Naslov
A report on the well-preserved Miocene volcanic cone from the Drava Depression, North Croatian Basin – inference from the deep seismic reflection data

Autori
Bigunac, Dijana ; Matoš, Bojan ; Šuica, Sanja

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, prošireni sažetak, znanstveni

Izvornik
6. hrvatski geološki kongres s međunarodnim sudjelovanjem: Knjiga sažetaka = 6th Croatian Geological Congress with international participation: Abstracts Book / Horvat, Marija ; Matoš, Bojan ; Wacha, Lara - Zagreb : Hrvatski geološki institut, 2019, 29-29

ISBN
978-953-6907-73-1

Skup
6. hrvatski geološki kongres s međunarodnim sudjelovanjem

Mjesto i datum
Zagreb, Hrvatska, 09.10.2019. - 12.10.2019

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
volcanic cone, tectonic activity, Drava Depression

Sažetak
The large volume of effusive volcanic rocks and pyroclastites in the Drava Depression indicates a close interplay between the magmatism and extensional tectonic activity during Lower to Middle Miocene (e.g. PAVELIĆ, 1998, PAVELIĆ & KOVAČIĆ, 2018). These findings are in accordance with the well-core data from numerous wells in the Drava depression. Volcanic breccias, andesitic-basaltic lava flows, as well as different types of acidic pyroclastic rocks (e.g. ash fall tuffs, pyroclastic flows) were reported from the cored syn-rift successions, but so far without research on the possible volcanic source areas. This study presents the first example of a preserved volcanic cone obtained from deep seismic reflection data and supported by the well data. Eroded volcanic features were inferred from the exposed volcanic successions only in one surface location near the study area. Lower Miocene volcanic activity was documented in the area of Mt. Krndija in the Slavonian Mountains (PAMIĆ et al., 1993) and was attributed to the initial phase of rifting in the Drava Depression. According to mineral paragenesis, structures and textures, the authors concluded that described trachyandesite represents the part of volcanic succession of the eroded volcanic dome that intruded the basement metamorphic complex and Lower Miocene coarse clastic sediments with tuff intercalations. K-Ar measurements gave the age of trachyandesite between 16 and 15.4 Ma (PAMIĆ et al., 1993). In this study, two 3D seismic volumes as well as a broad network of 2D seismic reflection profiles were used in the subsurface mapping of the Lower Miocene sedimentary bodies. These sediment successions belong to the Mosti Member, Moslavačka gora Formation, which is a common hydrocarbon-bearing formation in many parts of the Drava Depression. The study is a part of the corresponding author’s PhD research which also includes the conclusions about possible hydrocarbon traps. While exploring for stratigraphic and structural traps in order to improve the identification of possible hydrocarbon migration pathways, a part of conducted PhD research included detection of vertical hydrocarbon migration geological features i.e. gas chimneys. Their weak seismic expression is recognized both on 2D and 3D seismic sections as low-amplitude, chaotic, sub vertical features. In a few observed cases gas chimneys are also associated with small-scale folds above them. Gas chimneys were detected throughout Pannonian s.l. sediments, some of them reaching the base of Lake Pannonian clinoforms. Further detailed analyses of reflection seismic profiles revealed a well-preserved volcanic cone with gas chimneys associated to the main volcanic vent and two auxiliary ones. Petrographic data from well cores of the three deep exploratory wells show that magma firstly intruded the metamorphic basement, then the non-fossiliferous breccia and conglomeratic complex of possible Ottnangian age and was finally capped by Pannonian sediments.

Izvorni jezik
Engleski

Znanstvena područja
Geologija, Geofizika

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