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Copenhagen, Denmark

GEUS is an abbreviation for Danmarks og Grønlands Geologiske Undersøgelse, the Danish name for the independent sector research institute under the Ministry of Climate and Energy. The English name of this institute is Geological Survey of Denmark and Greenland, an advisory, research and survey institute in hydrogeology, geophysics, geochemistry, stratigraphy, glaciology, ore geology, marine geology, mineralogy, climatology, environmental history, air photo interpretation, geothermic energy fields concerning Denmark and Greenland.GEUS works in close corporation with Geologisk Institut and Geologisk Museum, both part of University of Copenhagen.It publishes a service paper called Greenland Hydrocarbon Exploration Information Service and a newsletter called Greenland Mineral Exploration Newsletter in co-operation with the Bureau of Minerals and Petroleum , a secretariat for the Joint Committee on Mineral Resources under Greenland’s home rule. Wikipedia.

Novel side chain methylated and hexacyclic hopanes have been identified in coals and oils from around the world. Extended hopanes (>C32) with an additional methyl in the side chain (" isohopanes" ) were identified by comparison with synthetic standards. The major C33-C35 isohopanes are 31-methylbishomohopanes, 32-methyltrishomohopanes and 33-methyltetrakishomohopanes. Extended hopanes methylated at C-29 were not detected. The 17α(H),21β(H)-31-methyltrishomohopanes show four peaks on gas chromatography because of the extra asymmetric carbon at C-31. Like regular hopanes, the isohopanes extend beyond C35. Low concentrations of novel hexacyclic hopanes having 35 or more carbons were also detected in oils and coal extracts. The C35 hexacyclic hopanes were identified as 29-cyclopentylhopanes. Isohopanes are released from the kerogen by hydrous pyrolysis and hydropyrolysis. The 22S/(22S+22R) ratio for 31-methylbishomohopanes and other isohopanes is around 0.60 at equilibrium in geological samples. They isomerize slightly more slowly than regular C33 hopanes. Isohop-17(21)-enes, 2α-methylisohopanes and two series of rearranged isohopanes were tentatively identified. Isohopanes can be biodegraded to form the corresponding 25-norhopanes. When 25-norhopanes are not formed, the isohopanes are much more resistant to biodegradation than regular hopanes. In biodegraded oil seeps from Greece, 30-norisohopanes were tentatively assigned. The composition and relative abundance of C33 and C34 isohopanes in a worldwide set of coals and crude oils was determined. Isohopanes are abundant in coal and coal-generated oils, where they can account for more than 5% of all extended hopanes, and low in abundance in oils from source rocks deposited under anoxic conditions. © 2011 Elsevier Ltd. Source

The glaciers in the Melville Bay region of northwest Greenland have shown a mean retreat since the earliest observations at the beginning of the 20th century. The largest, Steenstrup Gletscher, has retreated ∼ 20 km, partly during the period of atmospheric cooling 1940-80. Melville Bay airtemperature observations starting in 1981 indicate a regional change of +0.20° Ca -1. This exceeds the warming on the east coast of Greenland, confirming the west coast to be a region of relatively large change, also in a global perspective. The largest temperature increase is observed in the winter months (0.3-0.4° Ca-1). Results from a 4 year (2004-08) net ablation record obtained by an automatic weather station (AWS) near the calving front of Steenstrup Gletscher show an ablation rate that is relatively low for a low-elevation position on the Greenland ice sheet (2.4m ice equivalent per year). A first-order estimate from positive degree-day totals suggests that net ablation has roughly doubled since the 1980s. A surface energy and mass-balance model is applied to the Steenstrup AWS data to quantify the energy flux contributions to surface melt. Solar radiation is the main source for melt energy, but, due to shortwave radiation penetration into the ice, only one-third of the melt takes place at the glacier surface; nearly two-thirds occurs within the upper ice layers. Source

The Palaeoproterozoic Nagssugtoqidian Orogen extends over 250. km along the east coast of Greenland around the settlement of Tasiilaq. The orogen includes Archaean rocks from the adjoining Rae Craton to the north and the North Atlantic Craton to the south, and Palaeoproterozoic rocks. The Rae Craton consists of orthogneiss and amphibolite included in the Schweizerland and Kuummiut Terranes, and is tectonically overlain in the Kuummiut Terrane by ca. 2100-2200. Ma units that include marble, meta-pelite and -psammite and amphibolite assigned to the Helheim and Kuummiut units. The Kuummiut Terrane was probably subducted underneath the SE-trending ca. 1885. Ma Ammassalik Intrusive Complex, which has a high-temperature metamorphic halo and is characterised by a change from sinistral faulting to pure shear deformation. The southern Isortoq Terrane consists of medium-pressure amphibolite facies bimodal meta-volcanic and <1910. Ma meta-sedimentary rocks assigned to the Kap Tycho Brahe unit, which is in tectonic contact with orthogneiss and amphibolite of the North Atlantic Craton.The rocks of the Kuummiut Terrane were tectonically imbricated in ENE-verging structures during ca. 1870. Ma high-pressure metamorphism. This was followed by NE-SW convergence and close to orthogonal extrusion in the weakened crust, which is characterised by partial melting during decompression. The rocks of the Isortoq Terrane were imbricated in a SE-vergent thrust and ramp system either during oblique subduction of the Kuummiut Terrane or an earlier tectonic stage elsewhere. NE-SW compression, as in the northern terranes, formed SW-vergent thrust systems and folds. This was most likely caused by a change in the regional stress field during collision between ca. 1870 and 1820. Ma. In the north, the Schweizerland Terrane was juxtaposed to the Kuummiut Terrane in southeasterly direction, causing refolding of earlier structures in the lower amphibolite facies. This hinteland-type of deformation was possibly related to tectonism in western Greenland. The latest recognised deformation event was during ca. 1740-1680. Ma associated with NE-SW extension, which is interpreted as orogenic collapse. The complex structural evolution of the orogen was caused by oblique convergence during WSW-directed subduction, the convergence of irregularly shaped cratons and the change of the regional stress field from ENE-WSW to NW-SE during progressive collisional tectonics between the two Archaean cratons. © 2014 Elsevier B.V. Source

Lindstrom S.,Geological Survey of Denmark
Geological Magazine | Year: 2016

A review of the palynofloral succession at the well-documented Triassic-Jurassic boundary sites - Kuhjoch (Austria), St Audrie's Bay (UK), Stenlille (Denmark), Astartekløft (Greenland), Sverdrup Basin (Arctic Canada), Northern Carnarvon Basin (Western Australia), Southeast Queensland (eastern Australia) and New Zealand - show all sites experienced major to moderate re-organization of the terrestrial vegetation during the end-Triassic event. The changes led to subsequent taxonomic losses of between 17% and 73% of the Rhaetian pre-extinction palynoflora. The majority of the typical Rhaetian taxa that disappear are so far not known from in situ occurrences in reproductive structures of macrofossil plant taxa. From an ecological perspective, the most dramatic changes occurred in the Sverdrup Basin, Stenlille, Kuhjoch and Carnarvon Basin, where the pre- and post-extinction palynofloras were fundamentally different in both composition and dominance. These changes correspond to ecological severity Category I of McGhee et al. (2004), while the remaining sites are placed in their Subcategory IIa because there the pre-extinction ecosystems are disrupted, but recover and are not replaced post-extinction. Increased total abundances of spores on both hemispheres during the extinction and recovery intervals may indicate that environmental and/or climatic conditions became less favourable for seed plants. Such conditions may include expected effects of volcanism in the Central Atlantic Magmatic Province, such as acid rain, terrestrial soil and freshwater acidification due to volcanic sulfur dioxide emissions, fluctuating ultraviolet flux due to ozone depletion caused by halogens and halocarbon compounds, and drastic changes in climatic conditions due to greenhouse gas emissions. Copyright © Cambridge University Press 2015. Source

Pedersen S.A.S.,Geological Survey of Denmark
Geological Society Special Publication | Year: 2012

The glaciofluvial deposits are by volume and permeability the most important unit in the terrestrial glacial successions, and they are the obvious target for groundwater as well as hydrocarbon reservoir exploration. The dominant glaciofluvial units are related to the proglacial setting in the foreland of an advancing ice margin, which results in a coarsening-upwards sequence with fine-grained beds at the base and glaciofluvial gravel at the top. In a complete sequence a till caps the unit, and at its base a glacitectonite is formed by shearing related to the development of the deformational layer below the ice. The glacial deposits laid down during the same glacial advance represent a glaciodynamic sequence. An important feature added to this is the proglacial glaciotectonic deformation. The glaciotectonic architectural elements comprise thrust faulting, folding of hanging-wall anticlines, thrust-sheet duplexes, hydrodynamic breccias and mud diapirs, the structural style of which define the glaciotectonic complex. The glaciodynamic sequence corresponds to the glaciodynamic event related to one major ice advance. The glaciodynamic processes representing the event comprise deposition as well as deformation, creating a glaciogenic sedimentary succession and a set of glaciotectonic structures. These constitute the elements to be recognized for defining a glaciodynamic sequence. © The Geological Society of London 2012. Source

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