Present strain partitioning in SE Spain. Insights from CGNSS data
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<p>SE Iberia Tectonics is presently dominated by the NNW-SSE convergence between the Eurasian and Nubian plates. Farther east, the eastern Spanish coast and the Valencia Trough are dominated by ENE-WSW extension related to thermal subsidence. This extension has been interpreted as the final stage of abort rift responsible for the ENE motion of the Balearic promontory. Our data from 11 CGNSS stations permit us to discuss the deformation partitioning in SE Iberia related to the two abovementioned processes.</p><p>We identify three kinematic domains: a relatively stable domain, a domain moving towards NNW and undergoing NNW-SSE shortening, and a third domain relatively moving towards ENE and experiencing ENE-WSW extension. Our results indicate that plate convergence-related NNW-SSE shortening is mainly absorbed by the Eastern Betic Shear Zone (EBSZ), in agreement with previous studies, but also show that a significant fraction of this shortening is accommodated south of the EBSZ.</p><p>We also identify and quantify for the first time ENE-WSW extension northeast of the EBSZ. We propose that this extension could be absorbed by basement normal faults whose surface expression is obscured due to decoupling of deformation between the basement and the cover. Our results shed light on the tectonic puzzle of SE Spain.</p>Rift zone
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<p>Continental break-up at Rift-Rift-Rift triple junctions commonly represents the &#8220;prequel&#8221; of oceanic basin formation. Currently, the only directly observable example of a Rift-Rift-Rift setting is the Afar triple junction where the African, Arabian and Somalian plates interact to form three rift branches, two of which are experiencing oceanization (the Gulf of Aden and the Red Sea). The younger of the three (the Main Ethiopian Rift) is still undergoing continental extension. We performed analogue and numerical models simulating continental rifting in a Rift-Rift-Rift triple junction setting to investigate the resulting structural pattern and evolution. By adopting a parametrical approach, we modified the ratio between plate velocities, and we performed single-phase (all the three plates move) and two-phase models (with a first phase where only one plate moves and a second phase where all the three plates move). Additionally, the direction of extension was changed to induce orthogonal extension only in one of the three rift branches. Our single-phase models suggest that differential extension velocities in the rift branches determine the localization of the triple junction, which is located closer to the rift branch experiencing slower extension velocities. Furthermore, imposed velocities affect the distribution of deformation and the resulting pattern of faults. The effect of a faster plate is to favour the formation of structures trending orthogonal to dominant velocity vectors, while faults associated with the movement of the slower plates remain subordinate. In contrast, imposing similar velocities in all rift arms leads to the formation of a symmetric fault pattern at the triple junction, where the distribution of deformation is similar in the three rift branches. Two-phase models reveal high-angle faults interacting at the triple junction, confirming that differential extension velocities in the three rift branches strongly affect the fault pattern development and highlighting geometrical similarities with the Afar triple junction.</p>
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Using the two dimension seism survey,this paper deals with the tectonic characteristics and analysis the history of tectonic evolvement to the chosen classic seism surveys to meet the need of hydrocarbon exploration.The result of research shows that Tangyuan rift developed NW and NE two dimension rifts and the NE dimension rift controlled the dimension of Tangyuan rift and its sub-tectonic belts.The NW and NE dimension rifts cut each other and caused Tangyuan rift to exist in several blocks from north to south.The characteristics of tectonic in Tangyuan rift is that the west part is higher than the east part and the south higher than the north today.This rift had undergone three periods of development and six phases of evolvement.
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During the past decade, the Río Grande rift has been recognized as one of the major Cenozoic continental rift systems. The other widely recognized rift systems are the East African rift, the Rhine graben, and Lake Baikal. A series of special publications (Riecker, 1979; Baldridge et al., 1984; Keller, 1986) have drawn the attention of the international scientific community to the Río Grande rift. Early studies suggested this rift might only extend as far south as the Socorro, New Mexico región which is about 300 km north of El Paso/Juárez. However, more recent geological (Seaget and Margan, 1979) and geophysical (Daggett et al., 1986; Sinno et al., 1986; Keller et al., 1988) studies document that the rift can be differentiated from the Basin and Range province and extends for a significant distance into the State of Chihuahua.doi: sin doi
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In view of the geologic factors for that impacted on the coal mine production,for example,the rift tectonic,the magnetic intrusive rock and so on grew energetically,it very serious affected on coal mine production,research on the character of rift tectonic structure and the rule of intrusive mass growing was urgently needing solution subject of Daxing filed.Based on combined analysis of Daxin field’s geological record and well survy,the author make a lot of research about development of rift tectonics,range’s regularity and intrusive mass’s special spread regularity,summarize the characteristic of rift tectonics and control action to intrusive mass,provide reference to Daxin field’s excavate production.
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Uplifted flanks at intracontinental rifts are supported by flexural isostasy, as shown by the pattern of isostatic residual gravity anomalies associated with them. Models for flexural rift flank uplift differ in their kinematic description of extension, with respect to the asymmetry of rifting and the importance of brittle versus elastic upper crustal deformation. In this paper, I test different kinematic models of continental extension by comparing their predictions of rift flank topography and crustal structure with observations from the Baikal rift (SE Siberia). The rift is characterized by prominent flank topography on both sides of lake Baikal. The flanks reach similar elevations but differ in their structure: the tilt of the footwall flank is away from the basin, whereas the basinward part of the hanging wall flank tilts toward the basin center. Fission track data indicate that very little erosion affected the flanks since rifting started; geomorphological and sedimentological observations suggest that prerift relief was minor. Thus, the present‐day topography reflects rift‐related tectonic uplift. Pure‐shear “necking” and pure‐shear/simple‐shear “detachment” models of extension predict the topographic and Bouguer gravity anomaly patterns observed along a profile across the central Baikal rift equally well. They do not permit to discriminate between different scenarios that have been proposed for the central Baikal rift; that is, half‐graben versus full graben development; rifting at a continuous rate since the Oligocene versus a large increase in extension rate since the Pliocene. The models predict that the kinematics of rifting in Baikal are controlled by a midcrustal (20 km) depth of necking and/or a mid to lower crustal (20–30 km) detachment level; best‐fit elastic thicknesses are in the range 30–50 km. These predictions are in agreement with results from coherence studies of Bouguer gravity and topography, as well as with the rheology of the lithosphere underneath Baikal as inferred from heat flow, seismic refraction and seismological observations. In contrast, a “flexural cantilever” model with low (< 10 km) elastic thickness predicts topographic patterns which are very different from those observed, for a wide range of rifting scenarios. Significant (> 3 km) erosion of the footwall flank is required to fit the topography if a flexural cantilever model is applied; this is incompatible with the fission track data. Thus, the kinematics of extension at deep and narrow intra‐continental rifts such as Baikal appear to be controlled by a strong elastic lithosphere and require significant brittle deformation of the upper crust, as suggested by dynamic models for continental rifting.
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