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1.
Y. Rotstein J.-B. Edel G. Gabriel D. Boulanger M. Schaming M. Munschy 《Tectonophysics》2006,425(1-4):55-70
A compilation of gravity data from the Upper Rhine Graben (URG) is presented that includes all the main data sources from its German and French parts. This data is used to show that the URG consists of, at least, two arc-shaped and asymmetric rift units that tectonically are the basic building blocks of the graben. In this sense the URG does not differ from other continental rifts, such as the African rifts. This division should replace the now classical geomorphologic division of the URG into three segments, based on their different trends. Moreover, the gravity suggests that the faults in the central and southern segments are continuous and have the same trend, appearing to respond as a single kinematic unit. Changes in the gravity field in the graben are shown to reflect not only the structure of the graben, but also the highly variable composition of the basement. In this respect, the URG is quite different from some other Tertiary continental rifts, where possible changes in the composition of the basement are mostly masked in the gravity field by the effect of the overlying low-density sediments. This characteristic is used to study the extent of some of the main basement units that underlie the graben. 相似文献
2.
Processing of gravity and magnetic maps shows that the basement of the Upper Rhine Graben area is characterized by a series
of NE–SW trending discontinuities and elongated structures, identified in outcrops in the Vosges, Black Forest, and the Odenwald
Mountains. They form a 40 km wide, N30–40° striking, sinistral wrench-zone that, in the Visean, shifted the Variscan and pre-Variscan
structures by at least 43 km to the NE. Wrenching was associated with emplacement of several generations of plutonic bodies
emplaced in the time range 340–325 Ma. The sub-vertical, NE–SW trending discontinuities in the basement acted as zones of
weakness, susceptible to reactivation by subsequent tectonism. The first reactivation, marked by mineralizations and palaeomagnetic
overprinting along NE–SW faults of the Vosges Mountains, results from the Liassic NW–SE extension contemporaneous with the
break-up of Pangea. The major reactivation occurred during the Late Eocene N–S compression and the Early-Middle Oligocene
E–W extension. The NE–SW striking basement discontinuities were successively reactivated as sinistral strike-slip faults,
and as oblique normal faults. Elongated depocenters appear to form in association with reactivated Variscan wrench faults.
Some of the recent earthquakes are located on NE–SW striking Variscan fault zones, and show sinistral strike-slip focal mechanisms
with the same direction, suggesting also present reactivation. 相似文献
3.
4.
Yair Rotstein 《Tectonophysics》1984,108(1-2)
Seismological and other data from the boundaries of Anatolia are used to discuss the motion and plate tectonics of this block. Models which include a rotation of Anatolia around a single pole are shown to be inconsistent with much of this data. In particular a westward motion of Anatolia, which is the most commonly used model, should be reconsidered. Models which use a single pole of rotation fail because they assume the North Anatolian Fault to be an ideal transform fault which describes all of the motion between Anatolia and the Black Sea. In effect, internal deformation in the form of extension in western Anatolia and for the most part strike-slip faulting in eastern Anatolia, are important and account for some of the relative motion. Thus, a more appropriate model for this region is one which not only stresses the dominance of the North Anatolian Fault, but also recognises the importance of internal deformation and the limitation of classic plate tectonic models which this deformation implies. The preferred model for the motion of Anatolia is a nonuniform, tight, counterclockwise rotation approximated by the shape of the North Anatolian Fault as well as by the faults which splay from it to the south. Such a model is consistent with data from the boundaries of Anatolia including the source mechanism of earthquakes and depth of Benioff zone along the southern boundary of the block. Counterclockwise rotation of Anatolia is the natural consequence of the collision of Arabia with eastern Anatolia, coupled with subduction in the eastern Mediterranean. 相似文献
5.
Multichannel seismic reflection data from the Southern Kerguelen Plateau show many dipping basement reflectors associated with volcanic flows. These reflectors are quite similar in their shape to seaward-dipping basement reflectors observed along volcanic passive margins. On the Kerguelen Plateau the sources are updip of the basement reflectors, in the presently extinct and eroded volcanoes. We suggest that the same source/reflector geometry may also apply to the seaward-dipping basement reflectors observed along passive margins. We interpret these reflectors to be the result of volcanism on the passive margin which flowed in all directions into the newly created ocean basin at an early spreading stage. 相似文献
6.
Newly released seismic reflection data from the northern Jura Mountains and southern Rhine Graben provide the first high‐quality subsurface images from this area. These throw light on the details of the fault patterns in the area, and show that the Ferrette and Le Glaserberg Jura structures are largely the result of thrust faulting. However, the faults differ in their nature from those usually assumed in Jura tectonics: they are not low‐angle thrusts converging on a decollement zone in Triassic evaporites. They appear instead to be high‐angle faults that cross the entire sedimentary section, indicating that thick‐skinned tectonics prevailed in this part of the Jura. Embryonic Jura folds can be seen on the images from the nearby Mulhouse Horst, folds that are not supported by thickened Triassic evaporites. The existence of recent earthquake activity, taken together with the prevalence of thick‐skinned tectonics, suggests that occasional large earthquakes cannot be ruled out in this area. 相似文献
7.
Yair Rotstein 《Tectonophysics》1985,117(1-2)
A new tectonic model for the Aegean block is outlined in an effort to explain the widespread extension observed in this region. A key element in this model is the concept of “side arc collision” This term is used to describe the interaction of subducted oceanic lithosphere with continental lithosphere in a subduction arc in which oblique subduction occurs. In the Hellenic arc side arc collision is proposed for the northeast corner near Rhodes. The collision involves subducted African lithosphere, moving to the northeast almost parallel to the arc, with the continental mass of southwest Turkey. It affects the motion of the Anatolian-Aegean plate complex, but is not similar to continental collision since it occurs mostly at depth and involves only little, if any, of the shallow and rigid part of the continental lithosphere. The model assumes that Anatolia and the Aegean are part of one plate complex which undergoes counterclockwise rotation; if it were not for the side arc collision near Rhodes, the two blocks would exhibit similar deformation and might, in effect, be indistinguishable. At present, however, free and undisturbed rotation is possible only for the Anatolian block (excluding western Anatolia) where the motion is accommodated by subduction along the Cyprean arc. Further west the side arc collision inhibits this rotation along the subduction front. Still further west, undisturbed subduction along the central and western parts of the Hellenic arc is again possible and is well documented. On the other side of the Anatolian-Aegean plate complex, relatively free motion occurs along the North Anatolian fault zone including in the Aegean Sea. The combination of this motion in the north with the local obstruction of the rotation near Rhodes, must create a torque and a new pattern of rotation for the western part of the plate complex, thus creating a separate Aegean block. Since, however, the two blocks are not separated by a plate boundary, the Aegean block cannot move freely according to the new torque. Effective motion of the Aegean block relative to Europe and Anatolia, particularly in the north, is achieved through extension of the crust (lithosphere?). Thus the greatest amount of deformation (extension) is observed along the suture zone between the two blocks and, in particular, in the northeastern part of the Aegean block where motion relative to Anatolia must be greatest. 相似文献
8.
Deep seismic reflection studies in Israel - an update 总被引：1，自引：0，他引：1
Summary. The results of three deep crustal reflection lines are presently available from Israel. A 90 km line from near the Dead Sea rift to the Mediterranean coast was carried out for deep study. Two other lines in the Mediterranean coastal area were derived by recorrelation of oil exploration lines. The data shows a division between continental inner Israel and the coastal plain. In the first area a reflective lower crust is apparent with transparent upper crust and almost transparent upper mantle. Near the coast, in an area which was previously suggested as underlain by an ancient fossil oceanic crust, strong reflections characterize the uppermost mantle. Comparison between the reflection pattern and previous deep refraction and MT data indicates some agreement away from the coast and lack of correlation in the area of possible fossil oceanic crust near the coast. 相似文献
9.
10.
The Kerguelen Province, consisting of two oceanic plateaus (Kerguelen, Broken Ridge) and three basins (Enderby, Labuan and
Diamantina), covers a large area of ocean floor in the southeast Indian Ocean. As very few magnetic anomalies have been identified
in this area and only a few basement ages from the Kerguelen Plateau are known, reconstruction models of the Kerguelen Province
are not well constrained. In an effort to gain more understanding about the evolution of this area, we have used satellite
gravity to identify additional fracture zones. As they are likely to be associated with high frequency and low amplitude gravity
anomalies, we have computed the vertical derivative map instead of the regular satellite gravity map. Using this approach,
we have identified a series of fracture zones in the Enderby Basin, which are aligned with the Mesozoic fracture zones in
the Perth Basin and converge to the Kerguelen Fracture Zone. In the conjugate Bay of Bengal, we traced an equivalent pattern
of fracture zones which, together, better constrain the early evolution of this part of the Indian Ocean. Synthesis of these
images and the other available data from the Kerguelen Province, suggests that the spreading of India from both Australia
and Antarctica is closely related. Spreading between the three continents appears to have begun about the same time, in the
early Cretaceous and thus, the accretion of some parts of the Kerguelen Province must have occurred before the onset of the
quiet magnetic period at 118 Ma. At about 96–99 Ma, when the spreading direction in the Indian Ocean had changed into a N-S
direction, it also took place throughout the Kerguelen Province. We find that previously proposed slow spreading in the Diamantina
Zone and Labuan Basins, between 96–99 Ma and the initiation of the Southeast Indian Ridge at 43 Ma, could not have taken place.
Furthermore, we suggest that there is growing evidence that the same is true for spreading in the eastward continuation of
the Diamantina Zone and Labuan Basin, between Australia and Antarctica. Initiation of spreading in this area is likely to
be contemporaneous with the spreading in the Kerguelen Province and, thus, older than 96–99 Ma.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献