Carbon isotope chemostratigraphy of the Late Silurian Lau Event, Gotland, Sweden

University essay from Lunds universitet/Geologiska institutionen

Abstract: The positive δ13C excursion associated with the Late Silurian Lau Event (approximately 420 Ma) is recognized globally and considered to be one of the most prominent carbon isotope excursions of the Phanerozoic. Its maximum values are exceeded only by values from the Proterozoic. Over the last years the Lau Event has been studied in great detail on the island of Gotland, Sweden (Baltica palaeocontinent). These studies include lithological successions and high-resolution conodont biostratigraphy, as well as δ13C chemostratigraphy. For these reasons, Gotland is considered the standard classical model for studying the Lau Event. The purpose of the present study is to produce the first continuous, high-resolution δ13C stratigraphy across the stratigraphic range of the event. The δ13C record is based on two drill cores (Uddvide-1 and Ronehamn-1) and work as a standard model for global correlation of the event. The generated profiles have high positive peak values of 8.03 ‰ and 9.01 ‰ respectively in Uddvide-1 and Ronehamn-1 drill cores. Both profiles have the typical model of the Lau Event consisting of rising limb, plateau and falling limb. The correlation not only improves the knowledge on Ludlow stratigraphy but also helps to understand the evolution of climate, marine ecosystems and depositional environment during the Ludfordian. In doing so, the cause of this high positive δ13C excursion will be better understood.

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