Two small volcanoes, one inside the other: geophysical and drilling investigation of Bažina maar in western Eger Rift

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985530%3A_____%2F23%3A00574345" target="_blank" >RIV/67985530:_____/23:00574345 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216208:11310/23:10475531 RIV/00025798:_____/23:10168793

Výsledek na webu

<a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023EA003009" target="_blank" >https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023EA003009</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1029/2023EA003009" target="_blank" >10.1029/2023EA003009</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Two small volcanoes, one inside the other: geophysical and drilling investigation of Bažina maar in western Eger Rift

Popis výsledku v původním jazyce

Maar-diatreme volcanoes are small volcanic structures with a funnel-shaped crater surrounded by a tephra-ring. They are usually formed by the explosive phreatomagmatic eruptions when groundwater comes into the contact with magma. We focus on such a structure in the geodynamically active western Eger Rift (Czech Republic) and present results from multidisciplinary geophysical investigation calibrated by drilling in the newly discovered Pleistocene Bažina maar. We evaluated morphological (LiDAR-based DEM) data and confirmed the existence of a maar-diatreme structure by combined geophysical methods. In the map view, they revealed circular negative gravity anomaly, funnel-shape low-resistivity anomaly, and strong magnetic anomaly. These results allowed for the optimal location of two boreholes in the maar crater, which evinced its contact with country rocks and lithologies of the maar-diatreme filling. The drilling revealed coherent volcanic rocks and volcaniclastic deposits, moreover, it revealed a presence of a pyroclastic cone with the olivine nephelinite feeding conduit. Further investigations disclosed maar structure and subsequent pyroclastic cone(s) with several generations of eruptions and systematic decrease of water influence on the eruption style. Different eruption styles suggest a unique evolution of two volcanoes, one inside the other. The age of the Bažina maar eruption, estimated from the reverse polarity of the detected magnetic anomaly, implies that the effusion and solidification of the lava during the eruption must be older than 0.78 Ma (Pleistocene). This points to an active volcanism in the western Eger Rift in a span of ∼0.5 Ma, where Bažina represents the oldest (maybe opening) phase.

Název v anglickém jazyce

Two small volcanoes, one inside the other: geophysical and drilling investigation of Bažina maar in western Eger Rift

Popis výsledku anglicky

Maar-diatreme volcanoes are small volcanic structures with a funnel-shaped crater surrounded by a tephra-ring. They are usually formed by the explosive phreatomagmatic eruptions when groundwater comes into the contact with magma. We focus on such a structure in the geodynamically active western Eger Rift (Czech Republic) and present results from multidisciplinary geophysical investigation calibrated by drilling in the newly discovered Pleistocene Bažina maar. We evaluated morphological (LiDAR-based DEM) data and confirmed the existence of a maar-diatreme structure by combined geophysical methods. In the map view, they revealed circular negative gravity anomaly, funnel-shape low-resistivity anomaly, and strong magnetic anomaly. These results allowed for the optimal location of two boreholes in the maar crater, which evinced its contact with country rocks and lithologies of the maar-diatreme filling. The drilling revealed coherent volcanic rocks and volcaniclastic deposits, moreover, it revealed a presence of a pyroclastic cone with the olivine nephelinite feeding conduit. Further investigations disclosed maar structure and subsequent pyroclastic cone(s) with several generations of eruptions and systematic decrease of water influence on the eruption style. Different eruption styles suggest a unique evolution of two volcanoes, one inside the other. The age of the Bažina maar eruption, estimated from the reverse polarity of the detected magnetic anomaly, implies that the effusion and solidification of the lava during the eruption must be older than 0.78 Ma (Pleistocene). This points to an active volcanism in the western Eger Rift in a span of ∼0.5 Ma, where Bažina represents the oldest (maybe opening) phase.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10507 - Volcanology

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2023

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Earth and Space Science

ISSN

2333-5084

e-ISSN

2333-5084

Svazek periodika

10

Číslo periodika v rámci svazku

8

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

21

Strana od-do

e2023EA003009

Kód UT WoS článku

001042207400001

EID výsledku v databázi Scopus

2-s2.0-85166746351