Mass and hyperconcentrated flow deposits record dune damming and catastrophic breakthrough of ephemeral rivers, Skeleton Coast Erg, Namibia

Svendsen, Johan B.; Stollhofen, Harald; Krapf, Carmen; Stanistreet, Ian G.

doi:10.1016/s0037-0738(02)00334-2

Cited by 91 publications

(60 citation statements)

References 40 publications

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“…The lateral changes in thickness and various distribution grading patterns are consistent with this origin (e.g. Giordano et al 2002;Svendsen et al 2003). The good sorting in lithofacies 7 and 8 reflects the well-sorted nature of the parent primary deposits.…”

Section: Interpretation Of the Trapper Creek Lithofacies Associationsupporting

confidence: 65%

Silicic phreatomagmatism in the Snake River Plain: the Deadeye Member

Ellis

Branney²

2010

Bull Volcanol

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Non-welded rhyolitic pyroclastic units in the central Snake River Plain are interbedded with the much better exposed, large-volume 'Snake-River type' rheomorphic welded rhyolitic ignimbrites and rhyolite lavas. We document one such unit to investigate why it is so different from the interbedded welded ignimbrites. The newly recognised Deadeye Member of southern Idaho is a soilbounded eruption-unit that comprises ashfall layers and a 4-m-thick ignimbrite that extends for >35 km. The ignimbrite is non-welded, lithic-clast poor and varies from massive to diffuse low-angle cross-bedded. It contains abundant angular clasts of non-vesicular black glass, and upper parts contain accretionary lapilli. The ashfall layers above it contain coated ash pellets and ash clumps, which record moist aggregation of fine ash. The magmas of the Deadeye eruption were closely similar in composition and temperature to those that generated the intensely welded rheomorphic ignimbrites of the central Snake River Plain. We infer that the marked contrast in physical appearance of the Deadeye ignimbrite compared to the other, more typical Snake-River-type welded ignimbrites was the result of emplacement at relatively low temperatures during an eruption in a lacustrine environment. Magmatic volatiledriven fragmentation of the rhyolitic magma was influenced by interaction with lake water that also led to cooling. The Deadeye Member is the first-recorded example of explosive silicic phreatomagmatism in the central Snake River Plain.

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Section: Interpretation Of the Trapper Creek Lithofacies Associationsupporting

confidence: 65%

Silicic phreatomagmatism in the Snake River Plain: the Deadeye Member

Ellis

Branney²

2010

Bull Volcanol

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“…The C s in the study area are exceptionally high. Such high concentrations have not been reported from other loess areas in the world except from some badland areas (e.g., Svendsen et al 2003), and from lahars in volcanic regions (e.g., Lirer et al 2001;Lavigne and Suwa 2004). The high C s were probably caused by a combination of factors, in particular the highly erodible material on the slope surface and channel bank (Fig.…”

Section: General Environment Of Sediment Yieldmentioning

confidence: 66%

Spatial scale dependence of sediment dynamics in a gullied rolling loess region on the Loess Plateau in China

Fang

Qiangguo

et al. 2010

Environ Earth Sci

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Sediment dynamics is still imperfectly understood, especially at spatial scale in the highly erodible region of the Loess Plateau, and few studies have been heretofore conducted. Using 5-year continuous water and sediment records, three plots and three basins in the gullied rolling loess region were selected and sediment dynamics at spatial scale was studied. Results showed that the floods, where the peak discharge (Q p ) did not come earlier than the sediment peak, were predominant in slope zones, occupying [90 and [70% of the total for the Mao slope and for the Entire slope, respectively. However, in basins, most of the sediment peaks (C p ) lagged behind Q p , implying that slope zone was the main origin of sediment. More than 50% of the events presented clockwise hysteresis loops in the Mao slope area, while almost all the events had anticlockwise hysteresis loops in basins. This can be attributed to less occurring frequency of hyperconcentrated flow, as well as its instability in slope zones, compared to those in the basins. Within these contexts, gravitational erosion made the highest sediment concentration (C) in Tuanshangou basin and median developing status of C-discharge (C-Q) relationships in the Entire slope area. This study provides insights into the protection of slope surface and disruption of the development of hyperconcentrated flow to reduce soil loss.

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“…Possible modern analogs are the mass flows and hyperconcentrated flows generated by the breaching of dune dams by floods entering the Namib sand sea in southwestern Africa (Svendsen et al, 2003).…”

Section: Sandslide Facies Structureless Sandstones Lacking Orientedmentioning

confidence: 99%

The Geology of Ukhaa Tolgod (Djadokhta Formation, Upper Cretaceous, Nemegt Basin, Mongolia)

Dingus¹,

Loope²,

Dashzėvėg³

et al. 2008

Am Museum Novitates

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The lithostratigrahy and sedimentology of the fossiliferous Upper Cretaceous strata exposed in the Gobi Desert of Mongolia at Ukhaa Tolgod are described and mapped on aerial photos. Topographic features are also mapped by plane table and alidade.Five lithologic and sedimentologic facies are described: E-1, distinctly cross-stratified sandstone with fine structure, interpreted to represent eolian dune deposits; E-2, vaguely bedded sandstone with cross-stratified concretionary sheets, interpreted to represent eolian dune deposits modified by diagenetic formation of slope-parallel concretionary sheets of pedogenic calcite; S, structureless sandstone lacking concretions or cross-strata, interpreted to represent sandslide deposits generated by mass wasting along the lee slopes; C, conglomerate interpreted to represent basin-margin conglomerates washed into the dune field from adjacent topographic highs; and M, mudstone and siltstone interpreted to represent interdune deposition in ephemeral ponds and lakes. Facies E-2 and S have not been reported previously. Eleven stratigraphic sections at various localities within the Ukhaa Tolgod drainage basin are documented. The exposed composite section consists of about 75 m of pale orange sandstones, greenish-brown conglomerates, and brown siltstones that are products of an arid environment. Four schematic cross sections are documented to illustrate the lateral relationships among the five facies.

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Mass and hyperconcentrated flow deposits record dune damming and catastrophic breakthrough of ephemeral rivers, Skeleton Coast Erg, Namibia

Cited by 91 publications

References 40 publications

Silicic phreatomagmatism in the Snake River Plain: the Deadeye Member

Silicic phreatomagmatism in the Snake River Plain: the Deadeye Member

Spatial scale dependence of sediment dynamics in a gullied rolling loess region on the Loess Plateau in China

The Geology of Ukhaa Tolgod (Djadokhta Formation, Upper Cretaceous, Nemegt Basin, Mongolia)

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