Paleotopography and Sea-Level Controls on Facies and Thickness Variability
of Transgressive Limestones: Upper Pennsylvanian Merriam Limestone,
Kansas Geological Survey
Open-file Report 2003-26
- After erosion into Bonner Springs Shale and initial transgression, the
first Merriam deposits occur in channels, and drape channel margins. The
facies consist of silty-sandy skeletal PS, containing Bonner Springs clasts
and aligned skeletal fragments, deposited during continued transgression.
- With continued rise in sea-level, siliciclastic influx decreases, and
cleaner skeletal WS-PS containing whole, unabraded fossils is deposited
in channels, also draping the margins.
- Shallow-subtidal, low-energy brachiopod, Osagia WS forms in channels and
on surrounding highs, blanketing paleo- topography.
- High-energy, shallow-subtidal coated-grain GS (oncoids and ooids) form
on highs, with lower energy skeletal WS-PS deposited in quieter channel
areas. Beds in channels locally contain coated-grains likely washed in from
surrounding highs. Most accommodation in channels is filled.
- Siliciclastic influx into the area (either due to delta lobe switch or
sea-level fall?) further subdues any remaining topography.
- Deeper subtidal Phylloid-algal WS are deposited over the entire area,
displaying consistent thickness and facies character, indicating relief
had been largely filled.
Merriam Limestone Depositional Model
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Last updated May 2003