Arkell.1956.Jurassic..

68 THE PARIS BASIN
is less than 10 m. in most of Lorraine, but in the Thionville trough in
the extreme north borings prove it to reach 48 m.; and the lower part
passes laterally into the upper part of the Hettange Sandstone in the
vicinity of the Luxemburg border (Guillaume, 1941). In Luxemburg and
Belgium the Sinemurian passes laterally into the Virton Sandstone, 50 m.
thick, the upper part of which locally becomes decalcified and forms the
Stockem Sands (Maubeuge, 1948, 1952a, 1954a). In the Ardennes the
lower part of the Bucklandi Zone is a calcareous sandstone, the upper
part only consisting of Gryphaea limestones; and the Semicostatum Zone
is condensed as sandy marls and ironstone, while the Turneri Zone
begins the overlying series of sandy marls and marly limestones which
mainly represent the Obtusum Zone (Bonte, 1941, Table B, p. 82; Joly,
*93 6
)-
HETTANGIAN (up to 70 m.)
The type-locality, Hettange (marked Hettingen on some maps) is a
village a few miles on the Lorraine side of the Luxemburg border, 14 miles
south of the city of Luxemburg. In this district and in Luxemburg
territory the Gryphaea arcuata limestones, with Arietites, overlie the
Hettange Sandstone, which corresponds to the Zones of Psiloceras
planorbis and Schlotheimia angulata. The area from which the Hettangian
stage takes its name, however, is unfavourable for establishing an ammonite
succession. The whole stage consists of sandstone, more or less calcareous,
resting on Rhaetic Beds in some places, on Keuper Marls in others.
The basal part is unfossiliferous except for occasional oysters; higher up
are masses of Cardinia and Lima with a well-preserved and large fauna
of gastropods. The best works on the subject, and almost the only ones
providing adequate illustrations, are the early classics by Terquem (1855),
Terquem & Piette (1865), Chapuis & Dewalque (1853), and Chapuis
(1858). In parts of Luxemburg and Belgium, the Hettange Sandstone
passes laterally into the Jamoigne Marl, which contains Caloceras and
Schlotheimia (Chapuis & Dewalque, 1853). The Hettangian was said
by Terquem (1855, p. 6) to be usually 25-30 m. thick, but in some places
up to 100 m. Borings in the Thionville district proved 57-70 m. for the
Hettange Sandstone, but part of this represents the Lower Sinemurian
in sandstone facies (Guillaume, 1941). Westwards in the Ardennes
department of France the stage thins and becomes conglomeratic, and
is eventually overlapped by the Sinemurian (Bonte, 1941, p. 77, table B).
Farther south, in Meurthe & Moselle, although thicknesses are much
less, the facies is marly and calcareous and a much richer ammonite
fauna occurs (Gerard & Gardet, 1938). Against the Massif du Morvan
the Hettangian oversteps the Palaeozoic rocks, beginning with an oyster
lumachelle of Planorbis Zone age, and features similar to those in the
northern rim of the Paris Basin, near the Ardennes, are repeated (Mouterde
!953)-
http://jurassic.ru/