地震层析成像中LSQR算法的快速求解

针对传统LSQR反演算法计算时间长、占用内存大的不足,这里提出了一种LSQR的快速算法,通过线性三元组存储稀疏矩阵,实现相应的矩阵运算,使LSQR算法的运算速度及内存占用都有较大地改善。     

甘肃省临夏盆地更新世早期湖泊沉积孢粉记录的古气候演化

根据孢粉组合特征,将临夏盆地早更新统东山组(2.50-1.76Ma)的孢粉划分为3个孢粉带(含6个亚带),即3个植被、气候阶段,第一阶段(2.50-1.91Ma,带Ⅰ),植被类型是以柏科、榆属和禾本科为优势种的温带森林,气候表现为温凉稍干,并有逐渐干旱化的趋势.第二阶段(1.91-1.80Ma,带Ⅱ)是以云杉属、榆属和...     

Deposition Process of Dust Microparticles from Aerosol to Snow-Firn Pack on Glacier No. 1 in Eastern Tianshan Mountains, China

Samples were continuously collected from aerosol, fresh snow, and snow pits on Glacier No. 1 at Urumqi River source in eastern Tianshan (天山) Mountains. The deposition processes and the characteristics of mineral dust microparticles from aerosol to fresh snow, and then evolution to the snow pit were determined. Total dust microparticle concentration in the surface snow and aerosol showed a similar temporal variation trend, which was strongly associated with regional and local at-mospheric circulation in the ...     

高级变质作用对锆石U-Pb同位素体系的影响:胶东栖霞地区变质闪长岩锆石定年

文中对高级变质作用(高角闪岩相-麻粒岩相)条件下"干的"岩石体系中锆石U、Th、Ph行为进行了研究.样品为胶东栖霞地区太古宙变质基底的高角闪岩相-麻粒岩相变质闪长岩.矿物组合为单斜辉石+斜长石+钾长石+黑云母+石英.锆石呈近短轴状、等轴状和不规则状,阴极发光下具板状、杉树叶状、扇形结构,部分具封闭环带结构.锆石中存在斜...     

Physico-chemical characteristics and environmental significance of snow deposition on Haxilegen glacier No.51 in Tian Shan, China

Snow chemistry on the glaciers of alpine regions is a good indicator of atmospheric environmental change.We examine snow chemistry in three snowpits at different altitudes on the Haxilegen Glacier No.51,in the Kuitun River source,Tian Shan,China,during July-September 2004 to 2007.We use correlation analysis,factor analysis and sea-salt tracing methods to examine the characteristics and sources of major ions and mineral dust particles in the snow.Results show that mineral dust particles and major ions in the snow pits vary seasonally.During the Asian dust period in springtime,the concentration of mineral dust particles and major ions deposited in snow is high,while the concentration is relatively low during the non-dust period of summer and autumn.This may be caused by dust storm activity in central Asia.The order of major ionic concentrations in the snow packs was determined to be Ca2+ > SO42-> NH4+ > NO3-> Cl-> Na+ > Mg2+ > K+.Ca2+ was the dominant cation;SO42- was the dominant anion.We find,with the exception of NO3-,that the variabilities of ionic concentrations are highly correlated.Results show that the glacier region was significantly affected by dust activity and anthropogenic source.The major ions,especially Na+,originate from dust sources of central Asia and from the Ocean,transported by the westerly winds.     

Impact of the variation of westerly jets over East Asia on precipitation of eastern China in July

The impact of the northward jump and westward movement of the East Asian westerly jet core from the western Pacific Ocean to the Qinghai-Tibet Plateau on precipitation distribution of eastern China is studied. It is concluded that on the one hand, the northward jump of the jet causes the precipitation belt to move northward from the middle and lower reaches of the Yangtze River valley and withdraw during the Mei-yu season; on the other hand, the westward movement of the jet core has no correspondence with withdrawal of the Mei-yu season. However, the earlier or later occurrence of the westward movement of the jet has an influence on the process of the rain belt moving northward than the northward jump of the jet: the rain belt moves northward from the middle-lower Yangtze River valley to the Huaihe River and then to an area between the Yellow River and Huaihe River during years when the time of the westward movement of the jet core is later than that of the northward jump of the jet and from the middle-lower Yangtze River valley to an area between the Yellow River and Huaihe River in other years. Further analysis shows that: (1) The northward jump of the jet and the westward movement of the East Asian westerly jet core causes significant variation of the general atmospheric circulation in middle latitudes and water vapor transport from the western Pacific, but not from the Bay of Bengal. (2) Impact of the northward jump and the westward movement of the East Asian westerly jet core on circulation are different, therefore, water vapor transport from the western Pacific and its impact on the rain belt are different. The earlier or later occurrence of the westward movement of the jet core than the northward jump of the jet causes the process of circulation and water vapor transport to be different which produces a different process of the rain belt moving northward.     

A wind tunnel investigation on the transverse motion of aeolian sand

A wind tunnel experiment was performed to investigate aeolian grain motions in the transverse direction, which is perpendicular to the incoming flow and parallels the sand bed. The trajectories in the horizontal plane were recorded by high-speed camera. Statistical analysis of 630 trajectories shows that both the motion orientation and the time-averaged speed follow Gaussian distributions. An exclusive method was used to analyze the driving mechanism. It was concluded that the three-dimensional turbulent air flow, rather than the spin of grain or grain–bed collisions, controls the transverse motion.     

西安80坐标系向2000国家大地坐标系的转换

西安80和2000国家大地坐标系的起算点和参考椭球不同,两者之间的坐标转换根据区域大小和精度高低可采取不同的数据转换模型.     

河北省邯邢地区高岭石伊利石粘土矿床特征及找矿方向

邯邢地区高岭石、伊利石粘土矿赋存于石炭系本溪组、太原组,二叠系山西组、下石盒子组、上石盒子组的7个层位.矿体主要呈层状产出,厚度变化较大.矿石主要由片状高岭石组成,次要和少量矿物为绢云母、石英、黑云母等.矿床成因包括沉积矿床(如石炭-二叠系高岭石伊利石粘土矿)、风化残积矿床(如软质高岭石粘土矿床).该地区可划分出临城竹...     

Evidence of gas hydrate from downhole logging data in the Ulleung Basin, East Sea

The Gas Hydrate Research and Development Organization (GHDO) of Korea successfully accomplished both coring (hydraulic piston and pressure coring) and logging (logging-while-drilling, LWD, and wireline logging) to investigate the presence of gas hydrate during the first deep drilling expedition in the Ulleung Basin, East Sea of Korea (referred to as UBGH1) in 2007. The LWD data from two sites (UBGH1-9, UBGH1-10) showed elevated electrical resistivity (>80 Ω-m) and P-wave velocity (>2000 m/s) values indicating the presence of gas hydrate. During the coring period, the richest gas hydrate accumulation was discovered at these intervals. Based on log data, the occurrence of gas hydrate is primarily controlled by the presence of fractures. The gas hydrate saturation calculated using Archie’s relation shows greater than 60% (as high as ∼90%) of the pore space, although Archie’s equation typically overestimates gas hydrate saturation in near-vertical fractures. The saturation of gas hydrate is also estimated using the modified Biot-Gassmann theory (BGTL) by Lee and Collett (2006). The saturation values estimated rom BGTL are much lower than those calculated from Archie’s equation. Based on log data, the hydrate-bearing sediment section is approximately 70 m (UBGH1-9) to 130 m (UBGH1-10) in thickness at these two sites. This was further directly confirmed by the recovery of gas hydrate samples and pore water freshening collected from deep drilling core during the expedition. LWD data also strongly support the interpretation of the seismic gas hydrate indicators (e.g., vent or chimney structures and bottom-simulating reflectors), which imply the probability of widespread gas hydrate presence in the Ulleung Basin.