The Roza Member, Columbia River Basalt Group: A gigantic pahoehoe lava flow field formed by endogenous processes?

Thordarson, T.; Self, Stephen

doi:10.1029/98jb01355

Cited by 283 publications

(268 citation statements)

References 55 publications

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“…Such examination of the CRBG lava flows indicates that they were primarily emplaced as inflated pahoehoe lava flows [Self et al, 1997]. However, it is important to note that only one unit, the Roza Member of the Wanapum Formation, has the combination of exposure and preservation that has allowed the details of an entire flow field to be described [e.g., Shaw Thordarson and Self, 1998]. Most other CRBG flow fields are either too poorly exposed or too extensively eroded for such detailed study.…”

Section: Continental Flood Basaltsmentioning

confidence: 99%

Terrestrial analogs and thermal models for Martian flood lavas

Keszthelyi¹,

McEwen²,

Thordarson³

2000

J. Geophys. Res.

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199

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Abstract. The recent flood lavas on Mars appear to have a characteristic "platy-ridged" surface morphology different from that inferred for most terrestrial continental flood basalt flows. The closest analog we have found is a portion of the 1783-1784 Laki lava flow in Iceland that has a surface that was broken up and transported on top of moving lava during major surges in the eruption rate. We suggest that a similar process formed the Martian flood lava surfaces and attempt to place constraints on the eruption parameters using thermal modeling. Our conclusions from this modeling are (1) in order to produce flows > 1000 km long with flow thicknesses of a few tens of meters, the thermophysical properties of the lava should be similar to fluid basalt, and (2) the average eruption rates were probably of the order of 104 m3/s, with the flood-like surges having flow rates of the order of 10 s -106m3/s. We also suggest that these high eruption rates should have formed huge volumes of pyroclastic deposits which may be preserved in the Medusae Fossae Formation, the radar "stealth" region, or even the polar layered terrains.

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Section: Continental Flood Basaltsmentioning

confidence: 99%

Terrestrial analogs and thermal models for Martian flood lavas

Keszthelyi¹,

McEwen²,

Thordarson³

2000

J. Geophys. Res.

Self Cite

199

198

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“…If this analogy is correct, then the size of individual BRM flow fields must have been controlled by sustained high effusion and output volumes. Compared to Laki, a single BRM flow is estimated at between 300 km 3 -1,920 km 3 , a lava field 20 -128 times larger than that erupted by Laki, and more comparable with the Roza Member, suggested to have erupted as a single 14 year event by Thordarson and Self (1998). Thordarson and Self (1998) calculated eruption duration and hence eruption rate in Columbia River based on the relationship between the thickness of a flow lobe and the conductive cooling rate (Hon et al, 1994); a simplistic model which requires a full section 28 of intact crust to measure, something not readily available in the BRM.…”

Section: Flow Velocitymentioning

confidence: 99%

“…Compared to Laki, a single BRM flow is estimated at between 300 km 3 -1,920 km 3 , a lava field 20 -128 times larger than that erupted by Laki, and more comparable with the Roza Member, suggested to have erupted as a single 14 year event by Thordarson and Self (1998). Thordarson and Self (1998) calculated eruption duration and hence eruption rate in Columbia River based on the relationship between the thickness of a flow lobe and the conductive cooling rate (Hon et al, 1994); a simplistic model which requires a full section 28 of intact crust to measure, something not readily available in the BRM. However, Self (1993, 1998) found eruption rates of 2500 m 3 s -1 are comparable between Laki and Roza despite the differences in size and morphology between the two flows, and thus a reasonable assumption can be made for these figures to apply also to the BRM given its similarities with both.…”

Section: Flow Velocitymentioning

confidence: 99%

“…Other typical indicators of lava-water interaction such as peperite, hyaloclastites and pillow lavas are entirely absent from the observed outcrop, and all current observation indicates that these lavas were erupted into an unequivocally terrestrial environment. Thordarson and Self (1993) b c Hartley et al (2014) d Tolan et al (1989) e Thordarson and Self (1998) f g Self et al (2006) …”

Section: Interactions With Watermentioning

confidence: 99%

“…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).…”

Section: Introductionmentioning

confidence: 99%

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

Marshall

Widdowson

Murphy

2016

Palaeogeography, Palaeoclimatology, Palaeoecology

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The Kalkarindji continental flood basalt province of northern Australia erupted in the mid Cambrian . It now consists of scattered basaltic lava fields, the most extensive being the Antrim Plateau Volcanics (APV) -a semi-continuous outcrop (c. 50,000 km 2 ) reaching a maximum thickness of 1.1 km. Cropping out predominately in the SW of the APV, close to the top of the basalt succession, lies the Blackfella Rockhole Member (BRM). Originally described as 'basaltic agglomerate' the BRM has, in recent years, been assumed to be explosive tephra of phreatomagmatic origin, thus providing a potent vehicle for volatile release to the upper atmosphere. Our detailed field investigations reveal that this basaltic agglomerate is, in reality, giant rubble collections (15 -20 m thick) forming the upper crusts of rubbly pāhoehoe lava units 25 -40 m thick; covering 18,000 -72,000 km 2 and an estimated volume of 1,500 -19,200 km 3 . These flows, rheologically but not chemically, distinct from the majority of Kalkarindji lavas, indicate a fundamental change in eruption dynamics. A low volatile content, induced high amounts of pre-eruptive degassing causing super-cooling and an increase in crystal nucleation and viscosity. A more viscous lava and a consistently faster rate of effusion (analogous to that of Laki, Iceland) created the flow dynamics necessary to disturb the lava crust to the extent seen in the BRM. Volatile release is estimated at 1.65 × 10 4 -2.11 × 10 5 Tg total CO2 at a rate of 867 Tg a -1 and 9.07 × 10 3 -1.16 × 10 5 Tg SO2 at 476.50 Tg a -1 . These masses accounted for 0.5% of Cambrian atmospheric conditions whilst limiting factors reduced the effect of volatile delivery to the atmosphere, thus any potential global impact caused by these flows alone was minimal.

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Morphology and dynamics of inflated subaqueous basaltic lava flows

Deschamps

Grigné

Saout

et al. 2014

Geochem Geophys Geosyst

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During eruptions onto low slopes, basaltic Pahoehoe lava can form thin lobes that progressively coalesce and inflate to many times their original thickness, due to a steady injection of magma beneath brittle and viscoelastic layers of cooled lava that develop sufficient strength to retain the flow. Inflated lava flows forming tumuli and pressure ridges have been reported in different kinds of environments, such as at contemporary subaerial Hawaiian-type volcanoes in Hawaii, La R eunion and Iceland, in continental environments (states of Oregon, Idaho, Washington), and in the deep sea at Juan de Fuca Ridge, the Galapagos spreading center, and at the East Pacific Rise (this study). These lava have all undergone inflation processes, yet they display highly contrasting morphologies that correlate with their depositional environment, the most striking difference being the presence of water. Lava that have inflated in subaerial environments display inflation structures with morphologies that significantly differ from subaqueous lava emplaced in the deep sea, lakes, and rivers. Their height is 2-3 times smaller and their length being 10-15 times shorter. Based on heat diffusion equation, we demonstrate that more efficient cooling of a lava flow in water leads to the rapid development of thicker (by 25%) cooled layer at the flow surface, which has greater yield strength to counteract its internal hydrostatic pressure than in subaerial environments, thus limiting lava breakouts to form new lobes, hence promoting inflation. Buoyancy also increases the ability of a lava to inflate by 60%. Together, these differences can account for the observed variations in the thickness and extent of subaerial and subaqueous inflated lava flows.

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The Roza Member, Columbia River Basalt Group: A gigantic pahoehoe lava flow field formed by endogenous processes?

Cited by 283 publications

References 55 publications

Terrestrial analogs and thermal models for Martian flood lavas

Terrestrial analogs and thermal models for Martian flood lavas

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

Morphology and dynamics of inflated subaqueous basaltic lava flows

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