Transcript geo-4840 tectonics-s04

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
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
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.
Reading list:
EXAMINATION RELEVANT MATERIAL FOR GEO4840 TECTONICS, 2006:
Paper copies i n bold
1) ALL HANDOUT S AND LECTURES
2) STUDEN T CONTRIBUTIONS AND THE FIELDCOURSE
3) THIS READING LIST
1) Andersen T.B., (1998) Extensional tectonics in the Caledonides of southern Norway,
An overview. Tectonophysics, 285,333-351. (avai lable as PDF)
2) Andersen T.B., Jamtveit, B., Dewey, J.F. and Swensson, E. (1991): Subduction and
eduction of continenta l crust; majo r mechanisms during continent -continen t collision and
orogenic extensional col lapse. Terra Nova 3, 303-310 (available as PDF)
3) Austrhei m H. (1998): Influence of Fluid and Deformation on Metamorphism of
the Deep Crust and Consequences for the Geodynamics of Collision Zones. In.
Hacker & Liou (eds) When Continents collide: Geodynamics and Geochemistry of
Ultrahigh-Pressure Rocks, 297-323.
4) Burbank , D.W. (2002). Rates of erosion and their implications for exhumatio n. Min.
Mag. Vol. 66 (1), 25–52 (available as P DF)
5) Carswell, D. A., Brueckne r, H. K. Cuthber t, S. J. Metha, K. and O’Brie n, P. J. 2003
The timin g of stabilisation and the exhumatio n rate for ultra -hig h pressure rocks in the
Western Gneiss Region of Norway. J. metamorphic Geol. 21, 601–612 (available as
PDF)
6) Chemenda A. I., Mattauer, M. & Bokun, A.N. (1996): Continent al subduction an d a
mechanism for exhumation of hig h-pressure rocks: new modelling an d fiel d data from
Oman. EPSL, 143, 173-182 (available as PDF)
7) Dewey J.F. (1988): Extensional collapse of orogens, Tectonics, 7, 1123-1139.
8) Dewey J.F., Shackelton, R.M., Chengfa C. and Yiui n S. (1988): The tectonic
evolution of the Tibetan Plateau, Philos. Trans. Royal Soc. London, ser. A, 327, 379413.
9) Fossen, H . & Dunla p, J.W. 1998: 40Ar/39Ar dates and implications for the struct ural
development of southern N orway. Jl. Struct. Geol., 20, 765-781. (available as PDF)
10) Hacker, B.R., Andersen, T.B ., Root, D.B., Mattinson, J.M., & Wooden, J.L.
Exhumation o f high -pressure rocks beneath the Solund Basin, Norway. Jl Metamorphic
petrology, 613-629 (available as PDF)
11) Hacker, B.R., Mosenfelder, J.L., and Gnos, E., Rapid emplacement of the Oman
ophiolite : Thermal and geochronologic constra ints. Tectonics, v.15, pp. 1230-1247.
12) Hodges K.V., Parrish R. & Searle M.: Tectonic evolution of the Central
Annapurna Rang e, Nepalese Himalayas. Tectonics 15, 1264-1291
13) Hartz , E.H. ; Andresen, A. , Hodges, K.V., Martin, M.W. 2001 Syncon tractional
extension and exhumation o f deep crustal rocks in the east Greenland Caledonides
Tectonics Vol. 20 , No. 1 , p. 58 (2000TC900020) (available as PDF)
14) Jolivet , L. , Faccenna , C., Goffe, B., Burov, E. and Agard, P. (2003) Subduction
tectonics and exhymation of high -pressure metam orphic rocks in the Mediterranean
orotens. Am. J. Sci. Vol. 303, 353–409, (availa ble as PDF)
15)Krabbenda m, M & Dewey J.F. (1998) Exhumatio n of UHP rocks by transtensio n
in th e Western Gneiss Region, Scandinavian Caledonides. Geol. Soc. Spec. Publ. 135,
Reading list forts:
15)Krabbenda m, M & Dewey J.F. (1998) Exhumatio n of UHP rocks by transtensio n
in th e Western Gneiss Region, Scandinavian Caledonides. Geol. Soc. Spec. Publ. 135,
159-181.
16) Le Pich on, X., Fournier , M. & Jolivet, L. (1992): Kinematics , topograph y,
shortening an d extrusion i n the Indi a-Eurasia collision. Tectonics 11, 1085-1098
17) Osmundsen, P .T. & Andersen , T.B.: The Middle Devonian Basins of western
Norway: Sedimentary response to large -scale transtensional tectonics. Tectonophysics,
332, 51-68 (availa ble as PD F)
18) Platt J.P. (1993): Exhumatio n of high-pressure rocks: a review o f consepts and
processes. Terra Nova, 5, 119-133
19) Platt J.P. & Engla nd (1994): Convective removal of lithosphere beneath
mountai n belts: Thermal a nd mechanical consequences. Am. Jl. Sci., 293, 307-336.
20) Torsvik T. H., (1998) Palaeozoic palaeogeography: A North Atlanti c viewpoin t.
GFF, 120, 109-118.
21) Wernicke B . (1992): Cenozoic extensional tectonics of the U.S. Cordillera.I n
Burchfield B.C ., Lipman P. W. and Zorback M.L. (eds) Geology of NorthAmerica,
Vol G-3, The Cordilleran Orogen: Conterminous U.S. The Geological Society of
America.
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
1) Extensional detachments in Norway ()
2) Main tectonic units in the Scandinavian Caledonides ()
3) Main tectonic units in east Greenland Caledonides ()
4) Ophiolites in the Scandinavian Caledonides ()
5) Lower Palaeozoic rocks in the foreland Scandinavia ()
6) PT-time history of eclogites in Western Gneiss Complex()
7) Melanges and Olistostromes ()
8) Ultramafic rocks in the Western Gneiss Complex ()
9) The mineralogy of Ultra-high-pressure rocks ()
10)PT-time history of eclogites in the Caledonian nappes
MOUNTAIN CHAINS ARE THE MOST IMPRESSIVE
VISIBLE TOPOGRAPHIC FEATURES ON THE
EARTH´S SURFACE
The anatomy of mountain belts:
The product of complex interactions of thrusting and extension
accompanied by pro- and retrograde metamorphic reactions and
erosional 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
Various
stages of
orogenic
maturity
along strike
Andean
margins
Foreland
flexure
Common
internal
structure
of orogenic
belts (in
space and time)
Suture(s)
Hinterland orogenic plateau
Foreland
basin
Schematic view of stages in a classical Wilson cycle
5) Remnant stage
Continental collision, suture zones, deformation 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)
Exact estimates of material present in the orogen
Le Pichon et al., 1993
ESTIMATES OF MISSING CONTINENTAL MATERIAL
Topography and erosional levels are taken into consideration:
Dewey et al. (1986) ca 1,2 x
India
104
km2
Present continental
crust
erosion
Tarim
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?
1) LATERAL TRANSPORT OF MATERIAL
The lateral extrusion model
For SE Asia
Tapponnier et al., 1982, 1986
Fournier
Jolivet et al.
2) VERTICAL TRANSPORT OF MATERIAL
(SUBDUCTION / EDUCTION)