Intermediate-brightness spectrophotometric standards. Standards near +40° declination

The second stage in our program to compile a list of regional intermediate-brightness spectrophotometric standards has been completed. We have obtained spectral energy distributions for 24 stars with magnitudes $7\mathop m\limits_. 0 - 8\mathop m\limits_. 5$ near +40° declination. The range λλ3100–7600 Å was studied with a spectral resolution of 50 Å. The relative rms error of our results in the visible is 1–2%, increasing to 3–5% toward the edges of the studied wavelength interval. All the stars are referenced to a single standard, the circumpolar star HD 221525. The energy distributions were used to compute color indices in the UBV, WBVR, and UPXY ZV S systems, as well as in the system of the TYCHO catalog. The computed and observed values for stars in common with the TYCHO catalog are compared.     

The structure of the Precambrian and Lower Paleozoic basement of the Central Andes between 22° and 32°S. Lat.

Three major diastrophic cycles, defined by their structural style and their spatial distribution are recognized in the Andean Basement of this region. The oldest structures are related to the Panamerican Orogeny (500 to 700 m. a.) which produced in the Central Craton multiply deformed complexes of schists, gneisses and granites, that are covered discordantly by unmetamorphosed Cambrian and Ordovician beds. West of the Central Craton Ordovician sedimentary beds are folded with a simple structural style and intruded by granites. Both the sedimentry beds and the granites are covered discordantly by undeformed Devonian sequences. The folding of the Ordovician is attributed to the ocloyic phase of the Caledonian movements. West of the ocloyic belt is another foldbelt consisting of strongly folded Devonian beds attributed to the chanic phase (hercynian). The chanic belt is intruded by carboniferous and permian granites and covered discordantly by Carboniferous and Permian sequences.The features observed in the eastern slope of the Andes suggest that the Paleozoic foldbelts are intracratonic. Whether there are accreted terrains in the Pacific Coastal Cordillera is matter of controversy.

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Zusammenfassung Im Andenbasement dieser Region lassen sich drei diastrophische Hauptzyklen, die durch ihren strukturellen Baustil und ihre geographische Verbreitung definiert sind, unterscheiden. Die ältesten Strukturen sind verknüpft mit den Bewegungen der Panamerikanischen Orogenese (500–700 m. a.), welche im Zentralkraton einen polydeformierten Komplex von Schiefern, Gneissen und Graniten erzeugte. Diesem lagern diskordant kambrische und ordovizische Sequenzen ohne Metamorphose und präandiner Deformation auf. Nach Westen zu gibt es einen Gürtel stark deformierter ordovizischer Sedimente, die einen einfacheren Baustil als das präkambrische Basement aufweisen, und diskordant von undeformierten devonischen Abfolgen bedeckt sind. Die Faltung des Ordoviziums wird der Ocloyischen Phase der Kaledonischen Bewegung zugerechnet.Weiter westwärts tritt ein jüngerer Faltengürtel aus devonischen Sedimenten auf, die während der Chanischen Phase der Herzynischen Bewegung intensiv deformiert wurden, und von karbonischen und permischen Sequenzen diskordant überlagert sind.Der Ocloyische Gürtel ist von postordovizischen Graniten die von devonischen Schichten überlagert sind, und der Chanische Gürtel von karbonischen und permischen Graniten intrudiert. Im präkambrischen Basement des Zentralkratons treten einerseits präkambrische Granite auf, denen diskordant kambrische Schichten auflagern. Andererseits findet man Granite mit paläozoischen Isotopenaltern, letztere aber in Gebieten, wo wegen des Fehlens von Deckschichten eine stratigraphische Kontrolle unmöglich ist.Die gemachten Beobachtungen scheinen darauf hinzudeuten, daß die paläozoischen Faltengürtel intrakratonisch sind. Ob es allochtone »terrains« in der pazifischen Küstenkordillere gibt, ist Gegenstand der Kontroverse.

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Resumen En el basamento de los Andes de esta región se distinguen tres ciclos diastróficos mayores definidos por sus estilos estructurales y su distributión espacial. Las estructuras mas antiguas responden a movimientos que culminaron con la Orogénesis Panamericana (500–700 m. a.) que produjo en el Cratógeno Central un complejo de esquistos, gneises y granitos polideformados, al que se le superponen discordantemente secuencias cámbricas y ordovicicas sin metamorfismo ni déformatión preandina. Hacia el oeste hay un cinturón de sedimentos ordovícicos intensamente deformados con un estilo de plegamiento mas simple que el del basamento precámbrico y cubierto discordantemente por secuencias marinas devónicas sin deformatión. Los movimientos responsables de este plegamiento se atribuyen a la fase oclóyica de los movimientos caledónicos. Más hacia el oeste se manifiesta una franja de deformatión mas jóven atribuída a la Fase chánica de los movimientos hercínicos, en ella se encuentran sedimentitas devónicas intensamente plegadas cubiertas discordantemente por secuencias carbónicas y pérmicas.El cinturón oclóyico esta acompanãdo por granitos postordovícicos cubiertos por Devónico. Asimismo, el cinturón chánico (hercínico) esta intruido por granitos probablemente carbónicos. Con respecta a los granitos intruidos en el zócalo antiguo, hay algunos indudablemente precámbricos por estar cubiertos discordantemente por secuencias cámbricas sin metamorfismo, además hay granitos de edad dudosa que han dado valores isotópicos paleozoicos pero en lugares donde el control estratigráfico no es posible por ausencia de la cobertura paleozoica. De acuerdo a los hechos observados en la ladera oriental de los Andes surge la idea de que los cinturones de plegamiento paleozoicos son intracratónicos, aun es materia de controversia si en la Cordillera de la Costa junto al Pacifico hay terrenos alóctonos acrecionados.

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Carotenoid diagenesis in recent marine sediments—I. The Peru continental shelf (15°S, 75°W)

We report here the distribution of carotenoids in Peru marine surface sediments, including partial identification of 37 pigments, 33 of which have not been previously reported to occur in marine sediments. Our analysis demonstrates that zooplanktonic crustacea, diatoms, dinoflagellates, cryptomonads, purple nonsulfur photosynthetic bacteria, and unidentified species of photosynthetic bacteria are contributors to sedimentary organic matter. Fucoxanthin, fucoxanthinol, diadinoxanthin, peridinin and peridininol, the principal carotenoids of diatoms and dinoflagellates observed in sediment traps, are nearly absent from our sample, even though these phytoplankton are the primary source of organic matter. We attribute this to the presence of 5,6 epoxides in these pigments, a feature which causes rapid cleavage of the polyene and fragmentation to low molecular weight compounds.     

A sky survey at 102.5 MHz: Radio sources at declinations 27.5°–33.5° and 67.5°–70.5°

The results of observations on the Large Phased Array of the Lebedev Physical Institute made as part of a survey of the northern sky at 102.5 MHz are reported. Survey source lists for the declination ranges 27.5°–33.5° and 67.5°–70.5° are given, together with their coordinates, flux densities, and identifications with 4C objects. In total, there are 920 sources with flux densities S _102.5≥3.0 Jy in the two zones, which cover 0.73 star. The observing and data-reduction methods are described, and the reliability and completeness of the catalog are estimated.     

中国北方地区(33°～41°N,108°～115°E)过去500年夏季降水量的周期成分分析

利用连续小波分析和经验模态分解方法,对我国北方地区(33°～41°N,108°～115°E)1470 ～2002年每年夏季降水量指数的时间序列进行了周期成分分析,探索全球气候变暖下的该地区降水量的多尺度变化特征.小波分析表明,降水量指数的可能周期有2.57a,4.83a,10.65a,23.25a,48.56a,68.30a和105.90a的周期,在95％置信水平有统计意义的周期是2.57a和23.25a的周期.这些周期和自然因素导致的周期相联系,不仅包含了气候系统内部(平流层准2a振荡和厄尔尼诺/南方涛动)的非线性作用,还包含了气候系统外(主要是太阳活动)受强迫的周期变化,且二者在原始降水量中所在比重相当,共同反映了原始降水量的绝大部分变化.降水量不只是在百年尺度上受太阳活动的驱动,在数十年尺度上也受到太阳活动的影响.我国北方地区的夏季降水量指数和夏季温度指数同相位反相关,全球增温并没有明显地改变二者之间的反相关关系.近百年来全球变暖期间,夏季降水量出现明显的新特征:短周期成分(小于30a的周期)的振幅比以往要显著大,而长周期成分的振幅比以往要显著小,同时呈现降水量逐年减少的长期变化趋势.     

Giant radio-galaxy candidates at declinations from 3.5° to 12°

A search for extended radio sources with peak flux densities higher than 10 Jy at 110.6 MHz has been carried out, and two giant radio-galaxy candidates found. Data from a 24-hour survey in an area spanning ～8° in declination were used for the search.     

Sediment thickness map of the Indian region 79°E–86°E, 2°S–8°S based on satellite gravity interpretation

Satellite free air gravity anomalies over the Indian ocean region 79°E–86°E, 2°S–8°S were obtained from the website http://topex.ucsd.edu and a contour map was compiled. Five profiles of the anomaly have been interpreted in terms of two-dimensional structures in the ocean. Thickness of sediments lying on the oceanic crust determined from the interpretation of gravity profiles were used to compile an isopach map of the region 79°E–86°E, 2°S–8°S. This map in combination with one of the isopach maps compiled by previous workers, provides information regarding the thickness of sediments up to 6° S. According to this map sediment thickness varies from ～600 m over the middle part of the region to ～800 m further south, indicating that thinning of sediments in the middle part of the region is only localized. Information provided by this gravity study may be useful in planning detailed seismological studies to delimit the outer edge of the continental margin of Sri Lanka, defined according to the United Nations Convention of the Law of the Sea (UNCLOS).     

90°—75°勘探钻孔用的金属轻便钻塔

吉尔吉兹加盟共和国部长会议所属地质保矿管理局的地质勘探队1959年10月钻进90°—75°角的斜孔时,利用了由作者设计的金属轻便钻塔。     

Search for Dispersed Pulses at Declinations from +56° to +87°

Astronomy Reports - A survey of the northern hemisphere at the frequency 111 MHz is carried out. The total accumulation time for each point of the survey area was at least one hour. When searching...     

西南印度洋中脊48.6°~51.7°E沉积物地球化学特征

为了深入了解西南印度洋中脊调查区表层沉积物的物质来源和沉积环境,对大洋第30航次在该区域获取的21个表层沉积物样品进行了物相鉴定和主量元素、微量元素及稀土元素含量测试,分析结果显示,样品可分为Si质沉积物和Ca质沉积物两类,其中Si质沉积物富含Si、Mg、Fe、Al,稀土元素含量特征、轻重稀土元素分馏特征,以及稀土元素的北美页岩归一化曲线均表明沉积物保留了N-MORB的特征,主要为基性岩、超基性岩的风化产物;而Ca质沉积物富Ca、LOI、Sr,稀土元素以及微量元素之间的分配均指示沉积物物源为生源主导;所有站位均显示了两类沉积物不同程度的混杂,表明物质来源具有一定的多样性,调查区总体为稳定的偏氧化环境。     

La compression pré-campano-maastrichtienne dans le Mésozoïque des Andes de Bolivie : l’exemple de Tica Tica (20°01’lat. S et 66°17’ long. W)

Résumén

Dans la Cordillère Orientale des Andes de Bolivie, le Mésozoïque est eonservé le plus souvent dans des synclinaux discontinus, fréquemment chevauchés par des écailles de Paléozoïqne. Les sédiments mésozoïques, marins et continentaux de plateforme d’arrière-arc, ont jusqu’à présent été considérés comme déposés en régime extensif. Ils recouvrent en discordance le Paléozoïque plissé et l’aillé à l’Hercynien et, postérieurement, profondément érodé avant la sédimentation mésozoïque. Des paléofailles majeures N-S, NW-SE et NE-SW, héritées de structurations antérieures, ont influencé l’évolution géodynamique du bassin mésozoïque depuis la lin du Jurassique.

Dans la partie méridionale de la Cordillère Orientale, la région de Tica Tica présente de nombreux indices de serrage synsédimentaire depuis le début des dépôts mésozoïques jusqu’à la discordance campano-maastriehtienne (phase « péruvienne »). Le domaine de la Cordillère Orientale, avant-pays du bassin d’arrière-arc chiléno-péruvien, peut être ainsi interprété comme un secteur en compression sur lequel les transgressions successives, au Cénomanien, au Turonien et au Campano-Maastrichtien. soulignent divers instants d’un processus pratiquement continu de déformation.

Pendant le Tertiaire, les chevauchements andins réactivent les accidents majeurs préexistants : ils en inversent le mouvement, ou les déforment, ou bien les utilisent comme zones de coulissage. Ainsi, contrairement à ce qui a pu être proposé, le raccourcissement de la chaîne des Andes boliviennes, initié à la fin du Jurassique et faisant intervenir des fractures profondes, implique une participation, non seulement de la totalité de la pile séilimeutaire, mais très vraisemblablement aussi de son substratum précambrien comme c’est le cas dans le Nord-Ouest argentin.     

西南印度洋中脊45.3°E~56°E蚀变玄武岩地球化学

<正>大洋21航次第七航段在西南印度洋中脊45.3°E~56°E洋脊段采集了20个站位的玄武岩和橄榄岩等岩石样品。本文选择了10件新鲜的和发生不同程度蚀变的玄武岩进行岩石地球化学研究,探讨热液     

Dependence of albite dissolution kinetics on ph and time at 25°c and 70°c

The dissolution rate of albite has been measured as a function of pH and time at 25°C and 70°C in a single-pass flow-through leaching apparatus. Run times extended to 50 days in each experiment. Limited data were obtained at 25°C in the pH range 4–10. More extensive data were obtained at 70°C over the pH range 1.39–11.75.Dissolution rates were defined by release of Si, and in some cases also by Al and Na releases. Speciationsolubility calculations indicate the solutions were well undersaturated for all the likely possible secondary minerals. The fluid was maintained far from equilibrium with albite in all runs. Analysis of the data shows a general consistency with the transition state theory model of Helgesonet al. (1984).Feldspars leached at low and high pH at 70°C showed extensive development of prismatic etch pits demonstrating a surface reaction-controlled dissolution process.     

Untersuchungen über die Bildungsbedingungen von Quarz im Temperaturbereich zwischen 100° C und 250° C

The formation of quartz from amorphous silica under hydrothermal conditions has been investigated in the temperature range between 100° and 250°C. In this whole range and in an alkaline environment the conversion from amorphous silica occurs through two steps of intermediate phases. At first a hitherto unknown silica phase is formed: SiO₂-X (for X-ray patterns see Table 1). After this step α-cristobalite is crystallizing. The single phases are briefly described. The results of the experiments show a strong but mathematically not simple correlation between the rate of conversion and temperature. At higher temperature silica converts into quartz within several hours or days; at lower temperatures conversion rates measure in months and years. The influence of alkali concentrations and the influence of the type of starting materials on the course of reactions has been tested at several temperatures. With increasing alkali concentration time of reaction decreases always. If quartz fragments occur in the starting material the rate of conversion of all phases increases and the fragments grow in the solution. A certain correspondence between nature and experiments can be observed.     

Kaolinite and smectite dissolution rate in high molar KOH solutions at 35° and 80°C

Experiments measuring kaolinite and smectite dissolution rates were carried out using batch reactors at 35° and 80°C. No potential catalysts or inhibitors were present in solution. Each reactor was charged with 1 g of clay of the ≤2 μm fraction and 80, 160 or 240 ml of 0.1–4 M KOH solution. An untreated but sized kaolinite from St. Austell and two treated industrial smectites were used in the experiments. One smectite is a nearly pure montmorillonite, while the second has a significant component of beidellitic charge (35%). The change in solution composition and mineralogy was monitored as a function of time. Initially, the 3 clays dissolved congruently. No new formed phases were observed by XRD and SEM during the pure dissolution stage. The kaolinite dissolution is characterized by a linear release of silica and Al as a function of the log of time. This relationship can be explained by a reaction affinity effect which is controlled by the octahedral layer dissolution. Far from equilibrium, dissolution rates are proportional to a^0.56±0.12_OH⁻ at 35°C and to a^0.81±0.12_OH⁻ at 80°C. The activation energy of kaolinite dissolution increases from 33±8 kJ/mol in 0.1 M KOH solutions to 51±8 kJ/mol in 3 M KOH solutions. In contrast to kaolinite, the smectites dissolve at much lower rates and independently of the aqueous silica or Al concentrations. The proportionality of the smectite dissolution rate constant at 35 and 80°C was a^0.15±0.06_OH⁻. The activation energy of dissolution appears to be independent of pH for smectite and is found to be 52±4 kJ/mol. The differences in behavior between the two kinds of minerals can be explained by structural differences. The hydrolysis of the tetrahedral and the octahedral layer appears as parallel reactions for kaolinite dissolution and as serial reactions for smectite dissolution. The rate limiting step is the dissolution of the octahedral layer in the case of kaolinite, and the tetrahedral layer in the case of smectite.     

Petrogenetic conditions at 18°–20° N MAR: Interaction between hydrothermal and magmatic systems

The paper presents petrological and geochemical data on mantle peridotite, basalt, and metamorphic rocks sampled in Cruise 36 of the R/V Professor Logachev at the MAR axial zone between 17° and 20° N. These data are interesting not only as providing new information on the inner structure of the oceanic crust in the still-poorly known axial MAR segment but also in the context of the fundamental problem of interaction between magmatic and hydrothermal systems in slow-spreading mid-oceanic ridges. The MAR axial zone between 17° and 20° N was determined to host both weakly and strongly depleted residual peridodites, which suggests that the degree of mantle source melting significantly varied along the ridge axis in this segment. The MAR crest zone comprises slabs of serpentinized peridotite brought to the seafloor surface at various time. The most strongly depleted mantle peridotites likely uplifted later than the mildly and weakly depleted rocks in the same areas. A mantle reservoir beneath the MAR axial zone at 20° N is not isotopically related to the mantle source of the parental MORB melts, and high-Mg metabasites exposed at 17°56- N were derived from a crustal source that was modified near the root zone of a high-temperature hydrothermal system. The studied area seems to display traces of an extinct hydrothermal field and likely an ore occurrence related to it.