Tomographic determination of the upper crustal structure in the Jiashi strong earthquake swarm region

IntroductionBetween January and April of 1997, 7 earthquakes with M(6.0 occurred successively in Jiashi, Xinjiang. The continual occurrence of strong earthquakes within such a small area and in such a short period of time is exceptional for intraplate earthquakes. The Jiashi earthquake swarm took place on the northeast side of the Pamirs, where the Tarim basin, South Tianshan and West Karakoram meet (HU, et al, 1989). This is also a place where a number of active faults develop, so it is…     

德尔尼矿区外围找矿预测

德尔尼铜-钴矿区南部第二成矿带具有良好的化探异常显示。从水系分布看,该异常并非德尔尼矿区影响所致。建议对重点异常及其它异常分布区分别进行土壤及原生晕测量、开展1:1万和1:5万地质测量及相应的地质及物探工作。该区进一步找矿的前景乐观。     

合成甲烷水合物的拉曼光谱及其弹性波速度

我们在实验室合成了大长度的甲烷水合物,通过其拉曼光谱确定不同高压下的结构特征,并测定了其弹性波速度.多晶的甲烷水合物合成采用细粒冰作为开始材料,把这些冰粒包裹后放进一个金属压力容器中,压力容器浸没在一个水浴池里,水浴池开始温度约为0℃,向压力容器注入18 MPa的甲烷气,然后使水浴池缓慢升温到9℃,这个升温过程重复两次,整个过程用时最少2天.合成的甲烷水合物结构相对松散但尺度相对较大,直径25～38mm,长度90mm.     

A new cubic equation of state and its applications to the modeling of vapor-liquid equilibria and volumetric properties of natural fluids

A cubic equation of state was developed for both pure systems and mixtures in this study. It has only one empirical constant to be evaluated for each component and two constants for each binary. To test its validity, the saturated properties of 22 pure fluids were calculated with the new equation, as compared with the most frequently used or the most recently published cubic equations. The results indicate that the new equation is superior to the previous cubic equations in the overall performance in vapor pressures and saturated volumes. Its overall average deviation of the saturation pressures from experiments is 0.46%, and the maximum deviation is 3.6%. Its average deviation of the liquid volumes from experiments at the reduced temperatures T_r≤0.95 is 2.80%, and that of vapor volumes is 2.2%. Because of the high accuracy of the new equation for saturation pressures, it can be easily extended to binary mixtures for the prediction of vapor-liquid equilibria (both densities and compositions) with a simple mixing rule, as demonstrated by eight binary systems, including an aqueous mixture.     

Biogeochemical characteristics of the lower Mississippi River, USA, during June 2003

During June 2003, a period of mid level discharge (17,400 m⁻³ s⁻¹), a parcel of water in the lower Mississippi River was sampled every 2 h during its 4-d transit from river km 362 near Baton Rouge to km 0 at Head of Passes, Louisiana, United States. Properties measured at the surface during each of the 48 stations were temperature, salinity, dissolved organic carbon (DOC), total dissolved nitrogen, dissolved macronutrients (NO₃+NO₂, PO₄, Si(OH)₄), chlorophylla (chla; three size fractions: < 5 μm, 5–20 μm, and > 20 μm) pigment composition by HPLC, total suspended matter (TSM), particulate organic carbon (POC), and particulate nitrogen (PN). Air-water CO₂ flux was calculated from surface water dissolved inorganic carbon and pH. During the 4 d transit, large particles appeared to be settling out of the surface water. Concentrations of chla containing particles > 20 μm declined 37%, TSM declined 43%, POC declined 42% and PN declined 57%. Concentrations of the smaller chla containing particles did not change suggesting only large particulate materials were settling. There was no measurable loss of dissolved NO₃, PO₄, or Si(OH)₄, consistent with the observation that chla did not increase during the 4-d transit. DOC declined slightly (3%). These data indicate there was little autotrophic or heterotrophic activity in the lower Mississippi River at this time, but the system was slightly net heterotrophic.     

Evolution of soil properties on stabilized sands in the Tengger Desert, China

The spatial and temporal patterns of pedogenesis on stabilized dunes at Shapotou, northwestern China, were studied on the time sequences of 0, 18, 35 and 43 years. The spatial pattern of soil formation was estimated by measuring the thickness of accumulated sand fractions on the stabilized dune surface and by analyzing the characteristics and properties of soil. The results showed that the environment of soil formation and circulation of soil material were influenced in the processes of shifting-sand fixation, and the mean soil particle size changed from >0.2 to <0.08 mm in 0–20 cm soil depth with the succession from cultivated plants to natural vegetation. The capacity of available soil water increased fivefold. Deep infiltration of water in soil no longer occurred due to the increase in soil water capacity and the change of redistribution of soil water in profiles. Soil microorganisms evolved from simple to complex. Interaction of these processes obviously brought about accumulation of soil fertility, evolution of soil profiles and development of the profiles towards aripsamments. The difference of micro-topography is closely related to redistribution of material and energy in soil formation.     

河北遥测台网速报震级偏差与量规函数关系的研究

选取河北数字遥测地震台网自2001年11月正式运行至2004年6月所记录到的河北省及邻区64次较大的速报地震事件，计算单台震级与多台平均震级的偏差。分析发现，目前所用量规函数在震中距小于70km和大于390km时偏小，认为在大震速报中直接采用震中距70～390km的台站参与计算震级是一种更简便可行的办法；发现平均周期在0．2～0．6s的区间内△M相对稳定，因此，在读取最大振幅和周期时，应尽量避免较高频波段或较低频波段，如果是计算机自动读取振幅则应舍掉平均周期小于0．2s和大于0．6S的台站。     

海原断裂高湾子地点三维探槽的开挖与古地震研究

对海原断裂高湾子地点进行大比例尺地质地貌填图和三维探槽开挖，揭示出７次古地震事件，除１９２０年地震外，它们的年龄分别为距今（１０００４±３１９６），（６６８９±１６９），（６１２０±５０５），（４２０８±５７７），（２７６３±３７２）和（１００５±４６５）ａ；重复间隔分别为（３３１５±３２００），（５６１±５３２），（１９２０±７６６），（１４２５±６８６），（１５７８±５９５）和（９８０±４６５）ａ。事件Ⅲ，Ⅳ，Ⅴ，Ⅵ，Ⅶ的水平位移量分别为（５．６±２．３），（１．５±１．１），（１．５±１．１），（２±１）和（７±０．５）ｍ。显示出重复间隔时间的分段性和特征行为的分级性。两次类似１９２０年强度的地震间隔期间，有３次位移量为１～２ｍ的地震发生     

Geographical distribution of hypocentral depths of Chinese earthquakes

ＧｅｏｇｒａｐｈｉｃａｌｄｉｓｔｒｉｂｕｔｉｏｎｏｆｈｙｐｏｃｅｎｔｒａｌｄｅｐｔｈｓｏｆＣｈｉｎｅｓｅｅａｒｔｈｑｕａｋｅｓＸＩＮＧ－ＢＥＩＤＵＡＮ（段星北）ＩｎｓｔｉｔｕｔｅｏｆＧｅｏｐｈｙｓｉｃａｌ，ＳｔａｔｅＳｅｉｓｍｏｌｏｇｉｃａｌＢｕｒ...     

Carbon isotopic study of individual alcohol compounds in modern sediments from Nansha Islands sea area, China

Carbon isotopic compositions of individual n-alkanols and sterols in modern sediments from the Nansha Islands sea area are measured after derivatization to trimethylsilyl ethers by the new isotopic analytical technique of GC/C/IRMS. The effects of the three added silyl carbon atoms in every alcohol molecule on these compound isotopic compositions and the characteristics of their carbon isotopic compositions are studied. Then their biological sources are discussed using their carbon isotopic compositions. Project supported by the National Natural Science Foundation of China and Project of the Multidisciplinary Oceanographic Expedition of Chinese Academy of Sciences to Nansha Islands.