The Conundrum of Coal Bed Thickness: A Theory for Stacked Mire Sequences

Shearer, J.C.; Staub, James R.; Moore, Tim A.

doi:10.1086/629702

Cited by 37 publications

(26 citation statements)

References 13 publications

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“…Stacked mires produce vertical successions of changing petrography and palynology within coals. These successions are often bound by regionally extensive partings or high-ash layers (Shearer et al, 1994;Greb et al, 1999. No extensive partings or durains have been noted within the Colchester Coal, such that the coal at any of the locations sampled may represent the accumulation of a single, temporally extensive mire rather than stacked mires through time.…”

Section: Extent Of Desmoinesian Midcontinent Miresmentioning

confidence: 99%

Desmoinesian coal beds of the Eastern Interior and surrounding basins: The largest tropical peat mires in Earth history

Greb¹,

Andrews²,

Eble³

et al. 2003

Extreme Depositional Environments: Mega End Members in Geologic Time

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The Colchester, Springfield, and Herrin Coals of the Eastern Interior Basin are some of the most extensive coal beds in North America, if not the world. The Colchester covers an area of more than 100,000 km^, the Springfield covers 73,500-81,000 km^, and the Herrin spans 73,900 km^. Each has correlatives in the Western Interior Basin, such that their entire regional extent varies from 116,000 km^to 200,000 km^. Correlatives in the Appalachian Basin may indicate an even more widespread area of Desmoinesian peatland development, although possibly sUghtly younger in age. The Colchester Coal is thin, but the Springfield and Herrin Coals reach thicknesses in excess of 3 m.High ash yields, dominance of vitrinite macerals, and abundant lycopsids suggest that these Desmoinesian coals were deposited in topogenous (groundwater fed) to soligenous (mixed-water source) mires. The only modern mire complexes that are as widespread are northern-latitude raised-bog mires, but Desmoinesian Midcontinent paleomires were topogenous and accumulated within 10° of the paleo-equator.The extent and thickness of Desmoinesian paleomires resulted from the coincidence of prime peat-forming factors, including a seasonally wet paleoclimate; cyclothemic transgressions and base-level rise above extensive, low-relief cratonic areas floored by vast, impermeable paleosols; broad floodplains along large rivers with a groundwater table high enough to hydrologically link peatlands and keep them wet; low, relatively uniform rates of tectonic subsidence; and accumulation in a basin surrounded by low relief, which led to minimal sediment input.

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Section: Extent Of Desmoinesian Midcontinent Miresmentioning

confidence: 99%

Desmoinesian coal beds of the Eastern Interior and surrounding basins: The largest tropical peat mires in Earth history

Greb¹,

Andrews²,

Eble³

et al. 2003

Extreme Depositional Environments: Mega End Members in Geologic Time

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“…On this basis, volumetric growth rates of Holocene peat deposits do not provide a method of understanding thick coal and lignite without inferring significant hiatuses in the coal (Shearer et al 1994). These difficulties are not surprising as volumetric growth and density of Holocene peat, unlike carbon accumulation, is not well studied or understood.…”

mentioning

confidence: 99%

Use of carbon accumulation rates to estimate the duration of coal seams and the influence of atmospheric dust deposition on coal composition

Large

Marshall

2014

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Time contained within coal seams is most commonly estimated using a volumetric approach that fails to take into account processes of carbon accumulation and loss during peat formation and coalification. A more appropriate approach for estimating the time contained within a coal seam is to use Holocene long-term carbon accumulation rates, accounting for carbon loss during coalification. Using this approach the thickness of coal corresponding to 10 kyr of carbon accumulation is calculated for coals of all ranks and latitudinal settings. To test the validity of this approach, latitudinal patterns of Holocene dust deposition are used in conjunction with estimated rates of carbon accumulation to calculate the concentration of titanium in coal. The result is a statistically significant correlation that is optimized when latitudinal variation in carbon accumulation rate is considered. Overall, the use of carbon produces far greater accountability of time within coal-bearing stratigraphic sequences and is not influenced by the presence of hiatal surfaces within the coal. Estimated coal seam duration increases considerably, often removing the need to infer substantial intra-seam hiatuses. On the basis of the results, a re-evaluation of coal and coal-bearing stratigraphic sequences is recommended.

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“…Clastic splits within coals are clear indicators of cessation and re-establishment of peat accumulation (Staub 1991;Shearer et al 1994;Greb et al 2002;Davies et al 2006). Numerous studies, however, show evidence for periods of hiatus across surfaces within coal and peat successions without the deposition of clastic sediments (e.g.…”

mentioning

confidence: 99%

The significance of hiatal surfaces in coal seams

Jerrett

Davies²,

Hodgson

et al. 2011

JGS

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A widespread misconception is that coals correspond to single palaeo-peat bodies, which represent continuous and time-invariant records of peat accumulation. Evidence for the occurrence of intra-seam hiatal surfaces within datasets from bituminous coals, lignites and modern peats suggests that existing depositional models for peat and coal require modification. Recognition that coals may represent a succession of stacked mires separated by hiatal surfaces has implications for palaeoenvironmental and sequence stratigraphic studies that assume a continuous record of peat accumulation, as well as for the prediction of whole-seam composition and thickness trends.

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The Conundrum of Coal Bed Thickness: A Theory for Stacked Mire Sequences

Cited by 37 publications

References 13 publications

Desmoinesian coal beds of the Eastern Interior and surrounding basins: The largest tropical peat mires in Earth history

Desmoinesian coal beds of the Eastern Interior and surrounding basins: The largest tropical peat mires in Earth history

Use of carbon accumulation rates to estimate the duration of coal seams and the influence of atmospheric dust deposition on coal composition

The significance of hiatal surfaces in coal seams

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