Open AccessDepositional environment and burial history of a Lower Cretaceous carbonaceous claystone, Bornholm, Denmark
Author(s) -
Henrik I. Petersen,
J. A. Bojesen Koefoed,
Hans Peter Nytoft
Publication year - 1996
Publication title -
bulletin of the geological society of denmark
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.674
H-Index - 28
eISSN - 2245-7070
pISSN - 0011-6297
DOI - 10.37570/bgsd-1996-43-13
Subject(s) - sedimentary depositional environment , organic matter , kerogen , geology , cretaceous , palynofacies , source rock , maturity (psychological) , deposition (geology) , geochemistry , sediment , vegetation (pathology) , peat , paleontology , mineralogy , chemistry , ecology , structural basin , psychology , developmental psychology , medicine , organic chemistry , pathology , biology
A c. 1 m thick carbonaceous claystone from the type locality of the Lower Cretaceous Skyttegård Member (Rabekke Formation), Bornholm, has been investigated by organic pétrographie and organic geochemical methods in order to assess the depositional environment of the claystone and the thermal maturity ofthe organic matter. The claystone was deposited in a low-energy, anoxic lakewhich occasionally was marine influenced. The organic matter is terrestrial andcan be classified as kerogen type III and lib. Detrital organic matter and cutiniteare characteristic components. The organic matter is allochthonous but the transport distance was short, and the plant material was probably mainly derived fromplants growing at the edge of, or nearto, the lake. Source-specific biomarkerssuch as norisopimarane suggest that the plant litter was derived from a gymnospermous, low-diversity vegetation. Evidence for early angiospermous plantscannot be demonstrated with any certainty. A huminite reflectance value of0.24%Rm and several geochemical parameters indicate that the organic matter ishighly immature. It has only experienced coalification corresponding to the peatstage. Estimates show that, prior to uplift, the claystone was buried to a maximum of approximately 260 m. Reflectance data further suggest that a maximumc. 550 m thick sediment package was removed by erosion prior to deposition ofthe ?uppermost Jurassic-Lower Cretaceous sediments on Lower Jurassic strata.