Pub Date : 2019-07-08DOI: 10.34194/GEUSB-201943-02-03
R. Weibel, T. Thomsen
Titanite (CaTiSiO5) occurs as a rare mineral in magmatic and metamorphic rocks. It is commonly found in clastic sedimentary rocks as an accessory heavy mineral – a mineral of high density. Recently, U-Pb dating of single-grains of detrital titanite has been shown to be a useful tool in sedimentary provenance studies (e.g. McAteer et al. 2010; Thomsen et al. 2015). Titanite U-Pb geochronologies can add important information to constrain the sediment sources of rocks and basins, and can help date precipitation of titanite. However, there are a number of complicating factors that must be taken into consideration for reliable application of titanite U-Pb dating in provenance studies. First, titanite is less stable than zircon – the most commonly employed dating target. For example, in Palaeocene sediments in the North Sea, titanite rarely occurs as detrital grains at burial depths greater than 1400 m (Morton 1984). It can also show dissolution features due to weathering and burial diagenesis (e.g. Morton 1984; Turner & Morton 2007). Second, titanite may precipitate during burial diagenesis, which would reflect the burial history of sediments and not their provenance. Precipitation of authigenic titanite is documented from deeply buried (i.e. at temperatures greater than 100°C) volcaniclastic sandstones and mudstones (Helmond & Van de Kamp 1984; Milliken 1992) and intrusion-associated mineralisation in volcanic Permian sandstones (van Panhuys-Sigler & Trewin 1990). Moreover, titanite also occurs in shallow-buried Jurassic sandstones with no volcanic affinity (Morad 1988). Thus, the formation of titanite is not necessarily linked to a volcaniclastic source, but nevertheless, the presence of volcanic material seems to promote titanite precipitation. If authigenic titanite precipitation was incorrectly identified as detrital, this would have considerable implications for provenance investigations, as apparently titanite-rich source rocks would be wrongly inferred to be present in the sediment source area. Here, we present examples from the Kangerlussuaq Basin in southern East Greenland of what appeared to be detrital titanite. However, new U-Pb dating reveals that the titanite formed authigenically, and hence contributed to the burial history, and not the provenance, of the sediments.
钛矿(CaTiSiO5)作为一种稀有矿物存在于岩浆岩和变质岩中。它通常在碎屑沉积岩中被发现，作为一种辅助重矿物——一种高密度的矿物。最近，单粒碎屑钛矿的U-Pb定年已被证明是沉积物源研究的有用工具(例如McAteer et al. 2010;Thomsen et al. 2015)。钛矿U-Pb年代学可以为约束岩石和盆地的沉积来源提供重要信息，并有助于确定钛矿降水的年代。然而，为了在物源研究中可靠地应用钛矿U-Pb定年，必须考虑许多复杂的因素。首先，钛矿不如锆石稳定——锆石是最常用的测年目标。例如，在北海古新世沉积物中，埋深大于1400 m的钛矿很少以碎屑颗粒的形式出现(Morton 1984)。它也可以显示风化和埋藏成岩作用的溶解特征(如Morton 1984;Turner & Morton 2007)。其次，在埋藏成岩作用过程中可能有钛矿沉淀，这反映了沉积物的埋藏历史，而不是其物源。从深埋(即温度大于100°C)的火山碎屑砂岩和泥岩(Helmond & Van de Kamp 1984;Milliken 1992)和火山二叠纪砂岩的侵入相关矿化(van Panhuys-Sigler & Trewin 1990)。此外，钛铁矿也赋存于无火山亲和作用的浅埋侏罗系砂岩中(Morad 1988)。因此，钛矿的形成不一定与火山碎屑来源有关，但是，火山物质的存在似乎促进了钛矿的沉淀。如果自生钛矿沉淀被错误地识别为碎屑，这将对物源调查产生相当大的影响，因为显然富含钛矿的烃源岩将被错误地推断为存在于沉积物源区。在这里，我们展示了来自东格陵兰岛南部Kangerlussuaq盆地的似乎是碎屑钛矿的例子。然而，新的U-Pb测年显示，钛矿是自生形成的，因此对埋藏历史有贡献，而不是沉积物的来源。
{"title":"U-Pb dating identifies titanite precipitation in Paleogene sandstones from a volcanic terrane, East Greenland","authors":"R. Weibel, T. Thomsen","doi":"10.34194/GEUSB-201943-02-03","DOIUrl":"https://doi.org/10.34194/GEUSB-201943-02-03","url":null,"abstract":"Titanite (CaTiSiO5) occurs as a rare mineral in magmatic and metamorphic rocks. It is commonly found in clastic sedimentary rocks as an accessory heavy mineral – a mineral of high density. Recently, U-Pb dating of single-grains of detrital titanite has been shown to be a useful tool in sedimentary provenance studies (e.g. McAteer et al. 2010; Thomsen et al. 2015). Titanite U-Pb geochronologies can add important information to constrain the sediment sources of rocks and basins, and can help date precipitation of titanite. However, there are a number of complicating factors that must be taken into consideration for reliable application of titanite U-Pb dating in provenance studies. \u0000First, titanite is less stable than zircon – the most commonly employed dating target. For example, in Palaeocene sediments in the North Sea, titanite rarely occurs as detrital grains at burial depths greater than 1400 m (Morton 1984). It can also show dissolution features due to weathering and burial diagenesis (e.g. Morton 1984; Turner & Morton 2007). Second, titanite may precipitate during burial diagenesis, which would reflect the burial history of sediments and not their provenance. Precipitation of authigenic titanite is documented from deeply buried (i.e. at temperatures greater than 100°C) volcaniclastic sandstones and mudstones (Helmond & Van de Kamp 1984; Milliken 1992) and intrusion-associated mineralisation in volcanic Permian sandstones (van Panhuys-Sigler & Trewin 1990). Moreover, titanite also occurs in shallow-buried Jurassic sandstones with no volcanic affinity (Morad 1988). Thus, the formation of titanite is not necessarily linked to a volcaniclastic source, but nevertheless, the presence of volcanic material seems to promote titanite precipitation. If authigenic titanite precipitation was incorrectly identified as detrital, this would have considerable implications for provenance investigations, as apparently titanite-rich source rocks would be wrongly inferred to be present in the sediment source area. Here, we present examples from the Kangerlussuaq Basin in southern East Greenland of what appeared to be detrital titanite. However, new U-Pb dating reveals that the titanite formed authigenically, and hence contributed to the burial history, and not the provenance, of the sediments.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79777076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-08DOI: 10.34194/GEUSB-201943-02-01
W. Colgan, K. Mankoff, K. Kjeldsen, A. Bjørk, J. Box, S. Simonsen, L. Sørensen, S. A. Khan, A. Solgaard, R. Forsberg, H. Skourup, L. Stenseng, S. Kristensen, S. Hvidegaard, M. Citterio, N. Karlsson, X. Fettweis, A. Ahlstrøm, S. Andersen, D. As, R. Fausto
The Programme for Monitoring of the Greenland Ice Sheet (PROMICE) has measured ice-sheet elevation and thickness via repeat airborne surveys circumscribing the ice sheet at an average elevation of 1708 ± 5 m (Sorensen et al. 2018). We refer to this 5415 km survey as the ‘PROMICE perimeter’. Here, we assess ice-sheet mass balance following the input-output approach of Andersen et al. (2015). We estimate ice-sheet output, or the ice discharge across the ice-sheet grounding line, by applying downstream corrections to the ice flux across the PROMICE perimeter. We subtract this ice discharge from ice-sheet input, or the area-integrated, ice sheet surface mass balance, estimated by a regional climate model. While Andersen et al. (2015) assessed ice-sheet mass balance in 2007 and 2011, this updated input-output assessment now estimates the annual sea-level rise contribution from eighteen sub-sectors of the Greenland ice sheet over the 1995–2015 period.
{"title":"Greenland ice sheet mass balance assessed by PROMICE (1995–2015)","authors":"W. Colgan, K. Mankoff, K. Kjeldsen, A. Bjørk, J. Box, S. Simonsen, L. Sørensen, S. A. Khan, A. Solgaard, R. Forsberg, H. Skourup, L. Stenseng, S. Kristensen, S. Hvidegaard, M. Citterio, N. Karlsson, X. Fettweis, A. Ahlstrøm, S. Andersen, D. As, R. Fausto","doi":"10.34194/GEUSB-201943-02-01","DOIUrl":"https://doi.org/10.34194/GEUSB-201943-02-01","url":null,"abstract":"The Programme for Monitoring of the Greenland Ice Sheet (PROMICE) has measured ice-sheet elevation and thickness via repeat airborne surveys circumscribing the ice sheet at an average elevation of 1708 ± 5 m (Sorensen et al. 2018). We refer to this 5415 km survey as the ‘PROMICE perimeter’. Here, we assess ice-sheet mass balance following the input-output approach of Andersen et al. (2015). We estimate ice-sheet output, or the ice discharge across the ice-sheet grounding line, by applying downstream corrections to the ice flux across the PROMICE perimeter. We subtract this ice discharge from ice-sheet input, or the area-integrated, ice sheet surface mass balance, estimated by a regional climate model. While Andersen et al. (2015) assessed ice-sheet mass balance in 2007 and 2011, this updated input-output assessment now estimates the annual sea-level rise contribution from eighteen sub-sectors of the Greenland ice sheet over the 1995–2015 period.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88887506","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-01DOI: 10.34194/GEUSB-201943-01-01
W. Colgan, J. Box, S. Ribeiro, K. Kjeldsen
Between 1850 and 2006 global mean sea level rose by 24 ± 18 cm. It is projected to rise a further 52 ± 21 cm under the Representative Concentration Pathway (RCP) 4.5 scenario, which approximates the carbon emissions reductions of the ‘Paris Agreement’ climate pathway. It is projected to rise 74 ± 28 cm under the RCP8.5 scenario, which represents a ‘business-as-usual’ climate pathway (Box & Colgan 2017). These rates of recent and future sea-level rise are faster than those reconstructed for previous warm intervals, such as the Medieval Climatic Optimum (c. 1000 to 1400 CE) and the Holocene Thermal Maximum (c. 7000 to 3000 BCE) (Gehrels & Shennan 2015). Moreover, palaeo reconstructions indicate a global sea-level sensitivity of two metres per degree of warming (Levermann et al. 2013). The forces driving global sea-level change are complex. The global sea-level budget includes the transfer of land ice into the ocean, thermal expansion of seawater, changes in land water storage, and changes in ocean basin volume (Church et al. 2013). At the local scale, the evolving planetary gravity due to shifting water and ice masses, shifting oceanic and atmospheric currents and persistent tectonic and glacial isostatic adjustment processes can also be important. Sea-level changes around the globe are therefore far from uniform (Jevrejeva et al. 2016). Here, we highlight the value of combining palaeo reconstructions of sea level, the measured tide gauge record, and projections of future sea level. This allows us to understand local sea-level changes from the recent past in the context of global projections for the near future (0 to 2100 CE). We explore the strong differences in local sea-level histories and future projections at three Danish cities: Skagen and Esbjerg, as they have contrasting glacio-isostatic adjustment histories, and Copenhagen, where we also compare local and global drivers of present-day sea-level rise based on previously published research.
1850年至2006年间，全球平均海平面上升了24±18厘米。在代表性浓度路径(RCP) 4.5情景下(接近《巴黎协定》气候路径的碳减排)，预计海平面将进一步上升52±21厘米。在RCP8.5情景下，预计海平面将上升74±28厘米，这代表了“一切照旧”的气候路径(Box & Colgan 2017)。这些近期和未来的海平面上升速度比以前的温暖间隔重建的速度要快，例如中世纪气候最佳期(公元前1000年至1400年)和全新世热最大值期(公元前7000年至3000年)(Gehrels & Shennan 2015)。此外，古重建表明，全球海平面的敏感度为每升温一度2米(Levermann et al. 2013)。推动全球海平面变化的力量是复杂的。全球海平面预算包括陆地冰向海洋的转移、海水的热膨胀、陆地储水量的变化和海洋盆地体积的变化(Church et al. 2013)。在局部尺度上，由移动的水和冰块、移动的海洋和大气流以及持续的构造和冰川均衡调整过程引起的行星重力演化也可能是重要的。因此，全球海平面变化远非均匀(Jevrejeva et al. 2016)。在这里，我们强调将古海平面重建、测潮仪记录和未来海平面预测结合起来的价值。这使我们能够在对不久的将来(公元0年至2100年)的全球预测的背景下，了解最近的过去的局部海平面变化。我们探索了丹麦三个城市在当地海平面历史和未来预测方面的巨大差异:斯卡恩和埃斯比约，因为它们具有对比鲜明的冰川均衡调整历史;哥本哈根，我们还根据先前发表的研究比较了当前海平面上升的本地和全球驱动因素。
{"title":"Sea-level rise in Denmark: Bridging local reconstructions and global projections","authors":"W. Colgan, J. Box, S. Ribeiro, K. Kjeldsen","doi":"10.34194/GEUSB-201943-01-01","DOIUrl":"https://doi.org/10.34194/GEUSB-201943-01-01","url":null,"abstract":"Between 1850 and 2006 global mean sea level rose by 24 ± 18 cm. It is projected to rise a further 52 ± 21 cm under the Representative Concentration Pathway (RCP) 4.5 scenario, which approximates the carbon emissions reductions of the ‘Paris Agreement’ climate pathway. It is projected to rise 74 ± 28 cm under the RCP8.5 scenario, which represents a ‘business-as-usual’ climate pathway (Box & Colgan 2017). These rates of recent and future sea-level rise are faster than those reconstructed for previous warm intervals, such as the Medieval Climatic Optimum (c. 1000 to 1400 CE) and the Holocene Thermal Maximum (c. 7000 to 3000 BCE) (Gehrels & Shennan 2015). Moreover, palaeo reconstructions indicate a global sea-level sensitivity of two metres per degree of warming (Levermann et al. 2013). \u0000The forces driving global sea-level change are complex. The global sea-level budget includes the transfer of land ice into the ocean, thermal expansion of seawater, changes in land water storage, and changes in ocean basin volume (Church et al. 2013). At the local scale, the evolving planetary gravity due to shifting water and ice masses, shifting oceanic and atmospheric currents and persistent tectonic and glacial isostatic adjustment processes can also be important. Sea-level changes around the globe are therefore far from uniform (Jevrejeva et al. 2016). \u0000Here, we highlight the value of combining palaeo reconstructions of sea level, the measured tide gauge record, and projections of future sea level. This allows us to understand local sea-level changes from the recent past in the context of global projections for the near future (0 to 2100 CE). We explore the strong differences in local sea-level histories and future projections at three Danish cities: Skagen and Esbjerg, as they have contrasting glacio-isostatic adjustment histories, and Copenhagen, where we also compare local and global drivers of present-day sea-level rise based on previously published research.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85261103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-07-01DOI: 10.34194/GEUSB-201943-02-08
K. Svennevig, A. Solgaard, S. Salehi, T. Dahl-Jensen, J. M. Boncori, T. Larsen, P. Voss
The landslide of 17 June 2017 at Karrat Fjord, central West Greenland, triggered a tsunami that caused four fatalities. The catastrophe highlighted the need for a better understanding of landslides in Greenland and initiated a recent nation-wide landslide screening project led by the Geological Survey of Denmark and Greenland (GEUS; see also Svennevig (2019) this volume). This paper describes an approach for compiling freely available data to improve GEUS’ capability to monitor active landslides in remote areas of the Arctic in near real time. Data include seismological records, space borne Synthetic Aperture Radar (SAR) data and multispectral optical satellite imagery. The workflow was developed in 2018 as part of a collaboration between GEUS and scientists from the Technical University of Denmark (DTU). This methodology provides a model through which GEUS will be able to monitor active landslides and provide relevant knowledge to the public and authorities in the event of future landslides that pose a risk to human life and infrastructure in Greenland. We use a minor event on 26 March 2018, near the site of the Karrat 2017 landslide, as a case study to demonstrate 1) the value of multidisciplinary approaches and 2) that the area around the landslide has continued to be periodically active since the main landslide in 2017.
{"title":"A multidisciplinary approach to landslide monitoring in the Arctic: Case study of the March 2018 ML 1.9 seismic event near the Karrat 2017 landslide","authors":"K. Svennevig, A. Solgaard, S. Salehi, T. Dahl-Jensen, J. M. Boncori, T. Larsen, P. Voss","doi":"10.34194/GEUSB-201943-02-08","DOIUrl":"https://doi.org/10.34194/GEUSB-201943-02-08","url":null,"abstract":"The landslide of 17 June 2017 at Karrat Fjord, central West Greenland, triggered a tsunami that caused four fatalities. The catastrophe highlighted the need for a better understanding of landslides in Greenland and initiated a recent nation-wide landslide screening project led by the Geological Survey of Denmark and Greenland (GEUS; see also Svennevig (2019) this volume). \u0000This paper describes an approach for compiling freely available data to improve GEUS’ capability to monitor active landslides in remote areas of the Arctic in near real time. Data include seismological records, space borne Synthetic Aperture Radar (SAR) data and multispectral optical satellite imagery. The workflow was developed in 2018 as part of a collaboration between GEUS and scientists from the Technical University of Denmark (DTU). This methodology provides a model through which GEUS will be able to monitor active landslides and provide relevant knowledge to the public and authorities in the event of future landslides that pose a risk to human life and infrastructure in Greenland. \u0000We use a minor event on 26 March 2018, near the site of the Karrat 2017 landslide, as a case study to demonstrate 1) the value of multidisciplinary approaches and 2) that the area around the landslide has continued to be periodically active since the main landslide in 2017.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"18 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88830476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-06-26DOI: 10.34194/GEUSB-201943-02-02
J. K. Andersen, R. Fausto, K. Hansen, J. Box, S. Andersen, A. Ahlstrøm, D. As, M. Citterio, W. Colgan, N. Karlsson, K. Kjeldsen, N. Korsgaard, S. H. Larsen, K. Mankoff, Allan Ø. Pedersen, Christopher L. Shields, A. Solgaard, B. Vandecrux
The Greenland ice sheet has been losing mass in response to increased surface melting (Khan et al. 2015; van den Broeke et al. 2017) as well as discharge of ice from marine terminating outlet glaciers (van den Broeke et al. 2009; Box et al. 2018). Marine terminating outlet glaciers flow to the ocean where they lose mass by e.g. iceberg calving. Currently, the mass loss from the Greenland ice sheet is the largest Arctic contributor to global sea-level rise (van den Broeke et al. 2009, 2017; Box et al. 2018). Therefore, monitoring changes in the Greenland ice sheet is essential to provide policy makers with reliable data. There is a consensus that most marine terminating outlet glaciers have retreated in recent decades, and that the increased calving rates are a response to recent atmospheric and oceanic warming (e.g. Box et al. 2018; Moon et al. 2018). The rate of dynamic mass loss is determined by changes of the glacier calving front (i.e. its terminus) position, ice thickness and changes in ice flow. Ocean temperature and fjord circulation also influence the calving front stability by melting the glacier below the water line, thinning the ice that is in contact with water (Moon et al. 2014). Change in calving front position is therefore an important indicator for monitoring the dynamic behaviour of the upstream area of the ice sheet, which is further modulated by local topographic features and buttressing effects (Rignot & Kanagaratnam 2006; Nick et al. 2009). The Programme for Monitoring of the Greenland Ice Sheet (PROMICE) is dedicated to monitoring changes in the mass budget of the Greenland ice sheet, including monitoring of the calving front lines of marine terminating outlet glaciers. Here, we present an updated collection of annual measurements of end-of-melt-season calving front lines for 47 marine terminating outlet glaciers in Greenland between 1999 and 2018. We also present an example application of the data set, in which we estimate area changes for this group of glaciers since 1999. The Greenland calving front lines were measured from optical satellite imagery obtained from Landsat, Aster, and Sentinel-2 (Table 1). The PROMICE calving front product is freely available for download as ESRI shapefiles.
由于地表融化加剧，格陵兰冰盖的质量一直在下降(Khan et al. 2015;van den Broeke et al. 2017)以及海洋终端出口冰川的冰排放(van den Broeke et al. 2009;Box et al. 2018)。海洋终止出口冰川流向海洋，在那里它们因冰山崩解等原因失去质量。目前，格陵兰冰盖的质量损失是北极地区导致全球海平面上升的最大因素(van den Broeke et al. 2009, 2017;Box et al. 2018)。因此，监测格陵兰冰盖的变化对于向决策者提供可靠的数据至关重要。人们一致认为，近几十年来，大多数海洋终端出口冰川已经退缩，产犊率的增加是对最近大气和海洋变暖的响应(例如Box等人，2018;Moon et al. 2018)。动态质量损失率由冰川崩解锋(即其终点)位置的变化、冰厚和冰流的变化决定。海洋温度和峡湾环流也通过融化水线以下的冰川，使与水接触的冰变薄而影响产犊锋的稳定性(Moon et al. 2014)。因此，产犊前沿位置的变化是监测冰盖上游地区动态行为的一个重要指标，该动态行为受到当地地形特征和支撑效应的进一步调节(Rignot & Kanagaratnam 2006;Nick et al. 2009)。格陵兰冰原监测方案专门监测格陵兰冰原质量预算的变化，包括监测海洋终止出口冰川的产犊前沿。在这里，我们提供了1999年至2018年期间格陵兰岛47个海洋终止出口冰川融化季节结束产犊前线的年度测量数据的更新集合。我们还提供了一个数据集的应用实例，其中我们估计了自1999年以来这组冰川的面积变化。格陵兰产犊锋线是根据Landsat、Aster和Sentinel-2的光学卫星图像测量的(表1)。PROMICE产犊锋线产品可以作为ESRI shapefiles免费下载。
{"title":"Update of annual calving front lines for 47 marine terminating outlet glaciers in Greenland (1999–2018)","authors":"J. K. Andersen, R. Fausto, K. Hansen, J. Box, S. Andersen, A. Ahlstrøm, D. As, M. Citterio, W. Colgan, N. Karlsson, K. Kjeldsen, N. Korsgaard, S. H. Larsen, K. Mankoff, Allan Ø. Pedersen, Christopher L. Shields, A. Solgaard, B. Vandecrux","doi":"10.34194/GEUSB-201943-02-02","DOIUrl":"https://doi.org/10.34194/GEUSB-201943-02-02","url":null,"abstract":"The Greenland ice sheet has been losing mass in response to increased surface melting (Khan et al. 2015; van den Broeke et al. 2017) as well as discharge of ice from marine terminating outlet glaciers (van den Broeke et al. 2009; Box et al. 2018). Marine terminating outlet glaciers flow to the ocean where they lose mass by e.g. iceberg calving. Currently, the mass loss from the Greenland ice sheet is the largest Arctic contributor to global sea-level rise (van den Broeke et al. 2009, 2017; Box et al. 2018). Therefore, monitoring changes in the Greenland ice sheet is essential to provide policy makers with reliable data. \u0000There is a consensus that most marine terminating outlet glaciers have retreated in recent decades, and that the increased calving rates are a response to recent atmospheric and oceanic warming (e.g. Box et al. 2018; Moon et al. 2018). The rate of dynamic mass loss is determined by changes of the glacier calving front (i.e. its terminus) position, ice thickness and changes in ice flow. Ocean temperature and fjord circulation also influence the calving front stability by melting the glacier below the water line, thinning the ice that is in contact with water (Moon et al. 2014). Change in calving front position is therefore an important indicator for monitoring the dynamic behaviour of the upstream area of the ice sheet, which is further modulated by local topographic features and buttressing effects (Rignot & Kanagaratnam 2006; Nick et al. 2009). \u0000The Programme for Monitoring of the Greenland Ice Sheet (PROMICE) is dedicated to monitoring changes in the mass budget of the Greenland ice sheet, including monitoring of the calving front lines of marine terminating outlet glaciers. Here, we present an updated collection of annual measurements of end-of-melt-season calving front lines for 47 marine terminating outlet glaciers in Greenland between 1999 and 2018. We also present an example application of the data set, in which we estimate area changes for this group of glaciers since 1999. The Greenland calving front lines were measured from optical satellite imagery obtained from Landsat, Aster, and Sentinel-2 (Table 1). The PROMICE calving front product is freely available for download as ESRI shapefiles.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82117118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-06-24DOI: 10.34194/GEUSB-201943-01-06
O. Bennike, N. Nørgaard‐Pedersen, J. Jensen
The brackish water Baltic Sea and the more saline Kattegat in the north are connected by three straits, Lillebaelt, Storebaelt and Oresund. Storebaelt (the Great Belt) is the deepest and widest of the straits. The strait is characterised by deeply incised channels that are partly filled by sediments. The water depth in major parts of Storebaelt is about 20 m, though in some areas the channels are more than 50 m deep. The formation of the channels has been subject to discussion. Andersen (1927) suggested that the channels formed due to strong currents that are still active today or by fluvial erosion during the so-called continental period (Fastlandstiden) in the Early Holocene. At this time, the relative sea level in the region was lower than at present and a huge lake, the Ancylus Lake, which occupied the Baltic Basin, may have drained via Storebaelt. Andersen dismissed the idea that the channels were formed by subglacial erosion by meltwater during the last deglaciation. More Recently, Mathiassen (1997) interpreted some of the deposits in the channels as late glacial, a viewpoint followed by Bennike et al. (2004). However, the age of the late glacial deposits in the channels are poorly constrained. The first studies of sediment cores from Storebaelt were carried out by Krog (1973), Winn (1974) and Mathiassen (1997), but these studies concentrated on the Holocene development from mires to lakes to brackish and marine environments. Wiberg-Larsen et al. (2001) documented the presence of Early Holocene river deposits. Here we report on some new ages of macrofossils from late glacial deposits in the Storebaelt channels.
{"title":"The channels in Storebælt, Denmark: implications of new radiocarbon ages","authors":"O. Bennike, N. Nørgaard‐Pedersen, J. Jensen","doi":"10.34194/GEUSB-201943-01-06","DOIUrl":"https://doi.org/10.34194/GEUSB-201943-01-06","url":null,"abstract":"The brackish water Baltic Sea and the more saline Kattegat in the north are connected by three straits, Lillebaelt, Storebaelt and Oresund. Storebaelt (the Great Belt) is the deepest and widest of the straits. The strait is characterised by deeply incised channels that are partly filled by sediments. The water depth in major parts of Storebaelt is about 20 m, though in some areas the channels are more than 50 m deep. \u0000The formation of the channels has been subject to discussion. Andersen (1927) suggested that the channels formed due to strong currents that are still active today or by fluvial erosion during the so-called continental period (Fastlandstiden) in the Early Holocene. At this time, the relative sea level in the region was lower than at present and a huge lake, the Ancylus Lake, which occupied the Baltic Basin, may have drained via Storebaelt. Andersen dismissed the idea that the channels were formed by subglacial erosion by meltwater during the last deglaciation. More Recently, Mathiassen (1997) interpreted some of the deposits in the channels as late glacial, a viewpoint followed by Bennike et al. (2004). However, the age of the late glacial deposits in the channels are poorly constrained. \u0000The first studies of sediment cores from Storebaelt were carried out by Krog (1973), Winn (1974) and Mathiassen (1997), but these studies concentrated on the Holocene development from mires to lakes to brackish and marine environments. Wiberg-Larsen et al. (2001) documented the presence of Early Holocene river deposits. Here we report on some new ages of macrofossils from late glacial deposits in the Storebaelt channels.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89348103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-06-24DOI: 10.34194/GEUSB-201943-01-02
E. Pastén-Zapata, T. Sonnenborg, J. Refsgaard
Global Climate Models (GCMs) are the main tools used to assess the impacts of climate change. Due to their coarse resolution, with cells of c. 100 km × 100 km, GCMs are dynamically downscaled using Regional Climate Models (RCMs) that better incorporate the local physical features and simulate the climate of a smaller region, e.g. a country. However, RCMs tend to have systematic biases when compared with local observations, such as deviations from day-to-day measurements, and from the mean and extreme events. As a result, confidence in the model projections decreases. One way to address this is to correct the RCM output using statistical methods that relate the simulations with the observations, producing bias-corrected (BC) projections. Here, we present the first assessment of a previously published method to bias-correct 21 RCM projections of daily temperature and precipitation for Denmark. We assess the projected changes and sources of uncertainty. The study provides an initial assessment of the bias correction procedure applied to this set of model outputs to adjust projections of annual temperature, precipitation and potential evapotranspiration (PET). This method is expected to provide a foundation for further analysis of climate change impacts in Denmark.
全球气候模式(GCMs)是评估气候变化影响的主要工具。由于gcm的分辨率较粗，单元为约100 km × 100 km，因此可以使用区域气候模式(RCMs)动态缩小尺度，从而更好地结合当地的物理特征并模拟较小区域(例如一个国家)的气候。然而，与当地观测相比，rcm往往存在系统性偏差，例如与日常测量、平均和极端事件的偏差。结果，模型预测的可信度降低了。解决这个问题的一种方法是使用将模拟与观测相关联的统计方法来纠正RCM输出，从而产生偏差校正(BC)预测。在这里，我们首次评估了先前发表的一种方法，该方法可以对丹麦的日温度和降水的21个RCM预测进行偏差校正。我们评估预估的变化和不确定性的来源。该研究对应用于这组模式输出的偏差校正程序进行了初步评估，以调整年温度、降水和潜在蒸散(PET)的预估。该方法有望为进一步分析丹麦的气候变化影响奠定基础。
{"title":"Climate change: Sources of uncertainty in precipitation and temperature projections for Denmark","authors":"E. Pastén-Zapata, T. Sonnenborg, J. Refsgaard","doi":"10.34194/GEUSB-201943-01-02","DOIUrl":"https://doi.org/10.34194/GEUSB-201943-01-02","url":null,"abstract":"Global Climate Models (GCMs) are the main tools used to assess the impacts of climate change. Due to their coarse resolution, with cells of c. 100 km × 100 km, GCMs are dynamically downscaled using Regional Climate Models (RCMs) that better incorporate the local physical features and simulate the climate of a smaller region, e.g. a country. However, RCMs tend to have systematic biases when compared with local observations, such as deviations from day-to-day measurements, and from the mean and extreme events. As a result, confidence in the model projections decreases. One way to address this is to correct the RCM output using statistical methods that relate the simulations with the observations, producing bias-corrected (BC) projections. \u0000Here, we present the first assessment of a previously published method to bias-correct 21 RCM projections of daily temperature and precipitation for Denmark. We assess the projected changes and sources of uncertainty. The study provides an initial assessment of the bias correction procedure applied to this set of model outputs to adjust projections of annual temperature, precipitation and potential evapotranspiration (PET). This method is expected to provide a foundation for further analysis of climate change impacts in Denmark.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"173 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85589921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-06-17DOI: 10.34194/GEUSB-201943-01-05
N. Schovsbo, F. Jakobsen
Between 1993 and 2017, Denmark was one of the largest oil exporting countries in Europe having gained this position from its share in the highly prolific Danish Central Graben. However, outside the Central Graben few prospects have been adequately mapped, due to a lack of data in these socalled ‘white areas.’ As such, their potential for hydrocarbon accumulation remains uncertain. This paper presents an update of the prospect and play types in this area outside the Danish Central Graben, east of 6°15´E longitude (Fig. 1), based on results from the last 30 years of exploration activities. The paper is part of a resource assessment made by the Geological Survey of Denmark and Greenland (GEUS) to the Danish Energy Agency (Schovsbo & Jakobsen 2017) and is an update of a former review of the area made in 1987 (Thomsen et al. 1987). The succeeding exploration efforts have not changed the overall low expectation for the play types in the area. Here, we show that an uncertain resource is associated with both the Zechstein carbonate play in the North German Basin and the Upper Triassic – Lower Jurassic sandstone and lower Palaeozoic shale gas plays in northern Jylland. However, questions remain as to the source of hydrocarbons in the western offshore area. Specifically, we are unable to confirm (or refute) whether these structures are sourced via long-distance migration of hydrocarbons from the Danish Central Graben.
在1993年至2017年期间，丹麦是欧洲最大的石油出口国之一，其在高产的丹麦中央地堑中的份额获得了这一地位。然而，在中央地堑之外，由于缺乏这些所谓的“白色区域”的数据，很少有远景被充分地绘制出来。因此，它们的油气聚集潜力仍不确定。本文根据过去30年的勘探成果，对丹麦中央地堑外东经6°15′以东地区(图1)的前景和储层类型进行了更新。该论文是丹麦和格陵兰地质调查局(GEUS)向丹麦能源署(Schovsbo & Jakobsen 2017)进行的资源评估的一部分，是对1987年对该地区进行的前一次审查的更新(Thomsen et al. 1987)。后续的勘探工作并没有改变该地区对油气藏类型的总体低预期。本文认为，北德意志盆地的Zechstein碳酸盐岩和日德兰北部的上三叠统-下侏罗统砂岩和下古生代页岩气都具有不确定的资源。然而，对于西部近海地区的碳氢化合物来源仍然存在疑问。具体来说，我们无法证实(或反驳)这些构造是否来自丹麦中央地堑的长距离油气运移。
{"title":"Review of hydrocarbon potential in East Denmark following 30 years of exploration activities","authors":"N. Schovsbo, F. Jakobsen","doi":"10.34194/GEUSB-201943-01-05","DOIUrl":"https://doi.org/10.34194/GEUSB-201943-01-05","url":null,"abstract":"Between 1993 and 2017, Denmark was one of the largest oil exporting countries in Europe having gained this position from its share in the highly prolific Danish Central Graben. However, outside the Central Graben few prospects have been adequately mapped, due to a lack of data in these socalled ‘white areas.’ As such, their potential for hydrocarbon accumulation remains uncertain. This paper presents an update of the prospect and play types in this area outside the Danish Central Graben, east of 6°15´E longitude (Fig. 1), based on results from the last 30 years of exploration activities. The paper is part of a resource assessment made by the Geological Survey of Denmark and Greenland (GEUS) to the Danish Energy Agency (Schovsbo & Jakobsen 2017) and is an update of a former review of the area made in 1987 (Thomsen et al. 1987). The succeeding exploration efforts have not changed the overall low expectation for the play types in the area. Here, we show that an uncertain resource is associated with both the Zechstein carbonate play in the North German Basin and the Upper Triassic – Lower Jurassic sandstone and lower Palaeozoic shale gas plays in northern Jylland. However, questions remain as to the source of hydrocarbons in the western offshore area. Specifically, we are unable to confirm (or refute) whether these structures are sourced via long-distance migration of hydrocarbons from the Danish Central Graben.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88772141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-06-17DOI: 10.34194/GEUSB-201943-02-07
K. Svennevig
The landslide of 17 June 2017 in Karrat Fjord, central West Greenland, highlighted the need for a better understanding of landslides and landslide-generated tsunamis in Greenland and motivated a landslide screening project in 2018, led by the Geological Survey of Denmark and Greenland (GEUS; see also Svennevig et al. this volume). A central part of this project was to conduct a preliminary mapping of Quaternary and historical landslides in Greenland – the first effort of its kind. The main objective was to establish a landslide inventory database that can be used to identify areas prone to landslides and serve as a tool for gaining a better understanding of where, when and why catastrophic landslides take place in Greenland. This paper describes the workflow used to produce the preliminary landslide inventory of Greenland and discusses some of the initial results. To date (June 2019), I have mapped 564 landslides with the vast majority situated in the Nuussuaq Basin between Sigguup Nunaa (Svartenhuk Halvo), and Qeqertarsuaq (Disko) in West Greenland (Fig. 1). The inventory mapping is mainly based on observations and analyses of remotely sensed imagery and pre-existing geological maps. The mapping coverage was not systematic for all of Greenland, but focused on postglacial, potentially tsunamigenic landslides in inhabited coastal regions, i.e. on relatively large landslides on coastal slopes, mainly in West Greenland and small areas of East Greenland. However, smaller and inland landslides were included when they were encountered. Similarly, the less inhabited parts of Greenland were provisionally screened, but call for more thorough, systematic mapping in the future.
{"title":"Preliminary landslide mapping in Greenland","authors":"K. Svennevig","doi":"10.34194/GEUSB-201943-02-07","DOIUrl":"https://doi.org/10.34194/GEUSB-201943-02-07","url":null,"abstract":"The landslide of 17 June 2017 in Karrat Fjord, central West Greenland, highlighted the need for a better understanding of landslides and landslide-generated tsunamis in Greenland and motivated a landslide screening project in 2018, led by the Geological Survey of Denmark and Greenland (GEUS; see also Svennevig et al. this volume). A central part of this project was to conduct a preliminary mapping of Quaternary and historical landslides in Greenland – the first effort of its kind. The main objective was to establish a landslide inventory database that can be used to identify areas prone to landslides and serve as a tool for gaining a better understanding of where, when and why catastrophic landslides take place in Greenland. \u0000This paper describes the workflow used to produce the preliminary landslide inventory of Greenland and discusses some of the initial results. To date (June 2019), I have mapped 564 landslides with the vast majority situated in the Nuussuaq Basin between Sigguup Nunaa (Svartenhuk Halvo), and Qeqertarsuaq (Disko) in West Greenland (Fig. 1). The inventory mapping is mainly based on observations and analyses of remotely sensed imagery and pre-existing geological maps. The mapping coverage was not systematic for all of Greenland, but focused on postglacial, potentially tsunamigenic landslides in inhabited coastal regions, i.e. on relatively large landslides on coastal slopes, mainly in West Greenland and small areas of East Greenland. However, smaller and inland landslides were included when they were encountered. Similarly, the less inhabited parts of Greenland were provisionally screened, but call for more thorough, systematic mapping in the future.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74591099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The fully cored Upper Jurassic succession in the Blokelv-1 borehole in the Jameson Land Basin, East Greenland, is intersected by igneous intrusions at four levels; the intrusions comprise a c. 15 cm thick dyke and three sills with thicknesses of 0.7, 1.2 and 1.9 m. The sills consist of fine-grained, sparsely plagioclase-olivine-phyric basalt with chilled contacts to the sediments. Analyses of two sills gave very similar results. The sills are tholeiitic basalts with compositions similar to the main group of dykes and sills in the Jameson Land Basin, and the Blokelv-1 sills are thus considered to belong to this group which has been dated at c. 53 Ma. The intrusions form part of a 55–51 Ma suite of tholeiitic basalt intrusions that was emplaced over an area extending for over 500 km north-to-south within the sedimentary basins of East and North-East Greenland.
{"title":"Igneous intrusions in the cored Upper Jurassic succession of the Blokelv-1 borehole, Jameson Land Basin, East Greenland","authors":"Lotte Melchior Larsen","doi":"10.34194/geusb.v42.4323","DOIUrl":"https://doi.org/10.34194/geusb.v42.4323","url":null,"abstract":"The fully cored Upper Jurassic succession in the Blokelv-1 borehole in the Jameson Land Basin, East Greenland, is intersected by igneous intrusions at four levels; the intrusions comprise a c. 15 cm thick dyke and three sills with thicknesses of 0.7, 1.2 and 1.9 m. The sills consist of fine-grained, sparsely plagioclase-olivine-phyric basalt with chilled contacts to the sediments. Analyses of two sills gave very similar results. The sills are tholeiitic basalts with compositions similar to the main group of dykes and sills in the Jameson Land Basin, and the Blokelv-1 sills are thus considered to belong to this group which has been dated at c. 53 Ma. The intrusions form part of a 55–51 Ma suite of tholeiitic basalt intrusions that was emplaced over an area extending for over 500 km north-to-south within the sedimentary basins of East and North-East Greenland.","PeriodicalId":49199,"journal":{"name":"Geological Survey of Denmark and Greenland Bulletin","volume":"84 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77685927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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