TY - JOUR
T1 - Controls on peat accumulation and depositional environments of a coal-bearing coastal plain succession of a pull-apart basin; a petrographic, geochemical and sedimentological study, Lower Jurassic, Denmark
AU - Petersen, H.I.
AU - Nielsen, L.H.
N1 - Funding Information:
This paper was written during Ph.D. research stipendiates supported by the Danish Research Academy and the Geological Survey of Denmark (DGU), a nd under the supervision of B.E. Koch (University of Aarhus), E. Thomsen and J. Andsbjerg (DGU), and Prof. F. Surlyk (University of Copenhagen). J.A. Bojesen-Koefoed (DGU) is thanked for discussion on the geochemical section. The paper benefited from a constructive reading of an early version by D.J. Jutson (DGU) and F. Surlyk. H.P. Nytoft (DGU) is thanked for his laboratory assistance (GC/MS). Likewise, L.L. Nielsen, D. Dtihring, C. Guvad and S. Kopalsky (all DGU) are thanked for laboratory assistance. H. Zetterwall (DGU) did the drawings.
PY - 1995/3
Y1 - 1995/3
N2 - The paralic, Lower-Middle Jurassic Bagå Formation of the Island of Bornholm, Denmark, was deposited in a fault-bounded, subsiding, pull-apart basin. The formation is up to 400 m thick and contains more than 50 coal seams. Twelve of these have been investigated petrographically and geochemically to provide basic information on the composition of the relatively unknown Jurassic coals. The peat-forming environments represented by the seams and the associated siliciclastic sediments are interpreted. The seams represent three types of environments with organic matter deposition. Peat accumulation occurred in low-lying areas situated between river channels in a coastal plain environment undergoing overall transgression. The coals have a relatively uniform, huminite-rich petrographic composition, indicating that the precursor mires were dominated by persistent, water-saturated and anoxic conditions. The swamps were probably occupied by a small-statured flora with cellulose-rich tissues. Significant bacterial activity in the peat swamps is suggested by an abundance of hopanes. Influence from marine water was not common but occurred occasionally. During peat accumulation, the depositional conditions were stable and quiet. The small thicknesses of the seams (8-57 cm thick) indicate relatively short periods of peat formation (average c. 2300 yr), due to continued base-level rise, controlled by subsidence, and an overall eustatic rise, causing repeated changes in the sedimentary regimes. The coal seams are of low rank and were buried to a depth of 1100-1200 m before uplift, due to Late Cretaceous-early Tertiary basin inversion and Neogene uplift.
AB - The paralic, Lower-Middle Jurassic Bagå Formation of the Island of Bornholm, Denmark, was deposited in a fault-bounded, subsiding, pull-apart basin. The formation is up to 400 m thick and contains more than 50 coal seams. Twelve of these have been investigated petrographically and geochemically to provide basic information on the composition of the relatively unknown Jurassic coals. The peat-forming environments represented by the seams and the associated siliciclastic sediments are interpreted. The seams represent three types of environments with organic matter deposition. Peat accumulation occurred in low-lying areas situated between river channels in a coastal plain environment undergoing overall transgression. The coals have a relatively uniform, huminite-rich petrographic composition, indicating that the precursor mires were dominated by persistent, water-saturated and anoxic conditions. The swamps were probably occupied by a small-statured flora with cellulose-rich tissues. Significant bacterial activity in the peat swamps is suggested by an abundance of hopanes. Influence from marine water was not common but occurred occasionally. During peat accumulation, the depositional conditions were stable and quiet. The small thicknesses of the seams (8-57 cm thick) indicate relatively short periods of peat formation (average c. 2300 yr), due to continued base-level rise, controlled by subsidence, and an overall eustatic rise, causing repeated changes in the sedimentary regimes. The coal seams are of low rank and were buried to a depth of 1100-1200 m before uplift, due to Late Cretaceous-early Tertiary basin inversion and Neogene uplift.
UR - http://www.scopus.com/inward/record.url?scp=0028974716&partnerID=8YFLogxK
U2 - 10.1016/0166-5162(94)00020-Z
DO - 10.1016/0166-5162(94)00020-Z
M3 - Article
AN - SCOPUS:0028974716
VL - 27
SP - 99
EP - 129
JO - International Journal of Coal Geology
JF - International Journal of Coal Geology
SN - 0166-5162
IS - 2-4
ER -