![Page 1: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/1.jpg)
I.I. GeologyGeology
B.B. Plate TectonicsPlate Tectonics2.2. Mid-Ocean Ridge SystemMid-Ocean Ridge System
• Discovered from sea floor mapping with SONAR Discovered from sea floor mapping with SONAR during and after World War IIduring and after World War II
• Largest geological feature on EarthLargest geological feature on Earth• Ridges displaced in some areas by Ridges displaced in some areas by transform transform
faultsfaults
3.3. TrenchesTrenches• Conspicuous sea floor featuresConspicuous sea floor features• Especially common in the Pacific OceanEspecially common in the Pacific Ocean
![Page 2: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/2.jpg)
http://www.ngdc.noaa.gov/mgg/image/global_topo_large.gif
![Page 3: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/3.jpg)
Fig. 2.5
![Page 4: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/4.jpg)
I.I. GeologyGeology
C.C. Plate Tectonics - EvidencePlate Tectonics - Evidence1.1. ““Ring of Fire”Ring of Fire”
• Geological activity (e.g. earthquakes, Geological activity (e.g. earthquakes, volcanoes) associated with mid-ocean ridges volcanoes) associated with mid-ocean ridges and with trenchesand with trenches
![Page 5: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/5.jpg)
Fig. 2.6
![Page 6: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/6.jpg)
I.I. GeologyGeology
C.C. Plate Tectonics - EvidencePlate Tectonics - Evidence1.1. ““Ring of Fire”Ring of Fire”
• Geological activity (e.g. earthquakes, Geological activity (e.g. earthquakes, volcanoes) associated with mid-ocean ridges volcanoes) associated with mid-ocean ridges and with trenchesand with trenches
2.2. Closer to ridgesCloser to ridges• Younger rockYounger rock• Thinner covering of sedimentThinner covering of sediment
3.3. Magnetic anomaliesMagnetic anomalies• Caused by magnetic field reversalsCaused by magnetic field reversals• Symmetrical on either side of ridge axisSymmetrical on either side of ridge axis
![Page 7: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/7.jpg)
Fig. 2.7
![Page 8: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/8.jpg)
I.I. GeologyGeology
D.D. Plate Tectonics - MechanismPlate Tectonics - Mechanism1.1. Sea-Floor SpreadingSea-Floor Spreading
• Mid-ocean ridges contain Mid-ocean ridges contain riftsrifts where two pieces where two pieces of crust are moving apart and new oceanic crust of crust are moving apart and new oceanic crust is being created (spreading rate ca. 2-18 cm yis being created (spreading rate ca. 2-18 cm y-1-1))
• As rift widens, hot mantle material rises through As rift widens, hot mantle material rises through rift, cools and solidifies to form new oceanic rift, cools and solidifies to form new oceanic crustcrust
• Ridges = Ridges = spreading centersspreading centers• Theory generated by induction explains Theory generated by induction explains
observationsobservations• Younger rock closer to ridgesYounger rock closer to ridges• Thinner sediment closer to ridgesThinner sediment closer to ridges• Patterns of magnetic anomaliesPatterns of magnetic anomalies
![Page 9: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/9.jpg)
Fig. 2.8
![Page 10: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/10.jpg)
I.I. GeologyGeology
D.D. Plate Tectonics - MechanismPlate Tectonics - Mechanism1.1. Sea-Floor SpreadingSea-Floor Spreading
• LithosphereLithosphere made up of made up of lithospheric plateslithospheric plates• Plates may contain continental crust, oceanic Plates may contain continental crust, oceanic
crust, or bothcrust, or both• Plates rest on Plates rest on asthenosphereasthenosphere (plastic upper (plastic upper
mantle)mantle)• Plate boundaries correspond to locations of Plate boundaries correspond to locations of
mid-ocean ridges and to trenchesmid-ocean ridges and to trenches• Not all plates completely characterized yetNot all plates completely characterized yet
Fig. 2.9
![Page 11: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/11.jpg)
I.I. GeologyGeology
D.D. Plate Tectonics - MechanismPlate Tectonics - Mechanism2.2. SubductionSubduction
• Old crust destroyed when one plate dips below Old crust destroyed when one plate dips below anotheranother
• Oldest oceanic crust ~200 million years oldOldest oceanic crust ~200 million years old• Denser plate subducted beneath less dense Denser plate subducted beneath less dense
plateplate• Locations – oceanic trenches = Locations – oceanic trenches = subduction zonessubduction zones• Recycles crust and supports volcanic activityRecycles crust and supports volcanic activity• May result from collisions betweenMay result from collisions between
• Continental plate and oceanic plate (oceanic Continental plate and oceanic plate (oceanic plate subducted; usually forms volcanoes)plate subducted; usually forms volcanoes)
• Two oceanic plates (denser plate subducted; Two oceanic plates (denser plate subducted; usually forms island arc)usually forms island arc)
![Page 12: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/12.jpg)
Fig. 2.10
![Page 13: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/13.jpg)
Fig. 2.11
![Page 14: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/14.jpg)
I.I. GeologyGeology
E.E. Geological HistoryGeological History1.1. Continental DriftContinental Drift
• All continents joined together ~200 myaAll continents joined together ~200 mya• Pangaea – “supercontinent”Pangaea – “supercontinent”• Panthalassa – single ocean Panthalassa – single ocean Pacific Ocean Pacific Ocean• Tethys Sea – Shallow sea between Eurasia & Tethys Sea – Shallow sea between Eurasia &
Africa Africa Mediterranean Sea Mediterranean Sea• Sinus Borealis Sinus Borealis Arctic Ocean Arctic Ocean
• Laurasia separated from Gondwana ~180 myaLaurasia separated from Gondwana ~180 mya
![Page 15: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/15.jpg)
Fig. 2.14
![Page 16: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/16.jpg)
Fig. 2.14
![Page 17: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/17.jpg)
Fig. 2.14
![Page 18: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/18.jpg)
Fig. 2.14
![Page 19: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/19.jpg)
Fig. 2.14
![Page 20: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/20.jpg)
Global Plate TectonicsGlobal Plate Tectonics
Jurassic to Present DayJurassic to Present Day
ByBy
L.A. Lawver, M.F. Coffin, I.W.D. DalzielL.A. Lawver, M.F. Coffin, I.W.D. Dalziel
L.M. Gahagan, D.A. Campbell, and R.M. L.M. Gahagan, D.A. Campbell, and R.M. SchmitzSchmitz
2001, University of Texas Institute for 2001, University of Texas Institute for GeophysicsGeophysics
February 9, 2001February 9, 2001
![Page 21: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/21.jpg)
![Page 22: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/22.jpg)
![Page 23: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/23.jpg)
![Page 24: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/24.jpg)
![Page 25: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/25.jpg)
![Page 26: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/26.jpg)
![Page 27: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/27.jpg)
![Page 28: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/28.jpg)
![Page 29: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/29.jpg)
![Page 30: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/30.jpg)
![Page 31: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/31.jpg)
![Page 32: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/32.jpg)
![Page 33: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/33.jpg)
![Page 34: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/34.jpg)
![Page 35: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/35.jpg)
![Page 36: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/36.jpg)
![Page 37: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/37.jpg)
![Page 38: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/38.jpg)
![Page 39: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/39.jpg)
![Page 40: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/40.jpg)
![Page 41: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/41.jpg)
![Page 42: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/42.jpg)
![Page 43: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/43.jpg)
![Page 44: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/44.jpg)
We wish to thank the We wish to thank the PLATES’ sponsorsPLATES’ sponsorsfor their support:for their support:Conoco, TotalFinaElf, Conoco, TotalFinaElf, Exxon-Mobil, Exxon-Mobil, Norsk Hydro, and Norsk Hydro, and Statoil. Statoil.
![Page 45: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/45.jpg)
For more information, For more information, contact:contact:Lisa M. GahaganLisa M. GahaganInstitute for GeophysicsInstitute for Geophysics4412 Spicewood Springs Rd., 4412 Spicewood Springs Rd., Bldg. 600Bldg. 600Austin, TX 78759Austin, TX 78759
[email protected]@ig.utexas.edu
![Page 46: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/46.jpg)
Earth – Future Drift
![Page 47: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/47.jpg)
Earth – Future Drift
![Page 48: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/48.jpg)
Earth – Future Drift
![Page 49: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/49.jpg)
Earth – Future Drift
![Page 50: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/50.jpg)
Earth – Future Drift Link
![Page 51: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/51.jpg)
I.I. GeologyGeology
F.F. Geological ProvincesGeological Provinces1.1. Continental MarginsContinental Margins
• Boundaries between continental and oceanic Boundaries between continental and oceanic crustcrust
• Accumulate sediment deposits from rivers and Accumulate sediment deposits from rivers and streamsstreams
a.a. Continental shelfContinental shelf
b.b. Continental slopeContinental slope
c.c. Continental riseContinental rise
2.2. Deep-Ocean BasinsDeep-Ocean Basins
3.3. Mid-Ocean RidgesMid-Ocean Ridges
4.4. Hot SpotsHot Spots
![Page 52: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/52.jpg)
Fig. 2.17
![Page 53: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/53.jpg)
I.I. GeologyGeology
F.F. Geological ProvincesGeological Provinces1.1. Continental MarginsContinental Margins
a.a. Continental shelfContinental shelf• Shallowest part of continental marginShallowest part of continental margin• Underlie ~8% of ocean surfaceUnderlie ~8% of ocean surface• Richest, most productive parts of oceanRichest, most productive parts of ocean• Some parts exposed during times of low sea Some parts exposed during times of low sea
level and eroded by rivers and glaciers now are level and eroded by rivers and glaciers now are submarine canyonssubmarine canyons
![Page 54: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/54.jpg)
Fig. 2.19
California Coastline
Monterey Canyon
![Page 55: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/55.jpg)
I.I. GeologyGeology
F.F. Geological ProvincesGeological Provinces1.1. Continental MarginsContinental Margins
a.a. Continental shelfContinental shelf• Shallowest part of continental marginShallowest part of continental margin• Underlie ~8% of ocean surfaceUnderlie ~8% of ocean surface• Richest, most productive parts of oceanRichest, most productive parts of ocean• Some parts exposed during times of low sea Some parts exposed during times of low sea
level and eroded by rivers and glaciers now are level and eroded by rivers and glaciers now are submarine canyonssubmarine canyons
• Varies in width from 1 km (Pacific coast of S Am) Varies in width from 1 km (Pacific coast of S Am) to 750+ km (Arctic coast of Siberia)to 750+ km (Arctic coast of Siberia)
• Ends at Ends at shelf breakshelf break, usually at 120-200 m but up , usually at 120-200 m but up to 400+ m depth.to 400+ m depth.
![Page 56: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/56.jpg)
I.I. GeologyGeology
F.F. Geological ProvincesGeological Provinces1.1. Continental MarginsContinental Margins
b.b. Continental slopeContinental slope• Transition from continent to oceanTransition from continent to ocean• Furrowed with submarine canyons in many Furrowed with submarine canyons in many
areasareas• Canyons channel sediment and debris to deep Canyons channel sediment and debris to deep
sea floorsea floor
c.c. Continental riseContinental rise• Accumulated sediment, including Accumulated sediment, including deep-sea fansdeep-sea fans
• May be extensive in areas where large rivers May be extensive in areas where large rivers discharge into oceandischarge into ocean
![Page 57: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/57.jpg)
I.I. GeologyGeology
F.F. Geological ProvincesGeological Provinces1.1. Continental MarginsContinental Margins
d.d. Active marginsActive margins• Geologically activeGeologically active
• Usually subduction or Usually subduction or transform faulttransform fault
• Steep, rocky shorelineSteep, rocky shoreline• Narrow continental shelfNarrow continental shelf• Steep continental slopeSteep continental slope• Usually lack well-Usually lack well-
developed continental developed continental riserise
• Sediment removed Sediment removed by geological activityby geological activity
Fig. 2.20
![Page 58: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/58.jpg)
I.I. GeologyGeology
F.F. Geological Geological ProvincesProvinces
1.1. Continental MarginsContinental Marginse.e. Passive marginsPassive margins• Not geologically Not geologically
activeactive• Flat coastal plainFlat coastal plain• Wide continental Wide continental
shelfshelf• Gentle continental Gentle continental
slopeslope• Usually well-Usually well-
developed developed continental risecontinental rise
Fig. 2.20
![Page 59: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/59.jpg)
Fig. 2.20
![Page 60: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/60.jpg)
I.I. GeologyGeology
F.F. Geological ProvincesGeological Provinces2.2. Deep-Ocean BasinsDeep-Ocean Basins
• Mostly between 3000 and 5000 mMostly between 3000 and 5000 m• Predominantly abyssal plain
![Page 61: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/61.jpg)
I.I. GeologyGeology
F.F. Geological ProvincesGeological Provinces2.2. Deep-Ocean FloorDeep-Ocean Floor
• Mostly between 3000 and 5000 mMostly between 3000 and 5000 m• Predominantly abyssal plain• Seamounts – Undersea mountains• Guyots – Flat-topped seamounts• Rises – Large table-like features
• Common in Pacific
![Page 62: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/62.jpg)
California Coastline
Monterey Canyon
Fig. 2.19
![Page 63: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/63.jpg)
I.I. GeologyGeology
F.F. Geological ProvincesGeological Provinces3.3. Mid-Ocean RidgesMid-Ocean Ridges
• Central region – Central region – rift valleyrift valley• Fractures allow sea water to seep into crustFractures allow sea water to seep into crust
![Page 64: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/64.jpg)
Fig. 2.23
![Page 65: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/65.jpg)
I.I. GeologyGeology
F.F. Geological ProvincesGeological Provinces3.3. Mid-Ocean RidgesMid-Ocean Ridges
• Central region – Central region – rift valleyrift valley• Fractures allow sea water to seep into crustFractures allow sea water to seep into crust
• Water is heated by rock and rises back to Water is heated by rock and rises back to surface of sea floorsurface of sea floor
• Hot water picks up dissolved minerals (iron, Hot water picks up dissolved minerals (iron, manganese, sulfides)manganese, sulfides)
• Hot, mineral-rich water contacts cold sea waterHot, mineral-rich water contacts cold sea water• Precipitate formsPrecipitate forms• Black smokersBlack smokers• May be very May be very hot hot (350 (350 ooC or more)C or more)
![Page 66: I.Geology B.Plate Tectonics 2.Mid-Ocean Ridge System Discovered from sea floor mapping with SONAR during and after World War IIDiscovered from sea floor](https://reader035.vdocuments.us/reader035/viewer/2022062713/56649cb85503460f9497e261/html5/thumbnails/66.jpg)
Fig. 2.25