GEO-4840 TECTONICS-S05

GEO-4840 TECTONICS-S05

PART 1: LECTURES [Wed 12-14 (16)] 19/1 - 09/3PART 1: LECTURES [Wed 12-14 (16)] 19/1 - 09/3

PART 2: STUDENT PROJECTS [Presentations] 13/4PART 2: STUDENT PROJECTS [Presentations] 13/4

PART 3: FIELD TEACHING [Corsica] end AprilPART 3: FIELD TEACHING [Corsica] end April

PART 4: FIELD REPORTS [Hand in] 11/5PART 4: FIELD REPORTS [Hand in] 11/5

PART 5: EVALUATION [PROJECTS, REPORTS & EXAM] 14/6PART 5: EVALUATION [PROJECTS, REPORTS & EXAM] 14/6

LECTURES:Introduction and course content; Anatomy and tectonic processesin 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

GEO-4840 TECTONICS-S05

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.

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

1) The Herzynian basement of Corsica ()2) The main tectonic units of the Alps and their correlation

with Alpine Corsica. ()

3) The structural geology of Alpine Corsica, an overview ()

• The high-pressure metamorphism of Alpine Corsica ()

5) Exhumation of high-pressure rocks in the transect fromCorsica to the Apennines in Italy ()

• The Alpine ophiolitic rocks of Corsica ()

• Formation of Pseudotachylytes ()

• Formation of Olistostromes ()

MOUNTAIN CHAINS ARE THE MOST IMPRESSIVEVISIBLE TOPOGRAPHIC FEATURES ON THE

EARTH´S SURFACE

MOUNTAIN CHAINS ARE THE MOST IMPRESSIVEVISIBLE TOPOGRAPHIC FEATURES ON THE

EARTH´S SURFACE

The anatomy of mountain belts:The product of complex interactions of thrusting and extensionaccompanied by pro- and retrograde metamorphic reactions anderosional denudation

The anatomy of mountain belts:The product of complex interactions of thrusting and extensionaccompanied by pro- and retrograde metamorphic reactions anderosional denudation

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

Variousstages of orogenic maturityalong strike

Andean margins

Forelandflexure

Forelandbasin

Suture(s)

Hinterland orogenic plateau

Commoninternalstructureof orogenicbelts (inspace and time)

5) Remnant stageContinental collision, suture zones, deform-ation and metamorphism, mountain buildingExtensional collapse, faulting and collapsebasins4) Terminal stageNear closure of ocean, mature arcs andback-arc, accreationary wedges, HP-LTmetamorphic complexes(Mediterranean See area)

3) Vaning stage: Intra-oceanic subductionand island arcs transition to Andean margins. (SE Asia and Western Passific)

2) Mature stage Passive margins with largeshelf-areas (Atlantic Ocean)

1) Embryonic to Young stage.Rifts to small ocean basin with sea-floor spreading. (East African rift and Red Sea)

Schematic view of stages in a classical Wilson cycle

Le Pichon et al., 1993

Exact estimates of material present in the orogen

ESTIMATES OF MISSING CONTINENTAL MATERIALTopography 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 kmSurface loss during the past 45 myr from 57 to 62 x 105 km2

Rate of surface loss: ≈ 1,1 x 10 km2 x 10-6yrArial 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?

India Tarim

erosion

Present continentalcrust

1) LATERAL TRANSPORT OF MATERIAL

Tapponnier et al., 1982, 1986

The lateral extrusion modelFor SE Asia

FournierJolivet et al.

2) VERTICAL TRANSPORT OF MATERIAL(SUBDUCTION / EDUCTION)