NORSK POLARINSTITUTT SKRIFTER NR. 158 A. HJELLE and Y. OHTA Contribution to the geology of north western Spitsbergen NORSK POLARINSTITUTT OSLO 1974 DET KONGELIGE DEPARTEMENT FOR INDUSTRI OG HÅNDVERK NORSK POLARINSTITUTT Rolfstangveien 12, Snarøya, 1330 Oslo Lufthavn. Norway SALG AV BØKER SALE OF BOOKS Bøkene selges gjennom bokhandlere, eller The books are sold through bookshops, or bestilles direkte fra: may be ordered directly from: UNIVERSITETSFORLAGET Postboks 307 16 Pall Mall P.O. Box 142 Blindern, Oslo 3 London SW 1 Boston, Mass. 02113 Norway England USA Publikasjonsliste, som også omfatter Iand­ List of publications, including maps and og sjøkart, kan sendes på anmodning. charts, will be sent on request. NORSK POLARINSTITUTT SKRIFTER NR. 158 A. HJELLE and Y. OHT A Contribution to the geology of north western Spitsbergen NORSK POLARlNSTITUTT OSLO 1974 Manuscripts received June 1973 Printed May 1974 Aas & Wahl Contents Preface 5 AUDUN HJELLE: The geology of Danskøya and Amsterdamøya Abstract ........................................................................ 7 AHHOTal\IHl 7 Introduction g Geological setting ........................................................... 8 Previous work .......................................................... 8 Present work 10 Geomorphological outline ....................................................... lO The stratigraphic position of the metasediments ................................... 14 Petrography ................................................................... 17 Metasediments 17 Pelitic and psammitic rocks ............................................... 17 Marble. skarn mineralization ............................................. 17 Gneiss. migmatites. and syntectonic granitic rocks .................. ....... .. 18 Biotite gneiss ........................................................... IX Biotite-amphibole gneiss, amphibolite ....................................... 19 Granite gneiss, migmatite, syntectonic granite ............................... 22 Post-tectonic dyke rocks ..................................................... 24 Granitic dykes ........................................................... 24 Mafic dykes ............................................................. 27 Structure 27 Main events ................................................................. 27 The Fl phase ........................................................... 27 The F2 phase ........................................................... 29 The F3 phase ............................................................ 30 Joints .................................................................... 33 Metamorphism ................................................................. 33 Comparison with other metamorphic areas in Svalbard ............................. 35 Acknowledgements 36 36 References Plates YOSHIHIDE OHTA: Geology and structure of the Magdalenefjorden area, Spitsbergen Abstract ........................................................................ 39 AHHOTal\IIH 39 39 Introduction I. Geological setting ................................................... ...... 40 IL Lithological descriptions .. .. .. .. .. .. .. .. .. .. .. .. .. ... 40 A. Classification ............................................................ 40 B. Description .............................................................. 41 1 a. Pelitic biotite schist .................................................. 41 1b. Felsic biotite gneiss and quartzite ...................................... 41 2. Layered gneisses .... .. .. .. .. .. .. .. .. .. .. .. .. .. 41 3. Amphibolites and marbles ............................................ 4 2 4. The plagioc1ase porphyroblastie gneiss and nebulitic gneiss .......... .... 43 5. The migmatites .............. ..... ......... .......... .... .......... 43 6. The grey granite . ... ..... ...... ..... .... ... .......... ... ..... 44 7. Pink aplite and pink nebulitic gneiss .......................... .. .. ... 44 C. Summary of petrography ................................................ 44 Ill. Distribution of rocks and litho-stratigraphy .................................... 45 A. Distribution of rocks . .... ..... ............. ........... .... ..... .... ... 45 I. The fine-grained gneisses .............................................. 45 2. The layered gneisses, amphibolites, and marbles . .... ..... ...... ....... 47 3. The migmatites, plagioclase porphyroblastic gneiss and nebulitic gneiss .... 48 4. The grey granite ...... ..... .... ......... .... .... ............. 48 5. The pink aplite and pink nebulitic gneiss .... ... ... ... ... ................ 48 B. Lithostratigraphy ........................................................ 49 LV. Geological structure ....................... ....... .......... ...... .. ..... 50 A. Description of fold structures ..... .......... .................... ..... .. 50 B. Structural analyses ...................................................... 5 3 C. Summary of geological structure .......................................... 65 Acknowledgements 67 References 67 Plates YOSHIHIDE OHTA: Tectonic developmenl and bl/Ik chemistry of rocks FOIll the Smeerenhurgfjorden area, Spitsbergen Abstract ........................................................................ 69 AHHOTal\IlH . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 69 rntroduction ........ .... ..... ........ ... ......... ...................... ... ...... 69 I. Deformation episodes and metamorphism ...................................... 70 A. Deformation episodes . .. ...... ... ................... ................... 70 l. The Fl deformation, the SI and S" . ........ ............... ........... 70 2. The F2 deformation and S" . ........... .......... ...... ....... ... 72 3. The Fl disturbance and S. ................. .... ... ................. 73 4. The F 4 episode ...... ... ............ ......... ......... .......... ..... 74 B. Metamorphism . ... ..... .. ..... ....... .............. ....... ...... ... 74 1. Quartz ..... ....... ........... .... .... ...... ........ .. ....... ...... 75 2. Feldspars . ..... ....... ... ..................... ........ ........ 76 3. Biotite and muscovite . ......... ..... .... ..... ..... .... .... ........ ... 77 4. Cordierite . ... .... ... .. 77 5. Garnet .......... ... ... ...... .... ........................ ..... ... .. 78 n 6. SilJimanite . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ... 7. Spinel and corundum . .... .................... .. ..... ...... ... ... 80 8. Quartzo-feldspathic metatects . ........ ......... .... .......... ..... ... 82 C. Summary and discussion . .. 83 IL Modal and chemical compositions . .... ... ... ... .... ....... .... ...... ...... 85 A. Modal composition of the rocks .......... ...... ....... ............. ..... 85 B. Bulk chemical composition of the rocks . ........... .. .......... ...... ...... 93 l. Alkali compositions .................................................. 96 2. Niggli value-variation diagrams ........................................ 97 3. Cation ratios ........................................................ 100 C. Summary of bulk chemistry .............................................. 104 Ill. Summary ... ...... ....... ........ ................. ..... .............. .. .. 105 l. Deformation phases ........... ............ ... ... .......... ............. .. 105 2. Metamorphic grade and facies series . .. .. .. .. .. .. .. .. .. .. ... 105 3. Geochemical characteristics of the rocks .................... ......... .... ... 105 Acknowledgements ....... ..... ...... .... ... ................................ ... .. 106 References 106 Plates Preface When the observations of the Norsk Polarinstitutt geological reconnais­ sance expedition to Albert I Land in 1964 were compiled, it was c1ear that many of the questions which arose concerning the stratigraphic, structural and metamorphic development in north-west Spitsbergen could only be answered by more detailed mapping. This commenced in 1965, when A. HJELLE worked for two weeks on the north-west islands, and continued in 1966, when he and Y. ORTA worked jointly in the Smeerenburgfjorden-Sørgattet-Danskøya­ Amsterdamøya area. ORTA planned to continue his work further towards the east, on the east side of Svitjodbreen in 1968; however, unfavourable ice conditions that year prevented this, and instead he continued detailed mapping towards the south, in the Magdalenefjorden area. Each of the geologists worked with two assistants, and as helicopter trans­ port was not available, small boats were the main means of transportation. Preliminary maps (scale l: 50 000) served as a topographic base for the mapping together with oblique air photographs. These were supplemented in 1968 by vertical air photographs. The approximate location of the mapped area is north of 79 o 30' N, and west of Il o 30' E, within the sheets A4 and A5 of the Norsk Polarinstitutt l : 100 000 topographical map series. The total area mapped amounts to approximately 375 km2• The geology of Danskøya and AlTIsterdanløya north-west Spitsbergen By AUDUN HJELLE Abstract The area considered lies within the highly metamorphic part of the Caledonides of north-west Spitsbergen. The rocks comprise various para-gneisses, migmatites, syntec­ tonic granitic rocks, and post-tectonic granitic dyke intrusions. A sillimanite-cordierite­ almandine paragenesis in biotite gneiss and diopside-wollastonite in skarn rocks suggest the highest grade of metamorphism to be of upper amphibolite