Silurian solid bitumen from Huy: evidences for a petroleum system in Belgium

The discovery of a bitumen bed within the Silurian Bonne Esperance Formation near the city of Huy (Belgium) is the first clear evidence for a petroleum system in Belgium. The studied section near the city of Huy (Belgium) is part of a larger structural unit called the Condroz inlier. This structural unit is a wedge of Ordovician to Silurian aged marine sediments which was thrusted up along the Midi detachment fault during the Hercynian orogeny and forming the Ardennes Massif (Adams & Vandenberghe, 1999). To understand the geological processes involved in the formation of the bitumen bed, the Bonne Esperance Formation was logged and 82 samples were collected for XRF chemostratigraphy, five samples were collected (Figure 1, pictures 1-5) for biostratigraphic purposes and one sample was taken from the bitumen itself. ICP-MS, TOC, Rock-Eval pyrolysis and Gamma-ray measurements are underway to quantify the source rock potential of the Bonne Esperance Formation. Preliminary XRF measurements already show that especially the lower part of the Bonne Esperance Formation is enriched in elements linked to anoxic conditions/enrichment of organic material, which indicates that the Bonne Esperance Formation itself is the likely candidate source rock for the bitumen. The sample from the bed which includes the bitumen has already been tested to confirm the nature of the bitumen material. The sample was crushed and heated in a vial and the released hydrocarbons were then ignited with a flame (Figure 1, picture 6C). The First occurrence of the graptolites of the Family Monograptidae was used to pinpoint the location of the Ordovician-Silurian boundary (Akidograptus Ascensus zone at sample 4) (Maletz, 2017). Given the current results and the ongoing analyses a picture emerges of the Silurian of the Condroz inlier as being Belgium’s first and to date only petroleum system.

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(15) géologie