OC/GEO 103

Geography
Challenger Expedition

-C Wyville Thompson

-British

-1872-1876 (expedition dates)

-first major science expedition

-globe encircling voyage

-disproved the azoic theory (there IS life in deep ocean)

Continental Margins

1) Continental Shelf

2) Continental Slope

3) Continental Rise

4) Abyssal (Deep) Plains

Asthenosphere

-“Conveyer belt” the plates move on

-Molten part of the upper mantle

Lithosphere
-Plates,the Earth’s Crust
4 types of marine sediments

-terrigenous (land)

-biogenous (oceans)

-hydrogenous (precipitated from water)

-cosmogenous (outer space)

4 types of oceanography

-Physical

-Geological

-Chemical

-Biological

How old are the oldest sediments in the ocean? (years)
200 million years
What material is composed of CaC03?
Foraminifers
What is bathymetry?
Submarine Topography
Oceanic Crust is thinner than continental crust… which causes…
Oceanic crust to subduct beneath continental crust
Why is new crust formed?
Volcanism @ mid ocean ridges causes new crust to form.
What % of the Earth’s surface is covered by ocean?
71%
What is CCD or Carbonate Compensation Depth?

-The ocean depth which calcium carbonate sediments are not preserved

-Oozes limited to shallower depths of oceans

What are turbidites?
-Underwater avalanches of material that accumulate in the deep ocean
What are the main planktonic groups of animals & plants that produce biogenous sediments?

-Foraminifera – animals/zooplankton

-Coccolitohphors – plants/phytoplankton

-Radiolaria – animals

-Diatoms – plants

What are biogenic oozes made of?

-CaCO3 and Si02

-Skeletons of plankton

 

How are sediments classified?

-Size — little to big

-Composition — less dense to more dense

What are black smokers?

-Hydrothermal circulation

-Fluid vents from mantle

-Hot magma + Sea Water = Rock Formation

What is the Wilson Cycle?

“Ocean Basin Tectonics”

1. Stretching + Thinning –> Volcanoes

2. Opening Plate Tectonics

3. Mature Ocean

4. Sinking Plates, increasing depths

5. Ocean basins come together

5. Continental edges bang shut, cause increased elevation

What are large igneous provinces?

-Igneous = Melted Rock

-Initial plume and hotspot activity

 

What are plumes?

-Core produces heat

-Heat causes water to rise

-Forms “plume”

-Cools then falls

 

(Like a lava lamp)

What are hotspots?
Stationary source of volcanic heat
How does distribution of volcanoes relate to plate boundaries?

-Plates diverge

-Magma emerges

-Magma interacts w/ sea water and forms volcanoes

What does the location of Earthquakes tell us about plate tectonics?

-A plate is pushing into the interior of the Earth

-Trench forming

What are the 3 types of plate boundaries?

-Ridges or rises (seafloor created)

-Trenches (seafloor destroyed)

-Transform faults/fracture zones (Neither created nor destroyed)

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