LACUSTRINE ORGANIC FACIES - A BIOMARKER STUDY USING MULTIVARIATE STATISTICAL-ANALYSIS

Four distinct depositional settings in the Devonian Orcadian Basin of Scotland have been characterised by their mineralogy and organic geochemistry. With the help of multivariate statistical analysis, the data visualise the organic matter source input, the depositional environment and the level of thermal maturity. Principal component analysis proved invaluable for extracting information from a data set composed of a large number of parameters. The thermal maturity of the majority of the samples lies within a restricted range in the oil window and biomarker composition reflects predominantly organic input and depositional environment. Basin margin deposits are clearly differentiated from deeper water central lake deposits. Salinity and anoxicity variations are seen within the latter type of deposits.