The Donets Basin (Ukraine/Russia): coalification and thermal history

Abstract

The Donets Basin (Donbas) is one of the major late Paleozoic coal basins in the world. The Donbas Foldbelt is an inverted part of the Donets Basin characterized by WNW–ESE-trending folds and faults. The age of basin inversion is under discussion. Large parts of the Donets Basin host anthracite and meta-anthracite. Low-rank coals are restricted to the western and northern basin margins. Vitrinite reflectance patterns along the Gorlovka Anticline indicate syn-deformational coalification. Vitrinite reflectance isolines are displaced along thrusts, clear evidence that main coalification predates late faulting.

1-D and 2-D numerical models were applied to elucidate the factors that control coalification in the western Donets Basin (Krasnoarmeisk Monocline, Kalmius–Torets Depression, South Syncline).

The models indicate that the depth of the seams and the heat flow during maximum (Permian) burial are the most important parameters. The thickness of late Carboniferous and Permian rocks increased from the southwestern basin margin towards the basin center. Permian erosion along the Krasnoarmeisk Monocline and in the Kalmius–Torets Depression was on the order of 2–3 km. More rocks were eroded southeast of the Donetsk–Kadievka Fault Zone (4–5 km). Heat flow during maximum burial was in the range of 40–75 mW/m2. Heat flow in the Krasnoarmeisk Monocline and the Kalmius–Torets Depression increased in a northeastward direction from 40 to 55 mW/m2. Heat flow at the eastern edge of the Kalmius–Torets Depression and in the South Syncline was in the range of 60–75 mW/m2 and increased towards the southeast. The resulting coalification pattern in this area was overprinted by thermal events in the northern Krasnoarmeisk Monocline and the South Syncline. These are probably related to (Permian?) magmatic intrusions. Coked coal occurs at the contact to presumed Permian sills and dikes southwest of Donetsk.