Miocene extension and magma generation in the Apuseni Mts. (western Romania): a review

Seghedi, Ioan; Ntaflos, Theodoros; Pécskay, Zoltán; Panaiotu, Cristian; Mirea, Viorel; Downes, Hilary

doi:10.1080/00206814.2021.1962416

Cited by 6 publications

(17 citation statements)

References 81 publications

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“…Their formation assumes low-angle detachments with footwall exhumation controlling half grabens that disclosed deep crustal rocks [13][14][15][16]. The sedimentary graben infill (tens of meters up to a few km; e.g., [17,18] and references therein; [19] is associated with volcanic activity only in the main Békés-Zărand basin and some small associated basins [3,[20][21][22], where the geophysical data suggest asthenosphere upwelling up to 40-45 km depth [14,23]. The onset of extension began in Middle Miocene (i.e., ~16 Ma) when subsequent normal faulting and further activation of listric normal faults is related to brittle tectonics and clockwise rotation of the hanging walls coeval with the main collapse phase of the Pannonian Basin (e.g., [12,13,24,25] and finished during Late Miocene (Figure 2)).…”

Section: Local Geology and The Knowledge Summarymentioning

confidence: 99%

“…The volcano is situated at the limit between Mureş ophiolitic unit and Biharia unit (Figure 2). The inferred fault systems that considered the alignment of the main extrusive bodies and the prolongation of the basement faults suggest two main directions: (1) NNW-SSE, as the main local normal faults suggested to be associated with the ~16-12 Ma tectonic rotations, (2) NW-SE normal fault system mostly developed after ~12 Ma when rotations ceased, assumed to a change to the NW-SE contraction direction (e.g., [3,31], (3) NE-SW directed normal/transtensional faults are frequent underneath the main Bontău volcano edifice and are generally parallel with the boundary between the main tectonic units, as developed from the marginal fragmentation of the Mureş ophiolitic unit on contact with the Biharia unit (Figure 2). This complex tectonic system initiated by rotations with extension/transtension was responsible for the long-time build-up of a ~4 Myers (~14-10 Ma; [2,20]) Bontău calc-alkaline volcano.…”

Section: Local Geology and The Knowledge Summarymentioning

confidence: 99%

“…We separated the rocks in the diagrams according to their volcanological characteristics (complex volcanic Domes, remnants of the composite edifice, and blocks in DADs) and added the rocks of the Zărand-Brad-Zlatna basin for evaluation (Group 1-Z; [3]) where the Bontău volcanic complex developed. According to the TAS and Peccerillo and Taylor diagrams, the samples range from basaltic andesite to andesite (Figure 9).…”

Section: Rock Classificationmentioning

confidence: 99%

“…This study is dedicated to the Bontău volcanic complex, the major known andesitic composite volcano (e.g., [1]) and associated lava Dome structures that were rising inside the largest graben system in the southern part of the Apuseni Mts. during Middle-Late Miocene, known transnationally as Békés-Zărand basin, or nationally as Zărand basin (e.g., [2,3]; Figure 1). Recent field data acquisition along with additional rock sampling have led to a novel volcanological and petrological interpretation.…”

Section: Introductionmentioning

confidence: 99%

“…Minerals 2022, 12, 243 2 of 23 the largest graben system in the southern part of the Apuseni Mts. during Middle-Late Miocene, known transnationally as Békés-Zărand basin, or nationally as Zărand basin (e.g., [2,3]; Figure 1). Recent field data acquisition along with additional rock sampling have led to a novel volcanological and petrological interpretation.…”

Section: Introductionmentioning

confidence: 99%

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Construction and Destruction of Bontău Composite Volcano in the Extensional Setting of Zărand Basin during Miocene (Apuseni Mts., Romania)

2022

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The Eastern part of the Miocene Zărand extensional basin witnessed the generation and evolution of the largest composite volcano in Apuseni Mts., named recently Bontău. The volcano is filling the basin at the junction between the South and North Apuseni Mountains. The Bontău Volcano is known to be active roughly between ~14–10. In spite of heavily forested and poorly exposed volcanic deposits, it was possible to identify its complex evolution. The volcano suggests an original oval-shaped edifice base currently showing a north-oriented horseshoe-shaped debris avalanche eroded crater. The early effusive volcanic activity was contemporaneous with the emplacement of individual and/or clustered volcanic lava Domes. Late-stage summit dome generation was followed by several volcanic collapses all around the volcanic edifice producing large volcanic debris avalanche deposits (DADs), accompanied by numerous debris flows all around the volcano periphery. Thick pumice pyroclastic flow deposits found below DADs at the periphery may suggest that the slope failures were proceeded by a Plinian eruption. The debris avalanche crater is the last event in the volcano evolution exposing several intrusive andesitic-dioritic bodies and associated hydrothermal and mineralization processes, most probably including the former central vent area of the volcano. The volcano proximal effusive and explosive deposits display a change in the composition of the erupting magma (increased SiO2 from 53.4% to 60.6%) that resulted in an increase of viscosity and the construction of the summit lava domes. Such domes are however only found as various size blocks in DADs. The volcanism connects with the two steps of geotectonic evolution of the Zărand Basin: The initial construction period during regional extension started ~16 Ma up to 12.3–12.1 when the Bontău volcano and surrounding domes were generated. The second period, younger than 12 Ma, corresponds to NW-SE compressional tectonics developed only in the Bontău volcano with summit dome generation and, finally, assists volcano destruction and DADs generation. Newly performed geochemical and Sr and Nd isotopic data studies attest to a calc-alkaline character and suggest an evolution via assimilation-fractional crystallization processes of a dominant MORB-like mantle source magma. Also, they confirm the amphibole (± pyroxene) andesites to be the most evolved lithology. The stepwise changes in fracture propagation in the Zărand extensional setting along with a change to more hydrated and fractionated magma favored in ~4 Myrs of the evolution of the Bontău volcano lead to multiple pulses of the longest-lived magma chamber in the whole Miocene volcanism of the Apuseni Mts.

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Section: Local Geology and The Knowledge Summarymentioning

confidence: 99%

Section: Local Geology and The Knowledge Summarymentioning

confidence: 99%

Section: Rock Classificationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Construction and Destruction of Bontău Composite Volcano in the Extensional Setting of Zărand Basin during Miocene (Apuseni Mts., Romania)

2022

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Seismic attenuation tomography of Eastern Europe from ambient seismic noise analysis

Borleanu,

Petrescu,

Placinta

et al. 2023

Geophysical Journal International

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Summary The Eastern-Europe region (EER), is a complex geotectonic area that captures part of the Alpine-Himalayan Orogen, the subduction of multiple NeoTethys Branches and part of the East European Craton. It is one of the most exciting geological areas in Europe due to a diversity of tectonic processes acting within it: extensional basin evolution, oceanic subduction, post-collisional volcanism, as well as active crustal deformation associated with the push of the Adria plate or the pull of the actively detaching Vrancea slab. This makes EER an excellent natural laboratory to study the behavior of the lithosphere-asthenosphere system in a heterogeneous tectonic setting. To investigate the lateral heterogeneity and physical properties of the crust in the EER, we use ambient seismic noise data recorded by the vertical components of broadband stations that have been operational between 1999 and 2020 in Eastern Europe and surrounding regions. We used this significant amount of data and the latest processing techniques of the ambient seismic noise field based on the continuous wavelet transform to compute cross-correlations between various station pairs, turning every available seismic station into a virtual source. The coda of the inter-station cross-correlograms were used to determine coda quality factors (Qc) of Rayleigh waves in four different period ranges (3.0–5.0s, 5.0–10.0s, 10.0–20.0s and 20.0–30.0s) and to invert them in the 2D space, constructing the highest resolution attenuation tomography of the region. Our results reveal high attenuation features throughout the north-east Pannonian region, the Bohemian Massif, the East Carpathians, and the Moesian Platform. Nevertheless, our findings do not emphasize a close correlation between the depth of sedimentary basins and attenuation features identified at longer periods. In addition, Qc variations are larger at short periods, indicating higher heterogeneity in the uppermost crust of Eastern Europe. Our findings demonstrate the higher efficiency of noise correlation approaches relative to earthquake data analyses investigating Qc at low frequencies.

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Spatiotemporal distribution of magmatism and crustal inheritance within an extensional–rotational environment: an updated geochronology of the Miocene and Quaternary magmatism of the South Apuseni Mountains

Ene,

Tapster,

Smith

et al. 2024

JGS

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Magmatism with arc-like features, formed in extensional settings, was active in the South Apuseni Mountains, Romania, during the Neogene and Quaternary periods. To date the chronological framework is primarily restricted to K-Ar dates. We present newly determined LA-ICP-MS U-Pb zircon age data for subvolcanic and volcanic rocks (N=20) from 8 different Cenozoic volcanic-intrusive complexes and from Jurassic and Cretaceous lava flows. Our results support magmatic ages between c. 14 to c. 7 Ma, with Uroi, an alkaline intrusion, occurring significantly later at c. 1.5 Ma. Revising the timeline for the South Apuseni Mountains paleomagnetic rotations shows that most of the vertical-axis clockwise rotation of the Apuseni Mountains (54.4° ± 10.7°) took place between approximately 14 and 11 Ma, the age interval when the majority of magmas were emplaced. Xenocrystic zircon dates exhibit differences in age populations between individual volcanic-intrusive complexes. A Permo-Triassic population is almost ubiquitous, indicating that basement Permo-Triassic igneous rocks are more widespread than previously thought or that they were significantly involved in the generation of Neogene magmas. However, other observed age populations, such as Triassic or Paleogene have no clear correspondence in the known geological record, indicating the presence of a cryptic component interacting with Neogene magmas. Supplementary material: https://doi.org/10.6084/m9.figshare.c.6951429

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Miocene extension and magma generation in the Apuseni Mts. (western Romania): a review

Cited by 6 publications

References 81 publications

Construction and Destruction of Bontău Composite Volcano in the Extensional Setting of Zărand Basin during Miocene (Apuseni Mts., Romania)

Construction and Destruction of Bontău Composite Volcano in the Extensional Setting of Zărand Basin during Miocene (Apuseni Mts., Romania)

Seismic attenuation tomography of Eastern Europe from ambient seismic noise analysis

Spatiotemporal distribution of magmatism and crustal inheritance within an extensional–rotational environment: an updated geochronology of the Miocene and Quaternary magmatism of the South Apuseni Mountains

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