This Ph.D. project aims to aquire a better understanding of sedimentological and ecological processes within the immediate vicinity of Large Igneous Province (LIP) activity and of the effects that LIP volcanism may have on the environment. The Miocene Columbia River Flood Basalt Province (CRBP) comprises an up to 4500 m thick succession of basaltic lavas intercalated with fluvio-lacustrine siliciclastic and volcaniclastic sediments. Detailed field-based studies (logging of 47 interbed sites) and the generation of geochemical (XRF, SEM, and microprobe) and palynological data provide an integrative study of characterising and modeling sedimentological and ecological processes within the lava field. The generation of a sedimentary facies scheme allowed a reconstruction of the intra-lava drainage system through time. Drainage system evolution is largely controlled by CRBP volcanism which is capable of forcing fluvial systems to the margin of the lava field during the phases of high volcanic activity, while phases of waning effusion frequencies and volumes allow the fluvial environment to migrate back into the central part of the lava field. The composition of the siliciclastic sediments suggests external source areas mainly located in the Cascade Range west and north of the CRBP. High plant diversity and late successions occurred during the early stage of CRBP evolution, and were affected by the increased deposition of ash derived from Cascade Range volcanoes and the Yellowstone hot spot during the late stage of CRBP evolution. Interbed sites distal to the volcanic source are generally colonized by late-successional plants and suggest a relationship between nutrient flux, sedimentary environment and volcanism. Palaeoclimate reconstructions based on soil chemistry and floral composition suggest that climatic changes within the CRBP reflect the global trend of the Mid-Miocene Climate Optimum. The present work allows to model sedimentological and ecological processes within the CRBP and considers the various effects that volcanic activity has on the environment. The complexity and differences in the geology and igenous evolution of individual LIPs need to be considered when applying this model to other LIPs.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:606487 |
| Date | January 2014 |
| Creators | Ebinghaus, Alena |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=211228 |
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