Refertilization of ancient lithospheric mantle beneath the central North China Craton: Evidence from petrology and geochemistry of peridotite xenoliths

The petrology and geochemistry of peridotite xenoliths in the Cenozoic basalts from Fanshi, the central North China Craton (NCC), provide constraints on the evolution of sub-continental lithospheric mantle. These peridotite xenoliths are mainly spinel-facies lherzolites with minor harzburgites. The lherzolites are characterized by low forsterite contents in olivines (Fo < 91) and light rare earth element (LREE) enrichments in clinopyroxenes. In contrast, the harzburgites are typified by high-Fo olivines (> 91), high-Cr# spinels and clinopyroxenes with low abundances of heavy REE (HREE). These features are similar to those from old refractory lithospheric mantle around the world, and thus interpreted to be relics of old lithospheric mantle. The old lithospheric mantle has been chemically modified by the influx of melts, as evidenced by the Sr–Nd isotopic compositions of clinopyroxenes and relatively lower Fo contents than typical Archean lithospheric mantle (Fo > 92.5). The Sr–Nd isotopic compositions of harzburgites are close to EM1-type mantle, and of the lherzolites are similar to bulk silicate earth. The latter could be the result of recent modification of old harzburgites by asthenospheric melt, which is strengthened by fertile compositions of minerals in the lherzolites. Therefore, the isotopic and chemical heterogeneities of the Fanshi peridotite xenoliths reflect the refertilization of ancient refractory lithospheric mantle by massive addition of asthenospheric melts. This may be an important mechanism for the lithospheric evolution beneath the Central NCC.     

The geochemical characteristics and origin of crude oils in the Kekeya Oilfield,Xinjiang, China

GC/MS and GC/MS/MS techniques were employed to describe the characteristics of biomarker assemblages in two sets of hydrocarbon source rocks, Jurassic and Permian, in southwestern Tarim, and the parameters for the classification of the two sets of hydrocarbon source rocks have been established. It is found that diahopane and C30-unknown terpane are abundant in Permian samples, the contents of diahopane in Jurassic samples are relatively low, and terpenoids have been detected in Jurassic samples but not in Permian source rock samples. Kekeya crude oils are abundant in diahopane and C30-unknown terpane. The results of fine oil-rock correlation indicated that Kekeya crude oils were derived mainly from the Permian hydrocarbon source rocks. However, a small amount of diterpenoid was detected in the crude oils, indicating that the Jurassic hydrocarbon source rocks also made a certain contribution to Kekeya crude oils.     

Dynamical downscaling of regional climate over eastern China using RSM with multiple physics scheme ensembles

Theoretical and Applied Climatology - The parameterization of physical processes is one of the critical elements to properly simulate the regional climate over eastern China. It is essential to...     

A peak-cluster assessment method for the identification of upland planation surfaces

Residual upland planation surfaces serve as strong evidence of peneplains during long intervals of base-level stability in the peneplanation process. Multi-stage planation surfaces could aid the calculation of uplift rates and the reconstruction of upland plateau evolution. However, most planation surfaces have been damaged by crustal uplift, tectonic deformation, and surface erosion, thus increasing the difficulty in automatically identifying residual planation surfaces. This study proposes a peak-cluster assessment method for the automatic identification of potential upland planation surfaces. It consists of two steps: peak extraction and peak-cluster characterization. Three critical parameters, namely, landform planation index (LPI), peak elevation standard deviation, and peak density, are employed to assess peak clusters. The proposed method is applied and validated in five case areas in the Tibetan Plateau using a Shuttle Radar Topography Mission digital elevation model (SRTM DEM) with 3 arc-second resolution. Results show that the proposed method can effectively extract potential planation surfaces, which are found to be stable with different resolutions of DEM data. A significant planation characteristic can be obtained in the relatively flat areas of the Gangdise–Nyainqentanglha Mountains and Qaidam Basin. Several vestiges of potential former planation areas are also extracted in the hilly-gully areas of the western part of the Himalaya Mountains, the northern part of the Tangula–Hengduan Mountains, and the northeastern part of the Kunlun–Qinling Mountains despite the absence of significant topographical features characterized by low slope angles or low terrain reliefs. Vestiges of planation surfaces are also identified in these hilly-gully upland areas. Hence, the proposed method can be effectively used to extract potential upland planation surfaces not only in flat areas but also in hilly-gully areas.     

HBV相关肝病患者外周血NK细胞PD-1、Tim-3表达及意义

目的 了解HBV相关肝病患者外周血NK细胞表面PD-1、Tim-3的表达情况,探讨PD-1和Tim-3的表达与血清HBV-DNA载量的相关情况。方法 选择HBV感染相关肝病患者74例,其中CHB患者30例,LC患者24例,HCC患者20例,健康对照18例。应用流式细胞术检测NK细胞表面PD-1、Tim-3表达,荧光定量PCR检测HBV-DNA量,ELISA法检测细胞因子分泌水平。统计各组患者PD-1和Tim-3的表达率,比较各组差异,分析其与病情的相关性。结果 CHB、LC、HCC组外周血NK细胞表面PD-1和Tim-3的表达率分别为34.46%±7.31%、59.09%±12.35%、61.49%±15.26%和19.18%±6.05%、28.64%±11.20%、31.24%±11.85%,均高于对照组（P<0.01）,LC组和HCC组明显高于CHB组（P<0.01）,LC组和HCC组比较无统计学差异。在CHB组,PD-1的表达率与HBV-DNA呈负相关关系（R=-0.437,P=0.033）。CHB、LC、HCC各组血清中细胞因子TNF-α和IFN-γ水平分别为0.66±0.63、0.75±0.66、0.85±0.71和1.76±0.88、1.83±1.23、1.60±0.53,均低于健康对照组（P<0.01）。结论 HBV相关肝病患者NK细胞表面PD-1、Tim-3表达均增加,且与病情严重程度有关,增加表达的PD-1与血清HBV-DNA载量存在负相关性,HBV肝病各组血清TNF-α、IFN-γ分泌减少。     

Frost-heave properties of saturated compacted silty clay under one-side freezing condition

In seasonally frozen regions, the frost-heave properties of soil play a significant role in its upper-structure performance and durability. To investigate the frost-heave behaviors of saturated, compacted silty clay soil widely used as subgrade material, a series of one-side freezing tests was carried out; and the freezing depth and frozen front effected by the compactness, temperature, overburden pressure, and water-supply condition were analyzed and discussed. The results show that the moving speed of the frozen front and growth rate of the frozen depth are positively correlated. The frost heave is maximum in the frost-heave stability condition. The frost ratio of saturated soil is proportional to the water supply and cooling temperature under a one-side freezing condition. The frost ratio of saturated soil is inversely proportional to the initial compactness of the soil specimen and the overburden pressure.     

GPS及AVHRR资料在浅海潮间带测量中的应用

通过利用GPS及渔探器实测，并进行潮位订正，获得南通浅海海域大量测点的高程资料，通过对多时相各通道NOAA卫星照片进行筛选，挑选能反映浅海地貌的通道资料，从中读取各测点相对应的灰度值，在此基础上利用分级线性回归，建立不同高程范围内的高程，灰度线性回归方程，确定不同高程的灰度阈值，从而测量出南通市浅海海域不同高程以上的潮间带面积，分布。     

中国大气本底条件下不同地区地面臭氧特征

分析了晴天和阴天时瓦里关本底台、临安和龙凤山本底站地面 O3浓度的特点。晴天时 ,临安站地面 O3有明显日变化 ,以春季最大 (42 .9× 1 0 - 9) ,夏季最小 (2 0 .3× 1 0 - 9) ;龙凤山站日变化更规则 ,秋季最大 (约 2 7× 1 0 - 9) ;瓦里关本底台除了夏季有微弱日变化外 ,其它季节没有明显的日变化 ,日较差也很小 ,但夏季地面 O3浓度显著高於冬季 ;夏季晴天瓦里关地面O3浓度要比龙凤山、临安高 2 0× 1 0 - 9以上。阴天时 ,临安和龙凤山站除了日变化不很规则和日较差较小外 ,其它大致与晴天相同。阴天时瓦里关不仅没有日变化 ,而且日较差更小 ,但夏季地面 O3仍然高於冬季。太阳总辐射和 NOx 浓度是控制龙凤山和临安晴天和阴天地面O3浓度的决定性因子 ,它在不同季节和地区发挥着重要作用。夏季青藏高原周围地区气流向高原输送作用 ,是形成夏季瓦里关地面 O3高值以及微弱日变化的主要原因。在美国 MaunaLoa基准站也曾观测到类似的输送影响。O3在低对流层随垂直高度增加的分布特征 ,决定了东西部测点地面 O3的差异     

祁连山地震带两次中强地震前的加卸载响应比异常

研究了祁连山地震带两次中强地震前的加卸载响应比异常特征，讨论了基于天然地震序列的样本条件对加卸载响应比计算结果的影响，提出处理序列中4．0级以上地震的新方法。     

Seismic Response of Base-Isolated Structures underMulti-component Ground Motion Excitation

INTRODUCTIONConcept of base isolation has attracted considerable attention in recent years (Sun et al., 1994). The basic isolationsystem consists of an array of bearings between the base of thebuilding and its foundation. It shifts the fundamental frequencyof the structure away from the energetic region of the earthquake spectrum and limits the earthquake energy transmitted tothe superstructure (Tang and Liu, 1993 ). Base isolation isused widely to protect structures from the destructive…