排序方式： 共有9条查询结果，搜索用时 71 毫秒
1
1.
M.B. Cita J.M. Woodside M.K. Ivanov R.B. Kidd A.F. Limonov Scientific Staff of Cruise TTR - Leg 《地学学报》1995,7(4):453-458
Direct observation of active emission of fluids and mud from a submarine mud volcano were made for the first time in an extensive field of mud diapirs and mud volcanoes on the Mediterranean Ridge using a video camera towed 2 m above the seafloor in 1800 m of water. This recent research using both long range and deep-towed sidescan sonar systems indicates also that diapirism and eruption of mud along the crest of the ridge is more common than previously thought. The southwards increase in age of rock fragments carried within the erupted mud supports the hypothesis that the fluid mud becomes overpressured within a southward-dipping backthrust from the Inner Deformation Front of this accretionary prism. 相似文献
2.
A.H.F. Robertson R.B. Kidd M.K. Ivanov A.F. Limonov J. M. Woodside J. Galindo-Zaldivar L. Nieto 《地学学报》1995,7(2):254-264
Important new light is shed on subduction and incipient collisional processes in the Easternmost Mediterranean, notably the Plio-Quaternary uplift of the Troodos ophiolite, from new geophysical information collected during a cruise of the R.V. Gelendzhik in July 1993, as part of the Training-through-Research' programme. The data collected over the Eratosthenes Seamount formed part of the site-survey work for Leg 160 of the Ocean Drilling Program scheduled for spring 1995. The main results are that the Eratosthenes Seamount is in the process of actively subsiding, breaking-up and being thrust, beneath both Cyprus to the north and the Levantine Basin to the south. Northwards thrusting appears to post-date the Messinian, when evaporites accumulated around the lower flanks of a pre-existing seamount feature. Comparison with the geology of southern Cyprus and offshore areas suggests a causative link between northward underthrusting of the Eratosthenes Seamount and late Pliocene-mid Quaternary uplift of southern Cyprus, focused on the centre of the Troodos ophiolite. 相似文献
3.
Recent deep-towed, high resolution sidescan sonar records and seismic profiles have been collected on the lower Valencia Fan (Northwestern Mediterranean). Three morphological zones, channelled, transition and unchannelled, have been recognized in the Valencia Channel mouth. Sonographs from the transition zone show a progresive transversal gradation from depositional to erosional bedforms. This asymmetry may be due to the lateral inputs of sediment flows from the rhone deep-sea fan and to the effect of the Coriolis force, which could have diverted the flows to the southwest. Bedforms recorded in the study area include trains of starved ripples and dunes, sand ribbons, and fields of elongated scours. Most morphological features, bedforms and seismic characteristics of the Valencia Channel mouth are typical of channel-lobe transition zones. 相似文献
4.
Side-scan sonar, seismic and core data are used to identify mega-flutes, transverse and ‘V’ shaped bedforms in turbidites around the Valencia channel mouth, north-west Mediterranean. Long-range side-scan sonar data reveal a broad, curved, asymmetric, channel, that widens and terminates downfan. The western channel bank near the channel mouth has been partly eroded by turbidity currents that spilled out of the channel. Transverse bedforms on the east of the channel floor are interpreted as antidunes and, if this interpretation is correct, they indicate that the flow was probably supercritical at least locally within the channel. Trains of mega-flutes, are incised into coarse-grained sediments of the channel floor near the channel mouth. The association of mega-flutes and antidunes is thought to be diagnostic of channel–lobe transitions on deep-sea fans. The mega-flutes pass downfan into an area of streaks that diverge at up to 45° and indicates flow expansion from the channel mouth. About 75 km downfan from the channel mouth, deep-towed side-scan data record transverse bedforms (interpreted as antidunes) passing downfan into an area covered by ‘V’ shaped bedforms with upflow pointing apices (named chevrons here). The chevrons are commonly c. 200 m from limb to limb and c. 2 m in amplitude with flow-parallel wavelengths of c. 400 m. We propose that chevrons were formed by a strong, probably supercritical (or near critical) turbidity current spreading from the channel mouth and flowing towards the Balearic Abyssal Plain. Thinning of the turbidity current, resulting from flow spreading would allow the Froude number to remain high up to 100 km from the channel mouth and could explain the observed reduction in antidune wavelength. 相似文献
5.
Marine Geophysical Research - The Mediterranean Ridge is interpreted as a large accretionary complex, which originated due to the northern subduction of the African lithosphere below the Eurasian... 相似文献
6.
A newly discovered area of mud volcanism, about 170 km south of Crete, in the central–eastern part of the Mediterranean Ridge,
was named the “United Nations Rise” (UNR). A survey of the UNR area with the deep-towed ORE tech side-scan sonar equipped
with a subbottom profiler revealed the presence of some mud volcanoes and also showed various other sea-floor features, including
slumps, escarpments and pockmark-type depressions. Several of our interpretations were ground-truthed by coring. The UNR area
appears to belong to the Inner deformation front of the Mediterranean Ridge. 相似文献
7.
A. F. Limonov 《Geo-Marine Letters》1998,18(2):90-96
The eastern Mediterranean Ridge reveals a peculiar feature called the “United Nations Rise”. It is notable for its complex
morphology, interior structure, and mud volcanism. Its unusual structural–morphological characteristics are explained by its
location at a junction of the western and eastern branches of the ridge and by the probable tectonic escape of accretionary
prism sediments from the west. The geophysical data on the shallow structure of the eastern ridge branch showed some unusual
structural trends, which could not be expected from the overall tectonic stress distribution. They are interpreted as resulting
from the southward expansion of the Hellenic Arc. 相似文献
8.
Side-scan sonar images from the Lower Valencia Fan show that turbidite bedforms (chevrons) and net sediment aggradation vary
around a small fault scarp. One or more turbidity currents were affected by the fault, but the exact timing of the fault movement
in relation to the chevrons is not known. A scaled laboratory experiment showed that mean flow vector would not be affected
by a current flowing over an obstacle of similar height to flow depth ratio. 相似文献
9.
Erosional and depositional patterns in the Valencia Channel mouth: An example of a modern channel-lobe transition zone 总被引：1，自引：0，他引：1
Recent deep-towed, high resolution sidescan sonar records and seismic profiles have been collected on the lower Valencia Fan (Northwestern Mediterranean). Three morphological zones, channelled, transition and unchannelled, have been recognized in the Valencia Channel mouth. Sonographs from the transition zone show a progresive transversal gradation from depositional to erosional bedforms. This asymmetry may be due to the lateral inputs of sediment flows from the Rhone deep-sea fan and to the effect of the Coriolis force, which could have diverted the flows to the southwest. Bedforms recorded in the study area include trains of starved ripples and dunes, sand ribbons, and fields of elongated scours. Most morphological features, bedforms and seismic characteristics of the Valencia Channel mouth are typical of channel-lobe transition zones. 相似文献
1