Interaction between eustacy and block-faulting in the Carboniferous of the Visé-Maastricht area (Belgium, the Netherlands)

The Visé–Maastricht sedimentation area (VSA) is situated at the eastern end of the Brabant Massif and suffered
block-faulting tectonics during Lower Carboniferous time. The south edge of the VSA, the area corresponding now to the
vicinity of Visé, comprised three main tectonic blocks: the Hermalle-sous-Argenteau, Souvré and Bombaye blocks. They
were bounded to south by the Booze–Val-Dieu block. To the north, in the vicinity of Maastricht, blocks are not well differ-
entiated and are referred to as the Maastricht block system. From the end of the Tournaisian, the latter evolved into a rap-
idly subsiding graben, recording mainly debris fl ows and limestone turbidites, whereas the southern blocks remained rela-
tively high. Through much of Lower Carboniferous time, they were emergent, but during high eustatic sea levels, they were
fl ooded and covered by limestone deposits. The differences in the nature and the age of the deposits between blocks result
from the interaction between block-faulting and eustacy.
In the VSA, the Upper Devonian and Lower Tournaisian (Hastarian) deposits are similar to those known in the north part
of the Namur-Dinant Basin. But from the late Tournaisian (Ivorian), the uplift of the Booze–Val-Dieu block prevented all
connections with the Namur-Dinant Basin and the VSA became linked with the Campine Basin.
The Souvré block subsided from the latest Givetian to the late Frasnian and recorded a thick middle Frasnian limestone
series, but was later emergent, so much that karstic cavities developed. The Souvré block was submerged for a short time at
the top of the Tournaisian, during the very high highstand (HST) corresponding to eustatic sequence 4, and the caves fi lled
up with sediments.
The Hermalle-sous-Argenteau and the Bombaye blocks, situated respectively west and east of the Souvré block, evolved
in the same way during the late Devonian. They subsided slightly from the earliest Tournaisian to the late Viséan (Warnan-
tian), but usually remained emergent and recorded deposits only during times of high eustatic levels corresponding to the
early Tournaisian (for the Bombaye block), the end of the Tournaisian (HST of sequence 4), the end of the early Viséan (HST
of sequence 6), then the late Viséan (HST of sequences 9 and 10). In its southern part, the Hermalle-sous-Argenteau block
recorded also lowermost Viséan limestones correlated with the highstand of the eustatic sequence 5, probably as a result of
the tilting of the block to the south at this time.