An Early Cretaceous lacustrine record: Organic matter and organic carbon isotopes at Bernissart (Mons Basin, Belgium)

摘要: Abstract The early Cretaceous Bernissart lake deposits (Mons Basin, Belgium) constitute an important historical site in the field of palaeontology. In this study, we focus on organic matter (OM) content 50 m-long borehole core, “Ber 3”, drilled at Bernissart. Organic data (Rock-Eval, palynofacies, C/N ratios) and carbon-isotope measurements bulk OM selected, isolated wood fragments were collected. distribution exhibits two total carbon (TOC) cycles (12 m 38 m-thick, respectively) that are stacked a lower frequency cyclic pattern. A general increase situ aquatic production preservation through time is evidenced within freshwater masses. spectral analysis high-resolution gamma-ray record demonstrates sedimentation was controlled by orbitally-induced climatic changes. Precession, obliquity short- long-term eccentricity recognized. 12 m-thick 38 m-thick TOC fit well with 100 kyr short-term 400 kyr cycle, respectively. Long-term fluctuations interpreted as resulting from fluctuating levels time. Carbon-isotope evolution thought to reflect firstly local patterns sedimentation: (1) changing contribution amorphous versus terrestrial OM, (2), possible influence enhanced productivity. negative δ 13 C WOOD trend recorded seems equivalent published coeval CARB Upper Barremian Lower Aptian. This noted thus regarded reflecting changes ratios atmospheric CO 2 . Previous presented palynological suggest “middle” Lowermost Aptian stratigraphic range for succession According new dataset, refine age-assignment Bernissart: duration deposition now estimated between 0.55 2.2 myr