基于非结构有限元的时间域海洋电磁三维反演

海洋电磁法是一种有效的钻前储层评价手段,可识别出海底构造是否储油气,从而减少干井率降低勘探成本.近年来,频率域三维海洋电磁反演得到了快速发展,但受到空气波的影响,其在浅海环境中无法取得很好的效果.为解决这一问题,本文研究时间域海洋电磁数据三维正反演.正演模拟和计算中,我们选择基于非结构网格的矢量有限元方法.该算法中空间离散采用非结构四面体网格,可很好地拟合复杂海底地形条件和地下复杂结构;而对于时间离散,我们采用无条件稳定的后推欧拉方法,以确保任意时间步长数值计算的稳定性.反演计算中,灵敏度信息采用伴随正演隐式进行计算;同时,依据时间域反演方法的特点采用L-BFGS方法计算模型修正量.通过利用合成数据反演结果证明了本文提出的三维时间域反演方法可用于复杂海底环境,特别是在浅海环境下的有效性.     

Specific Relationship between the Surface Air Temperature and the Area of the Terra Nova Bay Polynya,Antarctica

Antarctic polynyas play an important role in regional atmosphere-ice-ocean interactions and are considered to help generate the global deep ocean conveyer belt. Polynyas therefore have a potential impact on the Earth’s climate in terms of the production of sea ice and high-salinity shelf water. In this study, we investigated the relationship between the area of the Terra Nova Bay polynya and the air temperature as well as the eastward and northward wind based on the ERA5 and ERAInterim reanalysi...     

松辽盆地北部存在前寒武纪基底的证据

目前对松辽盆地是否存在前寒武纪结晶基底的认识存在分歧。笔者对松辽盆地北部早白垩世火山岩中锆石SHRIMP定年研究过程中,在多个样品中发现了古老锆石,其年龄表明这些锆石主要形成于前寒武纪,并且认为它们可能来源于盆地北部深层的基底岩石,是火山喷发过程中捕获的。锆石年龄大致可分为3组:(1848±34)Ma、(1600±29)Ma和(1293±41)Ma,指示了盆地基底在古元古代和中元古代期间经历的多次构造-岩浆作用事件,由此认为松辽盆地北部存在前寒武纪基底。     

石榴石-黑云母地质温度计在四川拉拉铜矿床的应用

在晋宁运动中,拉拉铜矿床区发生了大规模的区域变质作用,由于其变质条件的资料较少,使得人们对矿床的成因机制存在诸多争论.采用石榴石-黑云母地质温度计和多硅白云母地质压力计,结合电子探针分析结果,对矿区内广泛出露的石榴石黑云母片岩进行了研究,得到区域变质作用的变质温度为500～560 ℃,变质压力上限为0.6～0.73GPa,变质程度为高绿片岩相.同时,根据野外观测及室内研究并结合前人工作,认为矿床主要存在两个成矿期次,即火山-喷气沉积成矿期和变质热液成矿期.     

A high-resolution Holocene diatom record on the North Icelandic shelf

A high-resolution diatom record from core MD99-2275 reveals a series of palaeoceanographic changes on the North Icelandic shelf since about 9000 cal. yr BP. The influence of relatively warm high-salinity Atlantic water-masses of the IC was strong in the study area during the Holocene Climate Optimum (8760 (base of record) to c . 5300 cal. yr BP) and peaked between c . 8000 and 7000 cal. yr BP. There is a general cooling trend from c . 7000 cal. yr BP to the present, which is indicated by an increase in the influence of cold Polar water-masses from the EGC and the EIC and a decrease in the influence of the IC. A major change in diatom assemblages at around 5300 cal. yr BP indicates a palaeoceanographic shift on the North Icelandic shelf in the mid-Holocene. In addition, several abrupt palaeoceanographic changes are distinguished. Enhanced influence of Polar waters is reflected during the intervals 8120–8000, 6650–6100, 4300–4100, 3000–2700, 1300–1100 and 600–200 cal. yr BP. The palaeoceanographic indication of the diatom record of core MD99-2275 is consistent with the indication of other environmental parameters from the same core, such as benthic and planktonic foraminifera as well as magnetic properties, and the results are also consistent with palaeoclimatic records from adjacent areas around Iceland and in the North Atlantic region.     

三维GIS平台复杂工况下的电气校验

针对传统输电线路设计过程中校验过程困难、精度低的问题,基于三维GIS平台设计了三维电气校验模块,利用悬链线理论、空间坐标转换、状态方程等计算方法实现了不同的工况条件下对"导线对地距离""导地线间距离""导线对地物距离""极限档距"及"安全间隙"的校验,校验算法的准确性通过了设计院的校核。通过多个工程的试用表明,该方法不仅提高设计人员的工作效率,而且可以提高电气校验的精度,研究结果对输电线路数字化设计过程中电气校验具有一定的参考价值。     

用接收函数方法研究中国及邻区上地幔间断面的埋藏深度

使用中国及邻区的18个数字化地震台的宽频带三分向远震记录图,筛选计算得到了263条径向接收函数,并拾取了在41Okm和660km间断面上的透射转换震相P4S、P660S与P波的到时差.通过调整各台站之下的速度模型中这两个间断面的深度,使理论接收函数的P4S、P660S与P波的到时差与观测值相符,最终确定这两个间断面的实际埋藏深度.结果表明,各台站之下4km间断面的平均深度为403km,具有明显的横向不均匀性和区域性,其中北京台、西安台、兰州台和恩施台等的埋藏深度较浅,琼中台、CHTO等台较深.660km间断面的平均埋藏深度为663km,也存在明显的横向不均匀性,其中牡丹江台和MAJO台的较深,琼中台和HYB台的较浅.     

藏东地区新生代构造体系与成矿的关系

区域构造和微构造分析表明，新生代藏东地区构造应力场自印支燕山期的NE-SW向挤压向喜马拉雅山期的NNE-SSW向压扭性转变，表现在：（1）沿昌都地块两侧及古生代一中生代形成的深大断裂带发生了大规模的右旋走滑活动，伴重型较强的碎裂岩化、拉伸线埂和剑鞘褶皱等，沿主断裂两侧叠加一系列NW、NNW及NE向雁行式排列的褶皱和张扭性断裂；（2）在区域上，沿大规模右旋走滑断裂两侧形成一系列雁行式排列的第三系走滑拉分盆地；（3）新生代岩浆活动沿走滑断裂两侧的张扭性次级断裂有规律分布，新生代构造体制的转变造成大规模成矿流体与富集，使新生代成为本区最重要的成矿时期，而北澜沧江，妥坝、温泉断裂带及车所乡断裂带北段是该期矿产最有利的富集部位。     

EXPERIMENTAL STUDY ON SALTATION OF SOLID GRAINS IN FLOWING WATER

This paper deals with the saltation of bed-load solid grains in flowing water. Experiments have been carried out by means of high-speed photographing and advanced data processing techniques while the analysis is made by combined method of mechani- cal and statistical theories. Experiments reveal that saltation is the main form of the bed-load transport under ordinary flow conditions. Taking successive saltation as the model of bed-load transport, systematic analysis has been made with regard to the forces acting on grains and the variation of their magnitudes along the saltation trajec- tories to obtain the kinematic and dynamic properties of these grains. The statistical analysis shows that the probability density functions of the relative height and length of saltation are in conformity with distribution, while the probability density functions of the relative velocities of saltation are in conformity with the Gaussian distribution.     

应用流式细胞术测定中国四种经济蟹类的基因组大小

The genome size(C-value) of an organism is referring to the DNA content of its non-replicated haploid chromosome complement,generally deduced from measuring somatic diploid nuclei.We presented genome size(C-value) data obtained by flow cytometry for four commercially important crabs(Portunus trituberculatus,Charybdis japonica,Scylla paramamosain,and Eriocheir sinensis) common in the coast of China.Gallus domesticus(2C=2.5 pg) was used as the internal standard.The results showed that the C-value for P.trituberculatus,C.japonica,S.paramamosain,and E.sinensis were(2.31±0.01) pg,(2.33±0.03) pg,(1.64±0.02) pg,and(2.29±0.03) pg,respectively.The C-value of P.trituberculatus,C.japonica and S.paramamosain were reported for the first time.The data represented by the four species indicated that they had lower DNA contents than average DNA values in crustaceans((4.99±0.48) pg),and three of the four values were very similar if not identical.The results provide useful data for future studies in the fields of biodiversity,species conservation,and phylogeny of these commercial crabs.They will also be helpful in instructing the hybridization breeding program and estimating the cost of the whole genome sequencing project.