marine geology & geography - aquatic...
TRANSCRIPT
11/12/2015
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MARINE GEOLOGY & GEOGRAPHY
MARINE GEOLOGY
Marine Geology
4 LAYERS OF THE EARTH
Layers of the Earth
CRUST
• THICKNESS: VARIES BETWEEN OCEAN & CONTINENTS 5-40 KM
• STATE: SOLID
• ELEMENTS: SILICON, ALUMINUM, CALCIUM, SODIUM, POTASSIUM
• LOCATION OF THE EARTH’S “PLATES”• FLOATS ON THE LAYER BENEATH• LEAST DENSE LAYER
• CONTINENTAL AND OCEANIC CRUSTS
• LITHOSPHERE= CRUSTS + UPPER MOST PART OF MANTLE
Layers of the Earth
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MANTLE
• THICKNESS: 2,750 KM
• STATE: PLASTIC- ABILITY OF A SOLID TO FLOW
• ELEMENTS: SILICON, OXYGEN, MAGNESIUM, IRON, ALUMINUM, CALCIUM
• CONVECTION CURRENTS• DUE TO UNEVEN HEATING IN THIS LAYER• CAUSE THE EARTH’S PLATES TO MOVE
• ASTHENOSPHERE AND MESOSPHERE
Layers of the Earth
OUTER CORE
• THICKNESS: 2,260 KM
• STATE: LIQUID
• ELEMENTS: IRON AND NICKEL
• EXTREMELY HOT
• RESPONSIBLE FOR OUR MAGNETIC FIELD
Layers of the Earth
INNER CORE
• THICKNESS: 1,228 KM
• STATE: SOLID
• TEMPERATURE AND PRESSURE IS SO GREAT, THAT THE METALS ARE SQUEEZED TOGETHER AND CANNOT MOVE.
• ELEMENTS: IRON AND NICKEL
Layers of the Earth
PLATE TECTONICS
• ALFRED WEGENER• KNOWN FOR HIS THEORY ON
CONTINENTAL DRIFT
• 1915- PUBLISHED THE ORIGINS OF CONTINENTS AND OCEANS
• CONTINENTAL DRIFT
• SUPERCONTINENT- PANGEA
Plate Tectonics
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PLATE TECTONICS
• CONTINENTAL DRIFT SUPPORTED BY:• IDENTICAL FOSSILS FOUND ON DIFFERENT CONTINENTS
• CONTINENTS “FIT” TOGETHER LIKE PUZZLE PIECES
• GEOLOGICAL FEATURES MATCH TOGETHER• COAL DEPOSITS IN EUROPE AND N. AMERICA
• MOUNTAIN RANGES IN AFRICA AND S. AMERICA
Plate Tectonics Plate Tectonics
PLATE TECTONICS
• SO WHAT CAUSED THE PLATES TO MOVE APART?
• THE CRUST IS MADE UP OF SEVERAL DIFFERENT PLATES THAT CAN MOVE INDEPENDENTLY OF ONE ANOTHER
• CONVECTION CURRENTS IN THE MANTLE PUSH/PULL THE PLATES
Plate Tectonics
PLATE BOUNDARIES
Plate Tectonics
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DIVERGENT BOUNDARIES
• OCEAN- (SEA-FLOOR SPREADING)• TWO PLATES MOVE AWAY FROM EACH OTHER
• MAGMA MOVES UP TO FILL THE SPACE CREATING NEW ROCK
• FORMS OCEAN RIDGES
• CONTINENTAL-• FORMS RIFT VALLEYS
Plate Tectonics
CONVERGENT BOUNDARIES
• PLATES MOVE TOWARDS EACH OTHER
• AKA: SUBDUCTION ZONES- AREAS OF PLATE DESTRUCTION
• 3 TYPES:• OCEANIC- OCEANIC
• OCEANIC- CONTINENTAL
• CONTINENTAL- CONTINENTAL
Plate Tectonics
CONVERGENT: OCEANIC- OCEANIC
• FORMS:• TRENCHES
• ISLAND ARCS
Plate Tectonics
CONVERGENT: OCEANIC- CONTINENTAL
• FORMS:• TRENCHES
• VOLCANIC ARCS
Plate Tectonics
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CONVERGENT: CONTINENTAL- CONTINENTAL
• FORMS:• MOUNTAINS
Plate Tectonics
TRANSFORM BOUNDARIES
• OCCURS AS TWO PLATES SLIDE PAST EACH OTHER
• NO PLATE DESTRUCTION
• EARTHQUAKES ARE COMMON DUE TO FRICTION
• OFFSETS GEOLOGIC FEATURES
Plate Tectonics
PLATE BOUNDARIES
Plate Tectonics
OTHER CIRCUMSTANCES
• SOME AREAS HAVE PLUMES OF MAGMA CLOSE TO THE SURFACE
• AKA: HOT-SPOTS
• RESPONSIBLE FOR SEVERAL ISLAND CHAINS INCLUDING HAWAII
• MAGMA RISES TO THE SURFACE AT VOLCANOES CREATING NEW ISLANDS
Plate Tectonics
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OTHER CIRCUMSTANCES
• HYDROTHERMAL VENTS• SEA WATER SEEPS THROUGH
CRACKS IN THE CRUST NEAR PLATE BOUNDARIES
• IT GETS HEATED CLOSE TO MAGMA CHAMBERS
• RUSHES BACK TO THE CRUST CARRYING NUTRIENTS
Plate Tectonics
BATHYMETRY
Bathymetry
BATHYMETRY
• THE UNDERWATER EQUIVALENT TO TOPOGRAPHY
• THE STUDY OF WATER DEPTH
• A BATHYMETRIC MAP SHOWS FLOOR RELIEF OR TERRAIN AS CONTOUR LINES
Bathymetry
BATHYMETRY
• INFORMATION COMES FROM:
• ECHOSOUNDERS (SONAR)• BOUNCE SOUND WAVES OFF
OF OCEAN FLOOR
• MAP THE DISTANCE FROM SEA LEVEL TO FLOOR
• CURRENT SONAR READS WIDE BANDS SIMULTANEOUSLY (MULTIBEAM))
Bathymetry
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BATHYMETRY
• INFORMATION COMES FROM:
• SATELLITES• MEASURE SLIGHT VARIATIONS
IN SEA LEVEL
• SEA LEVEL IS HIGHER ABOVE MOUNTAINS AND RIDGES THAN ABYSSAL PLAINS
• LIDAR (LASERS)
Bathymetry
BATHYMETRY
• WHO COLLECTS THE DATA?• ARMY CORPS OF ENGINEERS
• INLAND WATERWAYS, RIVERS, LAKES
• NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA)
• OCEANS, SEAS, GULFS
Bathymetry
OCEAN FLOOR FEATURES
• TWO MAIN DIVISIONS:• CONTINENTAL MARGIN
• CONTINENTAL SHELF
• CONTINENTAL SLOPE
• CONTINENTAL RISE
• OCEAN BASIN• PLAINS
• TRENCHES
• RIDGES & RISES
• SEA MOUNTS & GUYOUTS
• CORAL REEFS & ATOLLS
Ocean Floor Features
CONTINENTAL MARGIN
• CONTINENTAL SHELF• SUBMERGED PART OF
CONTINENT
• GENTLE SLOPE TO OCEAN BASIN
Ocean Floor Features
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CONTINENTAL MARGIN
• CONTINENTAL SLOPE• EXTENDS FROM SHELF BREAK
TO RISE
• BOUNDARY BETWEEN CONTINENTAL AND OCEANIC CRUST
• STEEP SLOPE
• CONTAINS SUBMARINE CANYONS
Ocean Floor Features
CONTINENTAL MARGIN
• CONTINENTAL SLOPE• SUBMARINE CANYONS
• FORM FROM• RIVER EROSION
• TURBIDITY CURRENTS
Ocean Floor Features
CONTINENTAL MARGIN
• CONTINENTAL RISE• FOUND AT BASE OF SLOPE
• FORMED FROM SEDIMENT DEPOSITION
• GENTLE SLOPE FROM SEA FLOOR TO SLOPE
Ocean Floor Features
CONTINENTAL MARGIN
• ACTIVE:• CONVERGENT PLATE BOUNDARIES
• TRENCHES
• NARROW MARGIN/ SHELF
• TECTONICALLY ACTIVE
• PASSIVE:• NO PLATE BOUNDARY
• WIDE MARGIN/ SHELF
• THICK SEDIMENT
• LITTLE TECTONIC ACTIVITY
Ocean Floor Features
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OCEAN BASIN
• OCEAN BASIN FLOOR:• ABOUT 30% EARTH’S
SURFACE
• BEGINS AT THE CONTINENTAL RISE
• MOSTLY ABYSSAL PLAINS WITH OTHER FEATURES
Ocean Floor Features
OCEAN BASIN
• ABYSSAL PLAIN• FLAT DEEP OCEAN FLOOR
• MAY BE MORE THAN 2 MILES DEEP
• THICK SEDIMENT ACCUMULATION
Ocean Floor Features
OCEAN BASIN
• TRENCHES• OCCUR AT SUBDUCTION ZONES
• OCEANIC CRUST IS FORCED INTO MANTLE
• ASSOCIATED WITH EARTHQUAKES
• DEEPEST= MARIANA’S TRENCH• 11000+ M
• LONGEST= PERU-CHILE TRENCH• 5900+ KM
Ocean Floor Features
OCEAN BASIN
• RIDGES & RISES• UNDERWATER MOUNTAIN RANGES
• FORMED BY SEA-FLOOR SPREADING
• CONTAIN CENTRAL RIFT VALLEY
• RIDGES• STEEP SLOPE (SLOW MOVING PLATES)
• RISES• GENTLE SLOPE (FAST MOVING
PLATES)
Ocean Floor Features
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OCEAN BASIN
• SEAMOUNTS & GUYOUTS• UNDERWATER VOLCANOES
NEAR RIDGES AND OVER HOT SPOTS
• MAY EMERGE AS ISLANDS
• SEAMOUNTS- STEEP SLOPE JUTTING UP FROM SEA FLOOR
• GUYOUTS- FLAT TOP DUE TO EROSION
Ocean Floor Features
OCEAN BASIN
• CORAL REEFS & ATOLLS• FORM AROUND VOLCANIC ISLANDS AND
SEAMOUNTS
• ONLY FORM IN SHALLOW WATERS
• DORMANT VOLCANOES/ SEAMOUNTS ERODE AWAY AND BECOME A BARRIER REEF AND EVENTUALLY AN ATOLL
• BARRIER REEF- ACTIVELY GROWING CORAL REEF SURROUNDING A RECEEDING ISLAND
• ATOLL- SHALLOW LAGOON SURROUNDED BY MATURE CORAL REEF
Ocean Floor Features
Ocean Floor Features
OCEANS OF THE WORLD
• REVIEW• AVERAGE DEPTH 2.3 MILES
• SALINITY= 35 PPT (3.5% SALT)
• MAJORITY IS <39°F (4°C)
• MAJORITY IS DARK
• CONTAINS >97% OF THE EARTH’S WATER
Oceans of the World
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OCEANS OF THE WORLD
• PACIFIC• LARGEST
• AVG. DEPTH 14,500 FT
• BASIN COVERS 33% OF THE EARTHS SURFACE
• HOLDS 52% OF THE EARTH’S WATER
• RING OF FIRE• HIGHLY TECTONICALLY ACTIVE
REGION
• 90% OF WORLD’S EARTHQUAKES
• MARIANA TRENCHOceans of the World Oceans of the World
OCEANS OF THE WORLD
• ATLANTIC• 2ND LARGEST• AVG DEPTH 12,500 FT• MANY SHALLOW MARINAL SEAS• LARGE MARGINS• MID-ATLANTIC RIDGE
• MOSTLY UNDERWATER MOUNTAIN RANGE
• SOME PEAKS RISE ABOVE SEA LEVEL TO FORM ISLANDS
• MANY BARRIER ISLANDS INCLUDING THE LONGEST S. PADRE
Oceans of the World
OCEANS OF THE WORLD
• INDIAN• SMALLEST OF THE LARGER OCEANS
• AVG DEPTH 13,000 FT
• ALMOST COMPLETELY IN THE S. HEMISPHERE
• 3 OF THE WORLDS LARGEST RIVERS DUMP INTO THE NORTH INDIAN
• CONTRIBUTES TO HIGH LEVELS OF SEDIMENT AND FRESHWATER IN THE OCEAN
Oceans of the World
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OCEANS OF THE WORLD
• SOUTHERN• NEWEST OCEAN
• AVG DEPTH 13,100 FT
• ONLY OCEAN THAT COVERS A FULL 360°
• OCEAN IS SEPARATE FROM BORDERING OCEANS DUE TO ANTARTIC CIRCUMPOLAR CURRENT
• YOUNGEST OCEAN GEOLOGICALLY SPEAKING
Oceans of the World
OCEANS OF THE WORLD
• ARCTIC• SMALLEST OCEAN
• AVG DEPTH 3,500 FT
• UNIQUE BECAUSE IT IS ALMOST COMPLETELY SURROUNDED BY LAND
• COVERED IN ICE MOST OF THE YEAR
• ONLY 2% OF THE WORLD’S OCEAN WATER
Oceans of the World