朝鲜海峡南部中陆架海侵沙脊在高能环境中的形成和发育

1　地质背景研究区为韩国海南部水深 60 ~ 100 m 的中陆架中部。韩国海南部陆架为构造上稳定、冰后期被淹没的浅水陆架(水深<120 m),陆源碎屑沉积厚。这些厚层沉积物显示了区域倾斜的前积层层理,表明它们为三角洲来源或浅水来源,尤其是晚第四纪沉积形成高频沉积层序,包含了一套与末次海平面循环(< 30 000aBP)相响应的低海面、海侵和高海面沉积(Yooand Park,2000)。低海面和高海面沉积分别位于外陆架和内陆架,而海侵沉积在陆架上分布广。海侵沉积可分为 5 个地层单元(Yoo andPark,2000),包括:①中陆架海侵层;②中陆架沙脊;③横切水道填…     

DNA adducts and polycyclic aromatic hydrocarbon (PAH) tissue levels in blue mussels (Mytilus spp.) from Nordic coastal sites

DNA adducts in gills and digestive gland, as well as polycyclic aromatic hydrocarbon (PAH) tissue levels were analysed in blue mussels (Mytilus spp.) from Nordic coastal areas (Iceland, Norway and Sweden) with diffuse or point sources of PAHs of various origins. Both DNA adduct and PAH tissue levels were generally low, indicating low PAH exposure to the mussels in the areas studied. DNA adducts were found to be higher in gills than in digestive gland of the mussels at all sites studied. Elevated DNA adduct levels in gills were found at 6 sites out of 18 compared to reference sites in respective coastal zones. Adduct levels ranged from 0.5 to 10 nmol adducts/mol normal nucleotides, being highest in mussels from Reykjavík harbour, Iceland (intertidal mussels), and from Fiskaatangen, Norway (subtidal mussels). Total PAH tissue levels in the mussels ranged between 40 and 11,670 ng/g dry wt., and were significantly correlated with DNA adduct levels (r(2)=0.73, p<0.001). PAH ratio values indicated that the PAHs were in most cases of pyrolytic origin, but with petrogenic input near harbours and an oil refinery.     

印度洋多金属结核地质特征与资源潜力

通过在中印度洋海盆结核区外的印度洋其他海域内收集到的298处多金属结核站位的分布、成分和赋存环境等地质特征,圈定了5处资源潜力区.文章对这些区域内海洋长周期沉积速率、底层水含氧量、底质类型、夏季海面平均生物生产力、底栖宏生物量密度、海底地形地貌特征和海底表层沉积物有机碳含量等数据信息进行加权评估,揭示各区域结核分布密度的高低状况,辅以结核主要有用组分含量的分类,确定了印度洋内各结核区资源潜力的划分标准.笔者认为加斯科因平原结核区为印度洋多金属结核高资源潜力区,马达加斯加海盆结核区和南澳大利亚海盆西部结核区为中等资源潜力区,克洛泽海盆结核区和南澳大利亚海盆东部结核区为低资源潜力区.未来在这些区域内,尤其是加斯科因平原结核区中有希望通过进一步调查研究,精确锁定具有更高资源潜力的次级面积结核勘探区,检验和完善资源潜力评估方法,精细量化揭示这些区域的资源潜力.     

侵蚀模型中的遍历理论

引言地貌学家用了20多年的时间先后建立了一些相当复杂的坡面侵蚀模型。例如,杨(Young.1972)总结了四类坡面演化模型:(1)根据直线后退建立的模型;(2)根据蠕动和流动机制建立的模型;(3)涉及形态相互作用的模型;(4)根据过程量测建立的模型。在前两个模型中,明显存在一种可以得出两个基本方程的逼近收敛性:(?)y/(?)t=-b((?)y/(?)x)。(1)式中 y 为高度;t 为时间:x 为位置,以距分水岭的长度来表示;b 为正常数。这个方程显然是描述坡面随时间变化而平行后退的现象,故 b 被称为“后退系数”。     

四颗南天脉冲星在1560 MHz上的偏振观测

本文给出88年6月和7月期间在澳大利亚Parkes进行的一次南天脉冲星偏振观测的部分有意义的结果。频率为1560MHz。采用了Jodrell Bank天文台新研制成的2×16×5MHz滤波系统,使这次观测具有很强的消色散能力和较高的灵敏度。这4颗南天脉冲星具有较强的线偏振,为首次获得的高频偏振资料。     

A Scheme for Objective Analysis of Wind Field Incorporating Multi-Weighting Functions in the Optimum Interpolation Method

A method of objective analysis scheme having three different weighting functions for different conditions of the wind flow has been developed for the Indian region, two of which are anisotropic and third one is isotropic. Basically Gandin’s Optimum Interpolation method is used. The “effective” distance between a grid point and observation point used for the anisotropic functions, has been applied to calculate weighting functions following Benjamin and Seaman (1985) and objective analyses were made at the 700 hPa level for three consecutive days from 6 July to 8 July 1979. The quantitative evaluation of the objectively analysed fields have been made by computing the R.M.S. errors. Ana-lyses obtained using multi-weighting functions (anisotropic) and those obtained using ordinary circular functions (isotropic-Gandin, 1963) have been compared. Also, the centres of the monsoon depressions obtained by this method have been compared with those of subjective analyses.     

值得重视的海域海相油气勘探

当前我国海域油气的勘探领域和勘探层位大部分局限于新生界,而对古生代海相地台沉积、特提斯海相沉积、南海生物礁、南海和冲绳等深水盆地领域的勘探涉足不深。通过海域海相油气的地质调查与研究以及新区评价,认为在我国海域拓宽找油的战略选区,力争海域海相油气勘探获得突破、发现储量规模大的整装油田是有可能的。     

He,Ne and Ar isotopic composition of Fe-Mn crusts from the western and central Pacific Ocean and implications for their genesis

The noble gas nuclide abundances and isotopic ratios of the upmost layer of Fe-Mn crusts from the western and central Pacific Ocean have been determined. The results indicate that the He and Ar nu- clide abundances and isotopic ratios can be classified into two types: low 3He/4He type and high 3He/4He type. The low 3He/4He type is characterized by high 4He abundances of 191×10-9 cm3·STP·g-1 on average, with variable 4He, 20Ne and 40Ar abundances in the range (42.8―421)×10-9 cm3·STP·g-1, (5.40―141)×10-9 cm3·STP·g-1, and (773―10976)×10-9 cm3·STP·g-1, respectively. The high 3He/4He samples are characterized by low 4He abundances of 11.7×10-9 cm3·STP·g-1 on average, with 4He, 20Ne and 40Ar abundances in the range of (7.57―17.4)×10-9 cm3·STP·g-1, (10.4―25.5)×10-9 cm3·STP·g-1 and (5354―9050)×10-9 cm3·STP·g-1, respectively. The low 3He/4He samples have 3He/4He ratios (with R/RA ratios of 2.04―2.92) which are lower than those of MORB (R/RA=8±1) and 40Ar/36Ar ratios (447―543) which are higher than those of air (295.5). The high 3He/4He samples have 3He/4He ratios (with R/RA ratios of 10.4―12.0) slightly higher than those of MORB (R/RA=8±1) and 40Ar/36Ar ratios (293―299) very similar to those of air (295.5). The Ne isotopic ratios (20Ne/22Ne and 21Ne/22Ne ratios of 10.3―10.9 and 0.02774―0.03039, respectively) and the 38Ar/36Ar ratios (0.1886―0.1963) have narrow ranges which are very similar to those of air (the 20Ne/22Ne, 21Ne/22Ne, 38Ar/36Ar ratios of 9.80, 0.029 and 0.187, respectively), and cannot be differentiated into different groups. The noble gas nuclide abundances and isotopic ratios, together with their regional variability, suggest that the noble gases in the Fe-Mn crusts originate primarily from the lower mantle. The low 3He/4He type and high 3He/4He type samples have noble gas characteristics similar to those of HIMU (High U/Pb Mantle)- and EM (Enriched Mantle)-type mantle material, respectively. The low 3He/4He type samples with HIMU-type noble gas isotopic ratios occur in the Magellan Seamounts, Marcus-Wake Seamounts, Marshall Island Chain and the Mid-Pacific Sea- mounts whereas the high 3He/4He type samples with EM-type noble gas isotopic ratios occur in the Line Island Chain. This difference in noble gas characteristics of these crust types implies that the MagellanSeamounts, Marcus-Wake Seamounts, Marshall Is- land Chain, and the Mid-Pacific Seamounts originated from HIMU-type lower mantle material whereas the Line Island Chain originated from EM-type lower mantle material. This finding is consistent with varia- tions in the Pb-isotope and trace element signatures in the seamount lavas. Differences in the mantlesource may therefore be responsible for variations in the noble gas abundances and isotopic ratios in the Fe-Mn crusts. Mantle degassing appears to be the principal factor controlling noble gas isotopic abundances in Fe-Mn crusts. Decay of radioactive isotopes has a negligible influence on the nuclide abundances and isotopic ratios of noble gases in these crusts on the timescale of their formation.