The Betsie Shale Member is a relatively thick and continuous unit that serves as a marker bed across the central Appalachian basin, in part because it includes an organic-rich shale unit at its base that is observable in drill logs.
Deposited during a marine transgression, the Betsie Shale Member has been correlated to units in both Wales and Germany and has been proposed to mark the boundary between the Lower and Middle Pennsylvanian Series within North America.
This investigation assigns a new Re–Os date to the base of the Betsie and examines the palynoflora and maceral composition of the underlying Matewan coal bed in the context of that date.
The Matewan coal bed contains abundant lycopsid tree spores along its base with assemblage diversity and inertinite content increasing upsection, as sulfur content and ash yield decrease.
Taken together, these palynologic and organic petrographic results suggest a submerged paleomire that transitioned to an exposed peat surface.
Notably, separating the lower and upper benches of the Matewan is a parting with very high sulfur content (28 wt.%), perhaps representing an early marine pulse prior to the full on transgression responsible for depositing the Betsie.
Results from Re–Os geochronology date the base of the Betsie at 323 ± 7.8 Ma, consistent with previously determined age constraints as well as the palynoflora assemblage presented herein.
Oil-gas reservoirs and metal deposits often co-exist in many sedimentary basins, and their genetic relations have been paid much attention.
Bitumen and heavy oil were often observed in the Jinding Zn-Pb deposit.
It has been a subject of debate whether the bitumen formed before or after the Zn-Pb mineralization, making it difficult to evaluate and the genetic relationship between the bitumen and Zn-Pb mineralization.
The bitumen in the Jinding Zn-Pb ores hosted in the breccia-bearing sandstones and sandy breccias of the Paleocene Yunlong Formation has been dated by the Re-Os method in this paper, and an isochron age of 68±5Ma (MSWD=9.2, n=6) has been obtained.
Therefore, the oil-gas reservoir in the Jinding ore district was formed earlier than the Zn-Pb mineralization.
The hydrocarbons in the reservoirs may have provided the condition for the production of reduced sulfur required for Zn-Pb mineralization through thermal chemical reduction of sulfates.