Imprints of hydrocarbon-bearing basinal fluids on a karst system: mineralogical and fluid inclusion studies from the Buda Hills,Hungary |
| |
Authors: | Email author" target="_blank">Zsófia?PorosEmail author Andrea?Mindszenty Ferenc?Molnár Jacques?Pironon Orsolya?Gy?ri Paola?Ronchi Zoltán?Szekeres |
| |
Institution: | 1.Department of Physical and Applied Geology,E?tv?s Loránd University,Budapest,Hungary;2.Department of Mineralogy,E?tv?s Loránd University,Budapest,Hungary;3.Université de Lorraine, CNRS, G2R Laboratory,Vandoeuvre-lès-Nancy,France;4.ENI Exploration and Production Division,San Donato Milanese,Italy;5.Separation Science Research and Education Laboratory,E?tv?s Loránd University,Budapest,Hungary;6.Geological, Geophysical and Space Science Research Group of the Hungarian Academy of Sciences,Budapest,Hungary |
| |
Abstract: | Calcite veins and related sulphate–sulphide mineralisation are common in the Buda Hills. Also, abundant hypogenic caves are
found along fractures filled with these minerals pointing to the fact that young cave-forming fluids migrated along the same
fractures as the older mineralising fluids did. The studied vein-filling paragenesis consists of calcite, barite, fluorite
and sulphides. The strike of fractures is consistent—NNW–SSE—concluding a latest Early Miocene maximum age for the formation
of fracture-filling minerals. Calcite crystals contain coeval primary, hydrocarbon-bearing- and aqueous inclusions indicating
that also hydrocarbons have migrated together with the mineralising fluids. Hydrocarbon inclusions are described here for
the first time from the Buda Hills. Mixed inclusions, i.e., petroleum with ‘water-tail’, were also detected, indicating that
transcrystalline water migration took place. The coexistence of aqueous and petroleum inclusions permitted to establish the
entrapment temperature (80°C) and pressure (85 bar) of the fluid and thus also the thickness of sediments, having been eroded
since latest Early Miocene times, was calculated (800 m). Low salinity of the fluids (<1.7 NaCl eq. wt%) implies that hydrocarbon-bearing
fluids were diluted by regional karst water. FT-IR investigations revealed that CO2 and CH4 are associated with hydrocarbons. Groundwater also contains small amounts of HC and related gases on the basin side even
today. Based on the location of the paleo- and recent hydrocarbon indications, identical migration pathways were reconstructed
for both systems. Hydrocarbon-bearing fluids are supposed to have migrated north-westward from the basin east to the Buda
Hills from the Miocene on. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|