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Outburst floods from glacial Lake Missoula largely explain erosion of the Channeled Scabland, a system of overfit, basaltic channels in Washington, northwestern United States. However, it is challenging to explain Missoula flood routing into Moses Coulee due to its topographic isolation from flood routes. To clarify flood pathways into Moses Coulee, we mapped channels that delineate a radial-anastomosing network connecting to Moses Coulee. Channels consist of coulee-like features eroded mainly in basalt. Channels climb adverse slopes and cross divides, and the network is draped with eskers and recessional moraines. These channel geometries and glacial landform associations suggest a tunnel channel network. Large channel dimensions and network anastomosis indicate formation in subglacial floods. The network connects to Moses Coulee with sufficient cross-sectional area to convey megafloods, hinting that subglacial floods may have been a significant source of Moses Coulee meltwater, in addition to possible diverted Missoula floods. [ABSTRACT FROM AUTHOR]

In this study, we present evidence of a Paleocene-Eocene Thermal Maximum (PETM) record within a 543-m-thick (1780 ft) deep-marine section in the Gulf of Mexico (GoM) using organic carbon stable isotopes and biostratigraphic constraints. We suggest that climate and tectonic perturbations in the upstream North American catchments can induce a substantial response in the downstream sectors of the Gulf Coastal Plain and ultimately in the GoM. This relationship is illustrated in the deep-water basin by (1) a high accommodation and deposition of a shale interval when coarse-grained terrigenous material was trapped upstream at the onset of the PETM, and (2) a considerable increase in sediment supply during the PETM, which is archived as a particularly thick sedimentary section in the deep-sea fans of the GoM basin. Despite other thick PETM sections being observed elsewhere in the world, the one described in this study links with a continentalscale paleo-drainage, which makes it of particular interest for paleoclimate and source-to-sink reconstructions. [ABSTRACT FROM AUTHOR]

Submarine canyons commonly occur on virtually all continental slopes. Their varied origins are widely studied but still debatable. Eastward (along-slope)–migrating submarine canyons, with nearly regular spacing, are well developed at the northern South China Sea. High-resolution three-dimensional seismic data show that these canyons are localized in the troughs between sediment waves. The waves were present on the slope since before ca. 10.5 Ma and were especially well developed during the late Miocene (ca. 10.5–5.5 Ma). This interval can be divided into two units, of which the upper unit (SU II) has larger sediment waves and much better-developed canyons compared to the lower unit (SU I). Submarine fans developed at the canyon mouths within SU II at the downdip termination of the confinement caused by the sediment waves. Gravity currents were captured between the waves, resulting in erosion mainly along the troughs between them. The canyons were forced to migrate eastward by the migration of the confining sediment waves. In this study, we present a new mechanism for the origin of such regularly spaced submarine canyons for the first time, which we attribute to the formation of regularly spaced sediment waves generated by contour currents. [ABSTRACT FROM AUTHOR]

The question of whether the Mediterranean Sea desiccated during the Messinian salinity crisis (MSC) has been strongly debated for decades. In the Levant Basin, this debate was recently reignited in relation to the latest stage of the crisis after cessation of salt deposition. The desiccation supporters argue that salt truncation--and its subsequent burial by a latest Messinian, clastic-rich evaporitic unit--occurred subaerially on a desiccated seafloor. However, we show that this latest Messinian unit contains a dense net of channels with meanders, levees, and overspill deposits and is very similar to the turbidite channels observed on the modern seafloor. The aggradation characteristics of these buried channels (levee height, channel depth, and channel-floodplain coupling) indicate a marine rather than fluvial origin. Our conclusion adds to the findings of a previous study that salt truncation occurred in deep waters by dissolution. In a wider perspective, we suggest that the flush of clastics into the basin during the last stage of the MSC indicates a combination of wet climate and sea-level rise that started before the Zanclean (earliest Pliocene). [ABSTRACT FROM AUTHOR]

High-resolution seismic, core, and chronological data from the Quaternary Golo deepsea fans, offshore Corsica, France, give new insights into rates of submarine fan growth. Average vertical deposition rates for units that represent the Late Pleistocene glacial periods are 0.1-0.5 m/k.y. Glacial-age deposits are sand rich; in contrast, post-glacial deposits lack a significant sand fraction and are dominated by carbonate-rich mud. As a result, seismically constrained volumetric rates of deposition for glacial periods with low sea level and a subaerially exposed shelf are ~0.23 km3/k.y., 2×-5× higher than rates during interglacials when sea level is high, the shelf is submerged, and sand is trapped in shallowmarine environments. At millennial time scales, variations in deposition rate reflect climatedriven sea-level changes, autogenic avulsion of river channels that extend across the shelf during low sea level, and autogenic avulsion of submarine channels that shift the locus of deposition laterally. Short-term deposition rates range from 8.6 m/k.y. at proximal portions of submarine fans to 0.4 m/k.y. along the distal fringe. Our data show that submarine fans can be dynamic environments with formation and evolution of levee-confined channels and lobe complexes in 103-104 yr, comparable to the time scales needed to form fluvial channel belts and delta lobes. [ABSTRACT FROM AUTHOR]

The article focuses on the interpretation of sediment waves and their relationship with regularly spaced, along slope migrating submarine canyons. Topics include the influence of synchronous interaction between turbidity currents and bottom currents on the development of canyons, while acknowledging the uncertainties in pale-flow directions; and the importance of considering wave asymmetry and contour/gravity current interactions in understanding submarine features.

The article focuses on the initiation and evolution of unidirectionally migrating deep-water channels (UCs) and challenges the interpretation of bottom-current sediment waves as the controlling factor. Topics include discrepancies in the morphology, architecture, and migration patterns of seismic facies associated with UCs compared to recognized criteria for bottom-current sediment waves; and development of UCs are influenced by interactions between turbidity and bottom-current sediment waves.