The 3D facies architecture of flood basalt provinces and their internal heterogeneity: examples from the Palaeogene Skye Lava Field

Abstract

Quantifying the facies architecture of flood basalt provinces is important as it can be used to understand the physical volcanology and rock property variations throughout the lava sequence. The 3D facies architecture and internal heterogeneity of the Skye Lava Field, for example, provides important insights into the evolution of the British Tertiary Igneous Province, and valuable information to aid in the exploration of potential offshore reservoirs underlying significant flood lavas along the North Atlantic margin. The volcanic stratigraphy of the Talisker Bay area of Skye comprises: (1) lower compound-braided lavas (flow lobes <3 m thick); (2) transitional lavas (flows <8 m thick); (3) upper tabular-type lavas (flows <20 m thick), representing a relative increase in eruptive volume. A 3D model of the lava sequence was reconstructed using detailed digital geological mapping, revealing estimated volumes of: the lower sequence (12.7 km 3 ), the transitional sequence (7.4 km 3 ) and the upper sequence (17.0 km 3 ). The lower sequence lavas formed on the flanks of a shield volcano and were sourced from the NE. Volcanological features such as lava feeder tubes, pahoehoe textures and lobes indicate a scale of volcanism similar to that of present-day Hawaii. The within-flow heterogeneity of the basalts is characterized using an ‘intrafacies scheme’, allowing comparison of variations in lithofacies with characteristic (geophysical) rock properties of compressional-wave velocity and density.

Understanding the offshore flood basalt sequence using onshore volcanic facies analogues: an example from the Faroe–Shetland basin

“…In this study, the offshore succession was interpreted using the character and geometry of the seismic reflections, combined with the understanding of facies architectures of flood volcanic rocks developed from studies of onshore exposures from key flood basalt sequences, such as the NAIP and the Etendeka province of Namibia (Planke, Alvestad & Skogseid, 1999;Jerram, 2002;Single & Jerram, 2004;Jerram & Widdowson, 2005;Nelson et al 2009). Precise identification of boundaries is difficult on seismic reflection data because of the complex scattering and absorption of the seismic energy by the heterogeneous basalts.…”

“…Planke, Alvestad & Skogseid, 1999;Planke et al 2000Planke et al , 2005Thomson, 2005) and detailed field studies of onshore successions of flood basalts and their associated sediments (e.g. Jerram, Mountney & Stollhofen, 1999;Mountney et al 1999;Jerram, 2002;Single & Jerram, 2004). Recent research interest has focused on being able to understand the 3D facies distribution of the lavas using their geophysical properties (Planke, Alvestad & Skogseid, 1999;Nelson et al 2009).…”

Rock Magnetic, Petrography, and Geochemistry Studies of Lava at the Ijen Volcanic Complex (IVC), Banyuwangi, East Java, Indonesia

“…Due to the complexity of these factors, researchers have extensively studied lava characterization [1][2][3][4][5][6]. Identification of lava characteristics is useful for understanding the geological conditions of a volcanic region, including the magmatism process and geological history.…”

The Giant Lavas of Kalkarindji: rubbly pāhoehoe lava in an ancient continental flood basalt province

“…These are relatively uncommon in CFBP successions (Applegarth et al, 2010;Brown et al, 2011). Between these two end members, however, there is now an established and well-defined spectrum of genetically related lava types Single and Jerram, 2004;Brown et al, 21 2011; Vye- Brown et al, 2013;Duraiswami et al, 2014). Where the flow is larger and more disturbed, 'slabby' pāhoehoe can be created by the rafting of large slabs into a jumble of tabular to curved pāhoehoe crusts disturbed, dislocated and tilted throughout the lava flow surface.…”

“…It was erupted onto the North Australian Craton during the mid-Cambrian period between 511 -505 ± 2 Ma (Glass and Phillips, 2006;Evins et al, 2009;Jourdan et al, 2014), which formed part of Gondwana (Foden et al, 2006;Torsvik and Cocks, 2009;Cocks and Torsvik, 2013). The composition and morphology of CFBP lavas are known to vary significantly within a province (Walker, 1971;Bondre et al, 2004;Single and Jerram, 2004;Bryan et al, 2010;Brown et al, 2011;Duraiswami et al, 2014), but the common CFBP lava emplacement mode is as extensive pāhoehoe flow fields emplaced by a process of endogenous inflation, as observed occurring on the flanks of modern day shield volcanoes such as in Hawai'i (Self et al, 1997Thordarson and Self, 1998;Bondre et al, 2004;Single and Jerram, 2004;Jerram and Widdowson, 2005;Waichel et al, 2006;Vye-Brown et al, 2013). Whilst this emplacement model is characteristic of the majority of the Kalkarindji basalt succession (Sweet et al, 1971;Bultitude, 1976;Mory and Beere, 1985), debate remains regarding the nature of the Blackfella Rockhole Member (BRM), because the appearance of these units differs significantly from those commonly observed in CFBP successions (Sweet et al, 1974;Mory and Beere, 1985;Jourdan et al, 2014).…”