Exam 13: The Ocean Floor

Radiolarian chert is a common sedimentary rock accreted along active margins in the circum-pacific.It is produced in the deep sea by the accumulation of siliceous radiolarian shells.What kind of sediment is radiolarian chert?

The gently sloping submerged surface extending from the shoreline toward the deep ocean is termed the ________.

Discuss the distribution of seafloor sediments in the ocean basins.What are the different types of sediments,and what are the factors that control their distribution (geologic setting,climate,etc.)?

-abyssal plain clay

manganese nodules calcareous ooze metal sulfides evaporites

A(n)________ is the vast,relatively deep,flat,sediment-covered portion of the deep-ocean basin.

Flat-topped volcanic structures located on the floor of the deep ocean basin are termed ________.

Which of the following is not true of deep ocean trenches?

The ________ Ocean is largest.

continental shelf continental rise continental slope continental volcanic arc

Convective cooling cools rocks much more rapidly than heat conduction.Hydrothermal circulation represents convective cooling at ocean ridges and is well known from things like black smokes,but only occurs close to the spreading ridge axis.When geophysicists measure the geothermal gradient in areas along ridges where there is no hydrothermal activity,the thermal gradient is far below what you would predict theoretically,but near hydrothermal vents it is far more than you would predict.Why would this be?

________ sediment consists of shells and hard parts of marine organisms.

The ________ Ocean has more extensive abyssal plains than the Pacific Ocean because it has fewer trenches to trap sediments moving down the continental slope.

Oil and gas resources are rare on the continental slope and continental rise.

The Atlantic and Pacific basins have oceanic ridges; the Indian Ocean has no oceanic ridge.

Subduction of oceanic lithosphere at the trenches can act like a bulldozer to produce ________.

"Black smokers" are associated with ________.

Which one of the following would most likely be covered with thick turbidite layers?

Valleys that lead from the continental shelf into deeper waters are known as ________.

In the Mississippi River delta in south Louisiana shallow subsurface imaging of the sediments reveal buried channels beneath delta sediments that are less than 10,000 years,and these channels extend offshore to the edge of the continental shelf.What is a simple explanation for these buried channels?