Abstract

The peat-to-coal transition is commonly assumed to be accompanied by compaction that decreases the thickness of the organic deposit to values of 10% or less of the original peat thickness. Decompaction modeling using such values for coal seams in contact with penecontemporaneous channel sandstones leads to impossible depositional geometries for the sandstones, which have a final thickness that is 90% of their original thickness. Similarly, decompaction modeling of the fragments of organic material within channel lags using the assumed large peat compaction value results in the destruction of the associated sedimentary structures, such as trough cross-beds. Dinosaur tracks in the roofs of coal mines show a shallow depth of penetration and a preservation of foot morphology that is not possible unless the peat the animals walked upon was very firm. These data confirm the macroscopic observations from coal balls that the compaction associated with the peat-to-coal transformation is minimal. Equally important, the data also show that most of the compaction occurs essentially at the surface and not at the depths where coalification takes place.

You do not currently have access to this article.