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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.

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geo 4840 tectonics s06
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

slide2

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

slide3

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.

slide6

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

slide7

MOUNTAIN CHAINS ARE THE MOST IMPRESSIVE

VISIBLE TOPOGRAPHIC FEATURES ON THE

EARTH´S SURFACE

slide8

The anatomy of mountain belts:

The product of complex interactions of thrusting and extension

accompanied by pro- and retrograde metamorphic reactions and

erosional denudation

slide9

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
slide10

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

slide11

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)

slide14

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

slide16

The lateral extrusion model

For SE Asia

Tapponnier et al., 1982, 1986

slide17

Fournier

Jolivet et al.

slide18

2) VERTICAL TRANSPORT OF MATERIAL

(SUBDUCTION / EDUCTION)