HYDROCARBON TRACES IN THE TERTIARY BASALTS OF THE FAEROE-ISLANDS

Hydrocarbons in the form of gases, oils and waxes have been observed i n the basalts of the Faeroe Islands in the North Atlantic. Gases and t races of oil were observed in the outflowing water of the deep Lopra-1 well drilled in 1981. The hydrocarbon gas was fairly dry, with stable isotopic ratios of delta(13)C(1-3) = 41.4; -32.4; -26.5 parts per tho usand respectively, typical of a thermogenic gas. High temperature gas chromatography of the oil showed that it consisted mostly of C13-60 n -alkanes. Biomarker distribution observed by GC-MS indicates that the oil was derived from a mature source rock deposited in an anoxic envir onment; this suggests that the source rock must lie beneath the known basalts. Waxes exhibiting bright yellow fluorescence under UV light we re observed as coatings on zeolite minerals widely distributed on the Faeroe Islands. The waxes consist predominantly of higher n-alkanes sh own by HTGC. The fluorescence indicates the presence of aromatic compo unds. Biomarker distribution indicated that the waxes were derived at least in part from a source rock containing some terrestrial organic m atter as testified by the low amounts of oleanane present. The waxes w ere probably deposited from traces of oil present in deeply circulatin g waters in fractures within the basalts. Coals which had been suspect ed to generate some of the hydrocarbons observed in the Faeroese basal ts were also examined. Vitrinite values of R-o=0.5% as well as GC-MS a nalyses of the Suduroy coal extracts showed that these coals are immat ure and have not generated significant hydrocarbons. (C) 1997 Elsevier Science Ltd.