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1.
Recently acquired (2005) multi-beam bathymetric and high-resolution seismic reflection data from the E–W-oriented Gulf of Gökova off SW Anatolia were evaluated in order to assess the uneven seafloor morphology and its evolution in terms of present-day active regional tectonics. Stratigraphically, the three identified seismic units, i.e., the basement, deltaic sediments deposited during Quaternary glacial periods, and modern gulf deposits, are consistent with those observed in previous studies. Structurally, the folds and faults with strike-slip and reverse components have been regionally mapped for the first time. Of these, NE–SW-oriented left-lateral strike-slip faults with compressional components forming the so-called Gökova Fault Zone intersect and displace two WNW–ESE-oriented submarine ridges and deep submarine plains. Thus, strike-slip faults are the youngest major structures in the gulf, and control present-day active tectonism. E–W-oriented folds on the inner and outer shelf, which are generally accompanied by reverse faults, delimit the margins of these submarine ridges, and deform the young basin deposits. These features also reveal the concomitant existence of a compressional tectonic regime. The compressional structures probably represent pressure ridges along left-lateral strike-slip fault segments. However, some E–W-oriented normal faults occur on the northwestern and partly also southern shelf, and along the borders of the adjacent deep submarine plains. They are intersected and displaced by the strike-slip faults. The lower seismicity along the normal faults relative to the NE–SW-oriented strike-slip faults suggests that the former are at present inactive or at least less active. 相似文献
2.
C. Kurtuluş B. Doğan F. Sertçelik M. Canbay H. M. Küçük 《Marine Geophysical Researches》2009,30(2):121-134
The Edremit Gulf, which developed during the Neogene-Quaternary, is a seismically active graben in NW Anatolia (Turkey) surrounded
by the Sakarya continent. The sedimentary deposits in the gulf overlie the bedrock unconformably and can be separated into
two parts as upper and lower deposits based on similarity of their seismic characteristics, and because the contact between
them is clear. The lower deposits are characterized in the seismic profiles by the absence of well defined, continuous reflectors
and are strongly disturbed by faults. A tectonic map and structural model of the Edremit Gulf was derived from interpreting
21 deep seismic profiles trending NE–SW and NW–SE within the gulf. Two fault systems were distinguished on the basis of this
compilation. The NNW–SSE trending parallel faults are low-angle normal faults formed after compression. They controlled and
deformed the lower basin deposits. A syncline and anticline with a broad fold-curvature length resulted in folds that developed
parallel to basin boundaries in the lower basin deposits. The ENE–WSW trending high-angle faults have controlled and deformed
the northern basin of the Edremit Gulf. The folds developed within the northern lower deposits originated from the listric
geometry of the faults. These faults are normal faults associated with regional N–S extension in western Anatolia. The Edremit
Gulf began to open under the control of low-angle NNW–SSE trending faults that developed after the compression of western
Anatolia in an E–W direction in the early Neogene. Subsequently, regional N–S extensional stress and high-angle normal faults
cut the previous structures, opened the northern basin, and controlled and deformed the lower basin deposits in the gulf.
As a result, the Edremit Gulf has not been controlled by any strike-slip faults or the Northern Anatolian Fault. The basin
developed in the two different tectonic regimes of western Anatolia as an Aegean type cross-graben from the Neogene to Holocene. 相似文献
3.
Multichannel seismic reflection and multi-beam bathymetry data were used to study the active tectonic and syn-tectonic stratigraphic setting of the Gulf of ?zmit in the Marmara Sea (Turkey). The gulf and its near surroundings are deformed by the northern strand of the dextral North Anatolian Fault. Three connected basins of the gulf, the western (Dar?ca), central (Karamürsel) and eastern (Gölcük) basins are formed by active faults, as observed in the stacked and migrated seismic sections, as well as the bathymetry map. The main branch and its surrounding sedimentary strata are confined by normal faults to the north and south. These normal faults converge at depth towards the main fault, forming a negative flower structure in the gulf. The average maximum sedimentation rate is 0.4 mm/year according to the three most recent seismo-stratigraphic units that are located to the south of the main fault branch within the central basin. A 20° south-dipping major discontinuity along the northern shoreline of the gulf represents the top of Paleozoic basement. 相似文献
4.
Erdal Dolu Erkan Gökaşan Engin Meriç Mustafa Ergin Tolga Görüm Hüseyin Tur Berkan Ecevitoğlu Niyazi Avşar Muhittin Görmüş Fatmagül Batuk Buğser Tok Oktay Çetin 《Geo-Marine Letters》2007,27(6):355-381
The Quaternary evolution of the Gulf of İzmit, situated on the tectonically active North Anatolian Fault Zone (NAFZ), was
investigated using seismic reflection, paleontologic, and sediment textural data. On the basis of seismic stratigraphic and
sedimentologic-paleontologic interpretations, four depositional units were distinguished within the Plio-Quaternary sequence
of the Gulf of İzmit. According to these data, Plio-Quaternary deposits supplied from the northern terrestrial area started
to accumulate during a progradational phase, in a south-facing half-graben. A coarse-grained sedimentary unit prograding into
the gulf from the south since 200 ka b.p. indicates a dramatic variation in the evolution of the gulf, with the initiation of a new strike-slip fault of the NAFZ
and a corresponding uplift of the Armutlu Peninsula in the south of the gulf. During the evolution of this fault from a wide
shear zone consisting of right-stepped strike-slip faults and pull-apart basins to a localized principal fault zone, sediments
were deposited under the influence of northerly prograding terrestrial and shallow-marine conditions due to relative sea-level
fluctuations in the Marmara Sea. During this period, the Gulf of İzmit was invaded mainly by Mediterranean and partly by Black
Sea waters. In the latest glacial period, shallow areas in the gulf became subaerially exposed, whereas the central and western
sub-basins of the gulf turned into lakes. The present evolution of the Gulf of İzmit is controlled by the after effects of
the new rupture of the NAFZ and the estuarine nature of the gulf environment. 相似文献
5.
Most of the basins developed in the continental core of SE Asia (Sundaland) evolved since the Late Cretaceous in a manner that may be correlated to the conditions of the subduction in the Sunda Trench. By the end of Mesozoic times Sundaland was an elevated area composed of granite and metamorphic basement on the rims; which suffered collapse and incipient extension, whereas the central part was stable. This promontory was surrounded by a large subduction zone, except in the north and was a free boundary in the Early Cenozoic. Starting from the Palaeogene and following fractures initiated during the India Eurasia collision, rifting began along large faults (mostly N–S and NNW–SSE strike-slip), which crosscut the whole region. The basins remained in a continental fluvio-lacustrine or shallow marine environment for a long time and some are marked by extremely stretched crust (Phu Khanh, Natuna, N. Makassar) or even reached the ocean floor spreading stage (Celebes, Flores). Western Sundaland was a combination of basin opening and strike-slip transpressional deformation. The configuration suggests a free boundary particularly to the east (trench pull associated with the Proto-South China Sea subduction; Java–Sulawesi trench subduction rollback). In the Early Miocene, Australian blocks reached the Sunda subduction zone and imposed local shortening in the south and southeast, whereas the western part was free from compression after the Indian continent had moved away to the north. This suggests an important coupling of the Sunda Plate with the Indo-Australian Plate both to SE and NW, possibly further west rollback had ceased in the Java–Sumatra subduction zone, and compressional stress was being transferred northwards across the plate boundary. The internal compression is expressed to the south by shortening which is transmitted as far as the Malay basin. In the Late Miocene, most of the Sunda Plate was under compression, except the tectonically isolated Andaman Sea and the Damar basins. In the Pliocene, collision north of Australia propagated toward the north and west causing subduction reversal and compression in the short-lived Damar Basin. Docking of the Philippine Plate confined the eastern side of Sundaland and created local compression and uplift such as in NW Borneo, Palawan and Taiwan. Transpressional deformation created extensive folding, strike-slip faulting and uplift of the Central Basin and Arakan Yoma in Myanmar. Minor inversion affected many Thailand rift basins. All the other basins record subsidence. The uplift is responsible for gravity tectonics where thick sediments were accumulated (Sarawak, NE Luconia, Bangladesh wedge). 相似文献
6.
The evolution of the North Aegean Sea is studied through the development of three deep basins: the North Aegean Trough, the North Skyros Basin and the Ikaria Basin. Bathymetric data, a 2D seismic dataset and the well-investigated stratigraphic records of the onshore deep basins of northern Greece and Western Turkey were used to make structural and seismic stratigraphic interpretations. The study area shows two sharp unconformities that correspond to the Eocene-Oligocene transition and the Miocene-Pliocene shift. These discontinuities were used as marker horizons for a more detailed structural and seismic stratigraphic interpretation resulting in the identification of several seismic units. A general seismic signature chart was established using onshore basin stratigraphy and well data, which was then used to constrain the ages of the different seismic units. The main features observed in the basins are interpreted as: 1) trans-tensional growth patterns in Pliocene and Quaternary sediments that combine NE–SW trending and steeply dipping fault zones that likely correspond to strike-slip corridors and E-W/WNW-ESE trending normal faults, 2) regional erosional truncations of Miocene sediments, likely related to the Messinian Salinity Crisis (MSC), 3) thick delta-turbidite deposits of Neogene age. Only the North Aegean Trough shows evidence of earlier development and polyphase deformation through inversion structures, and additional seismic units. Extension processes in the Aegean region have been driven by the Hellenic slab rollback since the middle Eocene. The widespread development of Neogene basins at the whole Aegean scale attests to a major tectonic change due to an acceleration of the trench retreat in the middle Miocene. The present study shows that the Neogene basins of the North Aegean Sea developed in dextral transtension with the northward migration of the associated NE-SW trending strike-slip faults. At regional scale, this tectonic pattern indicates that the westward escape of Anatolia started to interact with the trench retreat in the middle Miocene, around 10 Myr before the arrival of the North Anatolian Fault in the North Aegean Sea. 相似文献
7.
Active faults at a range in scales are observed in different directions (E-W, N-S and NE-SW) in the extensional tectonic regime of the Aegean region, western Turkey. However, mechanisms and types of faults in the Gulf of Izmir have not been investigated properly. Tectonic setting in the gulf together with the origin and characteristics of faults were studied in this study by integrating interpretation from various very high resolution acoustic data (multibeam bathymetry and CHIRP very high resolution seismic) acquired in the Gulf of Izmir.The Gulf of Izmir has thick, unconsolidated, stratified sediment cover. The water depth increases from the inner part (SE) to the outer part (NW) of the gulf with complex sea floor morphology. However, northeastern part of the coastal region is very shallow because of the sedimentary influx transported by the Gediz River. The western margin and the southern part of the gulf were formed under the influence of Uzunada (Uzun Island) and Izmir Faults, respectively. In the southern offshore, there is only one, E-W directional normal fault dipping through the north and corresponding to the offshore segment of the Izmir Fault Zone to the west. The acoustic data enable identification of the Uzunada Fault Zone extending as a simple lineament from near Guzelbahce in the south but bifurcating toward the NE of the Cicek Archipelago and terminating with left-lateral slip in the E-NE of the Hekim Island. After the sinistral strike-slip, the fault re-extends in the NW direction untill the mid of Uzunada as a single fault segment. Then, the fault is observed as a bunch of many active fault segments (like horse-tail splays) to the east of Uzunada with N-NW elongation through the outer gulf. These segments were chronologically succeeded from the east to the west. This progradational pattern is attributed to westward extension of the Gulf of Izmir with anti-clockwise rotational escape of the Anatolian Plate. In addition, progradation of faults was controlled by the NE-SW directional tear faults which may have played a key role in the shoreline extension and general pattern of the outer gulf islands. A very young graben in the central part of the gulf, also dislocated by the tear faults was observed parallel to the Uzunada Fault Zone as another indicator of ongoing fan-shaped opening of the gulf. These tectonic elements are consistent with earlier interpretation of GPS-based observations indicating a four-wheel gear system of rigid-body rotations. Additionally, a new fault extending from the far offshore of Foca to Suzbeyli village to the south was identified in this study. Its NW-SE extension is angular to the previous tectonic elements. All these elements apparently project at least 10 km farther northward, in the offshore Foca where the earthquake epicenters cluster. 相似文献
8.
The role of the Spitsbergen shear zone in determining morphology,segmentation and evolution of the Knipovich Ridge 总被引：1，自引：1，他引：1
Crane Kathleen Doss Hany Vogt Peter Sundvor Eirik Cherkashov Georgy Poroshina Irina Joseph Devorah 《Marine Geophysical Researches》2001,22(3):153-205
In 1989–1990 the SeaMARC II side-looking sonar and swath bathymetric system imaged more than 80 000 km2 of the seafloor in the Norwegian-Greenland Sea and southern Arctic Ocean. One of our main goals was to investigate the morphotectonic
evolution of the ultra-slow spreading Knipovich Ridge from its oblique (115° ) intersection with the Mohns Ridge in the south
to its boundary with the Molloy Transform Fault in the north, and to determine whether or not the ancient Spitsbergen Shear
Zone continued to play any involvement in the rise axis evolution and segmentation.
Structural evidence for ongoing northward rift propagation of the Mohns Ridge into the ancient Spitsbergen Shear Zone (forming
the Knipovich Ridge in the process) includes ancient deactivated and migrated transforms, subtle V-shaped-oriented flank faults
which have their apex at the present day Molloy Transform, and rift related faults that extend north of the present Molloy
Transform Fault. The Knipovich Ridge is segmented into distinct elongate basins; the bathymetric inverse of the very-slow
spreading Reykjanes Ridge to the south. Three major fault directions are detected: the N-S oriented rift walls, the highly
oblique en-echelon faults, which reside in the rift valley, and the structures, defining the orientation of many of the axial
highs, which are oblique to both the rift walls and the faults in the axial rift valley.
The segmentation of this slow spreading center is dominated by quasi stationary, focused magma centers creating (axial highs)
located between long oblique rift basins. Present day segment discontinuities on the Knipovich Ridge are aligned along highly
oblique, probably strike-slip faults, which could have been created in response to rotating shear couples within zones of
transtension across the multiple faults of the Spitsbergen Shear Zone. Fault interaction between major strike slip shears
may have lead to the formation of en-echelon pull apart basins. The curved stress trajectories create arcuate faults and subsiding
elongate basins while focusing most of the volcanism through the boundary faults. As a result, the Knipovich Ridge is characterized
by Underlapping magma centers, with long oblique rifts.
This style of basin-dominated segmentation probably evolved in a simple shear detachment fault environment which led to the
extreme morphotectonic and geophysical asymmetries across the rise axis. The influence of the Spitsbergen Shear Zone on the
evolution of the Knipovich Ridge is the primary reason that the segment discontinuities are predominantly volcanic.
Fault orientation data suggest that different extension directions along the Knipovich Ridge and Mohns Ridge (280° vs. 330°,
respectively) cause the crust on the western side of the intersection of these two ridges to buckle and uplift via compression
as is evidenced by the uplifted western wall province and the large 60 mGal free air gravity anomalies in this area.
In addition, the structural data suggest that the northwards propagation of the spreading center is ongoing and that a `normal'
pure shear spreading regime has not evolved along this ridge.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
9.
This study provides the results of the first integrated study of Oligocene–Pliocene basins around Norway.Within the study area, three main depocentres have been identified where sandy sediments accumulated throughout the Oligocene to Early Pliocene period. The depocentre in the Norwegian–Danish Basin received sediments from the southern Scandes Mountains, with a general progradation from north to south during the studied period. The depocentre in the basinal areas of the UK and Norwegian sectors of the North Sea north of 58°N received sediments from the Scotland–Shetland area. Because of the sedimentary infilling there was a gradual shallowing of the northern North Sea basin in the Oligocene and Miocene. A smaller depocentre is identified offshore northern Nordland between Ranafjorden (approximately 66°N) and Vesterålen (approximately 68°N) where the northern Scandes Mountains were the source of the Oligocene to Early Pliocene sediments. In other local depocentres along the west coast of Norway, sandy sedimentation occurred in only parts of the period. Shifts in local depocentres are indicative of changes in the paleogeography in the source areas.In the Barents Sea and south to approximately 68°N, the Oligocene to Early Pliocene section is eroded except for distal fine-grained and biogenic deposits along the western margin and on the oceanic crust. This margin was undergoing deformation in a strike-slip regime until the Eocene–Oligocene transition. The Early Oligocene sediments dated in the Vestbakken Volcanic Province and the Forlandssundet Basin represent the termination of this strike-slip regime.The change in the plate tectonic regime at the Eocene–Oligocene transition affected mainly the northern part of the study area, and was followed by a quiet tectonic period until the Middle Miocene, when large compressional dome and basin structures were formed in the Norwegian Sea. The Middle Miocene event is correlated with a relative fall in sea level in the main depocentres in the North Sea, formation of a large delta in the Viking Graben (Frigg area) and uplift of the North and South Scandes domes. In the Norwegian–Danish Basin, the Sorgenfrei-Tornquist Zone was reactivated in the Early Miocene, possibly causing a shift in the deltaic progradation towards the east. A Late Pliocene relative rise in sea level resulted in low sedimentation rates in the main depositional areas until the onset of glaciations at about 2.7 Ma when the Scandes Mountains were strongly eroded and became a major source of sediments for the Norwegian shelf, whilst the Frigg delta prograded farther to the northeast. 相似文献
10.
渤海湾及沿岸盆地的构造格局 总被引：4，自引：0，他引：4
渤海湾及沿岸盆地面积约20万平方公里,包括河北省,山东省北部和西部、辽宁省南部、河南省北部、天津市和北京市等陆地面积约12万7千平方公里,渤海海域面积为7万多平方公里。陆地面积大部被第四纪冲积层所覆盖。渤海最大深度为70米,平均深度为18米。这是一个大型的第三纪断陷-坳陷沉积盆地,是继大庆油田开发之后,在我国东部地区所开发的另一个重要的含油气盆地(图1)。 相似文献
11.
Cenozoic structures in the Bohai Bay basin province can be subdivided into eleven extensional systems and three strike-slip systems. The extensional systems consist of normal faults and transfer faults. The normal faults predominantly trend NNE and NE, and their attitudes vary in different tectonic settings. Paleogene rifting sub-basins were developed in the hanging walls of the normal faults that were most likely growth faults. Neogene–Quaternary sequences were deposited in both the rifting sub-basins and horsts to form a unified basin province. The extensional systems were overprinted by three NNE-trending, right-lateral strike-slip systems (fault zones). Although the principal displacement zones (PDZ) of the strike-slip fault zones are developed only in the basement and lower basin sequences in some cross sections, the structural deformation characteristics of the upper basin sequences also indicate that they are basement-involved, right-lateral strike-slip fault zones. According to the relationships between faults and sedimentary sequences, the extensional systems were mainly developed from the middle Paleocene to the late Oligocene, whereas the strike-slip systems were mainly developed from the Oligocene to the Miocene. Strike-slip deformation was intensified as extensional deformation was weakened. Extensional deformation was derived from horizontal tension induced by upwelling of hot mantle material, whereas strike-slip deformation was probably related to a regional stress field induced by plate movement. 相似文献
12.
Maarten Van Daele Aurélien van Welden Jasper Moernaut Christian Beck Franck Audemard Javier Sanchez François Jouanne Eduardo Carrillo Gustavo Malavé Andrés Lemus Marc De Batist 《Marine Geology》2011,279(1-4):37-51
The Gulf of Cariaco is a marginal basin located between the Cariaco Basin and the Paria Gulf, offshore NE Venezuela, along a system of active right-lateral strike-slip faults. It is connected to the Caribbean Sea via a shallow 58-m-deep sill implying that the gulf was disconnected from the global ocean during eustatic lowstands. A dense grid of high-resolution reflection seismic profiles has been used to determine the overall tectonic structure of the gulf and to establish the seismic stratigraphy of its sedimentary infill. Six unconformity-bounded seismic–stratigraphic units were identified in the upper ~ 200 m of the sedimentary infill. Detailed seismic–stratigraphic and seismic-facies analysis allowed defining a series of sedimentary features that can be used as indicators of past sea or lake level in the Gulf of Cariaco: i) delta offlap breaks, ii) evaporites, and iii) erosional unconformities. Using accurate measurements of these various indicators at several locations in the gulf and a simple total subsidence model, a relative sea/lake-level history encompassing the last 130 kyr could be reconstructed. In periods of connection with the open ocean, reconstructed relative sea level correlates well with eustatic sea level. In times of disconnection, distinct lake-level fluctuations occurred, which sometimes resulted in total dessication of the gulf. Lake-level fluctuations appear to correlate with major Heinrich Events, stadials and interstadials. MIS 4, the LGM and the Younger Dryas were thus identified in the Gulf of Cariaco sedimentary record. The last reconnection to the Caribbean Sea occurred during MWP1b (around 11.5 kyr). The very good fit of the Cariaco sea/lake-level curve with the eustatic sea-level curves (both in terms of amplitude and of timing) underscores potential for future paleoclimate research of the sedimentary record contained in this marginal basin, despite its active tectonic setting. 相似文献
13.
During two “Valdivia” cruises, 1971 and 1972, bathymetric and geologic studies have been made at the junction between the Gulf of Aden and the Afar rift systems, namely in the Gulf of Tadjura and the nearly closed basin of the Ghubbet el Kharab (western end of the Gulf of Aden). A predominantly east-northeast striking fracture zone determines the morphologic structure of the central part of the gulf. The western end of the Gulf of Tadjura, including the Ghubbet el Kharab, is characterized by northwest striking normal faults.Up to 40 m thick subrecent sediments of the Ghubbet, mainly composed of diatoms, clay minerals, and volcanic glass, are already affected by a system of normal faults. 相似文献
14.
南海晚新生代构造运动与天然气水合物资源 总被引：6，自引：0，他引：6
南海在新生代经历过两次海底扩张产生了南海洋盆.南海北部和南部原来都是被动大陆边缘,但北部在晚新生代由于菲律宾海板块与欧亚板块在台湾地区发生了碰撞,使陆缘遭受到北西向挤压,在陆缘上产生了北西向左旋走滑活动,我们命名此次构造活动为东沙运动;南部陆缘在早中新世末由于南移的南沙地块与婆罗洲地块发生了碰撞,加上此时北移的菲律宾海板块在明都洛岛地区与欧亚板块发生碰撞,以及南部的东南苏拉威西地块与西北苏拉威西地块发生碰撞,在南海南部产生了挤压构造,我们命名此次构造运动为南沙运动.这两次新生代的构造运动改变了南北陆缘的性质,北部陆缘有人因此称之为准被动陆缘,而南部陆缘的南部则变成了挤压边缘.南海南北陆缘在晚新生代受到的挤压活动,对油气成藏和天然气水合物的形成有重要的推动作用,因为挤压活动有利于流体的流动,进而在适当的地方形成油气藏和天然气水合物. 相似文献
15.
The North Anatolian Fault crosses the Sea of Marmara from east to west. Tectonic features of the Sea of Marmara were studied
using multi-channel deep seismic reflection data. The northern branch of the North Anatolian Fault is active as a right lateral
strike-slip fault zone and indicates both negative and positive flower structures. The North Anatolian Fault splays into two
faults at the Sea of Marmara as a northern branch and north segment of the southern branch. The northern branch named the
Main Marmara Fault extends in a complicated manner from the north of the Kapıdağı Peninsula to westward in the Sea of Marmara.
The north segment of southern branch extends between the Gemlik and Bandırma gulfs in the south of the Sea of Marmara. In
addition, uplift areas arose by compression and a push-up style in between the Kapıdağı Peninsula and the Main Marmara Fault.
The North Anatolian Fault is characterized by a negative flower structure in basins and push-up style in uplift areas in the
Sea of Marmara. An uplift area arose between the north segment of the southern branch and the northern branch of the North
Anatolian Fault. The north segment of the southern branch of the North Anatolian Fault is a strike-slip fault and displays
a pull-apart style in the seismic reflection data. 相似文献
16.
Mario González-Escobar Francisco Suárez-Vidal José Antonio Hernández-Pérez Arturo Martín-Barajas 《Geo-Marine Letters》2010,30(6):575-584
This study examines the structural characteristics of the northern Gulf of California by processing and interpreting ca. 415 km of two-dimensional multi-channel seismic reflection lines (data property of Petróleos Mexicanos PEMEX) collected in the vicinity of the border between the Wagner and Consag basins. The two basins appear to be a link between the Delfín Superior Basin to the south, and the Cerro Prieto Basin to the north in the Mexicali-Imperial Valley along the Pacific–North America plate boundary. The seismic data are consistent with existing knowledge of four main structures (master faults) in the region, i.e., the Percebo, Santa María, Consag Sur, and Wagner Sur faults. The Wagner and Consag basins are delimited to the east by the Wagner Sur Fault, and to the west by the Consag Sur Fault. The Percebo Fault borders the western margin of the modern Wagner Basin depocenter, and is oriented N10°W, dipping (on average) ～40° to the northeast. The trace of the Santa María Fault located in the Wagner Basin strikes N19°W, dipping ～40° to the west. The Consag Sur Fault is oriented N14°W, and dips ～42° to the east over a distance of 21 km. To the east of the study area, the Wagner Sur Fault almost parallels the Consag Sur Fault over a distance of ～86 km, and is oriented N10°W with an average dip of 59° to the east. Moreover, the data provide new evidence that the Wagner Fault is discontinuous between the two basins, and that its structure is more complex than previously reported. A structural high separates the northern Consag Basin from the southern Wagner Basin, comprising several secondary faults oriented NE oblique to the main faults of N–S direction. These could represent a zone of accommodation, or transfer zone, where extension could be transferred from the Wagner to the Consag Basin, or vice versa. This area shows no acoustic basement and/or intrusive body, which is consistent with existing gravimetric and magnetic data for the region. 相似文献
17.
This study presents an analysis of the single-channel high-resolution shallow seismic reflection data from Lake Erçek, eastern Anatolia, to provide key information on the deformational elements, on the fault patterns and on the overall tectonic structure of the Lake Erçek Basin. High-resolution seismic data reveal major structural and deformational features, including N–S trending normal faults and W–E trending reverse faults bounding the Lake Erçek Basin, basement highs and folded structures along the marginal sections of the lake. The N–S trending normal faults asymmetrically control the steep western margin and the gentle eastern deltaic section, while the W–E trending reverse faults appear at the northern and southern margins. The N–S trending normal faults, half-graben structure, and the gradual thickening of sediments in the Erçek Basin toward the fault scarps strongly suggest an extensional tectonic regime resulting from an N–S compression. The Erçek Basin is an extension-controlled depocenter; it is a relatively undeformed and flat-lying deep Basin, forming a typical example of the half-graben structure. The N–S trending normal faults appear to be currently active and control the lake center and the E-delta section, resulting in subsidence in the lake floor. In the N- and S-margins of the lake, there is evidence of folding, faulting and accompanying block uplifting, suggesting a significant N–S compressional regime that results in the reverse faulting and basement highs along the marginal sections. The folding and faulting caused strong uplift of the basement blocks in the N- and S- margins, subsequently exposing the shelf and slope areas. The exposed areas are evident in the erosional unconformity of the surface of the basement highs and thinned sediments. The tilted basement strata and subsequent erosion over the basement block highs suggest prominent structural inversion, probably long before the formation of the lake. New high-resolution seismic data reveal the fault patterns and structural lineaments of the Lake Erçek and provide strong evidence for an ongoing extension and subsidence. The present study provides new structural insights that will support future tectonic and sedimentary studies and the development of strategies related to active earthquake faults and major seismic events in the region of Lake Erçek. 相似文献
18.
We studied the active deformation zone of the middle strand of the North Anatolian Fault Zone through the southern part of
the Sea of Marmara by means of high-resolution as well as deep seismic reflection data. Our main objective was to investigate
the active deformation within the uppermost sedimentary layers at high resolution as well as deeper sedimentary layers, focusing
on the tectonic and stratigraphic setting between Gemlik and Bandırma. The middle strand of the North Anatolian Fault reaching
the Gulf of Gemlik is a main fault which has a lazy-S shape in the Gulf of Gemlik, and extends westwards to Bandırma as a
main fault which is an E–W-trending single right-lateral fault controlling the zone along the Gemlik and Bandırma sub-basins.
Small-scale faults, consistent with a dextral shear regime, are present in the vicinity of the main fault. Several oblique
fault groups parallel to the main fault were detected. The deformation in the Gulf of Gemlik is characterized by a series
of synthetic and antithetic faults emanating from the main fault. The boundary faults in the Gulf of Gemlik have a compressive
component, which indicates the sill areas of the gulfs of Gemlik and Bandırma to be push-up structures. Four seismic stratigraphic
units were identified in the sediments of the gulfs of Gemlik and Bandırma, providing evidence of tectonic influence. The
present tectonic structure between Gemlik and Bandırma is not a pull-apart structure. The microseismic study in this area
has shown that fault planes are either strike-slip or compressional, and that the stress tensor is compatible with pure strike-slip
in the E–W fault system. 相似文献
19.
Active tectonic morphology and submarine deformation of the northern Gulf of Eilat/Aqaba from analyses of multibeam data 总被引：1，自引：0，他引：1
Gideon Tibor Tina M. Niemi Zvi Ben-Avraham Abdallah Al-Zoubi Ronnie A. Sade John K. Hall Gal Hartman Emad Akawi Abdelrahmem Abueladas Rami Al-Ruzouq 《Geo-Marine Letters》2010,30(6):561-573
A high-resolution marine geophysical study was conducted during October-November 2006 in the northern Gulf of Aqaba/Eilat,
providing the first multibeam imaging of the seafloor across the entire gulf head spanning both Israeli and Jordanian territorial
waters. Analyses of the seafloor morphology show that the gulf head can be subdivided into the Eilat and Aqaba subbasins separated
by the north-south-trending Ayla high. The Aqaba submarine basin appears starved of sediment supply, apparently causing erosion
and a landward retreat of the shelf edge. Along the eastern border of this subbasin, the shelf is largely absent and its margin
is influenced by the Aqaba Fault zone that forms a steep slope partially covered by sedimentary fan deltas from the adjacent
ephemeral drainages. The Eilat subbasin, west of the Ayla high, receives a large amount of sediment derived from the extensive
drainage basins of the Arava Valley (Wadi ’Arabah) and Yutim River to the north–northeast. These sediments and those entering
from canyons on the south-western border of this subbasin are transported to the deep basin by turbidity currents and gravity
slides, forming the Arava submarine fan. Large detached blocks and collapsed walls of submarine canyons and the western gulf
margin indicate that mass wasting may be triggered by seismic activity. Seafloor lineaments defined by slope gradient analyses
suggest that the Eilat Canyon and the boundaries of the Ayla high align along north- to northwest-striking fault systems—the
Evrona Fault zone to the west and the Ayla Fault zone to the east. The shelf–slope break that lies along the 100 m isobath
in the Eilat subbasin, and shallower (70–80 m isobaths) in the Aqaba subbasin, is offset by approx. 150 m along the eastern
edge of the Ayla high. This offset might be the result of horizontal and vertical movements along what we call the Ayla Fault
on the east side of the structure. Remnants of two marine terraces at 100 m and approx. 150 m water depths line the southwest
margin of the gulf. These terraces are truncated by faulting along their northern end. Fossil coral reefs, which have a similar
morphological appearance to the present-day, basin margin reefs, crop out along these deeper submarine terraces and along
the shelf–slope break. One fossil reef is exposed on the shelf across the Ayla high at about 60–63 m water depth but is either
covered or eroded in the adjacent subbasins. The offshore extension of the Evrona Fault offsets a fossil reef along the shelf
and extends south of the canyon to linear fractures on the deep basin floor. 相似文献
20.
Çağatay M. N. Görür N. Alpar B. Saatçılar R. Akkök R. Sakınç M. Yüce H. Yaltırak C. Kuşcu I. 《Geo-Marine Letters》1998,18(1):1-9
The Gulf of Saros is an Upper Miocene transtensional basin in NW Anatolia, formed by the interaction between the North Anatolian
Fault and the N-S extensional tectonic régime of the Aegean. The present configuration of the basin evolved mainly during
the Plio-Quaternary under the increased activity of the North Anatolian Fault. During the late Miocene-late Quaternary, no
sedimentation took place on the shelves. After this long hiatus, an important change in tectonic style about 0.2 Ma BP allowed
sedimentation to resume in the gulf.
Received: 14 February 1997 / Revision received: 12 November 1997 相似文献