The impact of atmospheric heat sources over the eastern Tibetan Plateau and the tropical western Pacific on the summer rainfall over the Yangtze-River basin

The variability of the summer rainfall over China is analyzed using the EOF procedure with a new parameter （namely, mode station variance percentage） based on 1951-2000 summer rainfall data from 160 stations in China. Compared with mode variance friction, the mode station variance percentage not only reveals more localized characteristics of the variability of the summer rainfall, but also helps to distinguish the regions with a high degree of dominant EOF modes representing the analyzed observational variable. The atmospheric circulation diagnostic studies with the NCEP/NCAR reanalysis daily data from 1966 to 2000 show that in summer, abundant （scarce） rainfall in the belt-area from the upper-middle reaches of the Yangtze River northeastward to the Huaihe River basin is linked to strong （weak） heat sources over the eastern Tibetan Plateau, while the abundant （scarce） rainfall in the area to the south of the middle-lower reaches of the Yangtze River is closely linked to the weak （strong） heat sources over the tropical western Pacific.     

地表能量变化对多年冻土活动层融化过程的影响

利用青藏高原北部唐古拉综合观测场2006-2008年辐射平衡及活动层温度观测资料,分析了高原北部地表能量变化对活动层融化过程的影响.结果显示：该地地表能量具有明显的季节变化特征,总辐射、净辐射、土壤热通量及地面热源强度6-7月最大,11-12月最小;研究时段土壤热通量年平均值0.12MJ.m-2.d-1,活动层土壤以吸...     

末次间冰期以来源自中亚的粉尘记录的对比

中亚干旱区是全球重要的粉尘源区, 粉尘经过不同的大气环流系统的搬运和具体的沉积条件, 在其传输路径上沉积于不同的介质中, 如冰芯、黄土、湖泊和深海. 在前人所做工作的基础上, 以古里雅冰芯、宝鸡黄土剖面、琵琶湖风尘沉积、北太平洋风尘沉积和格陵兰冰芯等记录进行对比, 初步讨论近130 ka BP以来上述记录所反映的中亚粉尘的产生、搬运和沉积. 这些记录既表现出一致性, 也存在某些差异, 显示了搬运过程、沉积过程以及区域性因素对粉尘记录的影响.     

南支气流对高原低涡移出高原影响的数值试验

本文在对2000年以来移出青藏高原后活动时间长的高原低涡活动过程,进行对流层中层南支气流对高原低涡移出高原的影响的观测事实分析基础上,通过对2001年6月1~5日索县低涡移出高原活动的数值模拟和试验分析,得出了在高原低涡以南的南支气流减弱或者是没有南风或者是没有南风脉动的影响,会使低涡移出高原的速度减慢,移出高原12小时后减弱消失。低涡以南的南支气流起到了向低涡区输送水汽通量、正涡度平流的作用,提供利于低涡活动持续的条件。从而丰富了高原低涡东移的认识,为高原低涡洪涝暴雨的预报提供了科学依据。     

Geochemical Characteristics and Genetic Significance of Datangpo‐Type Manganese Ore Deposits during the Cryogenian Period

The Datangpo‐type manganese ore deposits, which formed during the Nanhuan (Cryogenian) period and are located in northeastern Guizhou and adjacent areas, are one of the most important manganese resources in China, showing good prospecting potential. Many middle‐to‐large deposits, and even super‐large mineral deposits, have been discovered. However, the genesis of manganese ore deposits is still controversial and remains a long‐standing source of debate; there are several viewpoints including biogenesis, hydrothermal sedimentation, gravity flows, cold‐spring carbonates, etc. Geochemical data from several manganese ore deposits show that there are positive correlations between Al₂O₃ and TiO₂, SiO₂, K₂O, and Na₂O, and strong negative correlations between Al₂O₃ and CaO, MgO, and MnO in black shales and manganese ores. U, Mo, and V show distinct enrichment in black shales and inconspicuous enrichment in Mn ores. Ba and Rb show strong positive correlations with K₂O in manganese ores. Cu, Ni, and Zn show clear correlations with total iron in both manganese ores and black shales. ∑REE of manganese ores has a large range with evident positive Ce anomalies and positive Eu anomalies. The Post Archean Australian Shale (PAAS) normalized rare earth element (REE) distribution patterns of manganese ores present pronounced middle rare earth element (MREE) enrichment, producing “hat‐shaped” REE plots. ∑REE of black shales is more variable compared with PAAS, and the PAAS‐normalized REE distribution patterns appear as “flat‐shaped” REE plots, lacking evident anomaly characteristics. δ¹³C values of carbonate in both manganese ores and the black shales show observable negative excursions. The comprehensive analysis suggests that the black shales formed in a reducing and quiet water column, while the manganese ores formed in oxic muddy seawater, which resulted from periodic transgressions. There was an oxidation–reduction cycle of manganese between the top water body and the bottom water body caused by the transgressions during the early Datangpo, which resulted in the dissolution of manganese. Through the exchange of the euphotic zone water and the bottom water, and episodic inflow of oxygenated water, the manganese in the bottom water was oxidized to Mn‐oxyhydroxides and rapidly buried along with algae. In the early diagenetic stage, Mn‐oxyhydroxides were reduced and dissolved in the anoxic pore water and then transformed into Mn‐carbonates by reacting with HCO₃^? from the degradation of organic matter or from seawater. In the intervals between transgressions, continuous supplies of terrigenous clastics and the high productive rates of organic matter in the euphotic zone resulted in the deposition of the black shales enriched in organic matter.     

北羌塘盆地中部上侏罗统研究新进展

北羌塘盆地腹地自然条件恶劣 ,地层研究难度极大。经在北羌塘盆地腹地东湖、河湾山、长水河及半岛湖等地进行了详细的岩石地层及生物地层研究工作 ,依据岩石特征和生物化石特征 ,将上侏罗统二分 :下部灰岩层为索瓦组 ,含 L acunosella triobatiformis- Pentithyris vulgaris、Radulopecten fibrosus- Gervillella aviculoides组合 ,其时限为牛津期 ;上部灰岩、碎屑岩互层为白龙冰河组 ,具 Radulopecten scarburgensis、R.moondanensis、Cladophylliaqeibulaensis、Stylosmilia chaputi化石 ,其主体时限为基默里奇期—提塘期 ,顶部可能跨入早白垩世。白龙冰河组的确立 ,是北羌塘盆地上侏罗统岩石地层与生物地层研究上一个新进展     

Motive force of Qinghai-Tibet Plateau moving to east

A calculation formula on spherical pattern of Qinghai-Tibet plateau moving model is established. Tibet massif moves norward by east in speed of 28 mm/a, Ganshu-Qinghai massif moves to northeast in speed of 15 mm/a, Qomolangma Feng moves northward by a few east in speed of 35 ～42 mm/a. The low latitude perimeter is longer than the nigh latitude perimeter. When the Tibet massif moves northward, its latitude perimeter must be contracted and the Tibet massif must move eastward by Coriolis. Coriolis force is inertial in earth rotation. It makes the fall body turning to east and the rising block turning westward. In the Northern Hemisphere, it makes the northward body turning to east and the southward block turning to west.This is the reason why the tectonic zones of western Pacific are different from those of eastern Pacific.     

Carbon and oxygen isotopic constraints on paleoclimate and paleoelevation of the southwestern Qaidam basin,northern Tibetan Plateau

We investigate the growth of the northern Tibetan Plateau and associated climate change by applying oxygen and carbon isotopic compositions in Cenozoic strata in the southwestern Qaidam basin. The X-ray diffraction and isotopic studies reveal that the carbonate minerals are mainly authigenic and they do not preserve any evidence for detrital carbonate and diagenesis. The isotope data show large fluctuations in the δ¹⁸O and δ¹³C values in the middle–late Eocene, indicating relatively warm and seasonal dry climate. The positive correlation of the δ¹⁸O and δ¹³C values in the Oligocene and the positive shift of the δ¹³C values from the Eocene to Oligocene suggest that the climate changed to arid in the Oligocene. However, the δ¹⁸O values show negative shift, which is closely related to the global cooling event. During the Miocene, the δ¹³C values vary between –2‰ and –4‰, whereas the δ¹⁸O values show continuous negative shift. The mean δ¹⁸O values decrease from –8.5‰ in the early Miocene to –10.0‰ in the late Miocene. The stable isotope-based paleoaltimetry results suggest that the elevation of the southwestern Qaidam basin was approximately 1500 m in the middle–late Eocene and Oligocene. Subsequently, during Miocene the crustal uplift process started and the elevation reached approximately 2000 m in the early Miocene and 2500 m in the late Miocene, which suggests large-scale growth of the northern Tibet Plateau during the Miocene.     

Characteristics of mineral element content of alpine vegetation in permafrost region on Qinghai-Tibetan Plateau

The content characteristics of 16 elements (Al, Ca, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Sr, and Zn) in 23 plant species collected from the Qinghai-Tibetan Plateau permafrost region were investigated using ICP-OES. Results show that the average contents of Ca, K, Mg, Fe and P were higher than 1,000 mg/kg, those of Al, Na, Zn and Cr ranged between 10–1,000 mg/kg and those of Cu, Li, Pb and Mo were less than 10 mg/kg. The levels of Al, Ca, K, Mg and Na were within the scope of the reported terrestrial plant element content, those of Sr, Fe and Cr were higher than the average of the terrestrial plants and the maximum content of Mn was higher than the upper limit of the reported Mn content. The main character of the element content was of the Ca>K type, however, in terms of Cyperaceae species the element content character was K>Ca type. The contents of Ca, Li, Mg and Sr in Gramineae and Cyperaceae species were higher than those in other species and the contents of Ca, K, Mg, Fe, P, Al and Na in all collected plants were higher than those of other elements. Zn had weak variability with the lowest coefficient (i.e., 7.81%), while other elements had strong variability. The ratio of maximum content to minimum content indicated Ca and K had less change than other elements in the Qinghai-Tibetan Plateau permafrost region. Element content of alpine vegetation in the Qinghai-Tibetan Plateau permafrost region mainly shows a positive correlation, among which the correlation coefficient between Al and Pb, Al and Fe, Mo and Cr, Pb and Fe, Sr and Li were higher than 0.9, and negative correlation had no statistical significance. The correlation between Al and Fe, Mg, Mn in the Qinghai-Tibetan Plateau permafrost region were consistent with that reported in Kunlun Mountains.     

青藏高原东部表土磁化率特征与环境意义

现代表土磁化率与气候因子关系的研究是黄土古气候重建的重要内容,在黄土高原地区取得了重要进展,但在青藏高原地区相对不足。在青藏高原东部系统采集了106个表土样品,分析了其磁化率的变化特征;并通过表土磁化率与气候因子的相关分析,讨论了气候因子对高原东部现代表土低频磁化率和频率磁化率的影响。结果表明：研究区表土磁化率特征主要受到温度和降水量的影响,水热组合差异影响表土磁化率值的高低。低频磁化率与气候因子的相关性较弱,总体上与温度的相关性优于降水量,可能表明其与气候因子的关系比较复杂;频率磁化率百分比与降水呈较好的正相关关系,表明该指标对降水量的变化更为敏感,可以用于青藏高原东部的古降水定量重建。