Reconstruction of drainage evolution in a Large Igneous Province: Intra-basaltic sedimentation in the Columbia River Basalt Province, Washington State, USA

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Abstract

1. Introduction
The Miocene Columbia River Basalt Province (CRBP) provides an excellent case study for drainage evolution, and the interplay between volcanism and the environment in Large Igneous Provinces (LIP’s). The CRBP lava field comprises a number of extensive basaltic lava flows, which are intercalated with sedimentary interbeds of fluvial, lacustrine and associated palaeosol environments. Based on sedimentary facies analysis, the intra-basaltic drainage system development can be grouped into an early, middle and late stage evolution.

2. Drainage system development
The three main stages of drainage evolution are closely linked with the LIP evolution: 1) an early stage of CRBP evolution characterised by high volcanic effusion rates. At this stage fluvial systems dominate the marginal lava field. Lacustrine settings and palaeosols existed within the central part of the CRBP. 2) a middle stage of CRBP evolution of waning volcanic activity, during which the drainage is dominated by lacustrine environments. 3) a late stage of CRBP evolution, which is marked by very low effusion rates and significant ash fall out events. The drainage is characterised by well established river systems advancing towards the lava field centre.

3. Influence of volcanism on sedimentation
Based on the present studies the CRBP drainage evolution is strongly driven by the interplay of changing effusion rates and volumes, lava field topography, lava flow distribution and the location of the volcanic centres. Ash fall out and the formation of local basaltic spatter cones influenced interbed composition, and may also have been affected location and flow orientation through damming.

4. Conclusions
The undertaken studies on the interbed sedimentology and adjacent basalt flows revealed a complex interplay between sedimentation processes, the environment and volcanic activity. Additionally, sedimentation within the CRBP is further affected by external volcanism of the Cascade Range and the Yellowstone Hotspot. This study provides a model for the control of CRBP drainage evolution in particular and can be used to improve our understanding of sedimentary processes in continental LIP’s in general.

Acknowledgements
We thank Stephen Reidel, Washington State University, and Stephen Self, Open University, Milton Keynes, UK, for assistance with field work and providing field material. We thank Richard Conrey and Laureen Wagoner, Washington State University, for geochemical investigations. This project is supported by the Sindri Group.

References
Barry, T.L., Self, S., Kelley, S.P., Reidel, S.P., Hooper, P.R. and Widdowson, M. (2010) New 40Ar/39Ar dating of the Grande Ronde lavas, Columbia River Basalts, USA: Implications for duration of flood basalt eruption episodes. Lithos, 118, 213-222.
Hole, M.J., Jolley, D.W., Hartley, A.J., Leleu, S., John, N and Ball, M. (in press) Magmatic controls on the drainage system of a low-volume lava field. Journal of the Geological Society.
Reidel, S.P., Fecht, K.R., Hagood, M.C. and Tolan, T.L. (1989) The geological evolution of the central Columbia Plateau. In: Volcanism and Tectonism in the Columbia River Flood-Basalt Province (Eds S.P. Reidel and P.R. Hooper), GSA Special Paper, 239, 247-264.
Tolan, T.L., Martin, B.S., Reidel, S.P., Anderson, J.L., Lindsey, K.A. and Burt, W. (2009) An introduction to the stratigraphy, structural geology, and hydrogeology of the Columbia River Flood-Basalt Province: A primer for the GSA Columbia River Basalt Group field trips. In: Volcanoes to Vineyards: Geological Field Trips through the Dynamic Landscape of the Pacific Northwest (Eds J.E. O'Connor, R.J. Dorsey and I.P. Madin), GSA Field Guide, 15, 599-643.
Original languageEnglish
Publication statusPublished - 14 Jul 2013
Event10th International Conference on Fluvial Sedimentology - Leeds, United Kingdom
Duration: 14 Jul 201319 Jul 2013

Conference

Conference10th International Conference on Fluvial Sedimentology
Country/TerritoryUnited Kingdom
CityLeeds
Period14/07/1319/07/13

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