A Late Cretaceous ensimatic arc developed during closure of the northern branch of Neo-Tethys(central-northern Turkey)     

Metin Beyazpirin?  Ali Ekber Ak?ay  Ali Yilmaz  Meftun Kerem S?nmez 《地学前缘(英文版)》2019,10(3):1015-1028

Studies on differentiation of ensimatic arc units from melange units in the Northern Anatolian Ophiolitic Belt(NAOB) are very rare. The study area represents the southern edge of the central part of the NAOB.The aim of the study is to distinguish the main units of NAOB and to define the geotectonic setting of the Darmik Ensimatic Arc Association(DEAA). To study the ensimatic arc units as an independent tectonic unit is important and facilitates understanding of the geological evolution of the NAOB. During field studies, the contact relationships within the Darmik Ensimatic Arc Association(DEAA) units and also with other tectonic units were reviewed. Then, paleontological, geochronological, petrological and also geochemical properties of the DEAA have been defined. In the present study, ensimatic arc units have been distinguished from ophiolitic association for the first time, in the region. As a result of the study, the DEAA is divided into two levels and lower level named as the Kartal unit and upper level named as the izibüyük unit. In the Kartal unit, basaltic and andesitic lavas with their equivalent pyroclastic rock units are dominant. Radiolarite and mudstones interbedded within the Kartal unit of DEAA have Turonian and Santonian age. In addition, the age of basalt samples of DEAA are 98.7 ± 2.4 Ma, defined using the~(40)Ar/39 Ar method. The izibüyük unit of DEAA comprises conglomerate, sandstone, claystone, mudstone,clayey limestone, micritic limestone with volcanic interbeds and also calciturbidites. Santonian-Maastrichtian ages were obtained from this unit of the DEAA. In conclusion, the age of DEAA is widely accepted as Late Cretaceous. After the evaluation of the analysis, the volcanics of the DEAA originated from calcalkaline-basalts, which reflect ensimatic arc magmatism.  相似文献   

The contribution of marine magnetics in the Gulf of Saint-Malo (Brittany,France) to the understanding of the geology of the North Armorican Cadomian belt     

Jean-François Oehler  Marie-Françoise Lequentrec-Lalancette 《Comptes Rendus Geoscience》2019,351(1):1-9

Marine magnetic data extracted from the geophysical database of the SHOM (the French Hydrographic and Oceanographic Service) offer a first overview of the magnetic offshore environment in the Gulf of Saint-Malo (Brittany, France). Their cross-interpretation with available geological and geophysical knowledge provides a new land and sea model of the western part of the Late Proterozoic North Armorican Cadomian belt. In particular, marine data exhibit relatively intense and heterogeneous magnetic signatures, mainly interpreted as the offshore prolongation of plutonic, volcanic, and metamorphic geologic formations recognized onshore. Imprints of major faults well known on land can be inferred at sea from discontinuities and shifting of magnetic anomalies or followed by high-resolution bathymetry. An impressive and dense dolerite dyke swarm propagated on more than 50 km from the coast seaward. Dykes are characterized by both 1-km-deep and less than 50-m-deep superficial magnetic responses, suggesting the existence of deeply rooted super dykes to which individual small-scale structures are connected.  相似文献   

Effect of micro and macro parameters in 3D modeling of grain crushing     

Nader  François  Silvani  Claire  Djeran-Maigre  Irini 《Acta Geotechnica》2019,14(6):1669-1684

Acta Geotechnica - Coarse granular materials exhibit important grain breakage in civil engineering structures, making it more complicated to predict the settlement and collapse of structures. A...  相似文献   

Contrasting oxygen fugacity of I- and S-type granites from the Araçuaí orogen,SE Brazil: an approach based on opaque mineral assemblages     

dos Santos Dias  Jordania Cristina  Gonçalves  Leonardo  Gonçalves  Cristiane C. 《Mineralogy and Petrology》2019,113(5):667-686

Mineralogy and Petrology - This study presents mineralogical characterization of opaque assemblages from I- and S-type granites from the Araçuaí orogen, southeastern Brazil that belong...  相似文献   

Implications of 2007’s Earthquake Activity in Eğirdir Lake (SW Anatolia) Based on Moment Tensor Solutions and Inversion of Stress State   总被引：1，自引：0，他引：1  

Selda Altuncu Poyraz  Alİ Pinar  Süha Özden  Mustafa Kemal Tunçer 《Pure and Applied Geophysics》2014,171(7):1299-1309

We analyzed the waveforms of the small- to moderate-sized earthquakes that took place in the northern part of the inner Isparta Angle (IA) to retrieve their source parameters and combine these results with the focal mechanism solutions of the larger events that occurred in 2007 in E?irdir Lake at the apex of IA. In total, source mechanisms of 20 earthquakes within the magnitude range 3.5 < M < 5.0 were calculated using a regional moment tensor inversion technique. The inversion of the focal mechanisms yields an extensional regime with a NNE–SSW (N38°E) trending σ ₃ axis. Inversion results are related to a mainly WNW–ESE oriented normal fault beneath E?irdir Lake. The R value of a NNE–SSW extensional regime is 0.562 showing a triaxial stress state in the region. The current stress regime results from complex subduction processes such as slab pull, slab break-off, roll-back and/or retreating mechanism along the Hellenic and Cyprus arcs and the southwestward extrusion of the Anatolian block since the early Pliocene.  相似文献   

A detailed analysis of microseismicity in Samos and Kusadasi (Eastern Aegean Sea) areas     

Onur Tan  Eleftheria E. Papadimitriou  Zumer Pabucçu  Vassilis Karakostas  Ahmet Yörük  Kostas Leptokaropoulos 《Acta Geophysica》2014,62(6):1283-1309

A detailed investigation of microseismicity and fault plane solutions are used to determine the current tectonic activity of the prominent zone of seismicity near Samos Island and Kusadasi Bay. The activation of fault populations in this complex strike-slip and normal faulting system was investigated by using several thousand accurate earthquake locations obtained by applying a double-difference location method and waveform cross-correlation, appropriate for areas with relatively small seismogenic structures. The fault plane solutions, determined by both moment tensor waveform inversions and P-wave first motion polarities, reveal a clear NS trending extension direction, for strike slip, oblique normal and normal faults. The geometry of each segment is quite simple and indicates planar dislocations gently dipping with an average dip of 40–45°, maintaining a constant dip through the entire seismogenic layer, down to 15 km depth.  相似文献   

Use of Chitosan with Different Deacetylation Degrees for the Adsorption of Food Dyes in a Binary System          下载免费PDF全文

Janaína O. Gonçalves  Diana A. Duarte  Guilherme L. Dotto  Luiz Antonio A. Pinto 《洁净——土壤、空气、水》2014,42(6):767-774

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Preconcentration and Determination of Endocrine Disruptor Pesticides in Well Water by Solidified Floating Organic Drop Microextraction          下载免费PDF全文

Füsun Okçu Pelit  Levent Pelit  Ceren Alaca  Hasan Ertaş  Fatma Nil Ertaş 《洁净——土壤、空气、水》2014,42(9):1284-1291

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Photosynthetic pigment changes and adaptations in biofilms in response to flow intermittency     

Xisca Timoner  Teresa Buchaca  Vicenç Acuña  Sergi Sabater 《Aquatic Sciences - Research Across Boundaries》2014,76(4):565-578

Among the environmental factors affecting benthic algae and cyanobacteria in streams, the one often producing the largest effects is flow intermittency. This study aimed to characterize the responses of algal assemblages to flow intermittency in a Mediterranean intermittent stream during the drying, non-flow (112 days), and rewetting phases. Algae growing in the epilithic, epipsammic and hyporheic streambed compartments were analyzed for pigment composition, and for the existence of structural changes in cells. Chlorophyll-a concentrations decreased between 60 to 90 % during the non-flow phase, indicating low resistance of algal assemblages to desiccation. In contrast, fast recoveries of Chlorophyll-a when flow resumed indicated high resilience. Pigment composition revealed that the epilithic algal assemblage was considerably different than the epipsammic and hyporheic ones. These differences were mainly attributed to the physical conditions prevailing on each streambed compartment that allowed the growth of different algal assemblages. During the non-flow phase, the synthesis of protective carotenoids (i.e. echinenone and scytonemin) and the occurrence of cell resistance structures (i.e. enlarged membrane thickness and resistant spores) enhanced resistance of the epilithic biofilm. The resistance observed in the epilithic biofilm might also be related to the tightly adhered growth-form of algae on this substratum. Main results suggest that algal assemblages in the epilithic compartment, which were the most exposed to desiccation, were structurally and functionally better adapted to flow interruption than those colonizing other streambed compartments, and that this compartment plays a crucial role in maintaining ecosystem functions under varying flow periods.  相似文献   

Source mechanism and stress analysis of 23 October 2011 Van Earthquake (Mw = 7.1) and aftershocks     

Doğan Kalafat  Kıvanç Kekovalı  Feyza Akkoyunlu  Zafer Ögütçü 《Journal of Seismology》2014,18(3):371-384

On 23 October 2011 at 1341 local time, a strong earthquake (Mw?=?7.1) occurred east of Lake Van (KOERI; Kandilli Observatory and Earthquake Research Institute). The focal parameters of the main shock and 29 aftershocks with M?≥?4.0 were obtained from regional broadband seismic data from KOERI network by using Regional Moment Tensor Inversion Code (Dreger 2002). It is confirmed that the main shock had thrust faulting mechanism. The stress tensor analysis was completed using the focal mechanism solutions and the software developed by (Gephart Comp Geosci 16: 953-989, 1990). The maximum principal stress (P compressional) of the main shock is aligned in a N-S (NNW/SSE) direction and the tensional axis (T dilatation) is aligned in an E-W (ENE-WSW) direction. The b value is calculated as 0.96 using the maximum likelihood method (Utsu 1999).  相似文献