Lacustrine deltaic sand bodies in the Pannonian Basin are excellent reservoirs, proven by many oil and gas fields, including one of the largest at Algyő, Hungary. The up-to 7 km-thick late Neogene basin-fill succession comprises deposits of the vast, long-lived Lake Pannon, the host of a splendid endemic biota. Coarsening-upwards deltaic cycles - from prodelta mudstones to fine-grained mouth-bar sands, to heterolithic interdistributary bay-filling deposits, small deltaic channel-fills, all locally cut by coarse-sand filled incised valleys - are usually stacked up to several hundred meters in the subsurface basin interiors. Outcrop analogs can be studied in the vicinity of lake Balaton due to an interplay of the complex Miocene paleotopography and the Neotectonic basin inversion. The few thousand-year-old lake literally opens a window to the underlying 8 Ma year-old lacustrine deltaic parasequences by the steep, abrasional coasts and by ultra-high resolution seismic reflection data, acquired on the lake.
After a panoramic introduction to the history of lake Balaton we are going to observe the sedimentary facies and fossils of mouth bar and interdistributary-bay fill deposits and their parasequences. In the next two stops, after a short tracking, volcanoclastics of diatrems cut into the deltaic suit will be seen. The interaction of post-extensional basaltic magmas and pore waters of the coeval delta plain led to phreatomagmatic explosions and the formation of spectacular sedimentary structures. Back to the lake shore you will see masses of the infamous „zebra mussel” and „quagga mussel” (Dreissena polymorpha and D. rostriformis bugensis). The origin of Dreissena goes back to Lake Pannon (and possibly beyond), thus the history of this originally brackish-water, endemic lacustrine genus includes eastward migration in the Neogene and invasive intercontinental colonization in the 20th century. The rich cultural heritage of the Lake Balaton environs will escort us all along the trip.