Abstract
Mid-Westphalian A to late Westphalian B sediments of the South Wales Coalfield comprise mainly lacustrine, raised mire and flood deposits developed in an upper coastal plain environment. Occasional high sinuosity, fine-grained channel systems drained the subdued topography of the Wales-Brabant Massif to the north and east of the basin. Low sinuosity channels with lithic, coarse-grained fills drained a rising source to the south. Direct marine influence was restricted to a single marine band. Facies distributions were controlled by (1) local scale (10 2 -10 3 m 2 ) autocyclic sedimentary processes, (2) regional scale (10 km 2 ) synsedimentary fault activity and differential subsidence and 3) basin-wide scale (10 2 km 2 ) response to changes in relative sea-level. Base-level changes are recorded by basin-wide bivalve horizons (up-dip or landward extension of marine bands) developed in lacustrine mudstones above basin-wide coal seams. Peat accumulation was terminated by a water table rise related to base-level rise. Following flooding, re-establishment of the clastic supply resulted in the gradual infilling of the basin-wide lake to produce coarsening- upwards cyclothems or parasequences. A eustatic origin for parasequence development is supported by the development of identical facies associations and parasequences in coeval sediments from the Pennine and Midland Valley Coalfields.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.