A palynological investigation of eight samples from the Jurassic of the Bedford district
Riding, James B.. 2005 A palynological investigation of eight samples from the Jurassic of the Bedford district. British Geological Survey, 7pp. (IR/05/002) (Unpublished)Before downloading, please read NORA policies.
Samples 1 and 2 from Oakley and Bromham respectively are thought to be from the Kellaways Clay Member. The occurrence of Callialasporites spp., Ctenidodinium sp., ?Gonyaulacysta jurassica and Leptolepidites spp. indicates that these samples are of Bathonian-Callovian (Mid Jurassic) age. A detailed lithostratigraphical determination cannot be made, however they are probably from the Cornbrash or Kellaways formations. Correlation to the Blisworth Clay Formation is deemed unlikely. Sample 3 from Box End is believed to be from the Whitby Mudstone Formation. The presence of Callialasporites spp. and Leptolepidites spp. indicates that this sample is of Mid-Late Jurassic age, thus an attribution to the Whitby Mudstone Formation is untenable. The sample is a dark grey mudstone, hence it is most likely that it is from the Northampton Sand, Grantham, Rutland or Blisworth Clay formations. 2 Sample 4 is also from Box End and is assumed to be from the Rutland Formation. The assemblage is dominated by Meiourogonyaulax reticulata. This, and other, dinoflagellate cysts recovered are indicative of a Bathonian age. The acme occurrence of Meiourogonyaulax reticulata is characteristic of the lowermost Blisworth Clay Formation of the English Midlands. Sample 5 from Oakley is also presumed to be from the Rutland Formation. The dinoflagellate cysts are dominated by Ctenidodinium sellwoodii, and this is characteristic of the Bathonian. The occurrence of Gonyaulacysta jurassica subsp. adecta and Meiourogonyaulax reticulata means that this horizon is also interpreted as being from the Blisworth Clay Formation. Sample 6 from Bromham is supposed to be from the lowermost Oxford Clay Formation. It produced a sparse palynoflora including Mendicodinium groenlandicum and Nannoceratopsis pellucida, which are characteristic of the Callovian. The low diversity of this sample means that it is from the Peterborough Member of the Oxford Clay Formation. Sample 7 is thought to be from the Oxford Clay Formation of Ravensden. Many key dinoflagellate cyst taxa were recorded which indicate an early Oxfordian age. This means that this sample is from the Weymouth Member of the Oxford Clay Formation. This conclusion is surprising because the Oxford Clay Formation in this area is largely Peterborough Formation. This sample is not thought to be of a till and more sampling is needed to determine the lateral extent of the Weymouth Member at Ravensden. Sample 8 from Bozeat is supposed to be from the Whitby Mudstone Formation. The spores and pollen indicate that the sample is late Pliensbachian to Toarcian in age. The dinoflagellate cysts are consistent with this assessment and refine this to early Toarcian, probably the D. tenuicostatum or the H. falciferum ammonite subzones. Sample 8 is therefore from the Whitby Mudstone Formation, specifically from the Grey Shale or Jet Rock members or equivalents.
|Item Type:||Report (UNSPECIFIED)|
|Programmes:||BGS Programmes > Geology and Landscape Southern|
|Additional Information:||This item has been internally reviewed but not externally peer-reviewed|
|Date made live:||29 Feb 2012 14:17|
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