Meso-neoproterozoic evolution of the Caledonian basement of SW Svalbard
2 Table of Contents
1. INTRODUCTION ... 7
2. GEOLOGICAL SETTING ... 9
2.1. North Atlantic Caledonides ... 9
2.2. Svalbard ... 10
2.3. Southwestern Basement Province ... 11
2.3.1. Oscar II Land ... 15
2.3.2. Prins Karls Forland ... 16
2.3.3. Nordenskiöld Land ... 17
2.3.4. Wedel Jarlsberg Land ... 19
2.3.5. Sørkapp Land ... 21
3. ANALYTICAL METHODS... 22
3.1. Electron microprobe ... 22
3.2. Raman spectroscopy ... 22
3.3. Zr in rutile thermometry ... 23
3.4. Sensitive High Resolution Ion Microprobe (SHRIMP) zircon dating ... 23
3.5. Chemical dating of monazite ... 24
4. HP ROCKS OF THE MOTALAFJELLA AREA ... 25
4.1. Introduction ... 25 4.2. Sample description ... 25 4.2.1. Eclogite ... 26 4.2.2. Blueschist ... 31 4.2.3. Metapelite ... 37 4.3. Pressure-temperature estimates ... 40 4.3.1. Quartz-in-garnet barometry ... 40 4.3.2. Zirconium-in-rutile thermometry ... 41 4.4. U-Pb geochronology ... 42 4.5. Discussion ... 45
4.5.1. P-T evolution of the Upper unit, Vestgötabreen Complex ... 45
4.5.2. The age of the early Caledonian HP metamorphism ... 46
4.6. Conclusions ... 46
5. NORDENSKIÖLD LAND BLUESCHISTS ... 47
5.1. Introduction ... 47
Meso-neoproterozoic evolution of the Caledonian basement of SW Svalbard
3
5.2.1. Petrography ... 47
5.2.2. Mineral chemistry ... 49
5.3. Pressure-temperature estimates ... 55
5.4. Discussion and conclusions ... 56
6. THE BERZELIUSEGGENE UNIT OF NORTHERN WEDEL JARLSBERG LAND 60 6.1. Introduction ... 60 6.2. Sample description ... 60 6.2.1. Petrography ... 60 6.2.2. Mineral chemistry ... 62 6.3. Pressure-temperature (P-T) estimates ... 63 6.3.1. Conventional geothermobarometry ... 66
6.3.2. Phase equilibrium modelling ... 67
6.4. Discussion ... 70
6.4.1. Metamorphic evolution and regional correlatives of the Berzeliuseggene unit ... 70
6.4.2. Structural implications ... 71
6.5. Conclusions ... 73
7. THE PINKIE UNIT OF SVALBARD ... 75
7.1. Introduction ... 75
7.2. Sample description ... 75
7.2.1. Petrography and textures ... 76
7.2.2. Mineral chemistry of garnet, staurolite, muscovite, biotite and plagioclase ... 78
7.2.3. Accessory phases ... 85
7.2.4. Monazite chemistry ... 85
7.3. P-T estimates ... 88
7.3.1. P-T-X-M diagrams ... 88
7.3.2. Quartz-in-garnet Raman barometry ... 90
7.3.3. Yttrium in monazite thermometry ... 91
7.4. Monazite dating ... 92
7.5. Petrochronological discussion ... 97
7.5.1. Growth of the garnet-I and reaction history ... 97
7.5.2. Growth of the garnet-II ... 98
7.5.3. Trace elements systematics and its implications for monazite growth ... 98
7.5.4. Formation of the fluorapatite-allanite coronas and fluids activity ... 100
Meso-neoproterozoic evolution of the Caledonian basement of SW Svalbard 4 7.6. Tectonic discussion ... 102 7.7. Conclusions ... 104 8. FINAL REMARKS ... 105 9. REFERENCES ... 106 10. LIST OF FIGURES ... 117 11. LIST OF TABLES ... 122 APPENDIX 1 ... 124
