Editorial     

John Wilson  Stewart Fotheringham  Gary Hunter  Jochen Albrecht 《Transactions in GIS》2006,10(2):153-153

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Ten Years On . . .     

John Wilson  Stewart Fotheringham  Gary Hunter  Jochen Albrecht 《Transactions in GIS》2006,10(3):333-333

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Determination of Porosity and Permeability out of Dispersion Analyses of Borehole Wall Displacements     

Michael Albrecht  Vladimir Mansurov 《Pure and Applied Geophysics》2006,163(10):2125-2140

Waves carried in the borehole can be measured by the use of controlled sources inside the borehole and receivers located in the same borehole as well. This article gives the theoretical background and develops a new method to determine rock-physical parameters out of such controlled measurements of waves carried inside the borehole. Theoretical dispersion curves of the group velocities are matched to dispersion analyses of registrations obtained in the borehole. This inversion process intends to determine the in situ porosity and permeability of the rock.  相似文献   

Petrology,geochemistry and U–Pb geochronology of magmatic rocks from the high-sulfidation epithermal Au–Cu Chelopech deposit,Srednogorie zone,Bulgaria     

Isabelle Chambefort  Robert Moritz  Albrecht von Quadt 《Mineralium Deposita》2007,42(7):665-690

The Chelopech deposit is one of the largest European gold deposits and is located 60 km east of Sofia, within the northern part of the Panagyurishte mineral district. It lies within the Banat–Srednegorie metallogenic belt, which extends from Romania through Serbia to Bulgaria. The magmatic rocks define a typical calc-alkaline suite. The magmatic rocks surrounding the Chelopech deposit have been affected by propylitic, quartz–sericite, and advanced argillic alteration, but the igneous textures have been preserved. Alteration processes have resulted in leaching of Na₂O, CaO, P₂O₅, and Sr and enrichment in K₂O and Rb. Trace element variation diagrams are typical of subduction-related volcanism, with negative anomalies in high field strength elements (HFSE) and light element, lithophile elements. HFSE and rare earth elements were relatively immobile during the hydrothermal alteration related to ore formation. Based on immobile element classification diagrams, the magmatic rocks are andesitic to dacitic in compositions. Single zircon grains, from three different magmatic rocks spanning the time of the Chelopech magmatism, were dated by high-precision U–Pb geochronology. Zircons of an altered andesitic body, which has been thrust over the deposit, yield a concordant ²⁰⁶Pb/²³⁸U age of 92.21 ± 0.21 Ma. This age is interpreted as the crystallization age and the maximum age for magmatism at Chelopech. Zircon analyses of a dacitic dome-like body, which crops out to the north of the Chelopech deposit, give a mean ²⁰⁶Pb/²³⁸U age of 91.95 ± 0.28 Ma. Zircons of the andesitic hypabyssal body hosting the high-sulfidation mineralization and overprinted by hydrothermal alteration give a concordant ²⁰⁶Pb/²³⁸U age of 91.45 ± 0.15 Ma. This age is interpreted as the intrusion age of the andesite and as the maximum age of the Chelopech epithermal high-sulfidation deposit. ¹⁷⁶Hf/¹⁷⁷Hf isotope ratios of zircons from the Chelopech magmatic rocks, together with published data on the Chelopech area and the about 92-Ma-old Elatsite porphyry–Cu deposit, suggest two different magma sources in the Chelopech–Elatsite magmatic area. Magmatic rocks associated with the Elatsite porphyry–Cu deposit and the dacitic dome-like body north of Chelopech are characterized by zircons with ɛHf_T90 values of ∼5, which suggest an important input of mantle-derived magma. Some zircons display lower ɛHf_T90 values, as low as −6, and correlate with increasing ²⁰⁶Pb/²³⁸U ages up to about 350 Ma, suggesting assimilation of basement rocks during magmatism. In contrast, zircon grains in andesitic rocks from Chelopech are characterized by homogeneous ¹⁷⁶Hf/¹⁷⁷Hf isotope ratios with ɛHf_T90 values of ∼1 and suggest a homogeneous mixed crust–mantle magma source. We conclude that the Elatsite porphyry–Cu and the Chelopech high-sulfidation epithermal deposits were formed within a very short time span and could be partly contemporaneous. However, they are related to two distinct upper crustal magmatic reservoirs, and they cannot be considered as a genetically paired porphyry–Cu and high-sulfidation epithermal related to a single magmatic–hydrothermal system centered on the same intrusion.  相似文献   

Neuere Veröffentlichungen     

H. Mädler  Rühl  Albrecht 《Ocean Dynamics》1975,28(5):227-228

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New design aspects of boomerang radio sondes for upper air research     

Hans J. Albrecht 《Pure and Applied Geophysics》1956,33(1):121-145

Summary This paper deals with an entirely new type of aerological instrument, the Boomerang Radio Sonde. Its purpose is the presentation of the author’s results of a fundamentally new development based upon application of modern aeronautic as well as electronic engineering and carried out by him during the period 1950 to 1955. Boomerang Radio Sondes as carrier of upper air research instruments were first suggested byFritz H. W. Albrecht in 1943, in order to generally simplify the notoriously expensive present-day programme of aerological measurements. An estimated saving of approximately 60 % of total expenses of an ordinary radio sonde network can be expected if Boomerang Radio Sondes are utilized. The introduction describes and discusses the design work performed in Germany, by a team of research workers underFritz H. W. Albrecht during the period 1945–48, until a number of circumstances forced the temporary discontinuance of the project. Since 1950 the author has been in charge of the entire further development of the project and his design results are presented under ? Aerodynamic Design ? and ? Design of Electronic Control ? describing an entirely new design of Boomerang Radio Sondes and complete removal of serious engineering obstacles encountered 1945–48. Under the heading ? Research Applications ? possibilities of this new aerological instrument carrier are discussed.

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Zusammenfassung Diese Arbeit behandelt ein vollkommen neuartiges aerologisches Ger?t, die Bumerang Radio Sonde. Ihr Zweck ist die Ver?ffentlichung der Ergebnisse des Verfassers bei der fundamental neuen Entwicklung, die auf der Anwendung von moderner Aerodynamik und Elektronik basiert und von ihm w?hrend der Zeit 1950 bis 1955 ausgeführt wurde. Bumerang Radio Sonden als Tr?ger für Instrumente zur Erforschung oberer Luftschichten wurden zuerst vonFritz H. W. Albrecht 1943 vorgeschlagen, um das notorisch teure gegenw?rtige aerologische Messprogramm einfacher und wirtschaftlicher zu gestalten. Eine gesch?tzte Erspaon rnis ungef?hr 60 % der Gesamtkosten eines normalen Radiosondendienstes kann erwartet werden, wenn Bumerang-Radio-Sonden benutzt werden. Die Einführung beschreibt und diskutiert die Konstruktionsarbeit, die in Deutschland durch eine Forschungsgruppe unterFritz H. W. Albrecht w?hrend der Zeit 1945–48 ausgeführt wurde, bis eine Anzahl von Umst?nden die vorübergehende Aufgabe des Projektes erzwang. Seit 1950 ist der Verfasser für die gesamte weitere Entwicklung des Projektes verantwortlich und seine Konstruktionsresultate sind unter ? Aerodynamic Design ? und ? Design of Electronic Control ? ver?ffentlicht, indem eine vollkommen neue Konstruktion von Bumerang Radio Sonden und eine vollst?ndige Beseitigung von 1945–48 vorhandenen technischen Hindernissen beschrieben ist. Unter der überschrift ? Research Applications ? werden Anwendungsm?glichkeiten dieses neuen aerologischen Instrumententr?gers beschrieben.

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Die alpidischen Stockwerke der südlichen Ägäis     

Dr. Albrecht Baumann  Dr. Gerhard Best  Prof. Dr. Horst Wachendorf 《International Journal of Earth Sciences》1977,66(1):492-522

Zusammenfassung Im Bereich der südlichen Ägäis überlagern vier allochthone Stockwerke den autochthonen Plattenkalk (Perm-Oligozän). Die allochthonen Serien entstammen ursprünglich konzentrisch angeordneten mesozoisch-alttertiären Faziesräumen der zentralen Ägäis. Die tektonische Abfolge aus neritischen Karbonaten, pelagischen Karbonaten und einem vulkano-sedimentären Komplex, die durch inkompetente Zwischenmittel (Mélange) getrennt werden, besteht über den gesamten Bogen. Fazielle und stratigraphische Merkmale sowie die Art der Deformation ermöglichen die Korrelation der Teilprofile des südägäischen Deckenstapels und dessen Anknüpfung an die südwestliche Türkei. Die kinematische Analyse des Deckenbaus führt zu dem Bild eines sich ausbreitenden Mantel-Diapirs, an dessen geneigter Grenzfläche ein gravitativer Transport ausgelöst wurde.

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In the realm of the Southern Aegean Arc four allochthonous units are piled up above the autochthonous Cherty Limestone (Permian-Oligocene). The allochthonous units are derived from different Mesozoic to Paleogene facies zones which originally were arranged in concentric belts in the Central Aegean Sea. The nappe pile consists — from bottom to top — of neritic carbonates, pelagic carbonates and a volcano-sedimentary complex along the entire arc. These competent units are separated by incompetent members of mainly flyschoid sediments, acting as lubricants. The intercalated sediments were deformed to mélanges due to tectonic transport. Facies analysis, stratigraphy and the style of deformation lead to a correlation of type sections of the southern Aegean nappe pile and its relation to the southwestern part of Turkey. The nappe transport is caused by diapiric uplift and lateral shifting of a thermal dome. A radial gravity transport occurred on its inclined boundary plane.

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Résumé Dans la région de l'Egée méridionale le Calcaire en plaquettes, en position autochthone (Permian-Oligocène) repose sous quatre unités allochthones. Les séries allochthones proviennent de différentes zones de faciès mésozoique-paléogène qui à l'origine étaient disposées concentriquement dans l'Égée centrale. Les nappes sont constituées tout le long de l'arc entier pour des carbonates néritiques, des carbonates pélagiques et un complexe volcano-sédimentaire. Ces unités compétentes sont séparées par des formations incompétentes, notamment des sédiments flyschoides qui ont servi de lubrificant. Ces sédiments intercalés ont été déformés en mélanges par le transport tectonique. Des caractéristiques de faciès et d'ordre stratigraphique, et le style de la déformation rendent possible la corrélation entre les fractions des nappes sud-égéennes et leur rattachement au sud-ouest de la Turquie. Le transport des nappes est lié au déploiement latéral de l'enveloppe d'un dôme diapirique, qui a déclanché un transport radial, par gravité, le long de sa base inclinée.

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Diese Untersuchungen wurden im Rahmen des Schwerpunktprogrammes Geodynamik des mediterranen Raumes der Deutschen Forschungsgemeinschaft durchgeführt und gefördert. Ausgehend von einer Geländetätigkeit auf Kreta in den Jahren 1973–1975 erfolgten im Herbst 1975 Vergleichsbegehungen auf dem Peloponnes, auf Rhodos und den Kykladen. Von den Mitarbeitern des Institutes für Geologie und Paläontologie der TU Braunschweig übernahmen dankenswerterweise FrauBeddies und FrauBusch die Niederschrift des Manuskriptes sowie Übersetzungsarbeiten. HerrStosnach führte freundlicherweise die Reinzeichnung der Abbildungen und Fotoarbeiten aus.  相似文献   

Dynamical evolution of the Oort cloud: II. A theoretical approach     

F. Mignard  F. Remy 《Icarus》1985,63(1):20-30

We investigate the dynamical evolution of a cloud of comets created by stellar perturbations. We first show the respective advantages of numerical simulations and of studies of more theoretical character. Then we investigate the probability distribution of the velocity changes imparted to comets by passing stars. This distribution is shown to be different from a Maxwellian distribution, mainly because of pronounced tails. The number of fairly large impulses is thus more important than it would be in the case of a Maxwellian distribution. Finally we estimate the probability for a comet to be ejected from the Solar System. About 10% of the cloud population is lost through this mechanism over the age of the Solar System. Taking advantage of the velocity change distribution, we study the random walk of semimajor axes of comets as a function of time. We derive the probability that a comet is lost into interstellar space as a function of its initial semimajor axis.  相似文献   

Description of an aerodynamic levitation apparatus with applications in Earth sciences     

Andreas Pack  Katrina Kremer  Nina Albrecht  Klaus Simon  Andreas Kronz 《Geochemical transactions》2010,11(1):4

Background  

In aerodynamic levitation, solids and liquids are floated in a vertical gas stream. In combination with CO₂-laser heating, containerless melting at high temperature of oxides and silicates is possible. We apply aerodynamic levitation to bulk rocks in preparation for microchemical analyses, and for evaporation and reduction experiments.  相似文献   

Sedimentological and stratigraphic evolution of northern Lebanon since the Late Cretaceous: implications for the Levant margin and basin     

Nicolas Hawie  Remy Deschamps  Fadi H. Nader  Christian Gorini  Carla Müller  Delphine Desmares  Ahmed Hoteit  Didier Granjeon  Lucien Montadert  François Baudin 《Arabian Journal of Geosciences》2014,7(4):1323-1349

This paper presents an updated review of the Upper Mesozoic and Cenozoic sedimentological and stratigraphic evolution of the Levant margin with a focus on the northern Lebanon. Facies and microfacies analysis of outcrop sections and onshore well cores (i.e., Kousba and Chekka) supported by nannofossil and planktonic foraminifers biostratigraphy, allowed to constrain the depositional environments prevailing in the Turonian to Late Miocene. The “Senonian” (a historical term used to define the Coniacian to Maastrichtian) source rock interval was subdivided into four sub-units with related outer-shelfal facies: (1) Upper Santonian, (2) Lower, (3) Upper Campanian, and (4) Lower Maastrichtian. This Upper Cretaceous rock unit marks the major drowning of the former Turonian rudist platform. This paper confirms the Late Lutetian to Late Burdigalian hiatus, which appears to be a direct consequence of major geodynamic events affecting the Levant region (i.e., the continued collision of Afro-Arabia with Eurasia), potentially enhanced by regressional cycles (e.g., Rupelian lowstand). The distribution of Late Burdigalian–Serravallian rhodalgal banks identified in northern Lebanon was controlled by pre-existing structures inherited from the pulsating onshore deformation. Reef barriers facies occur around the Qalhat anticline, separating an eastern, restricted back-reef setting from a western, coastal to open marine one. The acme of Mount Lebanon’s uplift and exposure is dated back to the Middle–Late Miocene; it led to important erosion of carbonates that were subsequently deposited in paleo-topographic lows. The Late Cretaceous to Cenozoic facies variations and hiatuses show that the northern Lebanon was in a higher structural position compared to the south since at least the Late Cretaceous.  相似文献