Changes

===Deep sea sandstones===

===Deep sea sandstones===

Deep marine sandstones are formed by processes operating in deep oceanic environment such as gravity flows and turbidity currents, driven by down-slope movement of sediment under gravity, and ocean-bottom currents driven by movement of ocean water in three-dimensional circulation pattern, at depths of >200m and on the contential slope and adjoining abyssal plain, and are often associated with pelagic limestone, which represents carbonate ooze formed by accumulations of planktonic organisms, and are commonly part of a submarine fan deposit. These sub marine fans have a central feeder channel within which sediments move by debris flow from which lesser channels branch out onto the middle part of fan. The sands in lesser channel and the lower parts of the fan is transported by stirred-up suspensions of sediment in water thus forming a sharp erosive base with a fining up grain size sequence of a few centimeters or tens of centimeters thick and a distinctive sedimentary profile. Petroleum which is generated from pelagic beds associated with these sandstones, and channel up-[[dip]] towards the main fan feeder channel, can be trapped in the sand beds of deep-water marine sandstones. Examples of deep-sea sandstone reservoirs include Ventura and Los Angeles basins and Frigg field in Eocene of the North Sea.

Deep marine sandstones are formed by processes operating in deep oceanic environment such as gravity flows and turbidity currents, driven by down-slope movement of sediment under gravity, and ocean-bottom currents driven by movement of ocean water in three-dimensional circulation pattern, at depths of >200m and on the contential slope and adjoining abyssal plain, and are often associated with pelagic limestone, which represents carbonate ooze formed by accumulations of planktonic organisms, and are commonly part of a submarine fan deposit. These sub marine fans have a central feeder channel within which sediments move by debris flow from which lesser channels branch out onto the middle part of fan. The sands in lesser channel and the lower parts of the fan is transported by stirred-up suspensions of sediment in water thus forming a sharp erosive base with a fining up [[grain size]] sequence of a few centimeters or tens of centimeters thick and a distinctive sedimentary profile. Petroleum which is generated from pelagic beds associated with these sandstones, and channel up-[[dip]] towards the main fan feeder channel, can be trapped in the sand beds of deep-water marine sandstones. Examples of deep-sea sandstone reservoirs include Ventura and Los Angeles basins and Frigg field in Eocene of the North Sea.

===Glacial sandstones===

===Glacial sandstones===