Oceanography Chapter 4

What three processes do does the distribution of biogenous sediment depend on?

*Productivity *destruction *dilution

what are CCD's?

Calcite compensation depth (CCD) is the depth in the oceans below which the rate of supply of calcite (calcium carbonate) lags behind the rate of solvation

know the order of coarseness of the following: Boulder, Pebble, Sand, Silt, and Clay

clay, silt, sand, pebble, boulder

What clues can ocean sediments provide about earth's history? list several

-Marine organism distribution -Ocean floor movements -Ocean circulation patterns -Climate change -Global extinction events •Deep Sea Drilling Project (DSDP) -Glomar Challenger drilling ship -Core collection in deep water -Confirmed existence of sea floor spreading •Ocean floor age •Sediment thickness •Magnetic polarity

Manganese nodules - formation, potential for economic resource, distribution

When cut in half, the nodules often reveal that they have been formed by precipitating layers around a central nucleation object (e.g. a piece of lithogenous sediment, coral, volcanic rock, a fish bone, or a shark's tooth).

what is calcareous ooze? what organisms form it where does it form?(including temp)? how is it affected by the lysocline and CCD? Which oceans have more of it and why?

-•Siliceous ooze is a type of biogenic pelagic sediment located on the deep ocean floor. -Plankton, diatoms, and radiolarians -Calcareous globigerina ooze occurs in the shallower parts of the South Pacific; Pacific Ocean - depending on depth, it's found above the CCD - If you look at the Atlantic versus the pacific, they're different, the Atlantic is shallower and because of that you have more calcareous ooze in the Atlantic.

how do sea floor sediments represent surface conditions? Include the role of fecal pellets.

About 99% of the particles that fall to the ocean floor do so as part of fecal pellets (produced by tiny animals that eat algae and protozoans - and excrete their hard parts)

where does siliceous ooze accumulate? and why?

Accumulates in areas of high productivity

what can sediments sorting (measure of grain size uniformity) tell you about transport process for lithogenous sediments?

Grain size determines just how far a piece of sediment can travel before coming to a halt.

know the 4 classifications of marine sediments.

Lithogenous - derived from land Biogenous - derived from organisms Hydrogenous or Authigenic - derived from water Cosmogenous - derived from outer space

what is the difference between calcareous and siliceous ooze?

Siliceous ooze -> typically forms below cool surface water regions, including upwelling areas Calcareous ooze -> is found on the shallower areas of the ocean floor beneath warmer surface water

what organisms form siliceous ooze?

Tests - shells of microscopic organisms Tests from diatoms and radiolarians generate siliceous ooze.

what can a grain size tell you about environmental energy?

Texture indicates environmental energy High energy (strong wave action) - larger particles Low energy - smaller particles

what is weathering?

Weathering (a process) is the breakdown of rocks at the Earth's surface, by the action of rainwater, extremes of temperature, and biological activity. There are three types of weathering, physical, chemical and biological.

what are evaporites and how do they form?

a natural salt or mineral deposit left after the evaporation of a body of water. -Minerals that form when seawater evaporates -Restricted open ocean circulation -High evaporation rates -Halite (common table salt) and gypsum

what are carbonates and how do they form?

aragonite and calcite minerals. Both formed from calcium carbonate (CaCO3). Aragonite has different crystalline structure and changes into calcite over time.

Explain dilution in regards to biogenous sediments.

below 30% dilution is not classified as ooze - oozes are uncommon along continental margins because of the abundance of lithogenous material

Explain destruction in regards to biogenous sediments.

biogenous sediment can dissolve before reaching the sea floor or before it has the chance to accumulate into deposits

where is lithogenous sediment found in highest concentrations?

deep sea sediment

Explain productivity in regards to biogenous sediments.

high productivity = more production of biogenous oozes on the ocean floor

explain the wentworth scale of grain size

used to determine the amount of sorting in a sediment deposit.

What controls marine sediment thickness?

· The marine sediment thickness. The first thing will be the distance of the source. The most important source of sediment is marine sediments

explain hydrogenous sediments

•Hydrogenic sediment is derived from material dissolved in water (chemical reactions) •Minerals precipitate directly from seawater, or -Manganese nodules -Phosphates -Carbonates -Metal sulfides •Dissolved salts are left behind when water evaporates (evaporites) • •Small proportion of marine sediments •Distributed in diverse environments

How are lithgenous sediments produced?

•Produced by weathering -Breaking of rocks into smaller pieces *most abundant chemical (mineral) composition

Differentiate between neritic and pelagic sediment deposits. what controls the distribution of pelagic and neritic sediments types?

- The neritic is closer to continental margin so they are closer to the biggest source of sediments which is streams and turbitinal sediments, so you will have more and bigger sediments - The pelagic sediments come from biological activity and deposition of sediments and is a slow process because its farther than the continental margin - The fecal penent is the process that makes the fecal sediments be in the same area and this is only in the Biogenous sediments

what are metal sulfides and where do they form?

-Contain: •Iron •Nickel •Copper •Zinc •Silver •Other metals deposited around hydrothermal vents (e.g. black smokers) along mid ocean ridge.

how are marine sediments collected?

-Cores - hollow steel tube collects sediment columns -Rotary drilling - collects deep ocean sediment cores

describe 4 transport mechanisms for lithogenous sediments.

-Streams Stream flow carries about 20 billion tons of sediment to the continental margins each year. -Wind -Glaciers -Gravity Transported sediment can be deposited in many environments (e.g. bays, lagoons, deltas, beaches, continental shelf, deep-ocean basin)

how can calcareous ooze be present below CCD?

Initially, calcareous ooze is deposited above the CCD (and there it will not dissolve) on a topographically high feature such as the mid-ocean ridge. Then, the calcareous ooze is covered by a deposit that is unaffected by the CCD, such as an abyssal clay or siliceous ooze, so that it is isolated from the environment. Finally, over millions of years, the ocean floor that was once at shallower depths is moved away from the mid-ocean ridge by the process of sea floor spreading, carrying with it the calcareous ooze covered by another sediment.

what are phosphates and where do they form?

coating on rocks and form nodules on continental shelf and other areas where water depth is less than 1,000 m.

explain cosmogenous sediments

•derived from extraterrestrial sources. Made up of 'space dust' that constantly rains down on Earth. -Macroscopic meteor debris that forms near an impact site when meteors collide with Earth at great speeds. • Microscopic spherules that are microscopic globular masses composed of silicate rock material (called tektites) or composed mostly of iron and nickel. Although they were once thought to be the product of meteors, it is now believed they are produced by collisions between asteroids, which produce microscopic space dust particles that drift harmlessly through Earth's atmosphere.