This field trip focuses on Miocene carbonate and Late Eocene coarse clastic, sandstone and carbonate reservoir rocks of the Pannonian Basin and their connection to fractured Mesozoic basement in the southern part of Budapest. The day is started at a Late Neogene outcrop west of Budapest. During successive stops Late Eocene antiforms will be visited: outcrops of high viscosity debris flows and basement structures along the “Budaörs shear zone” will be shown. Progressing towards the east we visit several Paleogene exposures, terminating the field trip at a spectacular horst along the Danube. Beneath the horst that is also one of the landmarks of Budapest lies a series of hot springs (i.e. the Buda thermal karst line) and some will be visited.
This field trip focuses on Miocene carbonate and Late Eocene coarse clastic, sandstone and carbonate reservoir rocks of the Pannonian Basin and their connection to fractured Mesozoic basement in the southern part of Budapest. The day is started at a Late Neogene outcrop west of Budapest. During successive stops Late Eocene antiforms will be visited: outcrops of high viscosity debris flows and basement structures along the “Budaörs shear zone” will be shown. Progressing towards the east we visit several Paleogene exposures, terminating the field trip at a spectacular horst along the Danube. Beneath the horst that is also one of the landmarks of Budapest lies a series of hot springs (i.e. the Buda thermal karst line) and some will be visited.
The Late Eocene sequence starts with shallow marine sandstone, conglomerate and breccia which clasts derived from local Triassic carbonate basement and locally Eocene volcanites. The series is overlain by shallow marine limestone, neritic and bathyal marl. Most beds were deposited by sediment gravity flows on the flanks of synsedimentarily growing basement antiforms.
The spectacular Triassic-basement-cored antiforms seem to constitute positive flower structures and are arranged en echelon, in an E-W to ENE-WSW trending shear zone south of Buda hills. Late Eocene sediments deposited by gravity flows on the flanks of these anticline suggest tectonic instability. Doming, faulting and pervasive brecciation of basement were contemporaneous with sedimentation, most of the faults do not continue into the Eocene sediments.
On top of the deep marine Eocene series comes an Oligocene succession constituted by deep lacustrine-marine clays and bathyal clays. In formerly uplifted parts a coarse clastic sandstone-conglomerate was deposited directly on Triassic basement. Both Late Eocene and Oligocene marls, clays can be effective source rocks.
Oligocene deep marine clays are superposed by a shallow marine-fluvial system in the Early Miocene. This system propagates from west to east and deposited sandstones and conglomerates. In the Middle Miocene locally volcanic tuffs and shallow water limestones were deposited. The limestones generally transgress local highs.
After a massive regression/inversion event in Late Miocene, locally hypersaline deposits interfinger with shallow oolithic limestone shoals in the Late Miocene Sarmatian. A synchronous tectonic activity is recorded by submarine fissure fillings.
Latest Miocene-Pliocene Pannonian clastics close the sedimentary cycle. These will constitute the topic of the post conference field trip.