AG 209 The Tectonic and Sedimentary History of Svalbard Excursion Report August 2006 Søren H. Rasmussen Front picture: Pyramiden Mountain The Tectonic and Sedimentary History of Svalbard 2 Index 1. Introduction..................................................................................................................................4 2. Festningen ....................................................................................................................................5 3. Botnheia .....................................................................................................................................11 4. Janusfjellet .................................................................................................................................12 5. Helvetiafjellet Formation ...........................................................................................................14 6. Basilikafjellet .............................................................................................................................15 7. Storvola ......................................................................................................................................18 8. Pyramiden Mountain..................................................................................................................19 9. Billefjorden Basin ......................................................................................................................20 10. Lövehovden Mountainside.....................................................................................................22 11. Midterhuken Mountainside....................................................................................................23 12. Mediumfjellet Mountainside..................................................................................................24 13. Grumantbyen Thrust ..............................................................................................................25 14. References..............................................................................................................................26 The Tectonic and Sedimentary History of Svalbard 3 1. Introduction This report is based on a field excursion from August the 11th to 20th 2006. The field excursion was a part of the two courses The Quaternary History of Svalbard (AG 210) and The Tectonic and Sedimentary History of Svalbard (AG 209). This report contains all visit locations that was related to the course The Tectonic and Sedimentary History of Svalbard. Guides was: Arvid Nøttvedt and Alvar Braathen. Figure 1 shows a bedrock map of Svalbard on this the visited locations mark. Figure 1: Stratigraphic map of Svalbard (Norwegian Polar Institute). The Tectonic and Sedimentary History of Svalbard 4 2. Festningen Visit on August the 11th and 12th. The profile along the coast from Isfjorden Radio in west to Grønfjorden in east, have one of the most completely bedrock section on Svalbard. In the western end Precambrian metamorphic rock and in east Tertiary sedimentary rock is exposed. This locality lays on the western side of the Central Tertiary Basin, therefore the layer dipping towards east, around 60 % in west and 100 % in east. Figure 3 show a stratiographic log with formations, groups and important member. All of these will by descript below. Billefjorden Group Orustdals Formation, Lower Carboniferous, is layer of sandstone, conglomerate and some coal. It is deposit alluvial as a fan, floodplain or braided stream. Under the Billefjorden Group is the Basement, between there is an unconformity. Deposit from Devon is missing. Gipsdalen Group Wordiekammen Formation, Lower Permian, is limestone. Limestone is shells or fragments from marine organisms. There for the depositing environment is at sea, with oxygen riche condition. Gipshuke Formation, Lower Permian, this is limestone and evaporate. Evaporite is precipitated from evaporate of saltwater. This mean that the sea has been shallow and still for some time, so concentration of salt could be high enough to precipitate. These Evaporites has change calcite with dolomite and are there for Dolostones. There are now fossils in this formation, with could be coursed by the high salt concentration, that animals and plants do not like. Tempelfjorden Group Kapp Starostin Formation, Upper Permian, limestone and shale. These layers contain fossils, and they are intact. This is evidence of climate shift. Figure 2 shows the border between Lower and Upper Permian. Figure 2: Border between Lower and Upper Permian. At the bottom of the picture is Gipshuke Formation and on top is Kapp Strarostin Fromation. The water is continuous shallow, with only little movement, otherwise the fossils would have broken. Water depth around 10 m. Fossils is in the first unit only Brachiopod, in the next unit the diversity of fossils becomes lager, example corals, see figure 4. This means that the water was becoming deeper, a transgression. Kapp Strarostin is special from other of the sedimentary rock. The Tectonic and Sedimentary History of Svalbard 5 Coal Basilika Fm. Cgl Firkant Fm. Tertiary Lower Cretaceous Mudst + sst Carolinefjellet Fm. Deltaic Mudst + sst Helvetiafjellet Fm. Fluvial sst Mudst + sst Rurvikfjellet Fm. Lower Cretaceous Upper Jurassic Mudst + sst Agardfjellet Fm. Lower Jurassic Cgl Brentskardhaugen Bed Upper Triassic Mudst + silt De Geerdalen Fm. + sst (Tschermarkfjellet Fm.) Sst Bravaisberget Fm. Middle Triassic Shale (Botnheia Fm.) Sst Tvillingodden Fm. Shale Sst Vardebukta Fm. Triassic Shale Upper Permian Limest Shale Kapp Starostin Fm. cementated Limest + evap Gipshuken Fm. Lower Permian Limest Wordiekammen Fm. Lower Sst + Carboniferous coal/shale Billefjorden Group + cgl Basement Figure 3: Strationgraphic log of Festningen Profil. The Tectonic and Sedimentary History of Svalbard 6 The rock is cementatede by silicate; the silicate comes from silicate riche sponge. The silicate makes the rock very strong, therefore Kapp Strarostin often is on top of mountains see figure 5. Figure 4: Brachiopod, Lower Kapp Strarostin sandstone, picture 2 cm high. Corals, Middle Kapp Strarostin limestone, picture around 4 cm high. Kapp Strarostin Vardebukta Formation Figure 5: Top of Kapp Strarostin, Upper Permian. Kapp Strarostin is harder therefore it makes the top. Vardekukta Formation is not as hard, there for this has been eroded more. 90 % of all living spices death at the end of Permian. This could be courts by a huge volcanic eruption from Siberia, that raise the CO2 level in the air and the water temperature in the sea. Or it could be meteor strikes in Antarctica. Sassendalen Group Vardebukta Formation, Lower Triassic. This sediment are softer, there is now cementation. Therefore deformations go into this formation, instead of example Kapp Strarostin. Sediments from Greenland were at this time transported to Svalbard, which still is under the sea. The basin gets filled with sediment, this result in a coarsening-upward of the sediments from mud/silt to sand. After a transgression it starts again. Tree times this goes on, this and the next two formations. In this formation there is to sills, one is seen on figure 6. Sills is intrusive igneous rock horizontal with the beds. Unlike dikes there goes through the layers. This Basaltic intrusive comes from volcanic activities at the end of Jurassic, when the Atlantic Ocean starts to open. The Tectonic and Sedimentary History of Svalbard 7 Shale Basalt Shale Figure 6: Sill, intrusive of igneous rock along the layers. Tvillingodden Formation, Lower Triassic, black shale. The black colour is from dead organisms. The total organic contain (TOC) is 6-8 %, with is high. Most of the organisms were algae. The condition at this time was anoxic, otherwise the carbon would have oxidised and not deposit. Anoxic condition only contains where the water is still, like an inlet. The rock is a source rock for oil, is has high carbon contain and has been heated, so there is kerogen in it. This rock contain kerogen type tree, because it is marine carbon. Bravaisberget Formation, Middle Triassic. Like Tvillingodden Formation. In this formation there is beginning to be biotutbation, disturbance of sediment by animals and plants. This is signs of oxygen at sea floor. Kapp Toscana Group De Geerdalen Formation, Upper Triassic, shale and some places red colour. The red colour comes from cementation with Siderite (Iron Carbonate). There is symmetric ripples, see figure 7. Symmetric ripples is from waves, when they move forward and backward. Ripples from stream, where the water flows in one direction are asymmetric. The ripples are a sign of shallow water, where the waves reach the seafloor, example near the shore. Figure 7: Symmetric ripples in De Geerdalen Formation. The Tectonic and Sedimentary History of Svalbard 8 Brentskardhaugen Bed, border between Triassic and Jurassic, this layer is around 10 cm thick. It is orange conglomerate with brown nods. The nods are fish bones there has rolled in mud and thereby getting bigger. The condition must have been low supply of sediments, otherwise the bones have been buried, and sill water so the nodes do not break or carry away. There is doubt about the bed belongs to Triassic or Jurassic. Between this to period there is an unconformity. Adventdalen Group Agardfjellet Formation, Upper Jurassic, layer of black shale and mudstone. Some mudstone layer contain vertical hole from animals, see figure 8. The energy level in the sea is higher in