British Pennsylvanian (Carboniferous) coal-bearing sequences: where is the time?
Andrew C. Scott
Rosemary S. Stephens
10.6084/m9.figshare.3453842.v1
https://geolsoc.figshare.com/articles/dataset/British_Pennsylvanian_Carboniferous_coal-bearing_sequences_where_is_the_time_/3453842
<p>The Lower and Middle Coal Measures of Langsettian (Westphalian A) and Duckmantian (Westphalian B) age (together equals Bashkirian
in part) in Britain comprise an alternation of clastic sediments and coal deposited on coastal and alluvial plains over a
period of 2–3.5 million years, depending on which time scale is accepted. In both the Pennine and South Wales Basins there
are no obvious unconformities. Many of the clastic sequences show evidence of rapid sedimentation (burial of trees, bivalve
escape burrows) that may suggest that a significant amount of time is taken up during the peat-forming intervals. Thickness
data from a range of boreholes that record continuous sections through this time period were collated. Coal and sediment thicknesses,
as well as coal to sediment ratios, are compared both within and across the basins. Data on the coals has allowed consideration
of the time taken to deposit the peats. This work considers the compaction of the peat to coal, as well as a range of peat
accumulation rates. Assuming the largest de-compaction rates and slowest accumulation rates of the coal formation, less than
50% of the allocated time can be accounted for. In addition however, calculations suggest that peat formation accounts for
less than 25% of the total time taken for sediment accumulation. It is suspected that there are major time gaps in the sequences,
most probably occurring between seat-earths and coal and within the coals, and it is believed that this finding has significance
for the debate over short-term climate changes in the Carboniferous and the causes of peat and sediment alternations.
</p>
2016-06-21 11:43:01
Middle Coal Measures
time gaps
time scale
clastic sequences show evidence
British Pennsylvanian
South Wales Basins
peat accumulation rates
sediment accumulation
climate changes
coal formation
time period
sediment thicknesses
peat formation accounts
sediment alternations
Thickness data
clastic sediments
Westphalian B
sediment ratios
accumulation rates
Geology