... from the Ty Gwyn copper deposit, North Wales. Analyses of five bitumen samples with variable mixtures of radiogenic and common lead yield a 207 Pb/ 206 Pb age of 248 ±21 Ma (Early Triassic). This age is interpreted as the date of hydrocarbon migration into the deposit and is reasonably consistent...

... surface, spoil material, Ty Gwyn copper deposit, Great Ormes Head, (field width = 2.3 cm). Uraniferous hydrocarbons from the Scandinavian Precambrian basement Numerous occurrences of uraniferous hydrocarbons in the Precambrian basement rocks of Scandinavia have been described (Uytenbogaardt 1960; Welin...

.... This gave very variable deposits and many disconformities in the Lower and Middle Ordovician. An evolutionary relation-ship between the four principal intrusive rock types is proposed to explain the restriction of certain types to particular stratigraphic horizons. Possibly the first British record...

... veinrock from the Ty Gwyn Copper Mine, Great Ormes Head, North Wales (Parnell 198th). Like the thoriferous nodules, all of the uranium is located within the hydrocarbon and it occurs as isolated micron-scale inclusions. The origin of the two types of deposit are probably similar. Where all components...

.... In places they are slightly displaced by the N-S veins. The major ore minerals are galena and sphalerite with traces of chalcopyrite; calcite is the predomin- ant gangue mineral with minor amounts of fluorite and quartz. Although nearly all the veins in North Wales were lead-zinc deposits the Ty Gwyn mine...

... mineralization as suggested by the Triassic Pb–Pb age for bitumen at Ty Gwyn copper deposit determined by Parnell & Swainbank (1990) and for base metal mineralization in Parys Mountain, North Wales of Fletcher et al. (1993) . Uplift, exposure and erosion related to the onset of the Variscan...

... magmatic mineralization and are not the cause of the metal enrichment in the Platreef. * Current address: 73 Hillside Court, Ty-Gwyn Road, Cardiff, CF23 5JB United Kingdom. This work was undertaken as part of DAH’s Ph.D. research, which was funded by a Natural Environment Research Council...