Low-grade metamorphic rocks from the Pulur complex,NE Turkey: implications for the pre-Liassic evolution of the Eastern Pontides     

Gültekin?Topuz  Rainer?AltherrEmail author  Muharrem?Sat?r  Winfried?H.?Schwarz 《International Journal of Earth Sciences》2004,93(1):72-91

In the Pulur complex (Sakarya Zone, Eastern Pontides, Turkey) a low-grade tectonometamorphic unit (Doankavak) is exposed in three tectonic windows beneath a complex medium-pressure high-temperature metamorphic unit of late Carboniferous age. The thrust plane between both units is transgressively covered by Liassic conglomerates. The Doankavak unit comprises a sequence of metabasites with MORB-type chemical compositions and phyllites, with subordinate calcareous phyllites, marbles, quarzofeldspathic schists and metacherts. This sequence is interpreted as a former accretionary complex related to the consumption of the Palaeotethys. Mineral parageneses in the metabasites allow for the distinction of two domains with slightly different peak metamorphic conditions, i.e. 375–425 °C/0.5–0.8 GPa (greenschist facies) and 400–470 °C/0.6–1.1 GPa (albite-epidote amphibolite facies). The age of metamorphism is constrained at ~ 260 Ma (early Late Permian) by two Rb-Sr mineral-whole rock ages (hornblende, phengite) and one ⁴⁰Ar/³⁹Ar single step total fusion age (phengite). In conjunction with previous data on other accretionary complexes in the Sakarya zone in Northern Turkey, the data presented in this study suggest a continuous subduction of the Palaeotethys at least from Early/Late Permian to Late Triassic and a discontinuous preservation of accretion complexes in both space and time.  相似文献   

Die F-Ionisation in den Morgenstunden     

O. Burkard  F. Mallinger  F. Schwarz 《Pure and Applied Geophysics》1952,23(1):43-59

Zusammenfassung Die Elektronenkonzentration in derF-Schicht der Ionosphäre wächst in den Morgenstunden nicht einfach proportional dem Cosinus des Einfallswinkels der Sonnenstrahlung, sondern sie folgt einem linearen Gesetz von der Formn=a. cos +b. Diese Gestzmässigkeit kann erklärt werden, wenn man die Schichtbildung nach denChapman'schen Ansätzen für eine gekrümmte Erde berechnet und einen Ionenvernichtungsprozess voraussetzt, demzufolge die Vernichtung der Ionen ihrer jewwiligen Konzentration linear proportional ist.Die genannten Grössena andb sind zeitlich und örtlich variabel, aus ihren Veränderungen schliessen wir auf Temperaturverhältnisse in der Ionosphäre, die dadurch ausgezeichnet sind, dass sie in ähnlicher Weise auch in der viel tiefer liegenden Stratosphäre wiedergefunden werden: In polaren Gegenden herrschen darnach im Polarsommer höhere, im Polarwinter dagegen tiefere Temperaturen als in den gemässigten Breiten.

---

Summary In the ionospheric F-layer the electron densityn increases with the formulan=a. cos+b in the morning ( is meaning the zenithangle of the sun). This experimental result may be explained by consideration of earth-curvature and by assumption of a linear recombination-law equally an attachment process. The constantsa andb vary with season and location. We conclude the temperature from these variations and we find for polar locations a greater temperature in the summer and on the other hand a smaller temperature in the winter as for temperate latitudes.

  相似文献   

Stellenangebote und Stellengesuche     

Dr. Friedrich Schwarz 《International Journal of Earth Sciences》1931,22(5):352-352

Ohne Zusammenfassung  相似文献   

Differentiation for High-Precision GPS Velocity and Acceleration Determination   总被引：7，自引：1，他引：6  

A. M. Bruton  C. L. Glennie  K. P. Schwarz 《GPS Solutions》1999,2(4):7-21

Accurate estimates of the velocity and acceleration of a platform are often needed in high dynamic positioning, airborne gravimetry, and geophysics. In turn, differentiation of GPS signals is a crucial process for obtaining these estimates. It is important in the measurement domain where, for example, the phase measurements are used along with their instantaneous derivative (Doppler) to estimate position and velocity. It is also important in postprocessing, where acceleration is usually estimated by differentiating estimates of position and velocity. Various methods of differentiating a signal can have very different effects on the resulting derivative, and their suitability varies from situation to situation. These comments set the stage for the investigations in this article. The objective is twofold: (1) to carry out a comprehensive study of possible differentiation methods, characterizing each in the frequency domain; and (2) to use real data to demonstrate each of these methods in both of the measurement and position domains, in conditions of variable, high, or unknown dynamics. Examples are given using real GPS data in both the measurement domain and in the position and velocity domain. The appropriate differentiator is used in several cases of varying dynamics to derive a Doppler signal from carrier phase measurements (rather than using the raw Doppler generated by the receiver). In the statistic case, it is seen that the accuracy of velocity estimates can be improved from 4.0 mm/s to 0.7 mm/s by using the correct filter. In conditions of medium dynamics experienced in an airborne gravity survey, it is demonstrated that accelerations as the 2–4 mGal level (1 mGal = 0.00001 m/s²) can be obtained at the required filtering periods. Finally, a precision motion table is used to show that when using the correct filter, velocity estimates under high dynamics can be improved by an order of magnitude to 27.0 mm/s. ? 1999 John Wiley & Sons, Inc.  相似文献   

The ROSAT Bright Survey: II. Catalogue of all high‐galactic latitude RASS sources with PSPC countrate CR > 0.2 s–1     

A.D. Schwope  G. Hasinger  I. Lehmann  R. Schwarz  H. Brunner  S. Neizvestny  A. Ugryumov  Yu. Balega  J. Trümper  W. Voges 《Astronomische Nachrichten》2000,321(1):1-52

  相似文献   

Groundwater Development in Israel          下载免费PDF全文

J. Schwarz  J. Bear  G. Dagan 《Ground water》2016,54(1):143-148

  相似文献   

Enhancement of prestack diffraction data and attributes using a traveltime decomposition approach     

Alexander Bauer  Benjamin Schwarz  Dirk Gajewski 《Studia Geophysica et Geodaetica》2016,60(3):471-486

Diffractions not only carry important information about small-scale subsurface structures, they also possess unique properties, which make them a powerful tool for seismic processing and imaging. Since a point diffractor scatters an incoming wave to all directions, a diffraction event implies better illumination than a reflection, because the rays travel through larger parts of the subsurface. Furthermore, unlike the reflection case, in which the emergence location of the reflected wave depends on the source position, in the case of non-Snell scattering, up-going and down-going raypaths are decoupled. Based on this decoupling, we introduce a diffraction traveltime decomposition principle, which establishes a direct connection between zero-offset and finite-offset diffraction wavefield attributes. By making use of this approach, we are able to enhance diffractions and obtain high-quality diffraction wavefield attributes at arbitrary offsets in the prestack domain solely based on zero-offset processing without any further optimization of attributes. We show the accuracy of the method by fitting diffraction traveltimes, and on simple waveform data. Application to complex synthetic data shows the ability of the proposed approach to enhance diffractions and provide high-quality wavefield attributes even in sparsely illuminated regions such as subsalt areas. The promising results reveal a high potential for improved prestack data enhancement and further applications such as efficient diffraction-based finite-offset tomography.  相似文献   

Triassic warm subduction in northeast Turkey: Evidence from the Ağvanis metamorphic rocks     

Gültekin Topuz  Aral I. Okay  Rainer Altherr  Winfried H. Schwarz  Gürsel Sunal  Lütfi Altınkaynak 《Island Arc》2014,23(3):181-205

Within the Tethyan realm, data for the subduction history of the Permo–Triassic Tethys in the form of accretionary complexes are scarce, coming mainly from northwest Turkey and Tibet. Herein we present field geological, petrological and geochronological data on a Triassic accretionary complex, the A?vanis metamorphic rocks, from northeast Turkey. The A?vanis metamorphic rocks form a SSE–NNW trending lozenge‐shaped horst, ～20 km long and ～6 km across, bounded by the strands of the active North Anatolian Fault close to the collision zone between the Eastern Pontides and the Menderes–Taurus Block. The rocks consist mainly of greenschist‐ to epidote‐amphibolite‐facies metabasite, phyllite, marble and minor metachert and serpentinite, interpreted as a metamorphic accretionary complex based on the oceanic rock types and ocean island basaltic, mid‐ocean ridge basaltic and island‐arc tholeiitic affinities of the metabasites. This rock assemblage was intruded by stocks and dikes of Early Eocene quartz diorite, leucogranodiorite and dacite porphyry. Metamorphic conditions are estimated to be 470–540°C and ～0.60–0.90 GPa. Stepwise ⁴⁰Ar/³⁹Ar dating of phengite–muscovite separates sampled outside the contact metamorphic aureoles yielded steadily increasing age spectra with the highest incremental stage corresponding to age values ranging from ～180 to 209 Ma, suggesting that the metamorphism occurred at ≥ 209 Ma. Thus, the A?vanis metamorphic rocks represent the vestiges of the Late Triassic or slightly older subduction in northeast Turkey. Estimated P–T conditions indicate higher temperatures than those predicted by steady state thermal models for average subduction zones, and can best be accounted for by a hot subduction zone, similar to the present‐day Cascadia. Contact metamorphic mineral assemblages around an Early Eocene quartz diorite stock, on the other hand, suggest that the present‐day erosion level was at depths of ～14 km during the Early Eocene, indicative of reburial of the metamorphic rocks. Partial disturbance of white‐mica Ar–Ar age spectra was probably caused by the reburial coupled with heat input by igneous activity, which is probably related to thrusting due to the continental collision between Eastern Pontides and the Menderes–Taurus Block.  相似文献   

Environmental Issues Pertaining to the Kwale Mineral Sands Project,Kenya's South Coast—Reply     

J. Schwarz 《Marine Georesources & Geotechnology》2013,31(2):145-149

Tiomin Resources Inc. (“Tiomin”), the proponent of the Kwale Mineral Sands Project in Kenya, presents a response to the article authored by J. O. Z. Abuodha and P. O. Hayombe, entitled “Protracted Environmental Issues on a Proposed Titanium Minerals Development in Kenya's South Coast”, published in Volume 24, Number 2, April–June 2006. This article contains a series of inaccuracies, some grossly misleading and many statements relate to outdated information. Tiomin is greatly concerned at the publication of such a misleading report and is obliged to state the facts correctly. This response seeks to identify the misrepresentation of statements and/or facts in the article and present a correct and accurate perspective on the environmental issues of the project.  相似文献   

南海南部SA09-040孔孢粉记录及古气候     

张玉兰  彭学超  贾丽  戴璐 《海洋学研究》2012,(3):29-34

依据南海低纬地区SA09-040孔高分辨率的孢粉记录,自下至上划分了4个孢粉组合带。从孢粉成分的变化,重建了22.25ka B P以来的植被与气候变化历史。结果表明:孢粉主要来源于婆罗洲和周围岛屿,孢粉1带(22.25～16.6ka B P),低山雨林植被发育,为暖热气候,从测年时间看,当时为末次冰期晚期。孢粉2带(16.6～10.82ka B P,为末次冰消期),植被以热带低山雨林和低地雨林为主,针叶的松数量较多,当时的气温比现在低。孢粉3带(全新世早期,10.82～6.43ka B P),植被以热带低山雨林和低地雨林为主,针叶松属数量减少,气温比前期升高,海平面也上升。孢粉4带(全新世中晚期,6.43ka B P至今),全新世中期为炎热、湿润的气候环境,全新世晚期可能与婆罗洲现今的植被景观相近,为热、湿的气候环境。  相似文献