Isotopic composition of a calcite-cemented layer in the Lower Jurassic Bridport Sands, southern England: Implications for formation of laterally extensive calcite-cemented layers

Journal Article · Thu Jul 01 00:00:00 EDT 1993 · Journal of Sedimentary Petrology; (United States)

OSTI ID:6121236

Bjoerkum, P A ^[1]; Walderhaug, O ^[2]

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1. Statoil, Stavanger (Norway)
2. Rogaland Research, Stavanger (Norway)

[delta][sup 18]O[sub PDB] and [delta][sup 13]C[sub PDB] values have been measured on 107 calcite cement samples from a laterally extensive (> 3 km) and continuous calcite-cemented layer 0.5 m thick in the coastal exposures of the Lower Jurassic shallow-marine Bridport Sands in Dorset, southern England. The samples were taken from a two-dimensional grid with 10-cm horizontal and vertical spacing between samples and along individual vertical lines across the calcite-cemented layer, [delta][sup 18]O[sub PDB] values vary between [minus]4.8% and [minus]9.2% and decrease radially outwards from points with lateral spacings on the order of 0.5-1 m in the middle of the calcite-cemented layer. The [delta][sup 18]O[sub PDB] values therefore indicate that the calcite-cemented layer was formed by merging of concretions. All [delta][sup 13]C[sub PDB] values measured are in the narrow range [minus]2.2% to [minus]0.5%, which suggests that the dominant source of calcite cement in the layer was biogenic carbonate.

• OSTI ID: 6121236
• Journal Information: Journal of Sedimentary Petrology; (United States), Vol. 63:4; ISSN 0022-4472
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CALCITE
CHEMICAL COMPOSITION
GEOLOGIC FORMATIONS
DIAGENESIS
GEOCHEMISTRY
UNITED KINGDOM
GEOLOGIC MODELS
ISOTOPE RATIO
JURASSIC PERIOD
OXYGEN ISOTOPES
SANDSTONES
CARBONATE MINERALS
CHEMISTRY
DEVELOPED COUNTRIES
EUROPE
GEOLOGIC AGES
ISOTOPES
MESOZOIC ERA
MINERALS
ROCKS
SEDIMENTARY ROCKS
WESTERN EUROPE
580000* - Geosciences