Seismic crustal structure between the Transylvanian Basin and the Black Sea, Romania

Hauser, F.; Rãileanu, V.; Fielitz, W.; Dinu, C.; Landes, M.; Bălă, Andrei; Prodehl, C.

doi:10.1016/j.tecto.2006.10.005

Cited by 71 publications

(92 citation statements)

References 44 publications

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“…The main results of our analysis suggesting a geometry of the southeastern Carpathians lithospheric structure showing alternating high and low velocity zones separated by high-angle thrust faults are in good agreement with the seismic reflection/refraction studies, tomographic inversion analysis and ray-trace modeling (e.g., BOCIN et al, 2005BOCIN et al, , 2009HAUSER et al, 2007;MAT¸ENCO et al, 2010). In addition, our results also suggest the persistence of these complex lateral variations in the mantle domain.…”

Section: Discussionsupporting

confidence: 90%

“…The assemblage of vertical faults interpreted on the basis of (near) vertical boundaries within the velocity model obtained by BOCIN et al (2009) closely matches the vertical boundaries obtained in our study. As shown by MERTEN (2010), the locus of postcollisional exhumation corresponds to the position where the basement beneath the nappe pile is in a shallow position (see also LANDES et al, 2004;BOCIN et al, 2005), and is spatially juxtaposed over a shallow Moho configuration (HAUSER et al, 2007). This suggests that post-collisional exhumation is possibly linked to processes taking place at deeper crustal levels.…”

Section: Resultsmentioning

confidence: 89%

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New Seismic and Tomography Data in the Southern Part of the Harghita Mountains (Romania, Southeastern Carpathians): Connection with Recent Volcanic Activity

Popa

Rădulian

Szakács

et al. 2011

Pure Appl. Geophys.

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The southern part of the southeastern Carpathians represents the site of the most recent volcanic eruptions of the entire Carpathian-Pannonian region. The products of these eruptions range from 42 to 10 Ka radiocarbon ages in the South Harghita Mountains (high K calc-alkaline rocks with adakite-like features), and at 1.2-0.6 Ma K-Ar ages in the Perşani Mountains (alkali basalts). They were emplaced in a post-collisional regime. Ciomadul volcano is located at the southernmost part of the NW-SE oriented Cȃlimani-Gurghiu-Harghita range crossing the inner part of the southeastern Carpathians and in the rough proximity of the Vrancea seismic zone (at ca. 60 km toward NW). Its magma generation is attributed to geodynamic events closely related to the seismogenic area. A number of particular geophysical and geochemical features located in the study region, including (1) the abrupt attenuation of the seismic waves originating from the Vrancea intermediate-depth foci, (2) the most intense heat-flow anomaly in Romania, (3) the most prominent 3 He/ 4 He anomaly measured in natural ''postvolcanic'' gas emanations, are all in favor of the hypothesis of a still existing hot local magma chamber. Data acquired during recent seismic monitoring of the Vrancea zone and its neighborhoods suggest an enhancement of the local seismicity beneath the southern edge of the South Harghita Mts., both at crustal and subcrustal levels. At the same time, recent tomography images obtained using local earthquake data correlate well with the presence of a vertically extended low-velocity zone coming from the upper mantle to the assumed magmatic chambers located in the crust. The present data, supporting the presence of an active crustal magma chamber beneath Ciomadul, allow us to consider that future volcanic activity at this volcano cannot be discarded.

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Section: Discussionsupporting

confidence: 90%

Section: Resultsmentioning

confidence: 89%

New Seismic and Tomography Data in the Southern Part of the Harghita Mountains (Romania, Southeastern Carpathians): Connection with Recent Volcanic Activity

Popa

Rădulian

Szakács

et al. 2011

Pure Appl. Geophys.

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“…This is interpreted as foreland-coupling (sensu Ziegler et al, 1995), exhumation related to high-angle reverse faulting in the central part of the orogen being associated with enhanced subsidence in the foreland . This interpretation is supported by the apparently folded, shallow Moho beneath the orogen (Hauser et al, 2007, see Schmid et al, 2008 and their East Carpathians profile in Plate 3). At the regional scale, this was coeval with the Plio-Quaternary inversion recorded in the Pannonian Basin, associated with fault reactivation, large-scale folding and present-day seismicity, generally interpreted as an effect of the push from the Adriatic indenter (e.g.…”

Section: Tectonic Constraintsmentioning

confidence: 84%

Tectonic significance of changes in post-subduction Pliocene–Quaternary magmatism in the south east part of the Carpathian–Pannonian Region

et al. 2011

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The south-eastern part of the Carpathian-Pannonian region records the cessation of convergence between the European platform/ Moesia and the Tisza-Dacia microplate. Magmatic activity in this area, in close proximity to the 'Vrancea zone', shows a shift from normal calc-alkaline to much more diverse compositions (adakite-like calc-alkaline, K24 alkalic, mafic Na-alkaline and ultrapotassic) in the Pliocene-Quaternary, suggesting a significant change in geodynamic processes at approximately 3 Ma. We review the tectonic setting, timing, petrology and geochemistry of the post-collisional volcanism to constrain the role of geodynamics on melt production and migration. The calc-alkaline volcanism (5.3-3.9 Ma) marks the end of normal subduction-related magmatism along the post-collision Călimani-Gurghiu-Harghita volcanic chain in front of the European convergent plate margin. At ca. 3 Ma magma compositions changed in South Harghita to adakite-like calc-alkaline and continued until recent times (< 0.03 Ma) interrupted at 1.6-1.2 Ma by generation of Na and K alkalic varieties, signifying changes in the source and melting mechanism. We attribute the progressive change in magma composition in front of the Moesian platform to two main geodynamic events: (1) slab-pull and steepening with opening of a tear window (adakite-like calc-alkaline magmas) and (2) inversion tectonics (Na and K alkalic magmas). Contemporaneous post-collision volcanism at the eastern edge of the Pannonian Basin at 2.6-1.3 Ma was dominated by Na alkalic and ultrapotassic magmas, suggesting a close relationship with thermal rifting and inversion tectonics. Similar timing, magma chamber processes and volume for K-alkalic (shoshonitic) magmas in the South Apuseni Mountains (1.6 Ma) and South Harghita area at a distance of ca. 200 km imply a regional connection with the inversion tectonics. Key words: Post-collisional slab mechanics, calc-alkaline, adakite-like, Na-alkalic, K-alkalic and ultrapotassic magmas. IntroductionPost-collision magmatism at convergent plate boundaries is very complex and is usually characterized by the presence of adakite-like and/or alkaline magmas, e.g. in the Mediterranean (Duggen et al., 2005), Tibet (Turner et al., 1996;Mo et al., 2006) and Baja California (Negrete-Aranda and Cañon-Tapia, 2008). The existence of such magmas may be associated with the post-collisional evolution of inherited slabs. A typical Africa-European collision zone includes a subduction stage characterized by roll-back associated with extensional back-arc volcanism in highly arcuate orogenic settings (Faccenna et al., 2004;Harangi et al., 2006). The SE Carpathians is a region where the post-collisional stage of a highly arcuate orogen is associated with unusual volcanism, where the final stage of roll-back of the slab can be seen in the high-velocity intermediate-depth mantle anomaly detected by seismic tomography studies (e.g., Martin et al., 2006), associated with the Vrancea seismic zone (e.g., Oncescu and Bonjer, 1997). After the collision at 11...

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“…The crustal interpretation is based on the cross section of Schmid et al [2008]. Dashed line at 30-40 km depth represents Moho depth extrapolated from Hauser et al [2007]. Numbers correspond to the six tectonic units described in the text (see Figure 5a [60] The new AFT and AHe data demonstrate that the SE Carpathians are characterized by two postcollisional exhumation stages.…”

Section: Collision Mechanicsmentioning

confidence: 99%

From nappe stacking to out‐of‐sequence postcollisional deformations: Cretaceous to Quaternary exhumation history of the SE Carpathians assessed by low‐temperature thermochronology

Merten¹,

Maţenco

Foeken

et al. 2010

Tectonics

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[1] Apatite fission track (AFT) and (U-Th)/He (AHe) thermochronology have been combined to constrain the exhumation history of the SE Carpathians. Cooling ages generally decrease from Cretaceous for the internal basement nappes (AFT ages), to Miocene-Quaternary (AFT and AHe, respectively) for the external sedimentary wedge. The AFT and AHe data show a Paleogene age cluster, which confirms a suspected but never demonstrated tectonic event. The new data furthermore suggest that the SE Carpathians have been affected by a middle Miocene exhumation phase related to continental collision, which occurred at rates of ∼0.8 mm/yr, similar to the one previously inferred for the East Carpathians. The SE Carpathian tectonic evolution, however, is overprinted by two younger exhumation events in the Pliocene-Pleistocene. The first exhumation phase (latest Miocene-early Pliocene) occurred at high exhumation rates (∼1.7 mm/yr) and is interpreted as a tectonic event and/or associated with a sea level drop in the Paratethys basins during the Messinian low stand. The youngest recorded tectonic phase suggests rapid Pleistocene exhumation (∼1.6 mm/yr) and is interpreted to represent crustal-scale shortening different in mechanics from collisional processes. The data suggest that the SE Carpathians did not develop as a typical double-vergent orogenic wedge; instead, exhumation was related to a foreland-vergent sequence of nappe stacking during collision and was subsequently followed by a large out-of-sequence shortening event truncating the already locked collisional boundary.

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Seismic crustal structure between the Transylvanian Basin and the Black Sea, Romania

Cited by 71 publications

References 44 publications

New Seismic and Tomography Data in the Southern Part of the Harghita Mountains (Romania, Southeastern Carpathians): Connection with Recent Volcanic Activity

New Seismic and Tomography Data in the Southern Part of the Harghita Mountains (Romania, Southeastern Carpathians): Connection with Recent Volcanic Activity

Tectonic significance of changes in post-subduction Pliocene–Quaternary magmatism in the south east part of the Carpathian–Pannonian Region

From nappe stacking to out‐of‐sequence postcollisional deformations: Cretaceous to Quaternary exhumation history of the SE Carpathians assessed by low‐temperature thermochronology

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