Mass-physical and geotechnical properties of surficial sediments and dense nearbed sediment suspensions on the Amazon continental shelf

Stability of Near-Surface Gassy Sediments, Amazon Continental Shelf

“…There is no correlation between the distribution of surficial sediment undrained shear strength 6 and the sesimically-determined zones of methane concentration 6 ; this indicates that modern oceanographic processes are responsible for the physical properties of the uppermost 50 cm on the continental shelf as opposed to their proximity to underlying methane concentrations. Cores 5 and 6 occur at the southern end of the transect, outside of the methane distribution zone.…”

Stability of Near-Surface Gassy Sediments, Amazon Continental Shelf

“…There is no correlation between the distribution of surficial sediment undrained shear strength 6 and the sesimically-determined zones of methane concentration 6 ; this indicates that modern oceanographic processes are responsible for the physical properties of the uppermost 50 cm on the continental shelf as opposed to their proximity to underlying methane concentrations. Cores 5 and 6 occur at the southern end of the transect, outside of the methane distribution zone.…”

Evidence of the activity of dissimilatory sulfate-reducing prokaryotes in nonsulfidogenic tropical mobile muds

“…The French Guiana mobile belt system is characterized by massive migrating mud banks which extend along the north-east coast of South America for more than 1600 km downdrift of the Amazon River (Faas, 1986;Froidefond et al, 1988;Eisma & Vanderma, 1991;Allison et al, 1996Allison et al, , 2000Kineke et al, 1996). The Gulf of Papua, located on the south coast of Papua New Guinea, consists of a half-moonshaped shelf area of more than 50 000 km 2 , with a radius of 200 km, into which numerous rivers, the Fly River being the largest, drain the highlands of New Guinea and transport huge quantities of highly weathered material (Walsh et al, 2004;Aller et al, 2004a).…”

“…The Gulf of Papua, located on the south coast of Papua New Guinea, consists of a half‐moon‐shaped shelf area of more than 50 000 km 2 , with a radius of 200 km, into which numerous rivers, the Fly River being the largest, drain the highlands of New Guinea and transport huge quantities of highly weathered material (Walsh et al , 2004; Aller et al , 2004a). During energetic trade‐wind conditions, the fine‐grained river‐borne sediments containing terrestrial/mangrove‐derived organic debris are frequently suspended by tidal currents and waves, and moved about as fluid mud (near‐bed suspensions having sediment concentrations of 10 g L −1 to more than 100 g L −1 (Faas, 1986; Kineke et al , 1996) shoreward of the 10 m isobath in a north‐easterly direction (Ogston et al , 2003). During periods of the north‐west monsoonal winds, the fluid mud is temporarily deposited within the topset zone (∼20 m shoreward) and stabilized for short (days to weeks) or long (weeks to months) periods of time (Harris et al , 1993; Wolanski & Alongi, 1995; Crockett et al , 2003).…”

Structure and diversity of the lobster community on the Amazon continental shelf

“…The sediments overlaying the continental shelf to the northeast of the mouth of the Amazon are rich in clays. This distribution of sediments probably reflects the effects of the reworking of the substrates by tidal currents throughout the Amazon estuary, as well as the transportation of clay to the northwest by the coastal currents, reaching a distance of some 1600 km, well beyond the mouth of the Orinoco River, forming the longest continuous mud deposit anywhere in the World (Fass, 1986).…”

Stability of Near-Surface Gassy Sediments, Amazon Continental Shelf

“…There is no correlation between the distribution of surficial sediment undrained shear strength 6 and the sesimically-determined zones of methane concentration 6 ; this indicates that modern oceanographic processes are responsible for the physical properties of the uppermost 50 cm on the continental shelf as opposed to their proximity to underlying methane concentrations. Cores 5 and 6 occur at the southern end of the transect, outside of the methane distribution zone.…”

Evidence of the activity of dissimilatory sulfate-reducing prokaryotes in nonsulfidogenic tropical mobile muds

“…The French Guiana mobile belt system is characterized by massive migrating mud banks which extend along the north-east coast of South America for more than 1600 km downdrift of the Amazon River (Faas, 1986;Froidefond et al, 1988;Eisma & Vanderma, 1991;Allison et al, 1996Allison et al, , 2000Kineke et al, 1996). The Gulf of Papua, located on the south coast of Papua New Guinea, consists of a half-moonshaped shelf area of more than 50 000 km 2 , with a radius of 200 km, into which numerous rivers, the Fly River being the largest, drain the highlands of New Guinea and transport huge quantities of highly weathered material (Walsh et al, 2004;Aller et al, 2004a).…”

“…The Gulf of Papua, located on the south coast of Papua New Guinea, consists of a half‐moon‐shaped shelf area of more than 50 000 km 2 , with a radius of 200 km, into which numerous rivers, the Fly River being the largest, drain the highlands of New Guinea and transport huge quantities of highly weathered material (Walsh et al , 2004; Aller et al , 2004a). During energetic trade‐wind conditions, the fine‐grained river‐borne sediments containing terrestrial/mangrove‐derived organic debris are frequently suspended by tidal currents and waves, and moved about as fluid mud (near‐bed suspensions having sediment concentrations of 10 g L −1 to more than 100 g L −1 (Faas, 1986; Kineke et al , 1996) shoreward of the 10 m isobath in a north‐easterly direction (Ogston et al , 2003). During periods of the north‐west monsoonal winds, the fluid mud is temporarily deposited within the topset zone (∼20 m shoreward) and stabilized for short (days to weeks) or long (weeks to months) periods of time (Harris et al , 1993; Wolanski & Alongi, 1995; Crockett et al , 2003).…”

Structure and diversity of the lobster community on the Amazon continental shelf

“…The sediments overlaying the continental shelf to the northeast of the mouth of the Amazon are rich in clays. This distribution of sediments probably reflects the effects of the reworking of the substrates by tidal currents throughout the Amazon estuary, as well as the transportation of clay to the northwest by the coastal currents, reaching a distance of some 1600 km, well beyond the mouth of the Orinoco River, forming the longest continuous mud deposit anywhere in the World (Fass, 1986).…”

Stability of Near-Surface Gassy Sediments, Amazon Continental Shelf

“…There is no correlation between the distribution of surficial sediment undrained shear strength 6 and the sesimically-determined zones of methane concentration 6 ; this indicates that modern oceanographic processes are responsible for the physical properties of the uppermost 50 cm on the continental shelf as opposed to their proximity to underlying methane concentrations. Cores 5 and 6 occur at the southern end of the transect, outside of the methane distribution zone.…”

Evidence of the activity of dissimilatory sulfate-reducing prokaryotes in nonsulfidogenic tropical mobile muds

“…The French Guiana mobile belt system is characterized by massive migrating mud banks which extend along the north-east coast of South America for more than 1600 km downdrift of the Amazon River (Faas, 1986;Froidefond et al, 1988;Eisma & Vanderma, 1991;Allison et al, 1996Allison et al, , 2000Kineke et al, 1996). The Gulf of Papua, located on the south coast of Papua New Guinea, consists of a half-moonshaped shelf area of more than 50 000 km 2 , with a radius of 200 km, into which numerous rivers, the Fly River being the largest, drain the highlands of New Guinea and transport huge quantities of highly weathered material (Walsh et al, 2004;Aller et al, 2004a).…”

“…The Gulf of Papua, located on the south coast of Papua New Guinea, consists of a half‐moon‐shaped shelf area of more than 50 000 km 2 , with a radius of 200 km, into which numerous rivers, the Fly River being the largest, drain the highlands of New Guinea and transport huge quantities of highly weathered material (Walsh et al , 2004; Aller et al , 2004a). During energetic trade‐wind conditions, the fine‐grained river‐borne sediments containing terrestrial/mangrove‐derived organic debris are frequently suspended by tidal currents and waves, and moved about as fluid mud (near‐bed suspensions having sediment concentrations of 10 g L −1 to more than 100 g L −1 (Faas, 1986; Kineke et al , 1996) shoreward of the 10 m isobath in a north‐easterly direction (Ogston et al , 2003). During periods of the north‐west monsoonal winds, the fluid mud is temporarily deposited within the topset zone (∼20 m shoreward) and stabilized for short (days to weeks) or long (weeks to months) periods of time (Harris et al , 1993; Wolanski & Alongi, 1995; Crockett et al , 2003).…”

Structure and diversity of the lobster community on the Amazon continental shelf

“…The sediments overlaying the continental shelf to the northeast of the mouth of the Amazon are rich in clays. This distribution of sediments probably reflects the effects of the reworking of the substrates by tidal currents throughout the Amazon estuary, as well as the transportation of clay to the northwest by the coastal currents, reaching a distance of some 1600 km, well beyond the mouth of the Orinoco River, forming the longest continuous mud deposit anywhere in the World (Fass, 1986).…”