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1.
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
2.
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
3.
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
4.
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
5.
Neslihan Ocako?lu 《Geo-Marine Letters》2012,32(1):17-28
New (2009) multi-beam bathymetric and previously published seismic reflection data from the NE-SW-oriented Fethiye Bay and
the neighboring N-S-oriented Marmaris Bay off SW Anatolia were evaluated in order to interpret the seafloor morphology in
terms of the currently still active regional tectonic setting. This area lies between the Pliny Trench, which constitutes
the eastern sector of the subduction zone between the African and Eurasian plates in the Eastern Mediterranean, and the Fethiye-Burdur
Fault Zone of the Anatolian Plate. The bathymetric data document the very narrow shelf of the Anatolian coast, a submarine
plain between the island of Rhodes and Marmaris Bay, and a large canyon connecting the abyssal floor of the Rhodes Basin with
Fethiye Bay. The latter are here referred to as the Marmaris Plain and Fethiye Canyon, respectively. Several active and inactive
faults have been identified. Inactive faults (faults f1) delineate a buried basin beneath the Marmaris Plain, here referred
to as the Marmaris Basin. Other faults that affect all stratigraphic units are interpreted as being active. Of these, the
NE-SW-oriented Marmaris Fault Zone located on the Marmaris Plain is interpreted as a transtensional fault zone in the seismic
and bathymetric data. The transtensional character of this fault zone and associated normal faults (faults f3) on the Marmaris
Plain correlates well with the Fethiye-Burdur Fault Zone on land. Another important fault zone (f4) occurs along the Fethiye
Canyon, forming the northeastern extension of the Pliny Trench. The transpressional character of faults f4 inferred from the
seismic data is well correlated with the compressional structures along the Pliny Trench in the Rhodes Basin and its vicinity.
These observations suggest that the Marmaris Fault Zone and faults f3 have evolved independently of faults f4. The evidence
for this missing link between the Pliny Trench and the Fethiye-Burdur Fault Zone implies possible kinematic problems in this
tectonic zone that deserve further detailed studies. Notably, several active channels and submarine landslides interpreted
as having been triggered by ongoing faulting attest to substantial present-day sediment transport from the coast into the
Rhodes Basin. 相似文献
6.
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
7.
Erkan G?ka?an Cem Gazio?lu Bedri Alpar Zeki Yücel ?ükrü Ersoy O?uz Gündo?du Cenk Yalt?rak Buser Tok 《Geo-Marine Letters》2002,21(4):183-199
Active faults aligning in NW–SE direction and forming flower structures of strike-slip faults were observed in shallow seismic data from the shelf offshore of Avcılar in the northern Marmara Sea. By following the parallel drainage pattern and scarps, these faults were traced as NW–SE-directed lineaments in the morphology of the northern onshore sector of the Marmara Sea (eastern Thrace Peninsula). Right-lateral displacements in two watersheds of drainage and on the coast of the Marmara Sea and Black Sea are associated with these lineaments. This right-lateral displacement along the course of these faults suggests a new, active strike-slip fault zone located at the NW extension of the northern boundary fault of the ?ınarcık Basin in the Marmara Sea. This new fault zone is interpreted as the NW extension of the northern branch of the North Anatolian Fault Zone (NAFZ), extending from the ?ınarcık Basin of the Marmara Sea to the Black Sea coast of the Thrace Peninsula, and passing through B üy ük ?ekmece and K ü ? ük ?ekmece lagoons. These data suggest that the rupture of the 17 August 1999 earthquake in the NAFZ may have extended through Avcılar. Indeed, Avcılar and İzmit, both located on the Marmara Sea coast along the rupture route, were strongly struck by the earthquake whereas the settlements between Avcılar and İzmit were much less affected. Therefore, this interpretation can explain the extraordinary damage in Avcılar, based on the newly discovered rupture of the NAFZ in the Marmara Sea. However, this suggestion needs to be confirmed by further seismological studies. 相似文献
8.
Erkan Gökaşan Cem Gazioğlu Bedri Alpar Zeki Yücel Şükrü Ersoy Oğuz Gündoğdu Cenk Yaltırak Buser Tok 《Geo-Marine Letters》2001,21(4):183-199
Active faults aligning in NW–SE direction and forming flower structures of strike-slip faults were observed in shallow seismic data from the shelf offshore of Avc?lar in the northern Marmara Sea. By following the parallel drainage pattern and scarps, these faults were traced as NW–SE-directed lineaments in the morphology of the northern onshore sector of the Marmara Sea (eastern Thrace Peninsula). Right-lateral displacements in two watersheds of drainage and on the coast of the Marmara Sea and Black Sea are associated with these lineaments. This right-lateral displacement along the course of these faults suggests a new, active strike-slip fault zone located at the NW extension of the northern boundary fault of the Ç?narc?k Basin in the Marmara Sea. This new fault zone is interpreted as the NW extension of the northern branch of the North Anatolian Fault Zone (NAFZ), extending from the Ç?narc?k Basin of the Marmara Sea to the Black Sea coast of the Thrace Peninsula, and passing through B üy ük çekmece and K ü ç ük çekmece lagoons. These data suggest that the rupture of the 17 August 1999 earthquake in the NAFZ may have extended through Avc?lar. Indeed, Avc?lar and ?zmit, both located on the Marmara Sea coast along the rupture route, were strongly struck by the earthquake whereas the settlements between Avc?lar and ?zmit were much less affected. Therefore, this interpretation can explain the extraordinary damage in Avc?lar, based on the newly discovered rupture of the NAFZ in the Marmara Sea. However, this suggestion needs to be confirmed by further seismological studies. 相似文献
9.
Hakan Alp 《Geo-Marine Letters》2014,34(5):447-455
A total of 42 km of high-resolution seismic reflection and bathymetric data were collected for the first time to document stratigraphic and structural features of the uppermost 5 m of the Holocene sedimentary infill of Küçükçekmece Lagoon along the Marmara Sea coast of Turkey. The lagoon gradually deepens from 1 m off the northern coast to a maximum of 20 m in the southern basin. Stratigraphically, the uppermost seismic unit is characterized by a generally parallel reflection configuration, indicating deposition under low-energy conditions. In the southern basin of the lagoon, the sub-bottom is locally characterized by frequency attenuated and chaotic reflections interpreted as gas-charged sediments. Structurally, the soft sediment of the first 5 m below the lagoon floor is locally deformed by active strike-slip fault zones, here named FZ1, FZ2, and FZ3. These fault zones are NW–SE oriented and follow the long axis of the lagoon, compatible with the geographic alignment of the lagoon, the onland drainage pattern, and the scarps of the surrounding terrain. Moreover, the fault zones in Küçükçekmece Lagoon are well correlated with active offshore faults mapped during previous studies. This suggests that the FZ1, FZ2, and FZ3 fault zones are not merely local fault systems deforming the Küçükçekmece Lagoon bottom, but that they may be part of a regional fault zone extending both north and southward to merge with the northern branch of the North Anatolian Fault Zone (NAFZ) in the Ç?narc?k Basin. This, however, needs to be confirmed by further structural and seismological studies around Küçükçekmece Lagoon in order to more firmly establish its link with the NAFZ in the Marmara Sea, and to highlight potential seismic risks for the densely populated Istanbul metropolitan area. 相似文献
10.
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
11.
Faulting, mass-wasting and deposition in an active dextral shear zone, the Gulf of Saros and the NE Aegean Sea, NW Turkey 总被引：1，自引：1，他引：0
Timur Ustaömer Erkan Gökaşan Hüseyin Tur Tolga Görüm Fatma Gül Batuk Doğan Kalafat Hakan Alp Berkan Ecevitoğlu Halim Birkan 《Geo-Marine Letters》2008,28(3):171-193
Structural, mass-wasting and sedimentation processes along an active dextral shear zone beneath the Gulf of Saros and the
NE Aegean Sea were investigated on the basis of new high-resolution swath bathymetric data and multi-channel seismics. A long
history of dextral shearing operating since the Pliocene culminated in the formation of a NE-SW-trending, ca. 800-m-deep basin
(the so-called inner basin) in this region, which is bordered by a broad shelf along its northern and eastern sides and a
narrow shelf at the southern side. The western extension of the North Anatolian Fault Zone (the Ganos Fault) cuts the eastern
shelf along a narrow deformation zone, and ends sharply at the toe of the slope, where the strain is taken up by two NE-SW-oriented
fault zones. These two fault zones cut the basin floor along its central axis and generate a new, Riedel-type pull-apart basin
(the so-called inner depression). According to the bathymetric and seismic data, these basin boundary fault zones are very
recent features. The northern boundary of the inner depression is a through-going fault comprising several NE-SW- and E-W-oriented,
overlapping fault segments. The southern boundary fault zone, on the other hand, consists of spectacular en-echelon fault
systems aligned in NE–SW and WNW–ESE directions. These en-echelon faults accommodate both dextral and vertical motions, thereby
generating block rotations along their horizontal axis. As the basin margins retreat, the basin widens continuously by mass-wasting
of the slopes of the inner basin. The mass-wasting, triggered by active tectonics, occurs by intense landsliding and channel
erosion. The eroded material is transported into the deep basin, where it is deposited in a series of deep-sea fans and slumps.
The high sedimentation rate is reflected in an over 1,500-m-thick basin fill which has accumulated in Pliocene–Quaternary
times. 相似文献
12.
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
13.
Denizhan Vardar Kurultay Öztürk Cenk Yaltırak Bedri Alpar Hüseyin Tur 《Marine Geophysical Researches》2014,35(1):69-85
Although there are many research studies on the northern and southern branches of the North Anatolian fault, cutting through the deep basins of the Sea of Marmara in the north and creating a series of pull-apart basins on the southern mainland, little data is available about the geometrical and kinematical characteristics of the middle strand of the North Anatolian fault. The first detailed geometry of the middle strand of the North Anatolian fault along the southern Marmara shelf, including the Gemlik and Band?rma Bay, will be given in this study, by a combined interpretation of different seismic data sets. The characteristic features of its segments and their importance on the paleogeographic evolution of the southern shelf sub-basins were defined. The longest one of these faults, the Armutlu-Band?rma segment, is a 75-km long dextral strike-slip fault which connects the W–E trending Gençali segment in the east and NE–SW trending Kap?da?-Edincik segment in the west. In this context, the Gemlik Bay opened as a pull-apart basin under the control of the middle strand whilst a new fault segment developed during the late Pleistocene, cutting through the eastern rim of the bay. In this region, a delta front forming the paleoshoreline of the Gemlik paleolake was cut and shifted approximately 60 ± 5 m by the new segment. The same offset on this fault was also measured on a natural scarp of acoustic basement to the west and integrated with this paleoshoreline forming the slightly descending topset–foreset reflections of the delta front. Therefore the new segment is believed to be active at least for the last 30,000 years. The annual lateral slip rate representing this period of time will be 2 mm, which is quite consistent with modern GPS measurements. Towards the west, the Band?rma Bay is a rectangular transpressional basin whilst the Erdek Bay is a passive basin under the control of NW–SE trending faults. When the water level of the paleo-Marmara lake dropped down to ?90 m, the water levels of the suspended paleolakes of Band?rma and Gemlik on the southern shelf were ?50.3 (?3.3 Global Isostatic Adjustment—GIA) and ?60.5 (?3.3 GIA) m below the present mean sea level, respectively. As of today a similar example can be seen between the Sea of Marmara and the shallow freshwater lakes of Manyas and Uluabat. Similarly, the paleolakes of Gemlik and Bandirma were affected by the water level fluctuations at different time periods, even though both lakes were isolated from the Sea of Marmara during the glacial periods. 相似文献
14.
The Aegean region is tectonically a complex area characterized mainly by the subduction of African oceanic lithosphere beneath the Aegean continental lithosphere including extensional subbasins and mantle driven block rotations. In this study, spatial distribution of earthquakes, b-value distribution, and heat flow data have been analyzed to reveal the deep structural features of the Aegean region. b-value distributions show two low NE–SW and NW–SE trending b-anomaly zones in the western and eastern side of the Crete, implying slab tear within the Aegean slab. Earthquake foci distribution indicates that the Aegean slab steepens in the eastern side of the Crete, compared to its western side. Earthquake foci reach maximum depth of 180 km along the Cycladic arc axis, suggesting northward subducted slab geometry. The low seismic activities and high b-value anomalies within Aegean basin, except North Aegean Trough, can be compared to higher heat flow. We concluded that collision-induced westward mantle flow beneath Turkey followed by hard collision between Arabian-Eurasian continental plates played a major role in the evolution of clockwise rotational retreat of the Aegean slab and slab steepening to the east of the Crete. 相似文献
15.
南海西南走滑断裂特征及其与油气的关系 总被引：3，自引：0，他引：3
本文基于我所１９８８年、１９８９年两次南沙地质调查以及大量地震剖面的综合分析，系统阐述了南海西南断裂构造的特征及性质，指出南海西南主千断裂为多期活动的走滑断裂，是它们控制了油气盆地的形成与演化以及局部油气藏的形成。 相似文献
16.
黄福林 《海洋地质与第四纪地质》1992,12(4):21-28
本文初步讨论了区内活动断裂的时空展布及一般特征,NNE—NE向继承性活动断裂是渤海海域及沿海大陆的主导构造,北黄海断裂活动与渤海相似,南黄海则以NEE向为主,苏北陆地及其近海兼有NNE—NE和NW向。资料表明,断裂的水平运动量大于垂直运动量,从各自的沉积厚度所估算的沉积速率说明早、晚第三纪和第四纪的构造强度是很近似的,因而华北和渤海区由走滑正断层反映的水平运动和差异升降运动仍处于十分活跃的发展阶段。 相似文献
17.
In this study, structural features in the Aegean Sea were investigated by application of Cellular Neural Network (CNN) and
Cross-Correlation methods to the gravity anomaly map. CNN is a stochastic image processing technique, which is based on template
optimization using neighbourhood relationships of pixels, and probabilistic properties of two-Dimensional (2-D) input data.
The performance of CNN can be evaluated by various interesting real applications in geophysics such as edge detection, data
enhancement and separation of regional/residual potential anomaly maps. In this study, CNN is used in edge detection of geological
bodies closer to the surface, which are masked by other structures with various depths and dimensions. CNN was first tested
for (prismatic) synthetic examples and satisfactory results were obtained. Subsequently, CNN/Cross-Correlation maps and bathymetric
features were evaluated together to obtain a new structural map for most of the Aegean Sea. In our structural map, the locations
of the faults and basins are generally in accordance with the previous maps from restricted areas based on seismic data. In
the southern and southeastern parts of the Aegean Sea, E–W trending faults cut NE–SW trending basins and faults, similar to
on-shore Western Anatolia. Also, in the western, central and northern parts of the Aegean Sea, all of these structures are
truncated by NE-trending faults. 相似文献
18.
渤海海域晚更新世—全新世的活动构造 总被引：2，自引：0，他引：2
利用在渤海最新获得的约5 000 km的浅层地震资料,发现在渤海海域发育大量晚更新世—全新世断裂和褶皱,进而对其分布、浅层结构、运动学性质和活动性进行了研究,绘制了渤海海域活动断裂分布图。研究结果表明:渤海晚更新世—全新世活动断裂主要走向为北北东向、北西向和近东西向,东西向断裂数量最多;断裂的形成受区域应力场和早期断裂的控制,而褶皱则以背斜居多,通常沿早期断裂带发育;就分布密度而言,辽东湾内断裂密度远小于其他海域,而同一构造单元其边界部位断裂密度大于单元内部;具继承性发展的断裂多具有复杂的破裂结构,破裂带剖面上呈耙形或"Y"字型,晚更新世沉积层变形明显;受断裂错动地层的形成时代表明,多数断裂的最新活动发生在晚更新世中期-晚期,部分断裂在全新世发生过活动;多数断裂具有明显正断拉张作用,而郯庐断裂带和张家口-蓬莱断裂带内次级断裂还可能具走向滑移分量;渤海浅层断裂的活动性与现代地震震中的分布具有较好的相关性,这对于渤海地震危险性评价具有重要意义。 相似文献
19.
This study analyzes the structural development of the Gunsan Basin in the central Yellow Sea, based on multi-channel seismic reflection profiles and exploratory well data. The basin comprises three depressions (the western, central, and eastern subbasins) filled with a thick (ca. 6000 m) Cretaceous to Paleogene nonmarine succession. It was initiated in the early Cretaceous due to intracontinental extension caused by oblique subduction of the Izanagi plate under the Eurasian plate and sinistral movement of the Tan-Lu fault. The basin appears to have undergone transtension in the late Cretaceous–Eocene, caused by dextral movement of the Tan-Lu and its branching faults. The transtension was accommodated by oblique intra-basinal normal faults and strike-slip (or oblique-slip) movement of a NE-trending bounding fault in the northern margin of the central subbasin. The entire basin was deformed (NE–SW contraction) in the Oligocene when tectonic inversion occurred, possibly due to the changes in strike-slip motion, from right- to left-lateral, of the Tan-Lu fault. During the early Miocene, extension resumed by reactivation of the pre-existing normal and transpressional faults. A combination of extension, uplift, and erosion resulted in differential preservation of the early Miocene succession. At the end of the early Miocene, extension ceased with mild contraction and then the basin thermally subsided with ensued rise in sea level. 相似文献
20.
Subsurface and seafloor fluid flow anomalies are gaining large interest after the finding of five new hydrocarbon discoveries and observation of large gas flares in the SW Barents Sea. In the present study, we have analysed structural and stratigraphic controls on fluid flow towards the seafloor using gravity cores selected based on subsurface gas anomalies observed on seismic data from the Veslemøy High, SW Barents Sea. The subsurface fluid flow at the Veslemøy High is observed to be controlled by 1) the morphology and orientation of regional faults, structural highs and sedimentary basins, 2) the presence of Paleocene silica ooze deposits that changes microstructure with temperature thereby controlling fluid flow and 3) the location of regional and local open faults formed by glacial loading and unloading. Analysis of extractable organic matter in subsurface Holocene sediments corroborates the active migration pathways inferred from seismic data. Micropalaeontological studies on benthic foraminifera reveal methane seep associated assemblages that confirm the interpretation of subsurface gas anomalies in seismic data. We ultimately link these new results to the geological evolution history of the region to give a comprehensive model for the fluid flow system within the study area. 相似文献