Norwegian Journal of Geology最新文献

{"title":"Palaeoecology and palaeoenvironments of the Middle Jurassic to lowermost Cretaceous Agardhfjellet Formation (Bathonian–Ryazanian), Spitsbergen, Svalbard","authors":"M. Koevoets, Ø. Hammer, C. Little","doi":"10.17850/NJG99-1-02","DOIUrl":"https://doi.org/10.17850/NJG99-1-02","url":null,"abstract":"We describe the invertebrate assemblages in the Middle Jurassic to lowermost Cretaceous of the Agardhfjellet Formation present in the DH2 rock core material of Central Spitsbergen (Svalbard). Previous studies of the Agardhfjellet Formation do not accurately reflect the distribution of invertebrates throughout the unit as they were limited to sampling discontinuous intervals at outcrop. The rock core material shows the benthic bivalve fauna to reflect dysoxic, but not anoxic environments for the Oxfordian – lower Kimmeridgian interval with sporadic monospecific assemblages of epifaunal bivalves, and more favourable conditions in the Volgian, with major increases in abundance and diversity of Hartwellia sp. assemblages. Overall, the new information from cores show that abundance, diversity and stratigraphic continuity of the fossil record in the Upper Jurassic of Spitsbergen are considerably higher than indicated in outcrop studies. The inferred life positions and feeding habits of the benthic fauna refine the understanding of the depositional environments of the Agardhfjellet Formation. The occurrence pattern of the bivalve genera is correlated with published studies of Arctic localities in East Greenland and Northern Siberia and shows similarities in palaeoecology with the former but not the latter. Ammonite biostratigraphy is used as a tool to date bivalve assemblage overturning events to help identify similar changes in other sections.","PeriodicalId":49741,"journal":{"name":"Norwegian Journal of Geology","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43212714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pegmatites of the Larvik Plutonic Complex, Oslo Rift, Norway: field relations and characterisation","authors":"Øyvind Sunde, H. Friis, T. Andersen","doi":"10.17850/NJG99-1-05","DOIUrl":"https://doi.org/10.17850/NJG99-1-05","url":null,"abstract":"The Larvik Plutonic Complex (LPC) contains pegmatites with a wide array of mineral assemblages and morphological features. The pegmatites have traditionally been described as nepheline syenite and syenite pegmatites which carry agpaitic or miaskitic mineral assemblages, respectively. However, several pegmatites fall outside this simple characterisation due to ‘agpaitic-like’ late magmatic mineral assemblages such as hiortdahlite and eudialyte group minerals. Morphological and mineralogical differences between pegmatites are not unique to, or related with, specific areas of the LPC. Compositional variation and deformation features of the host pluton are the main mechanisms for differing morphology and mineral assemblages between LPC pegmatites. Natrolite replacement of feldspathoid is the most common alteration feature in the nepheline syenite pegmatites. The extent of alteration is closely associated with crystallisation of saccharoidal albite and aegirine. Detailed description of a nepheline syenite pegmatite situated in the Sagåsen quarry provides new insights into the internal evolution and mineral distribution of a large representative pegmatite body. The most important mechanism driving hydrous alteration is the crystallisation of anhydrous primary minerals which leads to an immiscible hydrous fluid driving in situ alterations of primary mineral assemblages.","PeriodicalId":49741,"journal":{"name":"Norwegian Journal of Geology","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42326614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petroleum, coal and research drilling onshore Svalbard: a historical perspective","authors":"K. Senger, P. Brugmans, S. Grundvåg, M. Jochmann, A. Nøttvedt, S. Olaussen, Asbjørn Skotte, A. Smyrak‐Sikora","doi":"10.17850/NJG99-3-1","DOIUrl":"https://doi.org/10.17850/NJG99-3-1","url":null,"abstract":"Source at https://dx.doi.org/10.17850/njg99-3-1. © Copyright the authors. \u0000This work is licensed under a Creative Commons Attribution 4.0 International License","PeriodicalId":49741,"journal":{"name":"Norwegian Journal of Geology","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41843576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Anatomy of a mega-rock slide at Forkastningsfjellet, Spitsbergen and its implications for landslide hazard and risk considerations","authors":"D. Kuhn, T. Redfield, R. Hermanns, M. Fuchs, J. Torizin, D. Balzer","doi":"10.17850/NJG99-1-03","DOIUrl":"https://doi.org/10.17850/NJG99-1-03","url":null,"abstract":"Rock slope failures are a potential source of danger in polar regions. A causal connection between slope failures and climate-related glacial and deglacial processes has been inferred for the growing number of documented events. In this context, we investigated a large-scale rotational rock slide affecting the coastal ridge of Spitsbergen’s Forkastningsfjellet. Based on a detailed structural description, we discuss the kinematics, timing and potential drivers of rock slide activity and present a preliminary landslide hazard assessment. The Forkastningsfjellet rock slide has a footprint of at least 2.03 km2. A minimum rock mass volume of 0.10 km3 was displaced either catastrophically or over a longer time period. Initial movement in the hanging wall of a NW-dipping listric sliding surface led to the fragmentation of the sliding mass into separated tilt blocks that created the present-day, stair-stepped morphology. The main rock slide release was probably related to the deglaciation of Isfjorden and the resulting instability of the weakened rock mass along the oversteepened slopes during Allerød times (~13,900–12,700 BP). Mass wasting and seacliff erosion, mainly controlled by the inherent discontinuities of the fractured and tilted rock masses, currently take place along the steep slopes of the coastal tilt blocks. A preliminary hazard analysis suggests a medium to high hazard for a reactivation of the slide or individual blocks, but uncertainty margins for this classification are large due to a lack of data. Poor control of total displacement data in particular contributes to the uncertainty. A high-acceleration reactivation of a large compartment of the slide (e.g., on the order of 10 million m3) could cause a displacement wave several metres high in Longyearbyen. These results indicate a need for further multidisciplinary investigations to better understand the extent and nature of the rock slide and parameters such as displacement velocities to support a more reliable hazard and risk assessment for the Longyearbyen region.","PeriodicalId":49741,"journal":{"name":"Norwegian Journal of Geology","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41736090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Causes of bias and uncertainty in fracture network analysis","authors":"D. Peacock, D. Sanderson, E. Bastesen, A. Rotevatn, Tor H. Storstein","doi":"10.17850/NJG99-1-06","DOIUrl":"https://doi.org/10.17850/NJG99-1-06","url":null,"abstract":"Fault and fracture networks are analysed to determine the deformation history and to help with such applications as engineering geology and fluidflow modelling. These analyses rely on quantifying such factors as length, frequency and connectivity. Measurements may, however, be influenced by a range of factors relating to resolution, geology, methods used and to the analyst(s). These factors mean that it can be difficult to obtain a single correct solution, with bias and uncertainty being introduced by different analysts, even for something as simple as counting the number of joint intersection points on a well-exposed bedding plane. These problems suggest there are significant issues in comparing databases, for example when using outcrop analogue data to model subsurface data. Our recommendation is that analysts and modellers should be aware of the potential pitfalls in their measurements of structures and, therefore, be more cautious with resultant analyses and models. We suggest that analysts assess their results by testing the reproducibility. Simple ways of doing this include: (1) checking for change in measurements (e.g., fracture frequencies) during the course of a study; (2) remeasuring part of the fracture network to check if the same results are obtained, and; (3) get one or more other analysts to blind-test the fracture network.","PeriodicalId":49741,"journal":{"name":"Norwegian Journal of Geology","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42454466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deglacial patterns and ice-sheet dynamics in the fjords of southern Nordland, Norway","authors":"F. Høgaas, L. Olsen, L. Gislefoss, O. Longva, Anders Romundset, H. Sveian","doi":"10.17850/njg98-4-07","DOIUrl":"https://doi.org/10.17850/njg98-4-07","url":null,"abstract":"This paper presents results from glacial geomorphology mapping in and adjacent to Velfjorden and Ursfjorden in the southern Nordland region of Norway. Submarine and terrestrial landforms were studied and mapped using high-resolution multibeam bathymetric and airborne LiDAR data, in addition to reconnaissance in the field. The work unites ice-marginal deposits related to the established Tautra and Tjøtta glacial events which took place during the Younger Dryas (YD) chronozone. In Ursfjorden, an outlet glacier deposited a c. 100 m-high terminal moraine, whereas moraine ridges and a large sedimentary wedge were deposited in the inner part of Velfjorden. Highly elongated subglacial bedforms located inside the ice-marginal landforms reveal that the fjords were occupied by fast-flowing ice streams during YD. Eighteen new radiocarbon dates from the region, along with twelve recalibrated dates from previous studies, provide time-constraints for ice-sheet configuration and dynamics during deglaciation. Radiocarbon dates suggest that the outer coastal islands became ice-free prior to 14 cal ka BP. Glacially overridden shell-rich units dated to the Allerød Interstadial indicate that the YD ice sheet readvanced at least 5 km before depositing the terminal moraine in Ursfjorden. The ages of shells found near the distinct, regionally correlative, YD raised shoreline indicate that the glacial readvance culminated around early to mid-YD.","PeriodicalId":49741,"journal":{"name":"Norwegian Journal of Geology","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43483603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Late–/postglacial age and tectonic origin of the Nordmannvikdalen Fault, northern Norway","authors":"L. Olsen, O. Olesen, J. Dehls, G. Tassis","doi":"10.17850/njg98-3-09","DOIUrl":"https://doi.org/10.17850/njg98-3-09","url":null,"abstract":"The Nordmannvikdalen Fault (NF) represents one of the two observed postglacial faults in Norway. The two faults constitute the northernmost part of the Lapland province of postglacial faults, occurring in large tracts of northern Sweden and northern Finland. The 1.3 km-long, NW– SE-trending NF is thought to be a normal fault with scarp height increasing from less than 0.50 m in the NW to c. 1.50 m in the SE. A tectonic origin for the Nordmannvikdalen Fault, which seems to be aseismic today, has recently been questioned and alternative causes as either gravitational collapse or overburden creep have been suggested. We carried out three 3–5 m-deep trenches and two ground penetrating radar (GPR) profiles in September 2017 to study the fault at depth. The trenching reveals deformation structures within the lodgement till. The faulting led to cracking of the ground, forming a vertical wedge-shaped crevice, with a width similar to previously recorded large ice wedges and ice wedge casts (fossil ice wedges) in polygonal pattern ground in Arctic areas. The width increases with increasing scarp height, i.e., the vertical displacement. The crevice was filled with sediment, snow and water freezing to ice, with subsequent infilling, during melting seasons, of more debris from the side walls of the host material and cryoturbated and soliflucted soil. The Nordmannvikdalen Fault appears, from the trenching, to have been formed in one single seismic event. The new GPR data show bedrock reflectors dipping approximately 38–45° towards the NE, below the NF scarp. The average angle of the terrain slope between the Nordmannvikdalen Fault scarp and the valley floor is 14°, and the altitude difference between the fault scarp and the Nordmannvikdalen valley floor is approximately 200 m. We find no reason to downgrade the fault to ’very unlikely to be neotectonics’.","PeriodicalId":49741,"journal":{"name":"Norwegian Journal of Geology","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42787781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The late-glacial ice-dammed lake Nedre Glomsjø in Mid-Norway: an open lake system succeeding an actively retreating ice sheet","authors":"F. Høgaas, O. Longva","doi":"10.17850/njg98-4-08","DOIUrl":"https://doi.org/10.17850/njg98-4-08","url":null,"abstract":"","PeriodicalId":49741,"journal":{"name":"Norwegian Journal of Geology","volume":" ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48556555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relative permeability and residual gaseous CO2 saturation in the Jurassic Brentskardhaugen Bed sandstones, Wilhelmøya Subgroup, western central Spitsbergen, Svalbard","authors":"J. N. Moghadam, M. Nooraiepour, H. Hellevang, N. Mondol, Aagaard Per","doi":"10.17850/njg005","DOIUrl":"https://doi.org/10.17850/njg005","url":null,"abstract":"This study investigates fluid-flow properties of the low-permeability Brentskardhaugen Bed (Knorringfjellet Formation), Wilhelmøya Subgroup, western central Spitsbergen, Svalbard. To evaluate the two-phase relative permeability of the water-CO2 system, we performed unsteady state core-flooding experiments using deionised water and gaseous CO2. The absolute permeability and residual fluid saturations were also studied. Moreover, a core plug of the Berea sandstone was tested as a reference sample. The core-flooding experiments recorded microDarcy permeability values (0.022–0.039 mD) for various differential pressures (4 to 12 MPa). The poor grain sorting and the abundance of cement were the main factors controlling the low matrix permeabilities. Closure of sub-micron fractures was the likely reason for reduced permeability with increasing effective stresses. The experimental measurements showed that CO2 fractional flow reached unity at relatively low CO2 saturation (approximately 0.35–0.45). The irreducible water saturation and trapped CO2 saturation were 56% and 23%, respectively. The corresponding endpoint CO2 and water relative permeability were 0.18 and 0.47, respectively. The results, therefore, demonstrate low endpoint CO2 saturation and low relative permeability, in addition to high CO2 fractional flow at high water saturation. The trapped CO2 saturation was relatively high, which suggests a high CO2 immobilisation capability of the Wilhelmøya Subgroup sandstones. Moreover, a lower relative permeability was observed for gaseous CO2 compared to published results for supercritical CO2. In addition, the examined core sample showed a higher trapped CO2 saturation and higher endpoint CO2 relative permeability compared with the porous and permeable Berea sandstone.","PeriodicalId":49741,"journal":{"name":"Norwegian Journal of Geology","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67528098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mesozoic strata of Kong Karls Land, Svalbard, Norway; a link to the northern Barents Sea basins and platforms","authors":"S. Olaussen, G. B. Larssen, W. Helland‐Hansen, E. Johannessen, A. Nøttvedt, F. Riis, B. Rismyhr, M. Smelror, D. Worsley","doi":"10.17850/njg98-4-06","DOIUrl":"https://doi.org/10.17850/njg98-4-06","url":null,"abstract":"1Department of Arctic Geology, University Centre in Svalbard UNIS, 9171 Longyearbyen, Norway. 2Lundin Norway AS, NO–9405 Harstad, Norway. 3Department of Earth Science, University of Bergen, Allégaten 41, 5007 Bergen, Norway. 4EP Skolithos, 4022 Stavanger, Norway. 5Christian Michelsen Research AS, 5892 Bergen, Norway. 6Norwegian Petroleum Directorate, 4003 Stavanger, Norway. 7Geological Survey of Norway, P.O. Box 6215 Sluppen, NO–7491 Trondheim, Norway. 8PRW Geoconsultants, 3475 Sætre, Norway.","PeriodicalId":49741,"journal":{"name":"Norwegian Journal of Geology","volume":"1 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2019-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67528890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}