Quaternary evolution of Cedar Creek alluvial fan, montana

Cedar Creek alluvial fan is a textbook example of an alluvial fan because of its fan shape with smooth, concentric contours and excellent symmetry. Similar planimetric shapes have been used to infer uniform fan deposition; however, Cedar Creek alluvial fan is composed of four fan deposits of Quaternary age, Qf1 (oldest) to Qf4 (youngest), indicating that fan deposition was nonuniform in both time and space. Field studies indicate that deposition of Cedar Creek alluvial fan is related to glaciofluvial outwash activity during the Pleistocene and upper-fan entrenchment and lower-fan deposition during the Holocene.Qf1 and Qf2 deposits are sub-horizontally bedded, clast-supported sandy gravels uniformly imbricated upfan. Comparison of soil profiles developed in these deposits to radiogenically-dated chronosequences within the region indicates that Qf1 and Qf2 are correlative with Bull Lake and Pinedale-age deposits, respectively. These relationships are substantiated by physical correlation of Qf1 and Qf2 with Bull Lake and Pinedale moraines, respectively, in the Cedar Creek drainage basin. The sedimentology and timing of Qf1 and Qf2 indicate deposition in high-energy, proglacial, braided streams. Furthermore, the present morphology of Cedar Creek alluvial fan was established largely during aggradation of Qf1 and Qf2 when sediment supply to the fan was sufficient to activate 60% to greater than 90% of the total fan area. During Bull Lake glaciation, the apex of Qf1 deposition formed the apex of Cedar Creek alluvial fan as Qf1 covered more than 90% of the present fan area. During Pinedale glaciation, Qf2 deposition shifted downfan; Qf2 is inset into Qf1 above the intersection point, but below the intersection point it eroded and/or buried Qf1 as it activated as much as 60% of the fan area.Qf3 and Qf4, comprising 21% of the fan area, are inset into Qf2 in the lower fan area. Soil development in Qf3 and Qf4 deposits indicate episodic deposition and entrenchment beginning in early Holocene and continuing to present. A post-glacial decrease in sediment supply to Cedar Creek alluvial fan is indicated by sediment storage within the Cedar Creek drainage basin. Decreased sediment supply to the fan resulted in upper-fan entrenchment of Qf2 and deposition of Qf3 and Qf4 in the lower-fan area.     

Experience of geographical typology of secularization processes in the modern world

In the modern world, seven geographical types of development of secularization processes have been identified; the level of secularization is determined not only by the maturity of social space but also by the structure of geospace. The Latin type includes some countries of Southern and Western Europe, most of the population of which confess Catholicism. The countries of the Anglo-Scandinavian type are characterized by Protestant pluralism. The polarized type combines countries and territories in which Protestants and Catholics form stable, influential and competing blocs. The countries in which the secularization processes were unable to seriously shake the influence of religion in society, because it is the institute of church that was resisting the political and cultural infringement by neighboring states over centuries, refer to the type of religious infringement. The resettlement type is characteristic for the countries whose population was being formed as a result of migration of various confessional (primarily Protestant) groups. The post-socialist type includes the countries in which an active policy of not infrequently forced “political” secularization was pursued. The Confucianistic type combines the states, most of the population of which was pursuing various religious-cultural traditions, with Confucianism predominating in general, and with a widespread occurrence of polyconfessionalism. This geographical typology of secularization embraces the countries, the communities of which have gone through the stages of secular development. The spatial boundedness of the secularization processes in the world is determined by the fact that secularization itself is the product primarily of the entire Christian European civilization.     

Sediment storage and release from Himalayan piggyback basins and implications for downstream river morphology and evolution

Piggyback basins developed at the mountain fronts of collisional orogens can act as important, and transient, sediment stores along major river systems. It is not clear, however, how the storage and release of sediment in piggyback basins affects the sediment flux and evolution of downstream river reaches. Here, we investigate the timing and volumes of sediment storage and release in the Dehra Dun, a piggyback basin developed along the Himalayan mountain front in northwestern India. Based on OSL dating, we show evidence for three major phases of aggradation in the dun, bracketed at ca. 41–33 ka, 34–21 ka and 23–10 ka, each accompanied by progradation of sediment fans into the dun. Each of these phases was followed by backfilling and (apparently) rapid fan‐head incision, leading to abandonment of the depositional unit and a basinward shift of the active depocentre. Excavation of dun sediment after the second and third phases of aggradation produced time‐averaged sediment discharges that were ca. 1–2% of the modern suspended‐sediment discharges of the Ganga and Yamuna rivers that traverse the margins of the dun; this sediment was derived from catchment areas that together comprise 1.5% of the drainage area of these rivers. Comparison of the timing of dun storage and release with upstream and downstream records of incision and aggradation in the Ganga show that sediment storage in the dun generally coincides with periods of widespread hinterland aggradation but that late stages of dun aggradation, and especially times of dun sediment excavation, coincide with major periods of sediment export to the Ganga Basin. The dun thus acts to amplify temporal variations in hinterland sediment supply or transport capacity. This conceptual model appears to explain morphological features of other major river systems along the Himalayan front, including the Gandak and Kosi Rivers, and may be important for understanding sediment flux variations in other collisional mountain belts.     

A preliminary investigation of siliceous microfossil succession in late Quaternary sediments from Lake Baikal, Siberia

Siliceous microfossil assemblage succession was analyzed in a 100 m sediment core from Lake Baikal, Siberia. The core was recovered from the lake's central basin at a water depth of 365 m. Microfossil abundance varied greatly within the intervals sampled, ranging from samples devoid of siliceous microfossils to samples with up to 3.49 × 10¹¹ microfossils g^-1 sediment. Fluctuations in abundance appear to reflect trends in the marine ¹⁸O record, with peak microfossil levels generally representing climate optima. Microfossil taxa present in sampled intervals changed considerably with core depth. Within each sample a small number of endemic diatom species dominated the assemblage. Changes in dominant endemic taxa between sampled intervals ranged from extirpation of some taxa, to shifts in quantitative abundance. Differences in microfossil composition and the association of variations in abundance with climate fluctuations suggest rapid speciation in response to major climatic excursions.     

The Seyfert 1 galaxy Ark 120. Spectral variability in 1992–2005

We have studied the variability of the Hβ line and the adjacent continuum in the spectrum of the Seyfert galaxy Ark 120, based on spectral observations of the galaxy’s nucleus obtained in the Crimea in 1992–2005, supplemented by published data for 1988–1996. Irregular variability on various timescales (years to days) can be accompanied by periodic brightness variations in both the continuum and the Hβ line, with a period of P ～ 430 days and an amplitude of Δm ～ 0.2 ^m in the continuum, which were traced for more than 13 cycles. In total, in 1988–2005, the flux variations in the line lag those in the continuum by 55 ± 9 days if calculated from the peak of the cross correlation function, or by 72 ± 7 days, if calculated from the centroid of the CCF. The delay is correlated with the continuum brightness, increasing when the continuum flux increases. The Hβ line profiles indicate both a high degree of diversity and the presence of features that recur after various extended time intervals. Analysis of the evolution of the differences between each individual normalized line profile and the mean normalized profile indicates systematic motion of excesses relative to the average profile from negative to positive radial velocities. In contrast, parts of the Hβ line with low radiation relative to the mean normalized profile evolve in the opposite direction (from the red to the blue Hβ wing). This pattern is also typical for the rotating broad-line region, if this region has the form of a disk. The rotation period exceeds 9000–10000 days, or 25–27 years. The size of the broad-line region calculated form this period corresponds to a reverberation time of no fewer than 30 days, consistent with the results of cross-correlation analysis.     

Evaluation of effective management plan for an agricultural watershed using AVSWAT model,remote sensing and GIS

In the present investigation, an effort has been made to identify the critical sub-watersheds for the development of best management plan for a small watershed of Eastern India using a hydrological model, namely, AVSWAT2000. A total of 180 combinations of various management treatments including crops (rice, maize ground nut and soybean), tillage (zero, conservation, field cultivator, mould board plough and conventional practices) and fertilizer levels (existing half of recommended and recommended) have been evaluated. The investigation reveled that rice cannot be replaced by other crops such as groundnut, maize, mungbean, sorghum and soybean since comparatively these crops resulted in higher sediment yield. The tillage practices with disk plough have been found to have more impact on sediment yield and nutrient losses than conventional tillage practices for the existing level of fertilizer. Sediment yield decreased in the case of zero tillage, conservation tillage, field cultivator, moldboard plough, and conservation tillage as compare to conventional tillage. Lowest NO₃–N loss was observed in zero tillage in all the fertilizer treatments, whereas field cultivator, moldboard plough and disk plough resulted in increase of NO³–N loss. As compared to conventional tillage, the losses of soluble phosphorus were increased in moldboard plough. The losses of organic nitrogen were also increased as fertilizer dose increased. After zero tillage the conservation tillage preformed better in all the fertilizer treatments as per loss of organic nitrogen and organic phosphorus is concerned. It can be concluded that the sediment yield was found to be the highest in the case of disk plough followed by moldboard plough, field cultivator, conventional tillage, field cultivator and least in zero tillage practices. The nutrient losses were found to be in different order with tillage practices, resulted highest in disk plough tillage practices. In view of sediment yield and nutrient losses, the conservation tillage practice was found to be the best as the sediment yield is less than the average soil loss whereas nutrient loss is within the permissible limit.     

Recent trends in estuarine fisheries: Predictions of fish production and yield

Trends in global and United States fish catches were examined to determine the status of estuarine fisheries yields relative to those from other ecosystems. Potential marine fish production, based upon primary production relationships, was estimated globally and for specific marine ecosystems, including estuaries. While global fish catches increased substantially during the past two decades and continued to increase through 1989, catches of estuarine-dependent species have peaked or stabilized. In the United States, total catches have increased but many estuarine-dependent fisheries have declined, although the declines in catches are no more dramatic than those of heavily-fished continental shelf species. Overfishing probably is the primary cause of declines in estuarine and shelf fisheries. A few estuarine-dependent species of the United States have experienced substantial increases in harvests since 1970, for example, Pacific salmons, menhaden, and penaeid shrimps. The percentage contribution of major estuarine fisheries to the United States commercial catch declined between 1970 and 1990, although the yield of these species increased substantially. Global marine fisheries production at trophic level 2.5 was estimated to be 1,359 million tons. Potential yield was estimated to be 307 million tons, but the 1989 world marine catch was only 86.5 million tons. The major fraction, 196 million tons, of the estimated potential yeild was for the open ocean where technological constraints may prevent its full realization. Of the remaining 111 million tons of the potential, 18.0 million tons (16.2%) may come from estuaries and probably already is fully exploited. The potential catches from shelves, 68.5 million tons (61.6%), and upwelling areas, 24.8 million tons (22.2%), while considerably larger than those from estuaries, are lower in a relative sense (per unit area) than fisheries production and potential catch in estuarine zones. Relationships between fish production, fish harvest, and primary production were examined in specific estuaries. The developing role of aquaculture and its effect on estuarine fisheries are discussed.     

Magma mixing,the petrogenetic link between anorthositic suites and rapakivi granites, Åland,SW Finland

Summary The Åland, rapakivi batholith consists of several granites that differ texturally and mineralogically from quartz-porphyritic varieties to rapakivi varieties with K-feldspar ovoids (wiborgites and pyterlites) and aplitic granites. Closely associated with the batholith there is a mafc magmatic series of dolerite dykes, norites, anorthosites and monzodiorites.The earliest major intrusive phase of the Åland, rapakivi batholith consists of quartzporphyritic hornblende rapakivi. This rock contains small amoeboidal mafc enclaves, labradorite megacrysts, quartz ocelli, amphibole-mantled xenoliths and irregular clots of granophyric granite. These disequilibrium features are products of mixing between basaltic and granitic magmas. Geochemical modelling indicates that the quartzporphyritic hornblende rapakivi is a mixture of 15% hi-Fe monzodiorite (mafic endmember) and 85% quartz-feldspar porphyry (felsic end-member). The monzodiorite is derived from a norite-anorthosite-monzodiorite series. The quartz-feldspar porphyry is produced by partial melting of the country rock caused by intrusions of hot basic magma.Structural, textural and geochemical features suggest that magma mixing was an important petrogenetic process in the formation of the earliest rapakivi granite intrusions in the Åland, rapakivi batholith. Petrographic evidence of magma mixing can also be found in the major intrusion of the batholith, the wiborgite rapakivi granites. Chemically the mixing is difficult to specify in these rocks because of a high proportion of felsic component. Zircon and apatite fractionation trends, however, indicate that the wiborgite rapakivis also contain components from a mixed source.

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Magmamixing, die petrogenetische Verbindung zwischen Anorthositen und RapakiviGraniten, Åland, SW Finnland

Zusammenfassung Der Rapakivi Batholit von Åland besteht aus verschiedenen Graniten, die in ihrer Textur und Zusammensetzung das Feld von quarzporphyritischen über Rapakivigranite mit K-Feldspat-Ovoiden (Wiborgite und Pyterlite) und aplitischen Graniten abdecken. Eine mafische magmatische Serie von Dolerit-Gängen, Noriten, Anorthositen und Monzodioriten ist mit diesen Batholiten eng verbunden.Die erste größere Intrusivphase des Åland, Rapakivi Batholiten besteht aus quarzporphyritischem Hornblende Rapakivi. Dieses Gestein enhält kleine Amöboide, mafische Enklaven, Labradorit Megakristalle, Quarzocelli, Xenolithe mit Amphibolrändern und unregelmäßige Aggregate von granophyrischem Granit. Diese Produkte von Ungleichgewichts-Bedingungen gehen auf die Mischung zwischen basaltischen und granitischen Magmen zurück. Geochemische Modelle zeigen, daß der quarzporphyritische Hornblende-Rapakivi eine Mischung von 15%. eisenreichen Monzodiorit (mafisches Endglied) und 85% Quarz-Feldspatporphyr (felsisches Endglied) ist. Der Monzodiorit stammt von einer Norit-Anorthosit-Monzodiorit Serie. Der QuarzFeldspat-Porphyr entstand durch teilweise Aufschmelzung des Nebengesteines, die durch Intrusionen heißen basischen Magmas verursacht wurden.Strukturelle, texturelle und geochemische Daten zeigen, daß Magmamischung ein wichtiger petrogenetischer Prozeß der Bildung der frühesten Rapakivi-Granit-Intrusionen im Åland, Batholith waren. Petrographische Hinweise auf Magmamischung können auch in der größten Intrusion des Batholiths, dem Wiborg Rapakivi Granit, gefunden werden. Wegen des hohen Anteils felsischer Komponenten ist es schwierig, das Magmamixing in diesen Gesteinen chemisch zu quantifizieren. Zirkon- und Apatitfraktionierungs-Trends weisen jedoch darauf hin, daß auch die WiborgitRapakivis Komponenten aus einer gemischten Quelle enthalten.

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Formation Conditions of Host Rocks and Veins of Productive Deposits of the Astrakhan Gas–Condensate Field

Doklady Earth Sciences - One- (gas) and two-phase (aqueous solution plus gas) inclusions are studied in calcite taken from the Cheremshan horizon of the Bashkirian stage at a depth of...