Structural evolution and strike-slip tectonics off north-western Sumatra     

Kai Berglar  Christoph Gaedicke  Dieter Franke  Stefan Ladage  Frauke Klingelhoefer  Yusuf S. Djajadihardja 《Tectonophysics》2010,480(1-4):119-132

Based on new multi-channel seismic data, swath bathymetry, and sediment echosounder data we present a model for the interaction between strike-slip faulting and forearc basin evolution off north-western Sumatra between 2°N and 7°N. We examined seismic sequences and sea floor morphology of the Simeulue- and Aceh forearc basins and the adjacent outer arc high. We found that strike-slip faulting has controlled the forearc basin evolution since the Late Miocene. The Mentawai Fault Zone extends up to the north of Simeulue Island and was most probably connected farther northwards to the Sumatran Fault Zone until the end of the Miocene. Since then, this northern branch jumped westwards, initiating the West Andaman Fault in the Aceh area. The connection to the Mentawai Fault Zone is a left-hand step-over. In this transpressional setting the Tuba Ridge developed. We found a right-lateral strike-slip fault running from the conjunction of the West Andaman Fault and the Tuba Ridge in SSW-direction crossing the outer arc high. As a result, extrusion formed a marginal basin north of Simeulue Island which is tilted eastwards by uplift along a thrust fault in the west. The shift of strike-slip movement in the Aceh segment is accompanied by a relocation of the depocenter of the Aceh Basin to the northwest, forming one major Neogene unconformity. The Simeulue Basin bears two major Neogene unconformities, documenting that differences in subsidence evolution along the northern Sumatran margin are linked to both forearc-evolution related to subduction processes and to deformation along major strike-slip faults.  相似文献   

Eckfeld Maar: Window into an Eocene Terrestrial Habitat in Central Europe   总被引：1，自引：1，他引：0  

Herbert Lutz  Uwe KaulfuSS  Torsten Wappler  Werner L?hnertz  Volker Wilde  Dieter F. Mertz  Jens Mingram  Jens L. Franzen  Herbert Frankenh?user  Martin Koziol 《《地质学报》英文版》2010,84(4):984-1009

<正>To mark the occasion of the 175th anniversary of the Rheinische Naturforschende Gesellschaft in 2009 and of the centennial of the Mainz Natural History Museum in 2010,we present a short account of our present knowledge of the Eckfeld Maar after 20 years of continuous research.This paper does not attempt to include all of the detailed results on the geology of the Eckfeld site or its biota.To date,nearly 250 papers and books have been published since the start of our project.An up-to-date list of these publications can be found at www.eckfeldermaar. de.  相似文献   

Mining lakes as groundwater‐dominated hydrological systems: assessment of the water balance of Mining Lake Plessa 117 (Lusatia,Germany) using stable isotopes     

Hilmar Hofmann  Kay Knöller  Dieter Lessmann 《水文研究》2008,22(23):4620-4627

In the present study, the stable isotopes δ¹⁸O and δ²H were used for assessment of the water balance in a heterogeneously structured catchment area in the Lusatian Lignite Mining District, in particular, for estimation of the annual groundwater inflow and outflow (I_GW and O_GW) of Mining Lake Plessa 117. The application of stable isotopes was possible since the water exchange in the catchment area had reached steady‐state conditions after the abandonment of mining activities in 1968 and the filling of the voids and aquifers by re‐rising groundwater in the years thereafter. Diverging slopes of the Evaporation Line and the Global Meteoric Water Line manifested as evaporation from the lake catchment area. The calculated isotope water balance was compared with the commonly used surface water balance, which is unable to differentiate between I_GW and O_GW, and with a local groundwater model. The groundwater model calculated an I_GW of about 811 000 m³ yr^?1 and an O_GW close to zero, whereas the isotope water balance showed fluxes of about 914 000 and 140 000 m³ yr^?1, respectively. Considering the contribution of the groundwater inflow to the total annual input into the lake (ΔI_T) and the mean residence time (τ), where the groundwater model and the isotope water balance calculated 42 and 47% for ΔI_T and 4·3 and 3·9 years for τ, respectively, it was shown that both water balance calculation methods led to comparable results despite the differences in I_GW and O_GW. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Hydrostatic pressure tests for the permeability - formation factor relation on crystalline rocks from the KTB drilling project     

Dieter Freund  Georg Nover 《Surveys in Geophysics》1995,16(1):47-62

Transport properties (permeability and electrical conductivity) have been measured at different hydrostatic pressure runs on 7 crystalline rocks (gneisses and amphibolites) sampled from the KTB drilling project. The decrease of permeability by pressure are compared with the pressure-dependent data of the electrical conductivity (formation factor) resulting from complex impedance measurements. According to the equivalent-channel model (ECM), there exists a linear relationship between these parameters by representing both properties on logarithmic scales. The results show that it is possible to extrapolate high-pressure permeability from low-pressure (< 60 MPa) permeability data by using the pressure-dependent electrical conductivity (up to 300 MPa).  相似文献   

Die Hochflächen-Treppe der Nordeifel und ihre Beziehungen zum Tertiär und Quartär der Niederrheinischen Bucht     

Priv.-Doz. Dr. Dieter Richter 《International Journal of Earth Sciences》1962,52(1):376-404

The tableland of the northern Eifel consists of a whole series of levelling planations which descend like steps to the plain of the Lower Rhine or form broad terraces along the river valleys. A similar staircase structure can be seen in the Cretaceous range of the Aachener Wald. The oldest obliquely situated plateau of the Hohe Venn is a resurrected fossil peneplain which was formed before the Maastricht formation as can be proved by scanty remains of the flinty chalk (Maastricht) which still overlays this peneplain at the present time. Therefore the great elevation of the northern Eifel to heights of 2280 feet above sea-level did not follow until later than Upper Cretaceous.The indentation of this old Cretaceous peneplain presumably resulted in the formation of an older system of plateaus in Oligocene and in a system of young plateaus in Miocene which had the appearance of a staircase. These tableland systems originated in times of slight elevation in which superficial denudation must have predominated under the influence of a damp climate and intensive chemical decomposition of the rocks. During the Lower Miocene and Pliocene epochs considerable elevatory movements occurred which led occasionally to the formation of steep obsequent slopes at the edges of both systems. During the Lower Pleistocene epoch glacial conditions existed and at this time the main period of terrace formation occurred. In the course of this period there was a great gravel accumulation which was linked with lateral erosion and which, whith the aid of its valley terraces and rubble remains, can be traced as far as the foreland. A later, very marked incision of the rivers can be traced back to great elevations of land which occurred after this period. The rhythmic alternation of periods of elevation and inactivity can be seen in the morphological development of the northern Eifel. The individual periods of tableland and terrace formation can be related to corresponding sediments belonging to the Upper Tertiary and the Quaternary periods.

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Résumé Le paysage en plateaux emboîtés du Nord de l'Eifel se compose de toute une série de surfaces de nivellement qui descendent en gradins vers la plaine basse du Rhin inférieur ou constituent de larges terrasses le long des vallées fluviales. Une pareille structure en plateaux étagés est décelable dans la petite montagne crétacée du Aachener Wald. Le plus ancien haut plateau incliné des Hautes Fagnes représente une ancienne pénépleine à nouveau exhumée qui s'est formée avant le Maastrichtien comme on peut le démontrer par des restes peu abondants d'éluvions à silex (pierre à feu) qui lui servait autrefois de couverture. Le fort soulèvement du Nord de l'Eifel jusqu'à des hauteurs de 760 au dessus du niveau de la mer ne s'est produit par conséquent qu'après le crétacé supérieure.Á l'oligocène, un système plus ancien de surfaces applanies étagées et au miocène, un système de surfaces plus jeunes ont été probablement entaillés en gradins dans cette ancienne pénéplaine crétacée. Ces systèmes de plateaux emboîtés ont pris naissance à des époques de faible soulèvement, où l'érosion en surface a dû prédominer sous l'influence d'un climat humide et d'une décomposition chimique intensive de la roche. Au miocène inférieur et au pliocène ils ont chaque fois produit des mouvements de soulèvement assez forts qui ont entraîné la formation de versants à profil plus abrupt au bord des deux systèmes. Dans les conditions glaciaires, du pleistocène ancien, de l'époque des principales terrasses, il se produisit un important remblaiement de cailloutis uni à une érosion latérale et que l'on peut suivre jusque dans les parties avancées du territoire à l'aide de ses terrasses de vallées et de ses restes de cailloutis. Une forte entaille ultérieure des fleuves remonte à de vastes soulèvements de terrain postérieurs à cette époque. C'est ainsi que dans l'évolution morphologique du Nord de l'Eifel s'exprime l'alternance rythmique de périodes de soulèvement et de repos. Les différentes époques de formations de hauts plateaux étagés et de terrasses peuvent être mises en relation avec des sédiments correspondants parallèles du tertiaire supérieur et du quaternaire de la baie du Rhin inférieur.

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Limnologische Transport- und Nährstoffmodelle     

Dr. Dieter M. Imboden 《Aquatic Sciences - Research Across Boundaries》1973,35(1):29-68

Physical as well as biochemical processes have a significant influence on the material balance of a lake. Mathematical concepts are developed to treat transport phenomena with which a comparison of different lakes under certain systematic aspects becomes possible. A two-box model consisting of the subsystems epilimnion and hypolimnion, for lakes with one specific limiting nutrient factor (e.g., phosphorus) is employed to evaluate eutrophication processes. In particular, a theoretical basis forVollenweider's [3] empirical relation between specific phosphorus loading and the trophic state is presented. Finally, the inhomogeneous O₂-consumption in the deep part of the lake during summer stagnation is calculated with diffusion theory.   相似文献   

Untersuchung der CO2-Konzentration im Tropopausenniveau     

Dieter Jost 《Pure and Applied Geophysics》1971,86(1):209-218

Zusammenfassung Zwischen 50° bis 85°N Breite wurde die atmosphärische CO₂-Konzentration während mehrerer Messflüge registriert. Diese war oberhalb der Tropopause bis zu 7 ppm (im Mittel etwa 2 ppm) niedriger als in der oberen Troposphäre. Im Jahresmittel entspricht diese CO₂-Konzentrationsdifferenz einem Fluss von etwa 10^–2 g CO₂/cm² Jahr aus der nördlichen Troposphäre in die Stratosphäre. Die Bedeutung dieser CO₂-Konzentrationsunterschiede für den atmosphärischen CO₂-Haushalt sowie für die Strahlungsbilanz im Tropopausenniveau kann erst nach Vorlage weiterer, über das ganze Jahr verteilter Messdaten erfolgen.

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Summary CO₂-concentration was measured during several flights in northern latitudes (50°–85°). Above Tropopause CO₂-concentration was up to 7 ppm (as a mean some 2 ppm) smaller than in upper troposphere. As a mean this difference in CO₂-concentration cm² year conforms to a CO₂-flux of some 10^–2 g CO₂/cm² year from northern troposphere into stratosphere. The importance of these CO₂-differences for atmospheric CO₂-system and for radiation balance in tropopause-height may be considered as soon as more CO₂-concentration data for the whole year are available.

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AMS radiocarbon dating and varve chronology of Lake Soppensee: 6000 to 12000 14C years BP     

Irena Hajdas  Susan D Ivy  Jürg Beer  Georges Bonani  Dieter Imboden  André F Lotted  Michael Sturm  Martin Suter 《Climate Dynamics》1993,9(3):107-116

For the extension of the radiocarbon calibration curve beyond 10000 ¹⁴C y BP, laminated sediment from Lake Soppensee (central Switzerland) was dated. The radiocarbon time scale was obtained using accelerator mass spectrometry (AMS) dating of terrestrial macrofossils selected from the Soppensee sediment. Because of an unlaminated sediment section during the Younger Dryas (10000–11000 ¹⁴C y BP), the absolute time scale, based on counting annual layers (varves), had to be corrected for missing varves. The Soppensee radiocarbon-verve chronology covers the time period from 6000 to 12000 ¹⁴C y BP on the radiocarbon time scale and 7000 to 13000 calendar y BP on the absolute time scale. The good agreement with the tree ring curve in the interval from 7000 to 11450 cal y BP (cal y indicates calendar year) proves the annual character of the laminations. The ash layer of the Vasset/Killian Tephra (Massif Central, France) is dated at 8230±140 ¹⁴C y BP and 9407±44 cal y BP. The boundaries of the Younger Dryas biozone are placed at 10986±69 cal y BP (Younger Dryas/Preboreal) and 1212±86 cal y BP (Alleröd/Younger Dryas) on the absolute time scale. The absolute age of the Laacher See Tephra layer, dated with the radiocarbon method at 10 800 to 11200 ¹⁴C y BP, is estimated at 12350 ± 135 cal y BP. The oldest radiocarbon age of 14190±120 ¹⁴C y BP was obtained on macrofossils of pioneer vegetation which were found in the lowermost part of the sediment profile. For the late Glacial, the offset between the radiocarbon (10000–12000 ^14C y BP) and the absolute time scale (11400–13000 cal y BP) in the Soppensee chronology is not greater than 1000 years, which differs from the trend of the U/Th-radiocarbon curve derived from corals.  相似文献   

Conventional and ion-microprobe U-Pb dating of detrital zircons of the Tentudía Group (Serie Negra,SW Spain): implications for zircon systematics,stratigraphy, tectonics and the Precambrian/Cambrian boundary     

Hans-Jürgen Schäfer  Dieter Gebauer  Thomas F. Nägler  Luis Eguiluz 《Contributions to Mineralogy and Petrology》1993,113(3):289-299

Conventional multi-grain and ion-microprobe dating of detrital zircons from a very low grade metagraywacke of the Tentudía Group (upper part of the Serie Negra, Ossa-Morena Zone, SW Spain) reveals an uppermost Vendian age for the deposition of the metagraywacke. The youngest detrital zircon grain provides a maximum depositional age of about 565 Ma. Thus, these data contradict earlier Middle to Upper Riphean (ca. 1350-850 Ma) estimates on the age of the Tentudía Group and favour a Precambrian/Cambrian boundary falling into the range of 540 to 530 Ma. The presence of about 20% of Pan-African detrital zircons ranging from about 700 to 550 Ma indicates the derivation from Gondwana. From the upper intercept ages of the fan-shaped data field defined by conventionally determined zircon fractions, it can be deduced that 2.1 Ga old zircons as well as Archean zircons existed in the provenance(s) of the Serie Negra sediments. This mixing of crustal components of different ages is in line with the Nd crustal residence age of 1.9 Ga. The latter value, as well as other model ages of the Iberian Massif, indicates unusually high amounts of ancient crust to be present in the strata. This is different to other (meta)sediments of the European Hercynides and suggests that the Iberian strata of uppermost Precambrian age may contain the detritus of more internal, older parts of Gondwana than other European strata of comparable ages. Geochemical data on the analysed sample and further metagraywackes of the Tentudía Group argue for a deposition in an arc environment. Such a scenario would conform with the syn- to post-orogenic shallow marine deposition of the studied sediments. Furthermore, an upper time limit for the pre-Lower Cambrian deformational history, including two phases of regional deformation, is given by the maximum age of deposition, implying a very short time interval for deposition and deformation of the Tentudía Group. Concerning the U-Pb systematics of detrital zircon fractions, it is probable that numerous, previously published conventional multi-grain zircon data on (meta)sedimentary rocks of the European Hercynides readily can be explained by the presence of up to 20% of Pan-African detrital zircons and later Phanerozoic lead loss during metamorphic transformation of the sedimentary protoliths. Moreover, this implies that such metasediments originated from post-Pan-African sedimentary precursors.  相似文献   

A Pan-African alkaline pluton intruding the Saramuj Conglomerate,south-west Jordan     

Ghaleb Jarrar  Horst Wachendorf  Dieter Zachmann 《International Journal of Earth Sciences》1993,82(1):121-135

The geological setting, petrography and bulk mineral chemistry of a monzodiorite and a presumably consanguineous megaporphyry with large (up to 25 cm) labradorite megacrysts, both intruding the upper Proterozoic Saramuj Conglomerate in south-west Jordan (south eastern shore of the Dead Sea), were examined. The crystallization temperatures of the monzodiorite and the megaporphyry as determined from pyroxene thermometry and supported by contact metamorphic mineralogy are about 700 and 900°C, respectively. The intrusion depth of the monzodiorite is about 3–4 km. The monzodiorite was emplaced in the Saramuj Conglomerate at about 595 + 2 Ma ago according to Rb/Sr and U/Pb age determinations.The stratigraphic positions of the monzodiorite, megaporphyry and their host rock (the Saramuj Conglomerate) were compared with time-equivalent lithologies in the Arabian-Nubian Shield. Correspondence to: H. Wachendorf  相似文献