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Intro fieldcourse for Geo4840, Tectonics

Some practical info:

Time and place: 8-12. May, Atløy-Sunnfjord-BergenAccommodation: Old School at Herland on Atløy

Relatively primitive, sleeping bags, make your own breakfastno single rooms etc.

Exposed area, can be windy/rainy/warm/cold soprepare for all eventualities.

Good shoes/boots required

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Practical info:Detailed mapping on economics maps scale

1:5000.I will provide the detailed maps. For location and use in report you can use

the roadmaps; or(print from:

http://ngis2.statkart.no/norgesglasset/default.html )You can also print/look at arial photographs of

(variable quality)at: http://www.norgeibilder.no/

For the mapping we require normal writing and drawing equipment; GPS, hand-lense, compass w/clinometer, hard plate for maps, water/wind

protection.In the Brurestakken are we normally

refrain from use ofhammers because of frequent use and

destruction of outcrops, but you should bring hammers for other part or

the trip.I will provide GPS’s; if you own one

yourself or haveaccess to one, let me know.

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Remember:Reports from field course is 1/3 of the course evaluation.You deliver: Digital file + paper hard copy containing

a) Excursion report, with locations and descriptions illustrations/

discussion of all stops made during the field trip. (individual reports)

b) Report from the mapping containing1) Introduction, methods, map basis etc.2) Systematic description, illustrations and

measurements of rocks (contacts, petrography and primary

structures/sedimentology) 4) Systematic description and measurement of

deformation/metamorphism including folds, foliations

and linear structures, faults, veins etc.5) Presentation of map(s), cross-section(s) and

structural data(stereograms, kinematic/dynamic

interpretations)6) Summary/conclusions/problems/suggestions etc.

Please observe that you make a specific report for the Geo4840 part of the course, i.e. Sunnfjord area and the excursions connected to this.

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Intro field-course for Geo4840, TectonicsI will take over the group on Monday 8/5 after you havebeen working with Arild Andresen on structural problemsat Bremanger the week before. We will have ca 2.5 days of individual mapping in relativelysmall, but well exposed areas around the little mountaincalled Brurastakken (the bride’s-dress) near Herland onAtløy. The geology of Atløy is quite unique because it provides a structural/stratigraphic section from continental to oceanic rocks, and in addition evidence for several time-separted stages of deformation and metamorphism during evolution of the Scandinavian Caledonides.

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Intro field-course for Geo4840, TectonicsWe will focus EXCURSIONS:1) The Proterozoic basement with Caledonian overprint

(eclogite facies to decompression fabrics and mineralogy)2) Large-scale extensional mylonites in the Nordfjord-Sogn Detachment zone

THE MAPPING EXERCISEWith focus on the last point above

3) Caledonian infra-structure of the nappe complex

(The stratigraphy and tectonostratigraphy)a) Basement-cover nappes and evidence for

polyphase deformation and metamorphism

b) Ophiolite and sedimentary cover c) Accreation of oceanic rocks to the continent and the response in stratigraphy of the to this process.

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Bremanger

AtløyBergen area

Nordfjord-Sogn

Detachment Zone

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Bremanger

Atløy

Localitiesto be visited

SUMMARYOF

GEOLOGICALUNITS IN

THE SUNNFJORDREGION

Andersen et al. 1985-1995

U/Pb zircon syenitic gneiss: 1634±3 Ma

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N-S palaeo-reconstruction of stratigraphic units in theSjøralden formation of the Herland Group, Atløynotice that the vertical scale i x10 the horizontal

true scale

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HERLAND GROUP

HØYVIK GROUP

SUNNFJORD MELANGE