EPS SCI 15 Lecture 4 Review

Sediment is any particulate matter that can be:

transported by fluid flow and deposited.

Different types of sediments:

(1) Terrigenous

(2) Biogenic

(3) Chemogenic (also called hydrogenous orauthigenic)

(4) Volcanogenic

(5) Cosmogenic

Sediment size is classified (from smallest to largest) as:

The smallest fraction is easily transported and travels the longest distance.

(1) Clay

(2) Silt

(3) Sand

(4) Gravel (Pebbles, Cobbles, Boulders).

Marine Snow is:

a continuous shower of mostly organic detritus falling from the sunlit layers of the water

column.

Marine snow is made up of:

a variety of mostly organic matter such as dead algae and fecal pellets.

Marine Snow can contain:

calcareous or siliceous material from the shells of organisms. Calcareous shells

Where are calcerous shells more stable?

shallow waters

Where do calcerous shells dissolve?

dissolve below the Carbonate Compensation Depth, because the

cold water dissolves more CO2, making it more corrosive for calcium carbonate.

Where are siliceous shells more stable?

The deep ocean, where silicate concentrations in the water are high.

Where can calcareous and siliceous shells form biogenic oozes?

On the deep-sea floor, where other sources of sediment are rare

Authigenic sediments contain: (give an example)

Precipitates that are formed within the sediment. One example are manganese nodules, which are abundant in abyssal plains worldwide.

What do volcanic eruptions and weathering of volcanic rock deliver to marine sediments?

Volcanic material

What can some events such as major meteroid impacts form?

distinct layers of extraterrestrial dust with rare elements in sediments (Cosmogenic sediments)

What are seafloors around continents dominated by?

Terrigenous sediments

What sediments are found at abyssal plains?

Red clay and hydrogenous (authigenic) sediments

What does sediment accumulation on the floor depend on?

The age of the oceanic plate and the sedimentation rate.

Where do most sediments accumulate?

Most sediments accumulate around the continents

What can happen when the sediment burden at continental margins (steep slope) is too high?

Slope failure can lead to submarine landslides and tsunamis.

Where can we find records of events like slope failure?

We find records of such events in sediments: turbidites.

How can sediment cores be sampled?

by push cores, multicorer, gravity corer or drilling

Palaeoceanography is the study of:

the history of the oceans in the geologic past to reconstruct past conditions and processes.

Palaeoceanographers use specific environmental proxies to:

reconstruct past conditions and processes.