Extensive soft-sediment deformation and peperite formation at the base of a rhyolite lava: Owyhee Mountains, SW Idaho, USA

Article English OPEN
McLean, Charlotte E. ; Brown, David J. ; Rawcliffe, Heather J. (2016)

In the Northern Owyhee Mountains (SW Idaho), a >200 m thick flow of the Miocene Jump Creek Rhyolite was erupted on to a sequence of tuffs, lapilli-tuffs, breccias and lacustrine siltstones of the Sucker Creek Formation. The rhyolite lava flowed over steep palaeotopography, resulting in the forceful emplacement of lava into poorly consolidated sediments. The lava invaded this sequence, liquefying and mobilizing the sediment, propagating sediment sub-vertically in large metre-scale fluidal diapirs and sediment injectites. \ud The heat and the overlying pressure of the thick Jump Creek Rhyolite extensively liquefied and mobilised the sediment resulting in the homogenization of the Sucker Creek Formation units, and the formation of metre-scale loading structures (simple and pendulous load casts, detached pseudonodules). Density contrasts between the semi-molten rhyolite and liquefied sediment produced highly fluidal Rayleigh-Taylor structures. Local fluidisation formed peperite at the margins of the lava and elutriation structures in the disrupted sediment. The result is a 30-40 m zone beneath the rhyolite lava of extremely deformed stratigraphy. Brittle failure and folding is recorded in more-consolidated sediments, indicating a differential response to loading due to the consolidation state of the sediments. \ud The lava-sediment interaction is interpreted as being a function of: (1) the poorly consolidated nature of the sediments; (2) the thickness and heat retention of the rhyolite lava; (3) the density contrast between the lava and the sediment; and (4) the forceful emplacement of the lava. This study demonstrates how large lava bodies have the potential to extensively disrupt sediments and form significant lateral and vertical discontinuities that complicate volcanic facies architecture.
  • References (60)
    60 references, page 1 of 6

    Alfaro P, Delgado J, Estévez A, Molina J, Moretti M, Soria J (2002) Liquefaction and fluidisation structures in Messinian storm deposits (Bajo Segura Basin, Betic Cordillera, southern Spain). Int J Earth Sci 91:505-513

    Allen JRL (1982) Liquidization, liquidized sediment, and the sedimentation of dense particle dispersions. In: Sedimentary structures: their character and physical basis. Developments in sedimentology. 30B Amsterdam, Elsevier. ISBN: 978-0-444-41945-3

    Altaner SP, Grim RE (1990) Mineralogy, chemistry, and diagenesis of tuffs in the Sucker Creek Formation (Miocene), Eastern Oregon. Clay Clay Miner 38:561-572

    Anketell JM, Cegla J, Dzulynski S (1970) On the deformational structures in systems with reversed density gradients. Ann Soc Géol Pol 40:3-29

    Armstrong RL, Harakal JE, Neill WM (1980) K-Ar dating of Snake River Plain (Idaho) volcanic rocks-new results. Isochron 27:5-10

    Beresford SW, Cas RA (2001) Komatiitic invasive lava flows, Kambalda, Western Australia. Can Mineral 39:525-535

    Bonnichsen B (1982) Rhyolite lava flows in the Bruneau-Jarbidge eruptive center, southwestern Idaho: cenozoic geology of Idaho. Idaho Bur Mines Geol Bull 26:283-320

    Bonnichsen B, Kauffman DF (1987) Physical features of rhyolite lava flows in the Snake River Plain volcanic province, southwestern Idaho. Geol Soc Am Spec Pap 212:119-145

    Bonnichsen B, McCurry M., Godchaux MM (2004) Miocene Snake River Plain Rhyolites of the Owyhee Front, Owyhee County, Idaho. In: Haller KM and Wood SH (eds) Geological field trips in Southern Idaho, Eastern Oregon, and Northern Nevada: Geological Society of America. Rocky Mountain Section. Meeting and Geological Society of America. pp 156-175

    Bonnichsen B, Godchaux MM (compilers) (2006) Geologic map of the Murphy 30′ × 60′ Quadrangle, Ada, Canyon, Elmore, and Owyhee Counties, Idaho: Idaho Geological Society, scale 1:100000

  • Bioentities (1)
    1nom Protein Data Bank
  • Metrics
    No metrics available
Share - Bookmark