行星磁场与卫星引力及其相对运动的统计关系

从知道某些天体具有磁场起，人们就对其磁场的起源提出种种解释，例如有电池说，转子说，化石说，发电机说等等。但由于这些学说都分别与某些观测事实相抵触而未被公认，因此星球磁场的起源一直是未能解决的命题。余先河先生提出，星球的磁场起源可能与所受的引力有关，行星的磁场强度正比于其所受卫星的引力；正比于卫星与行星的引力连线转动的相对角速度。本文对这两方面的命题分别进行了相关分析，得到其相关系数分别为：ｒ＝０．８４８１和ｒ＝０．８４２５，它们都在ａ＝０．０１的信度水平上相关。结果表明余新河关于行星磁场起源的设想是有基础的。本文还对其统计结果和可能机制进行了讨论。     

Upwelling and river runoff as sources of dissolved nitrous oxide to the Alsea estuary,Oregon

Surface waters of Alsea Bay, an unpolluted estuary on the Oregon coast, were analysed for nitrous oxide, nitrate and nitrite on a weekly or biweekly basis during the summer of 1979. The estuary was found to be a variable source of N₂O to the atmosphere. Large and rapid increases in the concentrations of N₂O, NO₃^?, and NO₂^? occurred at the beginning of the sampling period and are attributed to the influx of nutrient-rich upwelling water into the estuary with the tide. The subsequent decline in concentrations of nitrate, nitrite and nitrous oxide over the remainder of the summer is attributed to a decrease in upwelling intensity, a decline in nitrification rates and to assimilatory nitrate reduction. Measurements of nitrous oxide at six stations along the Alsea River were also made in September and October before and after the onset of the rainy season. Samples taken after flood conditions were established were systematically 50% higher than pre-flood samples. The data suggest that soil runoff results in elevated concentrations of N₂O in rivers.     

Electric Discharges in the Protoplanetary Nebula as a Source of Impulse Magnetic Fields to Promote Dust Aggregation

Lightning discharge generated in the protoplanetary nebula is viewed as a temporally isolated surge in the flow of electrically charged particles, similar to that of terrestrial lightning. If the current is intense enough, a powerful circular impulse magnetic field is generated around the instantaneous virtual electric conductor. Such magnetic field is capable of magnetizing dust grains containing ferromagnetic components present in its vicinity to their saturation levels. As a result, dust grains attract one another, forming the aggregates. This magnetically driven attraction suggests an important process possibly operational at an early stage of the planetary accretion. Based on both a classical model for electric conductor, and the theory of Lienard–Wiechert electromagnetic potentials, our calculations show that the magnetic impulse due to a discharge channel of a few cm in diameter transferring a charge of about 10⁴ electrons reaches as high as 10 T. At these magnetic fields, the ferromagnetic dust grains, and possibly the already-formed larger aggregates as well, are easily magnetized to the saturation levels, producing compact clusters exhibiting permanent magnetic moments.     

今后几年的月球探测和月球科学

近年来月球探测已经进入了一个全新的时代。特别是 1 990年以来 ,多个月球探测计划已经被成功实现 ,而且另外还有多个探测计划也在准备当中 ,并将在未来的几年内发射升空。在这种背景之下 ,中国的航天机构和有关的科学家也开始积极酝酿和开发自己的月球探测计划。这些月球探测计划将利用卫星上搭载的各种仪器探测和测量月球的地质和地理特性、化学成分和矿物组成、月球物理学特征以及包含地球大气在内的地月空间环境和行星际空间环境 ;进一步研究月球的起源和演化 ,探明月面环境 ,研究太阳等离子体物理 ,提供月面天文台和月面长期科研基地的候选地址 ,调查月球上的可利用资源 ,为将来开发月球提供充实的背景资料。参与新一轮的月球探测同样也为中国天文学研究带来了新的机会。     

宁远保安地区基性─超基性火山岩基本特征

本文论述了保安地区火山岩的地质、岩石、副矿物、岩石化学、微量元素、稀土元素、稳定同位素、火山岩相及火山机构等特征。并对其演化规律、形成机制与成矿作用的关系，作了初步探讨。     

Extensional tectonic origin of gneissosity and related structures of the Feiran–Solaf metamorphic belt, Sinai, Egypt

The Feiran–Solaf metamorphic belt consists of low-P high-T amphibolite facies, partly migmatized gneisses, schists, amphibolites and minor calc-silicate rocks of metasedimentary origin. There are also thick concordant synkinematic sheets of diorite, tonalite and granodiorite orthogneiss and foliated granite and pegmatite dykelets. The gneissosity (or schistosity) is referred to as S₁, and is almost everywhere parallel to lithological layering, S₀. This parallelism is not due to transposition. The gneissosity formed during an extensional tectonic event (termed D1), before folding of S₀. S₁ formed by coaxial pure shear flattening strain (Z normal to S₀, i.e. vertical; with X and Y both extensional and lying in S₁). This strain also produced chocolate tablet boudinage of some layers and S₁-concordant sills and veins. S₁ has a strong stretching lineation L₁ with rodding characteristics. Within-plane plastic anisotropy (lower ductility along Y compared to along X) resulted in L₁-parallel extensional ductile shears and melt filled cracks. Continued shortening of these veins, and back-rotation of foliations on the shears produced intrafolial F₁ folds with hinges parallel to the stretching lineation. F₁ fold asymmetry variations do not support previous models involving macroscopic F₁ folds or syn-gneissosity compressional tectonics. The sedimentary protoliths of the Feiran–Solaf gneisses were probably deposited in a pre-800 Ma actively extending intracratonic rift characterizing an early stage of the break-up of Rodinia.     

Zircon U–Pb ages, Hf and O isotopes constrain the crustal architecture of the ultrahigh-pressure Dabie orogen in China

The crustal structure of the Dabie orogen was reconstructed by a combined study of U–Pb ages, Hf and O isotope compositions of zircons from granitic gneiss from North Dabie, the largest lithotectonic unit in the orogen. The results were deciphered from metamorphic history to protolith origin with respect to continental subduction and exhumation. Zircon U–Pb dating provides consistent ages of 751 ± 7 Ma for protolith crystallization, and two group ages of 213 ± 4 to 245 ± 17 Ma and 126 ± 4 to 131 ± 36 Ma for regional metamorphism. Majority of zircon Hf isotope analyses displays negative ε_Hf(t) values of − 5.1 to − 2.9 with crust Hf model ages of 1.84 to 1.99 Ga, indicating protolith origin from reworking of middle Paleoproterozoic crust. The remaining analyses exhibit positive ε_Hf(t) values of 5.3 to 14.5 with mantle Hf model ages of 0.74 to 1.11 Ga, suggesting prompt reworking of Late Mesoproterozoic to Early Neoproterozoic juvenile crust. Zircon O isotope analyses yield δ¹⁸O values of − 3.26 to 2.79‰, indicating differential involvement of meteoric water in protolith magma by remelting of hydrothermally altered low δ¹⁸O rocks. North Dabie shares the same age of Neoproterozoic low δ¹⁸O protolith with Central Dabie experiencing the Triassic UHP metamorphism, but it was significantly reworked at Early Cretaceous in association with contemporaneous magma emplacement. The Rodinia breakup at about 750 Ma would lead to not only the reworking of juvenile crust in an active rift zone for bimodal protolith of Central Dabie, but also reworking of ancient crust in an arc-continent collision zone for the North Dabie protolith. The spatial difference in the metamorphic age (Triassic vs. Cretaceous) between the northern and southern parts of North Dabie suggests intra-crustal detachment during the continental subduction. Furthermore, the Dabie orogen would have a three-layer structure prior to the Early Cretaceous magmatism: Central Dabie in the upper, North Dabie in the middle, and the source region of Cretaceous magmas in the lower.     

Microbial Diversity in Nankai Trough Sediments at a Depth of 3,843 m

Dense populations of bivalves, primarily Calyptogena sp., were observed at cold seeps of the Nankai Trough. Bacterial input to the sediment was estimated through determination of phospholipid ester-linked fatty acid (PLFA) and DNA profiles. Results indicated a bacterial biomass of 10⁹ cells (g dry wt)^-1 while individual fatty acid profiles revealed a predominance of monounsaturated fatty acids, mainly 18:1 isomers. The presence of these fatty acids can be interpreted to reflect a response to low temperature and a predominance of psychrophilic bacteria. DNA fragments encoding bacterial ribosomal RNA small-subunit sequences (16S rDNA) were amplified by the polymerase chain reaction method using DNA extracted directly from the sediment samples. From the sequencing results, at least 19 kinds of bacterial 16S rDNAs related to mostly the Proteobacteria and a few gram-positive bacteria were identified. These results suggest that the bacterial community in the Nankai Trough sediments consists of mainly bacteria belonging to the Proteobacteria , , and subdivisions. Bacteria belonging to the and subdivisions, which are known to include epibiont and sulfate reducing bacteria, respectively, were mostly detected in the sediment obtained from inside the area of the Calyptogena community, and the -Proteobacteria may function to supply reduced sulfur to bacterial endosymbionts of Calyptogena.     

Origin and evolution of alkali basaltic magma in the Okinawa Trough

I~IOXThe Okinawa Trough is an extending back--arc basin between the East China Sea Shelf andthe Ry'Ukyu Island Arc of Japan. There are widespreadly distributing acid pumice in the troughand a little basalt just in some area of the extending center. There have been some detailed rePOrtsabout the mineralogy and petrochemical feature of the subalkali tholeiite and alkali trachyte in thetrough (Zhai and Gan, 1995; Li et al., 1997; Qin and Zhai, 1988). This paper mainly reportselectron mic…