Structural and Tectonic Evolution of K-Rich Silica-Deficient Volcanic Provinces of Different Continents - Origin of Potassium-rich Silica-deficient Igneous Rocks - page 415

DRESDEN

ERFURT

K O LN

BRUXELLES

PRAHA

PARIS

WIEN

MUNCHEN

BERN

CENOZOIC ALKALINE
VOLCANICS

LYON

RIFT BASINS

MILANO

MAJOR WRENCH
FAULTS

ALPINE FOLD BELT

0 200 km

MARSEILLE

Fig. 14.1 The Cenozoic rift system of western and central Europe (after Ziegler 1992)

associated with Leine graben. This had major role in the localization of these
grabens. The Ruhr Valley graben dies out in the central areas of the Netherlands.
According to Ziegler (1992), the subsidence of Rhine Graben system started
during late Eocene and volcanism was more or less continuous throughout the
Cenozoic, but it was maximum during Quaternary. He further emphasized that the
area of Rhine Ruhr Valley triple junction was the main centre of volcanic

activity. There are however, smaller volcanic centres, which are located 100 km
east of the Rhine Graben. These centres include Rhon in the north and the Urach
and Hegau areas in the south. Neogene volcanism was extended over a broad area
on the Rhenish Shield. This area straddles the triple junction of the Rhine, Ruhr
Valley and Leine grabens. This zone of Neogene volcanism spreads over an
east

Leine

- -

west-trending zone, and is 250 km wide. The Quaternary volcanism was
concentrated over the east Eifel area, where the last volcanism took place
11,000 years ago (Mertes and Schminke 1983). The rate of up lift of the western
part of the Rhenish shield is estimated to be nearly 0.5 mm/year (Ziegler 1992).
Marine connection between Alpine foreland basin, the Paris and NW European
basins were severed during early Miocene, because of thermal uplift of the Massif
Central and the Rhenish Massif. Geological evidence suggests that uplift around the
southern Rhine Graben, Vosges

-

Black Forest rift dome started during the late
middle Miocene. The Vosges and Black Forest areas were further uplifted during

-