Neotectonic deformation in the transition zone between the Dead Sea Transform and the East Anatolian Fault Zone, Southern Turkey: a palaeomagnetic study of the Karasu Rift Volcanism     

O Tatar  J.D.A Piper  H Gürsoy  A Heimann  F Kobulut 《Tectonophysics》2004,385(1-4):17-43

In southern Turkey ongoing differential impingement of Arabia into the weak Anatolian collisional collage resulting from subduction of the Neotethyan Ocean has produced one of the most complex crustal interactions along the Alpine–Himalayan Orogen. Several major transforms with disputed motions, including the northward extension of the Dead Sea Fault Zone (DSFZ), meet in this region. To evaluate neotectonic motion on the Amanos and East Hatay fault zones considered to be northward extensions of the DSFZ, the palaeomagnetism of volcanic fields in the Karasu Rift between these faults has been studied. Remanence carriers are low-Ti magnetites and all except 5 of 51 basalt lavas have normal polarity. Morphological, polarity and K–Ar evidence show that rift formation occurred largely during the Brunhes chron with volcanism concentrated at 0.66–0.35 Ma and a subsidiary episode at 0.25–0.05. Forty-four units of normal polarity yield a mean of D/I=8.8°/54.7° with inclination identical to the present-day field and declination rotated clockwise by 8.8±4.0°. Within the 15-km-wide Hassa sector of the Karasu Rift, the volcanic activity is concentrated between the Amanos and East Hatay faults, both with left lateral motions, which have rotated blocks bounded by NW–SE cross faults in a clockwise sense as the Arabian Block has moved northwestwards. An average lava age of 0.5 Ma yields a minimum cumulative slip rate on the system bounding faults of 0.46 cm/year according with the rate deduced from the Africa–Arabia Euler vector and reduced rates of slip on the southern extension of the DSFZ during Plio-Quaternary times. Estimates deduced from offsets of dated lavas flows and morphological features on the Amanos Fault Zone [Tectonophysics 344 (2002) 207] are lower (0.09–0.18 cm/year) probably because they are limited to surface fault breaks and do not embrace the seismogenic crust.Results of this study suggest that most strike slip on the DSFZ is taken up by the Amanos–East Hatay–Afrin fault array in southern Turkey. Comparable estimates of Quaternary slip rate are identified on other faults meeting at an unstable FFF junction (DSFZ, East Anatolian Fault Zone, Karatas Fault Zone). A deceleration in slip rate across the DSFZ and its northward continuation during Plio-Quaternary times correlates with reorganization of the tectonic regime during the last 1–3 Ma including tectonic escape within Anatolia, establishment of the North and East Anatolian Fault Zones bounding the Anatolian collage in mid–late Pliocene times, a contemporaneous transition from transpression to transtension and concentration of all basaltic magmatism in this region within the last 1 Ma.  相似文献   

Fold-Thrust-Belt Structure of the Proterozoic Eastern Ghats Mobile Belt: A Proposed Correlation Between India and Antarctica in Gondwana     

T.K. Biswal  S. Sinha 《Gondwana Research》2004,7(1):43-56

The Proterozoic Eastern Ghats Mobile Belt along the east coast of India shares a thrusted lower contact with the surrounding cratons. The thrust, known as the Terrane Boundary shear zone, is associated with two large lateral ramps resulting in a curved outline on the northwestern corner of the mobile belt. The Eastern Ghats Mobile Belt is divided into two lithotectonic units, the Lathore Group and the Turekela Group, based on their lithological assemblages and deformational history. On the basis of published data from a Deep Seismic Sounding (DSS) profile of the Eastern Ghats crust, the Terrane Boundary Shear Zone is considered to be listric in nature and acts as the sole thrust between craton and mobile belt. The Lathore and Turekela Groups are nappes. With this structural configuration the NW part is described as a fold thrust belt. However, the thrusting postdates folding and granulite metamorphism that occurred in the Eastern Ghats, as in the Caledonide type of fold thrust belt of NW Scotland. The Terrane Boundary Shear Zone is interpreted to be contiguous with the Rayner-Napier boundary of the Enderby Land in a Gondwana assembly.  相似文献   

Deformation History of the Kunavaram Complex, Eastern Ghats Belt, India: Implications for Alkaline Magmatism Along the Indo-Antarctica Suture   总被引：1，自引：0，他引：1  

Saibal Gupta  Shamik Bose 《Gondwana Research》2004,7(4):1235-1241

The Kunavaram alkaline complex is a NE-SW trending elongate body located along a major lineament, the Sileru Shear Zone (SSZ) that is regarded as a Proterozoic suture related to Indo-Antarctica collision. The complex is hosted within migmatitic quartzofeldspathic gneisses, mafic granulites retrogressed to amphibolites, and quartzites. The structural evolution of the country rocks and the alkaline complex are similar. The first phase of deformation, D₁, produces a pervasive segregation banding (S₁) in all rock units within and outside the complex. A second deformation phase D₂ isoclinally folded S₁ along subvertical axial planes with shallow plunging axes. F₂ isoclinal folds are ubiquitous in the country rocks and the eastern extremity of the complex. In the interior of the alkaline body, D₂ strain decreases and S₁ is commonly subhorizontal. While amphibolite to granulite facies conditions prevailed during deformation, post-D₂ annealing textures testify to persisting high grade conditions. In the west, a NNE-SSW trending dextral shear zone with strike-slip sense (D₃) truncates the complex. Within this shear zone, quartzofeldspathic country rocks are plastically deformed, while hornblende-K-feldspar assemblages of the complex are retrogressed to biotite and plagioclase. Warping related to D₃ shears also resulted in fold interference patterns on the subhorizontal S₁ foliation in low D₂ strain domains. Based on its steep dip, north-easterly trend, and non-coaxial nature with dextral strike-slip sense, the D₃ shear zone can be correlated with the SSZ. Since this shear zone, i.e., the SSZ, is not associated with primary igneous fabrics and resulted in solid state deformation of the complex, it cannot be considered as a conduit for alkaline magmatism, but is probably responsible for the post-tectonic disposition of the pluton.  相似文献   

Analytical prediction of aggregates' effects on the ITZ volume fraction and Young's modulus of concrete          下载免费PDF全文

R. Zouaoui  K. Miled  O. Limam  A. Beddey 《国际地质力学数值与分析法杂志》2017,41(7):976-993

In order to evaluate analytically the ITZ volume fraction (f_ITZ) in concrete, a three phase model is proposed for the random concrete microstructure using the Voronoï tessellation. Within this model, the ITZ local thickness is a statistical variable depending on the local paste thickness available between each couple of neighbouring aggregates. The f_ITZ is found to not exceed 7% for typical concretes. Then, the concrete Young's modulus is predicted analytically using a four‐phase generalized self consistent model but in which the proposed f_ITZ is considered. It is found that the concrete Young's modulus increases when increasing aggregates volume fraction, aggregates maximum size and the proportion of coarse aggregates and when decreasing the ITZ thickness and Young's modulus. Finally, the validity of the proposed model is discussed based on a comparison between its predictions and three sets of experimental results related to normal and high strength concretes taken from literature. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Possible spatial variability in the Selwyn Block of Central Victoria: evidence from Late Devonian felsic igneous rocks   总被引：2，自引：0，他引：2  

J. D. Clemens  M. A. Elburg 《Australian Journal of Earth Sciences》2016,63(2):187-192

The Neoproterozoic to Cambrian Selwyn Block in Central Victoria forms the mainly unexposed basement to the Paleozoic metasediments, granitic rocks and felsic volcanic complexes of the Melbourne Zone of the Lachlan Orogen. The Late Devonian felsic rocks are largely products of partial melting of the Selwyn Block, and their chemistry implies that their sources were most probably arc-related andesite, dacite, volcaniclastic greywackes and some pelites. When plotted against the median longitudes of the plutons and volcanic complexes, the average values for ⁸⁷Sr/⁸⁶Sr_t and ?Nd_t (at 370 Ma) reveal broad trends interpreted to reflect possible compositional and/or age structure in the Selwyn Block. Assuming that the trends are real, from W to E, I-type sources are progressively less crustally evolved, probably younging eastward. The S-type sources show no trend in ?Nd_t, suggesting that there was efficient sediment mixing. The ⁸⁷Sr/⁸⁶Sr_t values, however, become more evolved eastward (opposite in sense to the apparent variation in the I-type sources). This is interpreted as the original Selwyn Block sediments having been more pelitic eastward, perhaps suggesting a deepening of the basin in this direction, as well as structurally upward in the succession. The opposite senses of variation highlights the spatial separation of the S- and I-type sources and suggest that the granitic magmas here are unlikely to represent any sort of mixing continuum.  相似文献   

Field evidence for normal fault linkage and relay ramp evolution: the Kırkağaç Fault Zone,western Anatolia (Turkey)     

Bora Uzel 《Geodinamica Acta》2016,28(4):311-327

Linking of normal faults forms at all scales as a relay ramp during growth stages and represents the most efficient way for faults to lengthen during their progressive formation. Here, I study the linking of normal faulting along the active K?rka?aç Fault Zone within the west Anatolian extensional system to reconstruct fault interaction in time and space using both field- and computer-based data. I find that (i) connecting of the relay zone/ramp occurred with two breaching faults of different generations and that (ii) the propagation was facilitated by the presence of pre-existing structures, inherited from the ?zmir-Bal?kesir transfer zone. Hence, the linkage cannot be compared directly to a simple fault growth model. Therefore, I propose a combined scenario of both hangingwall and footwall fault propagation mechanisms that explain the present-day geometry of the composite fault line. The computer-based analyses show that the approximate slip rate is 0.38 mm/year during the Quaternary, and a NE–SW-directed extension is mainly responsible for the recent faulting along the K?rka?aç Fault Zone. The proposed structural scenario also highlights the active fault termination and should be considered in future seismic hazard assessments for the region that includes densely populated settlements.  相似文献   

郯庐断裂带晚中生代演化历史及其对华北克拉通破坏过程的指示   总被引：13，自引：8，他引：5  

朱光  王薇  顾承串  张帅  刘程 《岩石学报》2016,32(4):935-949

郯庐断裂带晚中生代的演化历史是华北克拉通破坏过程的重要记录。中侏罗世末(燕山运动A幕),郯庐断裂带局部发生左行平移活动,而华北克拉通上出现了一系列北北东走向的缩短构造,指示了西太平洋伊泽奈崎板块俯冲的开始。晚侏罗世期间,郯庐断裂带没有发生活动,而华北克拉通出现局部伸展与岩浆活动及区域性隆升,应为弧后弱拉张背景。早白垩世初(燕山运动B幕),郯庐断裂带再次发生强烈的左行平移活动,华北克拉通北部与东部出现了一系列近南北向挤压产生的构造,应是鄂霍茨克洋最终关闭与伊泽奈崎板块高速俯冲双重作用的结果。随后的早白垩世期间,华北克拉通在弧后拉张背景下发生峰期破坏,郯庐断裂带呈现为强烈的伸展活动。早白垩世末的区域性挤压作用,结束了华北克拉通的峰期破坏,并使郯庐断裂带再次发生了一期左行平移活动。这期挤压作用出现在太平洋板块接替伊泽奈崎板块这一重大板块调整的背景之中。  相似文献   

肥东花岗质岩脉的变形及年代学特征对郯庐断裂带早白垩世构造活动的指示   总被引：1，自引：1，他引：0  

韩雨  牛漫兰 《岩石学报》2016,32(4):1049-1066

郯庐断裂带肥东段位于大别造山带与苏鲁造山带之间。在肥东段西韦采石场内发育了大规模的北北东向左行走滑韧性剪切带和一条低角度的韧性滑脱正断层。走滑韧性剪切带为郯庐断裂带走滑活动的产物,低角度滑脱正断层则代表了伸展背景下的构造活动。低角度滑脱正断层上、下盘发育未变形和变形的岩脉,走滑韧性剪切带内外也发育有受剪切带活动而变形的岩脉。对采石场内岩脉的构造和同位素年代学研究表明,低角度韧性滑脱正断层在129~126Ma之间发生过剪切活动,走滑韧性剪切带的活动时间在125Ma之后。综合研究认为,郯庐断裂带的伸展活动可能开始于早白垩世早期(130Ma),但在早白垩世并非一直处于伸展活动之中,125Ma之后的左行走滑活动很可能发生在早白垩世的晚期。  相似文献   

Geochemical and Geochronological Constraints on the Origin of the Meta-basic Volcanic Rocks in the Tengtiaohe Zone,Southeast Yunnan     

QIAN Xin  FENG Qinglai  WANG Yuejun  ZHANG Zhibin 《《地质学报》英文版》2016,90(2):669-683

The meta-basic volcanic rocks in the Tengtiaohe Zone yield zircon U–Pb ages of 258.8±2.5 Ma and 259.2±1.8 Ma, respectively which agree with the ages of flood basalts of ELIP and are similar to the basaltic rocks and komatiites from the Song Da Zone in northern Vietnam. The results suggest that the age of meta-basic volcanic rocks is Late Permian, rather than the Early Permian or Early Carboniferous ages as previously inferred. Most meta-basic volcanic rocks are strongly enriched in LREEs relative to HREEs and display trace element patterns similar to the ELIP high-Ti basalts, and are enriched in LILEs with negative Sr anomalies. Their initial ~(87)Sr/~(86) Sr ratios range from 0.705974 to 0.706188 and εNd(t) from-0.82 to-2.11. Their magmas were derived from an enriched and deep mantle source without significant crustal contamination. These meta-basic volcanic rocks formed in ELIP. Therefore, the Tengtiaohe Zone is not an ophiolite zone and can link to the Song Da Zone in northern Vietnam.  相似文献   

Review of Earth Critical Zone Research   总被引：2，自引：0，他引：2  

An Peijun  Zhang Zhiqiang  Wang Liwei 《地球科学进展》2016,31(12):1228-1234

Since the Earth Critical Zone put forward by National Research Council of America in 2001, it has got a lot of attention and some significant progresses have been made. This paper summarized those Earth Critical Zone projects and related research plans organized and implemented by the United States of America, Germany, Australia, France, China and the European Union, as well as main scientific problems and future development direction in the study of Earth Critical Zone. According to research status of China, the four main research contents should be strengthened including structure, formation and evolution mechanism of Earth Critical Zone, the coulpling interaction mechanism between migration and transformation of material and multi-processes, sevice function and evolution features of Earth Critical Zone and its support and effect on sustainable development, model simulation of process and system of Earth Critical Zone. In addition, our country should actively conduct cooperation and communication with the advanced countries, and enhance our involvement in international key research plans.  相似文献