GEO4840 TECTONICSS05 - PowerPoint PPT Presentation

Title: GEO4840 TECTONICSS05


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GEO-4840 TECTONICS-S05
PART 1 LECTURES Wed 12-14 (16) 19/1 - 09/3
PART 2 STUDENT PROJECTS Presentations 13/4
PART 3 FIELD TEACHING Corsica end April
PART 4 FIELD REPORTS Hand in 11/5
PART 5 EVALUATION PROJECTS, REPORTS EXAM
14/6
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GEO-4840 TECTONICS-S05

• LECTURES
• Introduction and course content Anatomy and
  tectonic processes
• in 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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• Student projects (written and oral presentation)
• All projects are related to the
  field-course/work/excursions.
• The student seminar day will be Wed. 13. April
• The Herzynian basement of Corsica ()
• The main tectonic units of the Alps and their
  correlation
• with Alpine Corsica. ()
• The structural geology of Alpine Corsica, an
  overview ()
• The high-pressure metamorphism of Alpine Corsica
  ()
• 5) Exhumation of high-pressure rocks in the
  transect from
• Corsica to the Apennines in Italy ()
• The Alpine ophiolitic rocks of Corsica ()
• Formation of Pseudotachylytes ()
• Formation of Olistostromes ()

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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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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)