Alblasserdam Member

Code
SLDNA
Status
Formal (Van Adrichem Boogaert & Kouwe 1993).
Lithological description

Typically dark to light grey, red and variegated clay- and siltstones, fine to medium grained sandstones with bed thicknesses up to a few metres, and massive, thick-bedded, coarse grained sandstones. Coal and lignite beds are associated with the grey claystones. Dispersed lignitic matter, siderite spherulites and concretions are common. Cored sections show extensive mottling of the variegated claystones. Sands occur as sheets, isolated or stacked channels.

Depositional setting

Fluvial-plain deposits, with sand concentrated in mostly channels and crevasse-splays. On the floodplains outside the channels, development of swamps and soils took place. The main sediment transport direction has been reconstructed as southeast-northwest.

Definition of lower boundary

The base is formed by the unconformable contact with the Altena Group.

Definition of upper boundary

Normally overlain by the massive sandstone of the coastal-plain Delft Sandstone Member, or the shallow-marine Vlieland Sandstone Formation. Locally the Delft Sandstone Member is not developed, and the Alblasserdam Member is overlain by the Rodenrijs Claystone Member. In areas of Subhercynian/ Laramide inversion the Alblasserdam Member is overlain by the Chalk Group, Lower North Sea Group or Middle North Sea Group.

Thickness indication
The total thickness is extremely variable, ranging from less than 100 m to more than 1300 m.
Geographical distribution
Regional correlation
UK: Cromer Knoll Group - Humber Group; GER: ?; BEL: -.
Age
Berriasian -Valanginian. In the Rotterdam area the age can range up to Hauterivian. The basal part can be of Kimmeridgian/Oxfordian age.
Holostratotype
Depth (thickness) AH:
1052 - 1942 m (890 m)
Parastratotype
Depth (thickness) AH:
900 - 1650 m (750 m)
Parastratotype
Depth (thickness) AH:
2224 - 2374 m (150 m)
Parastratotype
Depth (thickness) AH:
1888 - 2475 m (587 m)
Parastratotype
Depth (thickness) AH:
741 - 1096 m (355 m)
Origin of name
Named after the village of Alblasserdam near Rotterdam.
Previous name(s)
None.
Reviewed by (date)
Sander Houben (2017).
References
Van Adrichem Boogaert, H.A. & Kouwe, W.F.P. 1993. Stratigraphic nomenclature of The Netherlands; revision and update by RGD and NOGEPA, Section G, Upper Jurassic and Lower Cretaceous. Mededelingen Rijks Geologische Dienst, 50, 1-80..
Cite as
TNO-GDN ([YEAR]). Alblasserdam Member. In: Stratigraphic Nomenclature of the Netherlands, TNO – Geological Survey of the Netherlands. Accessed on [DATE] from http://www.dinoloket.nl/en/stratigraphic-nomenclature/alblasserdam-member.