Upper middle Cambrian through Furongian of Scandinavia with focus on trilobites, paleoenvironments and correlations

Sammanfattning: This thesis is based on studies of upper middle Cambrian through Furongian strata in Scandinavia with focus on trilobite biostratigraphy, taxonomy, paleoecology, and intercontinental correlation. The material studied derives mainly from Västergötland and Scania, southern Sweden. Three new trilobite species are described: Macropyge (Promacropyge) scandinavica, Elkanaspis kinnekullensis, and Parabolinella sandtorpensis. The former two proved important for correlations with China and North America, respectively, whereas the latter is important for our understanding of the systematic position of the genus Parabolinella. All these species were recovered from Mount Kinnekulle, Västergötland, Sweden. The strata studied at Kinnekulle show features here interpreted as indicative of an intrabasinal paleohigh, including current-oriented fossils, the presence of thin sand wedges, the large proportion of limestone, different limestone lithologies, and gaps in the succession. This is in contrast to the biostratigraphically complete, upper middle Cambrian through Furongian successions in Scania, where the strata are unaffected by water movements and reflect a deeper water setting on the outer shelf. The succession in Scania is, however, punctuated by five major fossil-barren intervals. The upper part of such an interval, in the uppermost middle Cambrian Agnostus pisiformis Zone, yielded phosphatocopines, protoconodont elements, and enigmatic trace fossils. Thus, these intervals, or at least parts of them, are, not necessarily barren of fossils, but of the normal, trilobite-dominated faunas. Moreover, the phosphatocopine-dominated and trilobite-dominated intervals represent two interdigitating biofacies of which the former, anomalous facies, correlates with a trilobite extinction event in North America and the onset of the globally recognizable Steptoean Positive Carbon Isotope Excursion (SPICE). The lowermost Furongian biozone in Scandinavia, the Olenus & A. (Homagnostus) obesus Zone, has here been replaced by two new zones; the globally recognized Glyptagnostus reticulatus Zone and the Olenus Zone. A drill core comprising middle Cambrian (Ptychagnostus atavus Zone) to Furongian (Parabolina spinulosa Zone) strata from Andrarum, Scania, southernmost Sweden, was sampled for ?13Corg-analysis. The resulting curve has a distinct positive ?13Corg excursion corresponding to the SPICE. This is the first time that the SPICE has been recorded in Baltica and from organic matter in an alum shale setting. A study from another drill core comprising upper Furongian strata recovered from c. 2500 m depth at Håslöv, in the southwesternmost tip of Scania, revealed a succession comparable to other sections and cores in Scania regarding biostratigraphy, lithology and the presence of major barren intervals. Moreover, from this drilling the conodont Cordylodus proavus Müller? was recovered from non-reworked sediments for the first time in Sweden. A review of 10 species and subspecies of upper Furongian trilobites originally described by Moberg and Möller (1898) and Moberg (1898), revealed that they, in fact, represent 12 species and subspecies. One species name was regarded as a junior subjective synonym, and lectotypes for three species were selected.