Volcanic Margins Research Consortium
Aspects of Mesozoic dinoflagellate cyst palaeobiology.
Mesozoic dinoflagellate cysts are among the most intensely studied fossil groups due to their substantial biostratigraphical significance. Due to the planktonic lifestyle of most of the parent dinoflagellates, their robust resting cysts have wide geographical distributions. In addition to many species being excellent index fossils, they can also be used in palaeobiology. Many Triassic, Jurassic and Cretaceous dinoflagellate cysts were sensitive to palaeoenvironmental perturbations, and therefore can be used as proxies. Recognisable dinoflagellate cysts emerged during the Middle and Late Triassic (~247–201 Ma), and became relatively diverse, especially in the high northerly latitudes. This inception of body fossils is considerably younger than the first records of dinoflagellate biomarkers. The earliest dinoflagellate cysts forms part of the dawn of the era of modern plankton, and coincides with the inception of calcareous nannoplankton and a sustained increase in sea level. The overwhelming majority of Triassic dinoflagellate cysts were wiped out during the end-Triassic mass extinction. Dapcodinium priscus, however, survived and may have been the rootstock of the subsequent recovery. During the Late Sinemurian (~192 Ma), the apparently early peridinioid species Liasidium variabile briefly flourished. Other evidence indicates that this species was strongly thermophylic. There was a major oceanic anoxic event (OAE) during the Early Toarcian (~182–179 Ma). This phenomenon badly disrupted the benthos, including dinoflagellate cysts, and the surface-dwelling prasinophytes briefly exploited the vacant ecological niche. In the Middle Jurassic, specifically the Middle Bajocian (~169 Ma), the gonyaulacacean dinoflagellates underwent a massive evolutionary radiation and became the dominant family. This was coincident with similar phemonena in other fossil groups, and may be the result of continental breakup and the consequent reconfiguration of ocean currents. This radiation strongly indicates there were major evolutionary and ecological innovations in pelagic ecosystems as a whole, and it may form part of the wider Mesozoic Marine Revolution. At the Middle–Late Jurassic (Callovian–Oxfordian) transition (~164–162 Ma), there is strong evidence for significant global cooling which may have been caused by the drawdown of carbon via the deposition of organic-rich shales. Arctic/cool water dinoflagellate cysts such as Gonyaulacysta dentata and Mendicodinium groenlandicum record this phenomenon. In terms of provincialism, Eurasian floras are markedly different in character to their Austral counterparts. The level of endemism increased in the Late Jurassic. During the latest Mesozoic (latest Cretaceous; Maastrichtian - ~72–66 Ma), global climates cooled, and rapid sea level falls suggest ephemeral high latitude ice sheets. In the expanded Maastrichtian succession on Seymour Island in the Antarctic Peninsula (64°S) there are several sporadic superabundances of the chorate dinoflagellate cyst Impletosphaeridium clavus. Three of these events are interpreted as periods of enhanced blooms, and appear to be associated with the melting of winter sea ice.
The Volcanic Margins Research Consortium (VMRC) provides the petroleum industry with training and research expertise in volcanology, sedimentology and structural geology of volcanic margins. The consortium comprises academic staff at the universities of Durham, Aberdeen, Glasgow, Leicester and CASP, and industry partners involved in the development of hydrocarbon prospects in the North Atlantic Igneous Province and the Faroes-Shetland Basin.
Training takes place during workshops, in the laboratory and on field courses and each industrial partner has the opportunity to fund PhD projects through the member universities.
VMRC Leader: Richard Brown