Anwendungsmöglichkeiten der Guinier-Kamera nach v. Wolff bei der röntgenographischen Tonuntersuchung

Ohne Zusammenfassung     

Geology, geochemistry and petrogenesis of intrusive rocks of the Wallagga area, western Ethiopia

Crystalline rocks from the western Ethiopian Precambrian terrain comprise two major rock groups: (1) the often migmatised eastern and western high-grade gneisses; and (2) the central low-grade metavolcanosedimentary rocks. Granitoid bodies of different ages and compositions intrude these rocks. Field observations, petrographic investigations, and geochemical features support a two-fold classification of the granitoid rocks. The volcanic arc granitoids (VAG) are most common and include the Ujjukka granite and granodiorite, and the Dhagaa Booqa and Guttin K-feldspar megacrystic granites. The second and geographically more restricted group represents within-plate or anorogenic (A-type) granitoids, typified by the Tullu Kapii syenite. Geochemically, the Tullu Kapii syenite is characterised by moderate to high contents of SiO₂, total alkalis, Y, Nb, Ta, Hf, Zn, Zr, Ga, ΣREE, higher ratios of Fe₂O_3(total)/MgO, , , and lower contents of CaO, MgO, Sr, and Ba, compared to the other granitoids. The VAG group shows chondrite-normalised REE patterns with slightly enriched LREE and flat HREE patterns without significant Eu anomalies. In contrast, the Tullu Kapii A-type granitoid is characterised by a nearly horizontal REE pattern with variable negative Eu anomalies. The Ujjukka granite and granodiorite; and the Dhagaa Booqa and Guttin K-feldspar megacrystic granites originated in a two-step process, which involves batch equilibrium melting of basaltic or andesitic material producing tonalitic magma, followed by fractional crystallisation. The Tullu Kapii syenite was the product of partial melting of source rocks enriched in high field strength elements.     

Imperfect fluid Friedmannian cosmology

The bulk viscosity is introduced into the frame of ordinary Friedmannian cosmology (under highly idealized assumption of the constant coefficient of bulk viscosity). Explicit solutions are given for the viscous flat universe filled with the dust-substratum and for the viscous radiative universe. The problem, how does the introduction of viscosity affect the appearance of singularity, is briefly discussed.     

循化-德地区新生代盆地发育及其对高原增生的指示

循化-贵德地区的循化盆地、贵德盆地和同仁盆地与拉鸡山和西秦岭北缘逆冲带相邻分布.盆地沉积地层主要由渐新统西宁群、渐新统上部至上新统贵德群和下更新统组成.它们由不整合界面分隔,划分为3个盆地相.盆地相1为西宁群,盆地相2为贵德群查让组、下东山组、贺尔加组和甘家砾岩组,盆地相3为共和组及下更新统.3个盆地相均在其中下部或底部发育湖泊沉积,向上转变为冲积扇-辫状河平原沉积体系,呈现出粒径向上不断加大的反序、进积沉积序列.盆地沉积、古流和沉积物碎屑成分分析表明,研究区在西宁群(盆地相1)沉积时期发育大型湖泊沉积盆地,盆地沉积物源主要来自于南侧的西秦岭逆冲带,而拉鸡山逆冲带处于沉积基准面之下,接受沉积;在贵德群(盆地相2)沉积时期,逆冲作用向北迁移,拉鸡山逆冲隆升,研究区盆地分割,主要沿拉鸡山逆冲带南北两侧发育点源扩散型冲积扇-辫状河平原沉积.研究区盆山系统演化对青藏高原远端增生过程具有重要的指示意义.研究结果表明,青藏高原新生代向北东的增生作用在渐新世(29～21.4Ma)已抵达西秦岭北缘地区,增生过程主要表现为向北的单向褶皱逆冲增厚隆升和前缘前陆盆地充填;中新世至上新世(20.8～2.6Ma)高原增生作用跨过研究区可能抵达祁连北缘和六盘山地区,增生过程主要表现为双向基底卷入式逆冲增厚隆升和分割式前陆盆地充填上新世至早更新世(2.6～1.7 Ma)高原远端主要表现为区域剥蚀夷平与山间盆地加积充填.     

The non-agricultural economy in post-socialist rural Romania: The insights and perceptions of national, regional and local institutions

This study evaluates some aspects of the socio-economic transformation of rural Romania with reference to the views of representative organisations (at national, regional and local levels) and other experts. Interviews conducted in ten communes of nine Romanian counties (‘judete’) focus attention on the advantages and disadvantages of system change experienced since 1989; the most important problems and constraints for future socio-economic change; and appropriate policies and perspectives for development in the immediate future. Wherever appropriate the claims of interviewees are substantiated through reference to statistics, drawn in many cases from Chambers of Commerce & Industry (CCI). Local level representatives presented much more negative views on recent change than their national and regional level counterparts, but all agreed on the crucial problem of capital shortage. Thus while specific programmes to assist rural areas are justified, they cannot fully succeed until the national economy is able to grow more rapidly and attract greater foreign investment. This revised version was published online in July 2006 with corrections to the Cover Date.     

The restricted stability of osumilite under hydrous conditions in the system K2O-MgO–Al2O3–SiO2–H2O

Osumilite_ss was synthesized as a single phase product in the model system K₂O-MgO-Al₂O₃-SiO₂ at 800° C/ 0.5 Kbar water pressure and at 800° to 840° C/1.0 Kbar total pressure with 0.3 in the gas phase. The experimentally determined solid solubility range of synthetic osumilites can be expressed by the formula KMg₂(Al_3-xMg_x) (Al_2–xSi_10+x)O₃₀ with 0x0.4. A survey of sixteen chemical analyses of natural osumilites from eleven occurrences shows a solid solubility characterized by 0x0.6. Reversed stability experiments for the synthetic osumilite KMg₂(Al_2.75Mg_0.25)(Al_1.75Si_10.25)O₃₀ determined at water pressure equal to total pressure demonstrate its restriction to water pressures below 0.8 Kbar (at 0.5 Kbar, the stability range is between 765° and 800° C). At the lower thermal stability limit osumilite+H₂O vapor break down to cordierite+K feldspar+phlogopite_ss+quartz, at the higher one to cordierite+K feldspar+phlogopite+liquid. Reduction of water fugacity will expand the stability field largely by shifting the lower and higher thermal stability limits to lower and higher temperatures, respectively. The dependence of osumilite stability on water fugacity makes osumilite a sensitive indicator mineral for dry conditions in rocks formed at total pressures higher than about 0.8 Kbar.     

Small landslide types and controls in glacial deposits: Lower Skagit river drainage,northern cascade range,Washington

Observations of 167 small, shallow landslides spanning a 22-year period on extensively logged slopes of Quaternary terraces in the lower Skagit and Baker Valleys, Washington, shows that there is a relationship between the common slope failures in this area and the slope angle, stratigraphy, and logging practices. Landslide frequency increases upvalley, as do mean annual precipitation and the frequency of perched water tables. Debris slides are most common, occur on steep slopes (>50%) composed of sand and gravel, and are most abundant in areas previously logged by the clear—cut method. Debris flows occur on shallower slopes (>30%) where the stratigraphy leads to perched water tables. Debris flows larger than 600 m² in area appear to be unrelated to logging practices. Slump flows, described here for the first time, occur on similar slope angles and stratigraphic situations as debris flows. They differ mainly by the presence of semiconsolidated material, usually till, at the slide head. Where till is breached—commonly along road cuts—water infiltration is increased, saturating underlying fine-grained deposits, which then fail by debris flowage. Secondary slumping of till happens when the slope steepens during debris flow failure. Small landslides surrounding Lake Shannon may contribute up to 80% of the total particulate matter yield to the fluvial system at present, increasing lake sedimentation by a rate of 5 mm/yr.     

Prospects for gradiometric aiding of inertial survey systems

The state of current and proposed moving-base gravity gradiometer instruments is briefly reviewed. The review perspective is directed toward their deployment as a source of additional gravimetric data during inertial surveys. In such gradiometer-aided surveys, the additional gravity gradient information could be used to:

1. Improve surveyed gravity vector accuracy
2. Extend the interval between zero velocity update stops
3. Accomplish varying combinations of the above.

The paper examines potential survey improvements associated with gradiometers having noise levels observed in laboratory prototypes. The additional improvements possible with future gradiometers are also discussed. These results are interpreted in light of present and likely future inertial survey system technology.