Continental crust and lithospheric mantle interaction beneath North China: isotopic evidence from granulite xenoliths in Hannuoba, Sino-Korean craton

Mafic granulite and pyroxenite xenoliths from Cenozoic alkaline basalts at Hannuoba, Hebei Province, North China have been selected for a systematic geochemical and Sr–Nd–Pb isotopic study, which provides a unique opportunity to explore nature of the lower crust and the interaction between the continental crust and lithospheric mantle beneath an Archean craton. The major, compatible and incompatible elements and radiogenic isotopes of these xenoliths suggest great chemical heterogeneity of the lower crust beneath the Hannuoba region. Petrological and geochemical evidences indicate a clear cumulate origin, and most likely, they are related to basaltic underplating in different geological episodes. However, the Sr–Nd–Pb isotopic compositions of the xenoliths reveal a profound enriched source signature (EM I) with some influence of EM II, which implies that some portion of pre-existing, old metasomatized subcontinental lithospheric mantle could have played an important role in their genesis. It is suggested that the interaction between continental crust and subcontinental mantle as manifested by basaltic underplating would be closely related to regional tectonic episodes and geodynamic processes in the deep part of subcontinental lithospheric mantle.     

辽东地区古元古代变基性岩床的成因和构造意义

辽东地区胶-辽-吉造山带发育大量的变基性岩墙/床,这些岩墙/床对研究造山带古元古代构造演化过程具有重要意义.本文通过对辽东地区辽河群中的变基性岩床进行岩石学、岩石地球化学和锆石LA-ICP-MS U-Pb年代学研究,探讨其成因和形成的构造背景,有助于深入认识胶-辽-吉造山带古元古代地质演化过程.辽东地区变基性岩床顺层侵入于辽河群大石桥组大理岩中,发生角闪岩相变质作用,岩石类型以斜长角闪岩和石榴斜长角闪岩为主,主要矿物为角闪石和斜长石,其他矿物有石榴子石、石英、黑云母、磁铁矿和黄铁矿等.变基性岩床样品的锆石具特征的环带结构和较低的Th/U值(0.01～0.34),指示锆石为变质成因,4个样品的锆石LA-ICP-MS U-Pb定年结果(1854±11 Ma、1846±12 Ma、1847±9 Ma和1848±7 Ma)表明基性岩床发生变质作用的时间为～1.85 Ga,与华北克拉通最终碰撞拼合的时间一致.根据基性岩床与胶-辽-吉造山带其他地区～2.1 Ga的基性岩具有相似的野外产状、岩石学和地球化学特征,推断其侵位时代可能为～2.1 Ga.基性岩床样品的SiO2含量为47.07％～52.18％,K2O+Na2O含量为1.78％～4.70％,MgO含量为3.92％～8.59％,属于拉斑玄武岩系列.大部分样品的稀土总量较低(47.3×10-6～109.5×10-6),富集轻稀土元素和大离子亲石元素(如Rb、Ba、La),亏损高场强元素(如Nb、Ta),Zr、Hf没有明显的亏损且未发生分馏作用.所有样品的Al2O3、CaO和Fe2O3T含量在主量元素相关性图解上分布规律且与MgO含量呈较好的相关性,Nb/La值(0.52～0.73)随SiO2和MgO含量的变化较小,表明岩浆在侵位过程中受地壳混染的程度较低,似"岛弧"型地球化学特征是富集岩石圈地幔源区遭受古俯冲组分改造的结果.结合已有的辽河群变质火山-沉积岩、辽吉花岗岩和基性岩的研究成果,胶-辽-吉造山带在～2.1 Ga处于陆内裂谷环境.     

黏粒和有机质对黄河口潮间带沉积物微团聚体的影响

微团聚体是形成沉积物结构的基本单元,沉积物的结构性影响了土体的稳定性、渗透性和强度等工程地质性质。对废弃黄河口刁口流路潮间带沉积物微团聚体受黏粒含量、有机质和生物黏液等胶结作用进行分析,结果表明,研究区沉积物多团聚成粉粒级微团聚体(0.05～0.01 mm),含量在85.3%～95.8%之间,与黄土高原土相比,0.05～0.01 mm微团聚体增加,而0.1～0.05 mm微团聚体减少,团聚性差,易于侵蚀;黏粒含量与团聚度表现出显著正相关性,说明黏粒含量增加了沉积物微团聚体的稳定性;沉积物中有机质含量在0.27%～0.61%之间,有机质含量较少,对沉积物微团聚体贡献少;生物扰动的螃蟹洞壁土、螃蟹掘出物的团聚度明显大于表层未受生物扰动土的团聚度,说明螃蟹分泌的黏液能加大微团聚体的稳定性。     

Levels of Metabolic Enzymes and Nitrogenous Compounds in the Swimming Crab Portunus trituberculatus Exposed to Elevated Ambient Ammonia-N

This study investigated the effects of ammonia-N(control and 1 and 5 mg L~(-1)) on the changes of metabolic enzymes activities and nitrogenous compounds levels in the gills, hepatopancreas, muscles, and hemolymph of the swimming crab Portunus trituberculatus. Results showed that the levels of hemolymph ammonia increased significantly at 6 h and then decreased to control level at 12 h. The activities of key enzymes involved in biosynthesis pathways of glutamine(Gln) and urea, such as glutamate dehydrogenase(GDH), glutamine synthetase(GS), and arginase(ARG), increased remarkably in different tissues of P. trituberculatus. Gln level was the highest in muscles, while urea content was the largest in hepatopancreas. The m RNA expression level of xanthine dehydrogenase(XDH) was downregulated sharply in gills but upregulated in the hepatopancreas and muscles. A small amount of uric acid was detected in the hemolymph. This result suggests that Gln in muscles may be used as an intermediary nitrogen repository, while urea may be primarily synthesized in the hepatopancreas and then transferred to other tissues via the hemolymph. Uric acid could be synthesized by the anabolism of purine nucleotides, in additon to the inhibitory activities of gills. In addition, the levels of Gln, urea and uric acid exhibited dose-and time-dependent effects with ammonia content. Therefore, P. trituberculatus could possibly convert ammonia into Gln, urea, or uric acid to detoxify ammonia during high ambient ammonia-N stress.     

Impacts of Aerosol-Radiation Interactions on the Wintertime Particulate Pollution under Different Synoptic Patterns in the Guanzhong Basin,China

The effects of aerosol–radiation interactions(ARI) are not only important for regional and global climate, but they can also drive particulate matter(PM) pollution. In this study, the ARI contribution to the near-surface fine PM(PM2.5)concentrations in the Guanzhong Basin(GZB) is evaluated under four unfavorable synoptic patterns, including "northlow", "transition", "southeast-trough", and "inland-high", based on WRF-Chem model simulations of a persistent heavy PM pollution episode in January 2019. Simulations show that ARI consistently decreases both solar radiation reaching down to the surface(SWDOWN) and surface temperature(TSFC), which then reduces wind speed, induces sinking motion,and influences cloud formation in the GZB. However, large differences under the four synoptic patterns still exist. The average reductions of SWDOWN and daytime TSFC in the GZB range from 15.2% and 1.04°C in the case of the"transition" pattern to 26.7% and 1.69°C in the case of the "north-low" pattern, respectively. Furthermore, ARI suppresses the development of the planetary boundary layer(PBL), with the decrease of PBL height(PBLH) varying from 18.7% in the case of the "transition" pattern to 32.0% in the case of the "north-low" pattern. The increase of daytime near-surface PM2.5 in the GZB due to ARI is 12.0%, 8.1%, 9.5%, and 9.7% under the four synoptic patterns, respectively. Ensemble analyses also reveal that when near-surface PM2.5 concentrations are low, ARI tends to lower PM2.5 concentrations with decreased PBLH, which is caused by enhanced divergence or a transition from divergence to convergence in an area. ARI contributes 15%–25% toward the near-surface PM2.5 concentrations during the severe PM pollution period under the four synoptic patterns.     

地磁偏角实时自动修正技术在油田定向钻井中的应用

在油田定向钻井的磁导向定位系统中，地磁偏角校正是一个不可缺少的基本要素，同时在磁偏角校正值精度直接影响定向井的导向定位精度。因此，作者提出了提高地磁偏角校正值精度的方法，并试图将地磁偏角实时自动修正技术引入我国油田定向钻井领域。     

双向近场地震作用下HDR隔震梁桥地震响应研究

以HDR隔震梁桥多自由度（MDOF）模型和等效双线性单自由度（SDOF）模型为研究对象，以典型近场地震动作为输入，研究HDR支座双向耦合效应对HDR隔震梁桥地震响应的影响。研究结果表明:不考虑双向耦合效应的HDR支座滞回曲线呈典型双线性；考虑双向耦合效应的HDR支座滞回曲线面积小于不考虑双向耦合效应的HDR支座滞回曲线面积。不考虑双向耦合效应的顺桥向HDR支座位移峰值d_b大于考虑双向耦合效应时，但横桥向的结果相反。近场地震作用下，对梁桥进行HDR支座隔震设计时，忽略双向耦合效应计算得到的墩底剪力峰值和弯矩峰值均偏于保守。可忽略HDR支座双向耦合效应对HDR隔震梁桥近场地震能量的影响。     

参考文献著录规则应用及注意的问题

通过对《文后参考文献著录规则》的学习和理解,阐明参考文献著录方法,列举了有关著录事例和著录时应注意的问题。为著者撰写学术论文提供参考,以便提高学术论文和科技期刊质量。     

MapInfo系统线(面)目标缓冲区构建模型存在的问题及其改进方法

通过对由MapInfo系统生成的几个典型的点和线(面)目标缓冲区实例的深入剖析,发现了MapInfo系统在线(面)目标缓冲区构建模型中存在的问题。在对其原因进行深入分析与验证的基础上,给出了具体的改进思路和方法。一方面为GIS用户避免对MapInfo系统的线(面)目标缓冲区分析工具的滥用,以及提高空间分析的精度和可信度提供了具体的改进方法与建议;另一方面又为有关软件开发人员研制新版MapInfo系统及其他GIS软件提供了有益的参考。     

长白山望天鹅火山双峰式火山岩的成因演化

望天鹅火山活动从早到晚分为三期：①长白期以粗面玄武岩为主,少量碱性玄武岩和玄武质粗安岩;②望天鹅期又分早晚两个亚期,早期玄武质粗安岩和粗面岩,晚期碱性流纹岩;③红头山期碱性流纹岩。望天鹅火山岩的岩石学、ＲＥＥ、不相容元素和Ｎｄ、Ｓｒ、Ｐｂ同位素（１４３Ｎｄ／１４４Ｎｄ、８７Ｓｒ／８６Ｓｒ、２０６Ｐｂ／２０４Ｐｂ分别变化于０．５１２５６７～０．５１２６４２、０．７０５１９８～０．７１６７４２和１７．４３４～１７．９３４）,揭示了岩浆源区明显受洋壳的俯冲和壳幔混合混染,三期火山岩具有共同的岩浆源区和紧密的成因演化关系,分离结晶作用控制了岩浆的演化过程。原始碱性系列玄武质岩浆经橄榄石、辉石的结晶分异,向粗面玄武岩演化;粗面玄武岩经斜长石强烈的结晶分离作用,还有辉石、钛铁氧化物和磷灰石的分离结晶作用形成具显著Ｅｕ、Ｓｒ、Ｂａ、Ｔｉ、Ｐ负异常的碱性流纹岩,导致本区火山岩缺失中性（ＳｉＯ２＝５７％～６３％）的安山岩和粗安岩,呈现双峰式火山岩组合的特点。