WELCOME Lecture on Chapter 11 Marine Geology

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WELCOME!Lecture on Chapter 11Marine Geology

• Dr. Ken Sprenke
• ksprenke_at_uidaho.edu

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Sea Floor Investigations sampling drilling echo
sounding seismic profiling...
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Atlantis The lost continent?
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Atlantis may have referred to the Island of
Thera, the site of a 1628 BC eruption that led to
the demise of the Minoan civilization.
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Ocean water originated as volcanic gas. Most of
the gas emitted by volcanoes is steam....
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Geologists recognize four oceans. What are
they? Atlantic Pacific Indian Arctic...
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Ocean-basin development
East African Rift Snake River Valley???
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Red Sea
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Atlantic, Indian, Arctic Oceans are surrounded
by continental margins.
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Pacific Ocean is surrounded by subduction zones
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The Mediterranean Sea is narrow and surrounded
by young mountains.
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Himalayas--the former Tethys Sea is completely
closed and rocks from both sides of the seas are
sutured together.
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The approximate mean elevation of the solid Earth
surface. The geological cycle that describes
the opening and closing of ocean basins. An
example of a new ocean basin trying to
form. An example of an ocean basin about to
close.
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Pioneering oceanographic work was done by Maurice
Ewing in the 30s, 40s, and 50s. The mid-Atlantic
ridge was a major discovery.
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Sea Floor Samplers
Clamshell
Piston Corer
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Sea-Going Research Vessel.
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Submersible Alvin
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Echo Sounding (Sonar) -used to find water depth
and to map sea floor topography
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Words that oceanographers use to describe the sea
floor....
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Turbidity Currents Under-Sea Landslides
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Active Margin
Passive Margin
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Match left with right ___Explosive volcanoes A.
Active margin ___Very broad B. Passive
margin ___Not seismic ___Mountain
building ___Offshore trench ___Island
arc ___Active faults ___Earthquakes ___Fishing
banks ___California coast ___East
coast ___Peruvian coast ___Brazil coast ___West
African coast
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The continental margin includes the shelf, slope,
and rise. The deep offshore ocean is the abyssal
plain.
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Match left with right ___Shallower than 150
m A. shelf ___Cut by submarine canyons B.
slope ___Turbidite sediments C. rise ___Tidal
effects ___Common glacial sediments ___Affected
by sea level change ___Slope less than a
degree ___Slope typical 2 to 4 degrees
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Gravity Map of the Oceans. Note the trenches,
seamounts, and mid-ocean ridges..
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Ocean Ridges Mountainous topography, new
volcanic rocks, central rift.
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An ophiolite suit the rocks that compose oceanic
crust.
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A black smoker on a midocean ridge. The source
of many of our present day mineral resources.
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Tube worms life forms that live without light,
deriving energy from black smokers.
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Transform faults offset mid-ocean ridges.
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Volcanic islands scalped by erosion are called
guyots.
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The deepest parts of the oceans where thick
sedimentary wedges accumulate. This mountain
chain includes the island of Iceland. The
mid-ocean ridges are formed from this rock
type. These undersea broad mountains and
plateaus were formed from extinct volcanoes. A
flat-topped seamount.
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Most deep sea sediments are fined-grained
pelagic sediments that are transported in
suspension far from land. However, some coarse
grained glacio-marine sediments are ice rafted
far from land
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Manganese nodules result from chemical reactions
in sea water.
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Deep sea seds are mostly pelagic clays
(brown/red clay from continents) calcareous
and silicic ooze (microscopic shells)...
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Critters that form the ooze...
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The geologic term for deep sea sediments. The
calcareous ooze represents the remains of these
organisms. Diatoms and radiolarians form this
pelagic sediment. These pelagic sediments are
clastic.
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Reef -mound-like -wave-resistant -composed of
organisms
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Atoll Volcanic Island has sunk but fringing reef
has continued to grow, creating a lagoon.
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Match left with right ___wide deep lagoon A.
Fringing reef ___shallow lagoon B. Barrier
reef ___attached to shore C. Atoll ___encircles
lagoon __ island has subsided
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A schematic picture of ophiolite suite layers
along with a magma chamber (1) sediments (2),
pillow basalts (3), basaltic sheeted dike swarms
(4), layered gabbro (5) and fractionation
cumulates (6)
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A sliver of oceanic crust that has been emplaced
on the continents by tectonic force. The rock
type of the deep oceanic crust (layer 3).
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Next class read Ch 12/13 Structural
Geology Project 8 due next Wednesday at 930
am. Review 9/10 due Friday at 5 pm.