GEO4840 TECTONICSs06

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GEO-4840 TECTONICS-s06
PART 1 Lectures Mondays 8-12 23/1 - 06/3
PART 2 Student projects Essay and
presentation Weeks 16-17
PART 3 Field teaching Western Norway Weeks
18-19
PART 4 Field reports Hand in Friday
2/6
PART 5 Evaluation projects, reports,
examination 14/6
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GEO-4840 TECTONICS-s06

• LECTURES
• Introduction and course content
• Tectonic processes and anatomy of mountain belts.
• Main themes
• 1) Material balance and properties
• Uplift and subsidence.
• Topography, crustal and lithospheric
  thicknesses/structure

2) Wilson cycle tectonics, Ocean-continent
transition, Oceanic complexes, exotic
terranes. Ophiolite obduction, (Oman,
Caledonian and Appalachian). Andean margins,
Incipient continental collision, Australia -
Banda Arc collision.  Continental collision
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LECTURES (continued) 3) Examples of
Continental collision zones The
Himalayan-Tibetan region The Caledonides,
with emphasis on Scandinavia
Mediterranean  4) From collision to extension,
Dynamics of orogenic wedges, Exhumation,
Renewed rifting.
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Reading list
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Reading list forts
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• Student projects (written with oral
  presentation)
• All projects are related to the
  field-course/work/excursions.
• The student seminar day will be Mon 24. and Wed
  26. April
• Extensional detachments in Norway ()
• Main tectonic units in the Scandinavian
  Caledonides ()
• Main tectonic units in east Greenland Caledonides
  ()
• Ophiolites in the Scandinavian Caledonides ()
• 5) Lower Palaeozoic rocks in the foreland
  Scandinavia ()
• PT-time history of eclogites in Western Gneiss
  Complex()
• Melanges and Olistostromes ()
• Ultramafic rocks in the Western Gneiss Complex ()
• The mineralogy of Ultra-high-pressure rocks ()
• PT-time history of eclogites in the Caledonian
  nappes

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MOUNTAIN CHAINS ARE THE MOST IMPRESSIVE VISIBLE
TOPOGRAPHIC FEATURES ON THE EARTHS SURFACE
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The anatomy of mountain belts The product of
complex interactions of thrusting and
extension accompanied by pro- and retrograde
metamorphic reactions and erosional denudation
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• MOUNTAIN BELTS, OLD (at least from Mid
  Proterozoic) and YOUNG,
• HAVE VERY SIMILAR INTERNAL STRUCTURES
• FORELAND
• CONTINENTAL BASEMENT-CORED NAPPES
• SUTURE WITH OCEANIC AND EXOTIC TERRANES
• HINTERLAND / PLATEAU REGIONS
• FORELAND

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Various stages of orogenic maturity along strike
Andean margins
Foreland flexure
Suture(s)
Common internal structure of orogenic belts
(in space and time)
Hinterland orogenic plateau
Foreland basin
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Schematic view of stages in a classical Wilson
cycle
5) Remnant stage Continental collision, suture
zones, deform- ation and metamorphism, mountain
building Extensional collapse, faulting and
collapse basins 4) Terminal stage Near closure of
ocean, mature arcs and back-arc, accreationary
wedges, HP-LT metamorphic complexes (Mediterranean
See area) 3) Vaning stage Intra-oceanic
subduction and island arcs transition to Andean
margins. (SE Asia and Western Passific) 2)
Mature stage Passive margins with
large shelf-areas (Atlantic Ocean) 1) Embryonic
to Young stage. Rifts to small ocean basin with
sea-floor spreading. (East African rift and Red
Sea)
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(No Transcript)
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Exact estimates of material present in the orogen
Le Pichon et al., 1993
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ESTIMATES OF MISSING CONTINENTAL
MATERIAL Topography and erosional levels are
taken into consideration Dewey et al. (1986) ca
1,2 x 104 km2 Le Pichon et al (1993) Linear
shortening between 1850 - 2600 km Surface loss
during the past 45 myr from 57 to 62 x 105
km2 Rate of surface loss 1,1 x 10 km2 x
10-6yr Arial deficit in sections 33 - 52 x 105
km2 (max) 18 - 30 x 105 km2
(min) (Depends on estimates of original surface
elevation) WHAT IS THE EXPLANATIONS FOR THE
DEFICIT?
erosion
India
Tarim
Present continental crust
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• LATERAL TRANSPORT OF MATERIAL

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The lateral extrusion model For SE Asia
Tapponnier et al., 1982, 1986
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Fournier Jolivet et al.
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2) VERTICAL TRANSPORT OF MATERIAL (SUBDUCTION /
EDUCTION)