Stream‐driven, high‐density gravelly traction carpets: possible deposits in the Trabeg Conglomerate Formation, SW Ireland and some theoretical considerations of their origin

Todd, S. P.

doi:10.1111/j.1365-3091.1989.tb02083.x

Cited by 266 publications

(151 citation statements)

References 48 publications

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“…The erosional surface between the lower and the upper sequences was perhaps generated in the delta slope by a gravity-induced slump or a slide. This surface was than rapidly filled with the sediments of the prograding upper sequence units (Lewis, 1980;Lowe, 1982;Nemec and Steele, 1985;Todd, 1989;Nemec, 1990;Dorsey et al, 1995;Falk and Dorsey, 1998;Sohn, 2000;Bassett, 2003, 2007).…”

mentioning

confidence: 99%

The Late Quaternary Tectono-Stratigraphic Evolution of the Lake Van, Turkey

Görür¹,

Çağatay²,

Zabcı³

et al. 2015

Bulletin of the Mineral Research and Exploration

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Many of the terraces around the Lake Van record a relatively short period of the much longer geological history of the Lake Van Basin. Their deposition took place during the last ca. 125 ka BP. They accumulated in a large array of shallow lake and lake margin environments, such as alluvial fan/braided river, beach, Gilbert-type delta, nearshore lake and offshore lake. Variability of their lithofacies provides evidence for climatic and tectonic controls of their depositional conditions. During their deposition high relief areas in the watershed delivered abundant detritus to the coastal areas of the lake. The sedimentation was therefore dominated by terrigenous clastic deposits. The highest concentrations of the coarse clastic sediments were at the mouths of the major streams where they formed Gilbert-type deltas. These river-dominated lacustrine deltas formed during rising lake levels and are relatively more abundant and thicker in the eastern margin of the lake, indicating that this margin mostly had a low-energy coast sheltered from the prevailing westerly winds. However, some areas of the same margin adjacent to deltas were also supplied with sediments by waves and storm-induced longshore currents to form beaches. Storms and storm-generated traction currents were perhaps active agents along the shores of the Lake Paleo-Van as suggested by the presence of the coarse-grained material in its nearshore facies. Somehow, during times of lake highstands, turbidity currents seem not to have played an important role in the sediment transportation along the lake margin, because the nearshore sediments hardly show any evidence of turbidite depositon, such as graded bedding and sole-marks. The offshore lake was relatively quite standing water, depositing laterally persistent, thinly-bedded to varved and fine-grained sandstones and mudstones in part with hydroplastic disruptions, such as slumps and convolute beddings. Because of the lack of sufficient datings of the terrace sequences around Lake Van, we cannot correlate them unequivocally. However, the absence of large-scale cyclicity within a given terrace sequence in each locality suggests that deposition of each terrace occurred during a separate lake level fluctuation each reaching to higher level than the modern lake level followed by a regression. The available age data suggest that high lake levels, reaching up to 1760 m asl, occurred during the last interglacial (MIS 5; 123-71 ka BP), 26-24 ka BP, 22-21 ka BP and 10-6 ka BP. The younging of the terrace deposits along with the decrease in elevation suggests either a gradual decline of lake level with time, or the effect of the cumulative uplift with time or both. The fluctuating lake level was probably due to a combination of climatic, volcanic and tectonic processes. Considering the hydrologically closed nature of the lake, climate probably played more important role than the others. Since the formation of the youngest terrace sediments of 6 ka BP, perhaps the climate in the basin has been mostly relatively more ar...

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mentioning

confidence: 99%

The Late Quaternary Tectono-Stratigraphic Evolution of the Lake Van, Turkey

Görür¹,

Çağatay²,

Zabcı³

et al. 2015

Bulletin of the Mineral Research and Exploration

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“…Sieve conglomerate facies (Todd, 1989). It is thought to represent bedforms, which were frozen because of rapid draining out of water; sand infiltrated from above as the flow waned.…”

Section: Faciesmentioning

confidence: 99%

Precambrian basin-margin fan deposits: Mesoproterozoic Bagalkot Group, India

Bose

Sarkar

Mukhopadhyay

et al. 2007

Precambrian Research

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Three-dimensional facies variability in coarse clastic sedimentary rocks (breccia, conglomerates and coarse-grained sandstones) at the base of the Ramdurg Formation suggests terrestrial scree and fans giving way downslope to fluvial sediments along the margin of the Mesoproterozoic Bagalkot basin in India. In consistency with the basic tenet of Precambrian alluvial sedimentation, fluvial architectural elements and field location-specific consistency in channel-flow direction support an invariably braided pattern for the rivers, although the architectural element-packaging pattern does show distinct changes downslope, with channel belts thinning and becoming more regular in their geometry. With possible persistence of a semi-arid climate, downslope change in flow durability in the channels was controlled primarily by water discharge, depending on position of the channels with respect to the mean level of the water table-basin-margin slope intersection.Confined between an unconformity below and a granular lag succeeded by thoroughly wave-featured sandstone, and argillite-carbonate above, the coarse and poorly sorted clastic sedimentary rocks of the basal Ramdurg are interpreted as a base-level lowstand product, for which the sedimentation rate exceeded the rate of space creation for sediment accumulation. Consequently, the fan succession as a whole is coarsening-upward. Fluvial sections, nonetheless, fine upward as the depositional slope gradient became openUP progressively reduced with aggradation of channels. Tectonics-related slope variation along and across the basin-margin, devoid of vegetation, dictated the sediment distribution and sequence building pattern primarily. Eventual termination of this basinmargin depositional system was caused by later enhancement in the rate of base-profile rise.

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“…Sheet-like beds of clastsupported conglomerate are a typical structure of broad gravel bars in terrestrial gravelly braided rivers (Boothroyd and Ashley 1975;Hein and Walker 1977). Such gravel bars are mainly deposited by high-magnitude flood flows, which are similar to subaqueous turbidity currents in high sediment concentration, grain-supporting forces, and the structures of resultant deposits (Todd 1989;Maizels 1993). Although little is known about the gravel bars formed by turbidity currents, the stacked sheets of Lago Sofia Conglomerate are interpreted to be an analog of the terrestrial sheet-like gravel bars.…”

Section: Stacked Sheetsmentioning

confidence: 99%

Sedimentary Facies and Architecture of a Gigantic Gravelly Submarine Channel System in a Cretaceous Foredeep Trough (the Magallanes Basin, Southern Chile)

Cheo¹,

Kim²,

Jo³

et al. 2017

Ocean and Polar Research

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: The Lago Sofia conglomerate in southern Chile is a deep-marine gravelly deposit, which is hundreds of meters thick and kilometers wide and extends laterally for more than 100 km, filling the foredeep trough of the Cretaceous Magallanes Basin. For understanding the depositional processes and environments of this gigantic deep-sea conglomerate, detailed analyses on sedimentary facies, architecture and paleoflow patterns were carried out, highlighting the differences between the northern (Lago Pehoe and Lago Goic areas) and southern (Lago Sofia area) parts of the study area. The conglomerate bodies in the northern part occur as relatively thin (< 100 m thick), multiple units intervened by thick mudstone-dominated sequences. They show paleoflows toward ENE and S to SW, displaying a converging drainage pattern. In the southern part, the conglomerate bodies are vertically interconnected and form a thick (> 400 m thick) conglomerate sequence with rare intervening fine-grained deposits. Paleoflows are toward SW. The north-to-south variations are also distinct in sedimentary facies. The conglomerate bodies in the southern part are mainly composed of clast-supported conglomerate with sandy matrix, which is interpreted to be deposited from highly concentrated bedload layers under turbidity currents. Those in the northern part are dominated by matrix-to clast-supported conglomerate with muddy matrix, which is interpreted as the products of composite mass flows comprising a turbidity current, a gravelly hyperconcentrated flow and a mud-rich debris flow. All these characteristics suggest that the Lago Sofia conglomerate was formed in centripetally converging submarine channels, not in centrifugally diverging channels of submarine fans. The tributaries in the north were dominated by mass flows, probably affected by channel-bank failures or basin-marginal slope instability processes. In contrast, the trunk channel in the south was mostly filled by tractive processes, which resulted in the vertical and lateral accretion of gravel bars, deposition of gravel dunes and filling of scours and channels, similar to deposits of terrestrial gravel-bed rivers. The trunk channel developed along the axis of foredeep trough and its confinement within the trough is probably responsible for the thick, interconnected channel fills. The large-scale architecture of the trunk-channel fills shows an eastward offset stacking pattern, suggesting that the channel migrated eastwards most likely due to the uplift of the Andean Cordillera.

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Stream‐driven, high‐density gravelly traction carpets: possible deposits in the Trabeg Conglomerate Formation, SW Ireland and some theoretical considerations of their origin

Cited by 266 publications

References 48 publications

The Late Quaternary Tectono-Stratigraphic Evolution of the Lake Van, Turkey

The Late Quaternary Tectono-Stratigraphic Evolution of the Lake Van, Turkey

Precambrian basin-margin fan deposits: Mesoproterozoic Bagalkot Group, India

Sedimentary Facies and Architecture of a Gigantic Gravelly Submarine Channel System in a Cretaceous Foredeep Trough (the Magallanes Basin, Southern Chile)

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