activated the diagenetic pyrite in meta-quartz sandstone leading the hydrothermal pyrite enriched in Cu,Mo,Ag,Sb,Te,Hg,Tl,Pb and Bi,but the hydrothermal pyrite in meta-(ultra)mafic rock is enriched in Co and Ni as the meta-(ultra)mafic rock host rock contain high content of Co and Ni.However,Au and As shear similar range in both types of host rocks indicating that these two elements most likely come from the deep source fluid rather than the host rocks.It was shown in the disseminated orogenic gold deposit that similar hydrothermal alteration with mineral assemblage of carbonate(mainly dolomite and ankerite),sericite,pyrite and arsenopyrite develops in all types of host rocks.This is different from the Nevada Carlin type,in which alteration is mainly dissolution and silicification of carbonate host rock.On the other hand,Au mainly occur as invisible gold in both disseminated orogenic and Carlin gold deposits.  相似文献   

基于纹理合成的三维地形水墨风格渲染研究     

彭湃  李少梅 《测绘与空间地理信息》2017,(3)

提出了基于纹理合成的三维地形水墨风格渲染的方法,以规则格网DEM为数据源,基于OSG进行三维地形建模,在此基础上提取山体特征线,然后生成一幅灰度控制图像。对Efros01纹理合成算法进行改进,利用灰度控制图像指导水墨纹理的合成,将得到的纹理图像映射到三维地形上,实现对三维地形的水墨风格渲染,通过对水墨纹理样本的选择和纹理合成参数的设置能够实现对纹理合成过程的交互控制。结果表明,该渲染方法对三维地形的水墨风格渲染具有较好的效果。  相似文献   

Biodiversity Assessment of Mammal and Bird Species from Camera Trap Data in Yanchiwan National Nature Reserve,Gansu Province,China     

ZHANG Chengcheng  WANG Jun  Justine Shanti ALEXANDER  DOU Zhigang  WU Liji  DONG Wantao  Dabuxilite  YANG Jucai  SHI Kun 《资源与生态学报(英文版)》2018,9(5):566-574

Camera traps serve as an important tool for monitoring species diversity. We used data from camera traps set for capturing snow leopards (Panthera uncia) in the Yanchiwan National Nature Reserve, Gansu Province, China, to assess species richness with respect to mammal and birds species. We also assessed survey efficiency for species detection, and conducted an initial analysis of species interactions. The survey effort of 10, 171 camera workdays yielded 2, 868 suitable animal image events involving 17 mammal and 20 bird species. Among these, the dhole (Cuon alpinus) is considered to be Endangered, the snow leopard and white-lipped deer (Cervus albirostris) Vulnerable, and the Pallas’s cat (Feli smanul), mountain weasel (Mustela altaica), Himalayan griffon (Gyps himalayensis) and cinereous vulture (Aegypius monachus) Near Threatened under the IUCN red list. Fourteen species were also listed as key protected wild animals according to China national standards. Both the rarefaction curves and richness estimators suggested our sampling for mammal and pheasant species is sufficient, while more survey efforts are still needed to detect other bird species. With a focus on the dominant species Eurasian lynx (Lynx lynx), occupancy models were used to estimate site use and detection probability for selected species, and to investigate predator-prey relationships between lynx on the one hand and woolly hare (Lepus oiostolus), pika (Ochotona spp.) and Tibetan partridge (Perdix hodgsoniae) on the other. We give recommendations on how to increase efficiency in camera-based species inventory and biodiversity monitoring.  相似文献   

湘南地区“黄沙坪式”铅锌矿床地质特征及找矿方向   总被引：9，自引：0，他引：9  

黄革非 《湖南地质》1999,(Z1)

“黄沙坪式”铅锌矿是实现湘南地区新一轮铅锌找矿重大突破的主攻类型。本文系统介绍了这类矿床的地质特征和成矿规律,指出了主要找矿标志和优选靶区,并提出了下步工作建议  相似文献   

输导层和岩性圈闭中石油运移和聚集模拟实验研究   总被引：48，自引：5，他引：43       下载免费PDF全文

曾溅辉  王洪玉 《地球科学》1999,24(2):193-196

利用二维模型进行了输导层和岩性圈闭中石油运移与聚集模拟实验研究。结果表明：（１）地怪中的高渗透带是石油运移的主要通道,对油的运移和聚集构成重要的影响;（２）当上覆地层渗透性较大时,下部地层中的油可向上覆地层运移,并在运移过程中发生弥散和扩散作用,导致油的散失量增大;（３）油驱水过程中的排水过程滞后于注油过程,排出的水量并不随注油量加而线性增加,而是脉冲式变化。  相似文献   

近海多功能混凝土平台选型与优化   总被引：2，自引：0，他引：2  

衣伟  宋玉普  张燕坤 《海洋学报》1999,21(3):126-133

提出了一种适合近海边际油田开发的多功能混凝土平台型式,并对其进行了优化设计.分析了各约束对平台造价的影响,确定了平台的应用范围.优化分析中采用了约束单调性分析、初始点自动给定等方法,加快了优化的迭代收敛速度,并对初稳性高度GM值采用了模糊优化方法,考虑了影响GM值的主观因素.  相似文献   

Accounting for uncertainty in the development of harvest strategies for the Northwestern Hawaiian Islands lobster trap fishery     

DiNardo  G. T.; Wetherall  J. A. 《ICES Journal of Marine Science》1999,56(6):943-951

  相似文献   

¹³C示踪技术在利玛原甲藻中腹泻性贝毒合成研究的应用          下载免费PDF全文

张昊宇  谭志军  郑关超  吕颂辉  杨越聪  吴海燕 《海洋与湖沼》2023,54(2):457-464

选取具有显著产毒差异的利玛原甲藻(Prorocentrum lima) SHG株与2XS株为研究对象,以2-¹³C-甘氨酸为示踪原料结合高分辨质谱方法,为腹泻性贝类毒素及其酯化态毒素合成与代谢途径的研究提供新方法和思路。结果表明,两株藻共发现16种腹泻性贝毒及其酯化态毒素成分。对照培养条件下SHG株(大田软海绵酸毒素含量为7.88 pg/cell,鳍藻毒素1含量为4.35 pg/cell)的产毒能力高于2XS株(大田软海绵酸毒素5.70pg/cell),而甘氨酸作为氮源培养条件可显著提高两株藻的产毒总量(P<0.05)。¹³C-甘氨酸标记组与甘氨酸培养组单细胞产毒量无显著变化(P>0.05)。腹泻性贝毒被标记后其同位素异构体丰度发生变化,其中酯化态受¹³C标记的影响程度更高,二级质谱图清晰表示出其碎片离子及脱水峰的标记情况。该方法直观阐明了甘氨酸可作为P. lima标记原料的产毒供体,并使用稳定同位素标记方法首次实现了酯化态的同步标记,有助于腹泻性贝毒生成机制的进一步研究。  相似文献