ALBERT

Description: On the Qinghai-Tibetan Plateau, the ecological crisis appears in every physical and social aspect, and typically affects the rangelands on which most local people depend for their livelihood. Until today, however, changes in land use and vegetation cover on this Plateau have not yet been adequately and practically treated in studying the framework of sustainability. This thesis deals first with the basic ecological influences and interactions before reviewing their implications for development. The limitations of an ecological perspective is recognized, but this stems mainly from the misapplication of perspective and should not detract from its value. Ecology is undoubtedly the most basic and pervasive of the many determinants of the pastoral production systems of the high-frigid land. To ignore ecology or to fail to take it into account is to court disaster. The amount of literature reflects the importance of the subject but is not reviewed here in any detail; rather the aim is simply to set the scene for later discussions.

Description: thesis

Description: DFG, SUB Göttingen

Description: Der vorliegende Band 52 der Abhandlungen „Anthropogeographie“ des Instituts für Geographische Wissenschaften der Freien Universität Berlin erfasst mit 54 Beiträgen den wissenschaftlichen Forschungsstand der IGU-Kommission “Urban Development and Urban Life”. Die vorgelegten Fassungen stellen die diskutierte und revidierte Form der Beiträge dar, die während der Jahrestagung der Kommission vom 15. bis 20. August 1994 in Berlin gehalten wurden. Die Tagung selbst stand unter dem Thema “Urban Transition and Quality of Life” und forderte damit in den jeweils zwei Einführungs- und zahlreichen weiterführenden Referaten der drei Arbeitsthemen 1) “Restructuring Urban Systems in Central and Eastern Europe“, 2) “Unemployment and Informal Economy in Cities” und 3) “Urban Identity, City Image and Urban Marketing” zu Bewertungen des Forschungsstandes bzw. kritischen Stellungnahmen durch aktuelle Forschungen heraus.

Description: 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0004.pdf"〉Titelseite〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0005.pdf"〉Titelseite〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0006.pdf"〉Vorwort〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0007.pdf"〉Foreword〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0008.pdf"〉Inhaltsverzeichnis〈/a〉〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0009.pdf"〉I. Introduction〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0010.pdf"〉Reflections Between Urban and University Structures and Planning〈/a〉〈br〉(Dietz, K., Braun, G. O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0011.pdf"〉Berlin - Metropolis in Transition: The State of Urban Development in 1994〈/a〉〈br〉(Ellger, C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0014.pdf"〉Planning for the Future of Berlin〈/a〉〈br〉(Branoner, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0016.pdf"〉Strategic Planning in Berlin〈/a〉〈br〉(Braun, G. O.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0019.pdf"〉Change in the Urban Structure in the Five New Länder: The Example of Eisenach〈/a〉〈br〉(Cassel, M., Schwaderer, G.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0021.pdf"〉II. Restructuring of Inter- and Intra-Urban Systems〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0022.pdf"〉Questions on Hierarchical Change in Urban Systems in Eastern and Central Europe〈/a〉〈br〉(Rey, V.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0026.pdf"〉Urban and Urban System Development in Central and Eastern Europe〈/a〉〈br〉(Grimm, F.-D., Taege, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0030.pdf"〉The Impact of Recent Socio-Political and Economic Changes on the Development of Slovenian Towns〈/a〉〈br〉(Pak, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0033.pdf"〉An Urban Evolution Model Applied to Romania's Towns〈/a〉〈br〉(Ianos, I.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0038.pdf"〉Warsaw: Development Problems and Strategies〈/a〉〈br〉(Korcelli, P., Potrykowska, A., Weclawowicz, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0039.pdf"〉The Urban System and Emerging Structure: An Application of Gibb's Measure to the Case of India〈/a〉〈br〉(Mookherjee, D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0041.pdf"〉Reorganisation of the Urban System in Sri Lanka〈/a〉〈br〉(Wanasinghe, D. S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0046.pdf"〉The Formation of an European Urban System〈/a〉〈br〉(Rozenblat, C., Pumain, D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0051.pdf"〉On the Impact of Internationalization Process on the Finnish Settlement System〈/a〉〈br〉(Palomäki, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0055.pdf"〉Global Perspective of Seoul as a World City in the Region of Pacific Rims〈/a〉〈br〉(Kim, I.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0057.pdf"〉Urban Systems Dynamics: Evidence for the Toronto Urban System: 1930-1991〈/a〉〈br〉(Preston, R. E.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0060.pdf"〉The Growth of Toronto: A Market-Share Approach〈/a〉〈br〉(Simmons, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0064.pdf"〉Industrial Restructuring and Urban Development: An Examination in Metropolitan Detroit〈/a〉〈br〉(Sinclair, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0067.pdf"〉Counter-Urbanization in Perspective: Images and Reality in Settlement System Change〈/a〉〈br〉(Davies, W.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0069.pdf"〉Urban Region as a Geoeconomic and Geopolitical Unit in "A Europe of Regions"〈/a〉〈br〉(Vartiainen, P.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0070.pdf"〉The Ethnic and Social Division of a World City: The Case of London〈/a〉〈br〉(Petsimeris, P.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0075.pdf"〉Transformation in the South African Apartheid City – Residential Desegregation in Pietersburg: A Case Study〈/a〉〈br〉(Donaldson, S. E., Kotze, N. J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0078.pdf"〉Intra-Urban Distribution of Ethnic Minorities in Munich and Duisburg〈/a〉〈br〉(Yamamoto, K.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0083.pdf"〉New Urban Poverty in the Basque Country and Navarra〈/a〉〈br〉(Ferrer, M., d’Entremont, A., Ciscar, I., Saracibar, M. A.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0085.pdf"〉Polarization and the Dutch Welfare State. The Case of Amsterdam〈/a〉〈br〉(Ostendorf, W., Musterd, S.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0088.pdf"〉III. Informal Economy〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0089.pdf"〉The Labour Market and the Role of Informality in Urban Mexico〈/a〉〈br〉(Aguilar, A. G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0092.pdf"〉The Informal Economy in Chinese Cities〈/a〉〈br〉(Qi, S. D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0093.pdf"〉The Urban Informal Sector: A Third World Experience〈/a〉〈br〉(Geeta Reddy, A., Rajkumar, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0094.pdf"〉Informal Urban Economy in the Lake Chad Basin〈/a〉〈br〉(Simeu-Kamdem, M.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0095.pdf"〉IV. Recent Urban Processes〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0096.pdf"〉City Challenge: Involving the Community in UK Urban Policy? 〈/a〉〈br〉(Lewis, J. R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0098.pdf"〉Intra-Metropolitan Relocation of Work Places: The Case of Stockholm〈/a〉〈br〉(Mahieu, R.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0102.pdf"〉Problems of Mobility and Traffic in the Ruhr〈/a〉〈br〉(Lötscher, L., Fleisgarten, S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0103.pdf"〉Moscow 1993: The Emergence of Housing Market and the Problems of Intra-Urban Segregation〈/a〉〈br〉(Vendina, O. I.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0107.pdf"〉V. Urban Marketing, City Management, Urban Identity〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0108.pdf"〉Urban Marketing: A Review〈/a〉〈br〉(Borchert, J. G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0109.pdf"〉Urban Identity, City Image and Urban Marketing〈/a〉〈br〉(Dematteis, G.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0110.pdf"〉The Hidden Faces of the City〈/a〉〈br〉(Racine, J.-B.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0111.pdf"〉The City of Bergen. Image and Marketing〈/a〉〈br〉(Sjøholt, P.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0113.pdf"〉Structural Underpinnings of an Olympic City Bid〈/a〉〈br〉(Davies, R. J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0116.pdf"〉Double Cities: Identity and Marketing of a New Urban Product〈/a〉〈br〉(Buursink, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0118.pdf"〉Corporate Space and Emerging Spatial Order in Japan〈/a〉〈br〉(Fujita, N.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0125.pdf"〉The Development of International Tourism in Tallinn, Estonia〈/a〉〈br〉(Kuus, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0126.pdf"〉Conflict, Consent, Cooperation: Comprehensive Planning in Germany Beyond Market and State〈/a〉〈br〉(Helbrecht, I.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0127.pdf"〉Urban Strategies: Mega Events. A Copenhagen Perspective〈/a〉〈br〉(Thor Andersen, H., Wichmann Matthiessen, C.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0129.pdf"〉From Spaces of Planning to Places of Resistance〈/a〉〈br〉(Haarni, T.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0132.pdf"〉VI. Re-Cycling Urban Landscape〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0133.pdf"〉The Role of Gentrification in the Changing Ecology of Income: Evidence From Canadian Cities and Implications for Further Research〈/a〉〈br〉(Bourne, L. S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0134.pdf"〉Gentrification and the Youth Movements of the 1960s〈/a〉〈br〉(Ley, D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0135.pdf"〉Recycling Urban Landscapes - Beyond the Power〈/a〉〈br〉(Andersson, H.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0136.pdf"〉Why was the Central City Population Stabilized? The Case of Copenhagen〈/a〉〈br〉(Illeris, S.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0138.pdf"〉Toronto's Underground City: Excavating the Terms of Access〈/a〉〈br〉(Hopkins, J.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0140.pdf"〉The Interpretation of Sea in Urban Planning and Everyday Life: The Case of Helsinki〈/a〉〈br〉(Karvinen, M.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0141.pdf"〉Urban Destinies - What are the Trends?〈/a〉〈br〉(Wärneryd, O.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0142.pdf"〉VII. Urban Modelling〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0143.pdf"〉DUVA – A Concept for a Metadata Driven Statistical Production and Information System〈/a〉〈br〉(Kopp, N.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0145.pdf"〉A New Era for Urban Modelling?〈/a〉〈br〉(Pumain, D.)〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0146.pdf"〉Competing Order Parameters in a Self-Organizing City〈/a〉〈br〉(Portugali, J., Benenson, I.)〈/li〉 〈/body〉 〈/html〉 〈br〉 〈html〉 〈body〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0150.pdf"〉Authors and Addresses〈/a〉〈/li〉 〈li〉〈a href="https://gdz.sub.uni-goettingen.de/download/pdf/PPN1030505985/LOG_0151.pdf"〉[Werbung]〈/a〉〈/li〉 〈/body〉 〈/html〉

Description: conference

Description: DFG, SUB Göttingen

Description: Since the 14th century, moderate seismic activity with 14 earthquakes of magnitude MW≥5.0 occurred in Western Europe in a region extending from the Lower Rhine Graben (LRG) to the southern North Sea. In this paper, we investigate how well this seismic activity could reflect that of the future. The observed earthquake activity in the LRG is continuous and concentrates on the Quaternary normal faults delimiting the LRG, which are also the source of large surface rupturing Holocene and Late Pleistocene earthquakes. The estimated magnitudes of these past earthquakes range from 6.3±0.3 to 7.0±0.3 while their average recurrence on individual faults varies from ten thousand to a few ten thousand years, which makes foreseeing future activity over the long-term possible. Three of the largest historical earthquakes with MW≥5.5 occurred outside the LRG. Late Quaternary activity along the fault zones suspected to be the source of two of these earthquakes, i.e. the 1580 Strait of Dover and 1692 northern Belgian Ardennes earthquakes, is very elusive if it exists. Hence, similar earthquakes would be very infrequent at these locations suggesting that the seismicity outside of the LRG would be episodic and clustered on some faults during periods of a few hundreds of years interrupted by long periods of inactivity typically lasting for some tens to hundreds of thousand years. Seismic moment release estimation and its comparison between recent geological and historical seismicity periods lead us to suggest that the high seismicity level observed between AD 1350 and AD 1700 west of the LRG would be uncommon.

Description: research

Description: In the weekly newspaper of Osnabrück (Germany) of November 3, 1770, a report about a local earthquake was published. Pastor Buck described ground motion effects in the manor ‘Haus Horst’, 1.5 km away from the village of Alfhausen: ‘roof tiles rattled, a chimney fell down, inside the house the top of a stove was overturned, abraded chalk trickled down in all rooms; in the nearby villages, people felt the shaking, and especially the churches suffered noticeably’. The epicentral intensity was estimated to VII (MSK) by Ahorner et al. (1970), but later modified to VI (EMS) by Meier & Grünthal (1992) considering Buck’s report in detail. Since this event is the only documented earthquake in this region, a reliable characterization of its parameters is important. Our re-examination reveals that some reported effects are quite contradictory. Contrary to Buck’s statement, no documents of damages on churches or costs of repairs could be found in the parish registers. As a result, the event appears to be a tectonic earthquake with an epicenter at Alfhausen / Haus Horst. Applying intensity-attenuation relationships, a revised value of the epicentral intensity of I_0≤V (EMS-98) with a focal depth of z≥2 km was derived. A cavity collapse due to leaching processes as a cause of the effects can be ruled out here. However, several details given in the primary source turned out to be unrealistic or at least exaggerated. The tectonic earthquake on September 3, 1770 near Alfhausen should be classified therefore as uncertain or even doubtful.

Description: research

Description: Central Europe is an intraplate domain which is characterized by low to moderate seismicity with records of larger seismic events occurring in historical and recent times. These records of seismicity are restricted to just over one thousand years. This does not reflect the long seismic cycles in Central Europe which are expected to be in the order of tens of thousands of years. Therefore, we have developed a paleoseismic database (PalSeisDB) that documents the records of paleoseismic evidence (trenches, soft-sediment deformation, mass movements, etc.) and extends the earthquake record to at least one seismic cycle. It is intended to serve as one important basis for future seismic hazard assessments. In the compilation of PalSeisDB, paleoseismic evidence features are documented at 129 different locations in the area of Germany and adjacent regions.

Description: research

Description: Current procedures to collect macroseismic data in Germany are diverse and scattered. At least 10 institutions collect macroseismic data by internet. Several institutes have a long tradition in seismology and have collected macroseismic data using paper forms for many decades. In addition, the responsibilities for geoscientific issues in Germany are a matter of the federal states and several of them have a state earthquake service. The only institution that automatically calculates and maps intensities online in near real time is Erdbebenstation Bensberg in cooperation with the Royal Observatory of Belgium. Baden-Württemberg uses a short form internet questionnaire at the moment. 5 state earthquake services (Bayern, Hessen, Niedersachsen, Rheinland-Pfalz, Sachsen) have implemented the standard German earthquake questionnaire (Kaiser 2014) which is adapted from the standard questionnaire developed by the ESC Working Group on Internet Macroseismology published by Musson & Cecić (2012). Most institutions express their strong need to implement standard procedures for automatic intensity assignment and a standard format for the exchange of questionnaire responses. References Kaiser, D. (2014): Der neue einheitliche Erdbeben-Fragebogen. Mitteilungen / Deutsche Geophysikalische Gesellschaft, 2/2014, 29-33. Musson, R. M. W. & Cecić, I. (2012): Intensity and Intensity Scales. In: New Manual of Seismological Observatory Practice 2 (NMSOP-2).- Deutsches GeoForschungsZentrum GFZ, 1-41; Potsdam. doi:10.2312/GFZ.NMSOP-2_ch12

Description: lecture

Description: We develop empirical relationships between the surface wave magnitude MS and macroseismic data, i.e. the epicentral intensity I0, isoseismal radii R(I) of different intensities I and the focal depth h. The basis of this study is formed by carefully selected instrumental parts (since 1900) of 2 earthquake catalogues: Kárník 1996 (Europe and the Mediterranean), and Shebalin et al. 1998 (Central and Eastern Europe). We use the orthogonal regression because we presume that all parameters are in error and because it has the advantage to provide a reversible regression equation. From Shebalin et al.1998 catalogue we obtain MS = 0.65 I0 + 1.90 log(h) – 1.62 with equivalent error δMS = ±0.21. In order to establish a relationship between MS and isoseismal radii we apply a theoretically based model which takes into account both exponential decay and geometrical spreading. From Shebalin et al. 1998catalogue we find MS = 0.673 I + 2.44 log (S(I)) + 0.00163 S(I) – 2.48 with δMS = ±0.28. Here I is the macroseismic intensity (I = 3…9) of the isoseismal in the focal distance S(I) [km]. Kárník 1996 gives isoseismal radii for I = 3 and 5. We obtain: MS = 0.808 I + 2.84 log (S(I)) + 0.00190 S(I) – 3.71 with δMS = ±0.65. These equations make possible reliably estimates of MS . We recommend them for application. The use of high quality data only as input in the regression analysis provides reliable relationships to estimate magnitudes. The magnitude estimation of a historical earthquake from the epicentral intensity gives reliable results only if the focal depth is known well enough. The relationship using isoseismal radii is of greater practical importance as it allows more reliable magnitude estimations of historical earthquakes. We observe regional variations in the relationships which need further investigation.

Description: poster

Description: The earthquake catalogue of southwestern Germany for the last millennium now contains about 30,000 digital macroseismic intensity data points (IDPs). Intensity assessments are based mainly on primary sources using the European Macroseismic Scale 1998 (EMS). The article describes a guideline for best practice of conventional macroseismic evaluation in application to historical and modern-time earthquakes in SW-Germany. Suitability of various diagnostics for intensity assessment is discussed. Assumptions to estimate damage grades and vulnerability classes of buildings are presented. Data restrictions and treatment of special cases are outlined. Further topics are quantification of uncertainties and IDP quality as well as substitutes for intensity. An essential task is to bridge the gap between information from historical sources and seismological needs for use in the earthquake catalogue, thus all issues have a focus on historical earthquakes. Questions of completeness, subjectivity, transparency, and interdisciplinary work are addressed also. Special emphasis is given to a well balanced use of the EMS scale throughout all time periods leading to consistent assessments in the catalogue.

Description: research

Description: Geometric 3D models are a very efficient tool to visualize geological units and structural features that have been presented before just in two dimensions on maps or cross-sections. Most of the information of 3D models is presented as 3D views, virtual wells or horizontal or vertical cross-sections. However, are there further options to transfer as much as possible of the complex information of a 3D model in an adequate way to the user? Is it useful and promising to analyse 3D objects like surfaces or volumes in GIS software? In our investigation we performed a GIS based analysis of an existing geotechnical-geological 3D model of periglacial sediments. The two steps were multiple raster calculations to create geotechnical maps and a digital analysis of surface parameters based on geomorphological techniques and statistics. The investigation area is located in southern Lower Saxony and covers the city of Goettingen and surrounding regions within the valley of the river Leine. The valley is filled by unconsolidated, periglacial sediments of Quaternary age with a variable thickness ranging from 1 to 70 m. The analysed 3D model was constructed with GoCAD in a former project (Nix et al. 2009). The model is based on a heterogenous dataset comprising well data, thematic maps, and outcrop descriptions. Finally, the surfaces and volumes of the following units were modelled, with a special focus on their different geotechnical properties: (1) anthropogenic material, (2) floodplain and slope deposits, (3) freshwater limestone, peat and organic clay, (4) loess, displaced loess, and loess loam, (5) fluvial gravel, (6) outwash fan material, (7) solifluction material, (8) mixed, hetereougenous fillings of subrosion sinks and (9) the surface of the underlying hardrocks. Each top and bottom surface of the Gocad volumes was exported as raster file with additional information stored in an associated attribute table. In ArcGIS various geoprocessing tools were used to calculate and analyse these rasters and to develope thematic geotechnical and geological maps. The geomorphological analysis was subdivided in several steps. Firstly, the surfaces were described visually, concerning their outline, shape and distribution, as well as superficial structures like distinct edges, holes, channels. Secondarily, descriptive statistic parameters of thickness, area and elevation of each surface were calculated. Thirdly, geoprocessing tools of the Spatial Analyst were performed on each surface. Finally, several surfaces were combined to analyse them together, calculating ratios and overlay combinations. Seven thematical geoengineering and geological maps were created, each of them presenting one portion of the three-dimensional dataset: Map of the stratigraphy and depth of the Quaternary base, Map of the thickness of the Quaternary sediments, Distribution map of model units 1 m below ground level, Distribution map of model units 2 m below ground level, Maps of types of different foundation soils, Distribution map of sediments with low loading capacity and Map of distribution and quality of the wells. While the map creation focused on the geotechnical aspects of the model, the applied geomorphological analysis revealed various parameters and values that are related to the geological formation of the model units. Despite the complex dataset represented by the analysed 3D model, thematical information could be transfered into 2D as thematic maps. Some geological characteristics and parameters of the model units were extracted by the descriptive and GIS-based analysis. References Nix, T., Wagner, B., Lange, T. , Fritz, J., Sauter, M. (2009): 3D-Baugrundmodell der quartären Sedimente des Leinetals bei Göttingen. – 17. Tagung für Ingenieurgeologie, S. 223-227, Zittau

Description: poster

Description: The mineralogy, chemical composition, and physical properties of cratonic mantle eclogites with oceanic crustal protoliths can be modified by secondary processes involving interaction with fluids and melts, generated in various slab lithologies upon subduction (auto‐metasomatism) or mantle metasomatism after emplacement into the cratonic lithosphere. Here we combine new and published data to isolate these signatures and evaluate their effects on the chemical and physical properties of eclogite. Mantle metasomatism involving kimberlite‐like, ultramafic carbonated melts (UM carbonated melts) is ubiquitous though not pervasive, and affected between ~20% and 40% of the eclogite population at the various localities investigated here, predominantly at ~60–150 km depth, overlapping cratonic midlithospheric seismic discontinuities. Its hallmarks include lower jadeite component in clinopyroxene and grossular component in garnet, an increase in bulk‐rock MgO ± SiO2, and decrease in FeO and Al2O3 contents, and LREE‐enrichment accompanied by higher Sr, Pb, Th, U, and in part Zr and Nb, as well as lower Li, Cu ± Zn. This is mediated by addition of a high‐temperature pyroxene from a UM carbonated melt, followed by redistribution of this component into garnet and clinopyroxene. As clinopyroxene‐garnet trace‐element distribution coefficients increase with decreasing garnet grossular component, clinopyroxene is the main carrier of the metasomatic signatures. UM carbonated melt‐metasomatism at 〉130–150 km has destroyed the diamond inventory at some localities. These mineralogical and chemical changes contribute to low densities, with implications for eclogite gravitational stability, but negligible changes in shear‐wave velocities, and, if accompanied by H2O‐enrichment, will enhance electrical conductivities compared to unenriched eclogites.

Description: Plain Language Summary: Oceanic crust formed at spreading ridges is recycled in subduction zones and undergoes metamorphism to eclogite. Some of this material is captured in the overlying lithospheric mantle, where it is exhumed by passing magmas. Having formed in spreading ridges, these eclogites have proven invaluable archives for the onset of plate tectonics, for the construction of cratons during subduction/collision, as probes of the convecting mantle from which their precursors formed, and as generators of heterogeneity upon recycling into Earth's convecting mantle. During subduction and until exhumation, interaction with fluids and melts (called metasomatism) can change the mineralogy, chemical composition, and physical properties of mantle eclogites, complicating their interpretation, but a comprehensive study of these effects is lacking so far. We investigated mantle eclogites from ancient continents (cratons) around the globe in order to define hallmarks of metasomatism by subduction‐related fluids and small‐volume ultramafic carbonated mantle melts. We find that the latter is pervasive and occurs predominantly at midlithospheric depths where seismic discontinuities are detected, typically causing diamond destruction and a reduction in density. This has consequences for their gravitational stability and for the interpretation of shearwave velocities in cratons.

Description: Key Points: Exploration of metasomatic effects during subduction of ancient oceanic crust and after its emplacement into cratonic lithospheric mantle. Metasomatism by kimberlite‐like ultramafic melt affected between 20% and 40% of mantle eclogite suites worldwide, mostly at 2–5 GPa. Metasomatism lowers FeO, hence density in eclogite; no significant effect on shearwave velocities.

Description: German Research Foundation http://dx.doi.org/10.13039/501100001659

Description: National Research Foundation (NRF) http://dx.doi.org/10.13039/501100001321

Description: Wilhelm and Else Heraeus Foundation http://dx.doi.org/10.13039/501100011618

Description: Deutsche Forschungsgemeinschaft (DFG, INST

Description: research

Description: Considering the importance of migration research and the dearth in literature on migration, the following study has been done, with the intention of examining the complex interrelation between internal migration and the development process in Bangladesh. Thereby, emphasis has been given to the investigation and analysis of the causes of rural-urban migration and its spatial as well as socioeconomic consequences, with examples from Dhaka. To construct a framework for the present study, some consideration has been given to both theoretical as well as empirical studies on internal migration. The discussion of general theories which follows in the next section, has mainly been done to assess the validity of these in the analysis of internal migration in the Third World countries.

Description: research

Description: DFG, SUB Göttingen

Description: Pyrroloquinoline quinone (PQQ) is an important cofactor of calcium‐ and lanthanide‐dependent alcohol dehydrogenases, and has been known for over 30 years. Crystal structures of Ca–MDH enzymes (MDH is methanol dehydrogenase) have been known for some time; however, crystal structures of PQQ with biorelevant metal ions have been lacking in the literature for decades. We report here the first crystal structure analysis of a Ca–PQQ complex outside the protein environment, namely, poly[[undecaaquabis(μ‐4,5‐dioxo‐4,5‐dihydro‐1H‐pyrrolo[2,3‐f]quinoline‐2,7,9‐tricarboxylato)tricalcium(II)] dihydrate], {[Ca3(C14H3N2O8)2(H2O)11]·2H2O}n. The complex crystallized as Ca3PQQ2·13H2O with Ca2+ in three different positions and PQQ3−, including an extensive hydrogen‐bond network. Similarities and differences to the recently reported structure with biorelevant europium (Eu2PQQ2) are discussed.

Description: Pyrroloquinoline quinone (PQQ) is an important cofactor of calcium‐ and lanthanide‐dependent alcohol dehydrogenases. The crystal structure of a Ca–PQQ complex (Ca3PQQ2·13H2O) is reported for the first time outside a protein environment. image

Description: research

Description: Induced earthquakes are of public concern and of legal significance if they are felt or if they cause damage. Models to describe the relation between macroseismic intensities, magnitude, and distance from the epicenter or hypocenter are therefore of fundamental importance. With the aim of developing such models for induced earthquakes in Germany, the following data were analyzed: The earthquake database for Germany GERSEIS contains parameters for ~180 induced seismic events with information on magnitude M and intensity I, of which 47 include information on mean isoseismal radii. In addition, the published macroseismic maps of seismic events in mining areas in Germany were evaluated. In Germany, earthquakes caused by mining with moderate to severe building damage (intensity 7 and 8) have so far only occurred in potash and salt mining. Slight building damage (intensity 6) has also been caused by seismic events in coal mining. Over the past 20 years, the frequency of felt earthquakes has increased in regions with natural gas production and in recent years also in regions of deep geothermal energy production. Focal depths show a large influence on the relationship between M and I. Intensity 5 has been observed for shallow (~1 km depth) events with magnitudes as small as ML=1.8. Simple models of the form I = a + b M + c log R, with R = hypocentral distance, can be fitted to the observations. Models for tectonic earthquakes do not fit for induced earthquakes; for induced earthquakes I is smaller for a given M and R. Major differences were found between different mining areas: In natural gas production areas intensity 5 effects were observed at greater hypocentral distances for a given magnitude, compared to coal and potash mining areas. Since macroseismic data (especially intensity data points) in Germany are available almost exclusively in analog form and are often difficult to access, it is necessary to establish a database for induced earthquakes with macroseismic data.

Description: research

Description: In Structural Geology, many projects start with intensive field-based data acquisition campaigns, which might be performed in quite different types of natural or artificial outcrops. For some years, this field work has been substantially influenced and transformed by various close-range sensing techniques that allow the field geologist to create a digital outcrop model (DOM) and to take along plenty of geometrical and spectral information about the outcropping rocks. In general, DOMs can be utilized for outcrop visualization, documentation, manual outcrop analysis (“point-picking”), extraction of spectral data and/or semi-automatic extraction of geometric data. Within a structural investigation DOMs might be deployed for fold analysis, fault analysis, extraction of fracture networks, fracture roughness estimation, detection of neotectonic activities or digitization of geological features for 3D-models of various scales resulting in a large number of analyzing techniques. Latter might be carried out on point clouds or meshes (with or without spectral information) and may differ in pre-processing and processing steps as well as in software solution. Therefore, the analyzing structural geologist faces various tools, data formats, file types, operations and outcomes. Our investigation focus on the compilation of useful, transparent, sustainable and comparable workflows or “pipelines”, which can be executed by open-source/open-access solutions.

Description: poster

Description: Apart from the traditional contribution of geographers to the study of population, this particular thesis attempts to divert the emphasis of geographical enquiry towards the examination of how particular innovations affect the population distribution and the organization of human society. It deals specifically with questions concerning the demographic, social and economic impact of population mobility on both sending in receiving areas. It attempts to shed light on the different variables that work to produce a selective type of population mobility within a particular socio—economic set-up. Although various aspects of population mobility have been studied in some detail during the present decade, no attempt has been made, however, towards a concrete presentation of its multiple causes and its socio-economic impact on the areas and people that are left behind. Far from assuming complete coverage of all interrelated fields of study we attempt here to draw attention t0 the expected socio-economic repercussions of population mobility as induced by a particular factor, namely agricultural mechanization. Certain limitations‚ however, have made it difficult to deal with every aspect of population mobility in the Sudan.

Description: thesis

Description: DFG, SUB Göttingen

Description: Jede Gesellschaft (und jede Stadtregion) muss auf die Auswirkungen dieser Transformation (erhöhte Wohnraumnachfrage, schnelles Wirtschaftswachstum, starkes Dezentralisierungspotential neuer Technologien, drohender Bedeutungsverlust der Kernstadt) reagieren. Wir betrachten im Rahmen dieser Arbeit räumliche Entwicklungen als "kulturelle“ Antwort auf solche Veränderungen. Denn während der ökonomische und technologische Wandel ein eher universelles Phänomen darstellt, unterscheiden sich doch die Strategien zur räumlichen Handhabung und Gestaltung von Wachstum von Land zu Land enorm. So gesehen ist die uns umgebende Realität von Suburbanisierung und Dezentralisierung eben auch das Resultat von Entscheidungen, die unter spezifischen politischen und ideologischen Bedingungen getroffen worden sind. Für die Analyse der Wachstumsideologien haben wir drei westliche Industriestaaten ausgewählt: Kanada, die USA und die Bundesrepublik Deutschland. Dabei wurden sowohl die lokale bzw. regionale als auch die Ländern Provinz- bzw. Bundesebene untersucht. Für die lokale Ebene wurden Flächennutzungsmaßnahmen und statistische Wachstumsindikatoren von sechs "Fallbeispielen" analysiert und verglichen: Frankfurt/M.‚ München, Toronto, Vancouver, San Francisco und Los Angeles/San Diego. Für die überregionale Ebene ergänzt ein Vergleich staatlicher Steuerungsmaßnahmen die Analyse und Interpretation lokaler Trends.

Description: thesis

Description: DFG, SUB Göttingen

Description: This publication developed from the 5th International Colloquium on “Historical Earthquakes, Paleoseismology, Neotectonics and Seismic Hazard” which was held from 11 to 13 October 2017 at the Federal Institute for Geosciences and Natural Resources (BGR) in Hannover, Germany. It comprises four contributions: Brüstle, W., Braumann, U., Hock, S. & Rodler, F.-A. (2020). Best practice of macroseismic intensity assessment applied to the earthquake catalogue of southwestern Germany. In: Kaiser, D. (Ed.). Historical Earthquakes, Paleoseismology, Neotectonics, and Seismic Hazard: New Insights and Suggested Procedures, DGEB-Publikation 18, Deutsche Gesellschaft für Erdbebeningenieurwesen und Baudynamik. doi: 10.23689/fidgeo-3864 Camelbeeck, T., Vanneste, K., Verbeeck, K., Garcia-Moreno, D., Van Noten, K. & Lecocq, T. (2020). How well does known seismicity between the Lower Rhine Graben and southern North Sea reflect future earthquake activity? In: Kaiser, D. (Ed.). Historical Earthquakes, Paleoseismology, Neotectonics, and Seismic Hazard: New Insights and Suggested Procedures, DGEB-Publikation 18, Deutsche Gesellschaft für Erdbebeningenieurwesen und Baudynamik. doi: 10.23689/fidgeo-3866 Hürtgen, J., Reicherter, K., Spies, T., Geisler, C. & Schlittenhardt, J. (2020). The Paleoseismic Database of Germany and Adjacent Regions PalSeisDB v1.0. In: Kaiser, D. (Ed.). Historical Earthquakes, Paleoseismology, Neotectonics, and Seismic Hazard: New Insights and Suggested Procedures, DGEB-Publikation 18, Deutsche Gesellschaft für Erdbebeningenieurwesen und Baudynamik. doi: 10.23689/fidgeo-3867 Leydecker, G. & Lehmann, K. (2020). The earthquake of September 3, 1770 near Alfhausen (Lower Saxony, Germany): a real, doubtful, or a fake event? In: Kaiser, D. (Ed.). Historical Earthquakes, Paleoseismology, Neotectonics, and Seismic Hazard: New Insights and Suggested Procedures, DGEB-Publikation 18, Deutsche Gesellschaft für Erdbebeningenieurwesen und Baudynamik. doi: 10.23689/fidgeo-3865

Description: Introduction to DGEB-Publikation Nr. 18 Deutsche Gesellschaft für Erdbebeningenieurwesen und Baudynamik (DGEB)

Description: editorial

Description: Quantitative fold structure analyses at different scales are essential for deducing deformation mechanisms and the reconstruction of the deformation history of orogens. However, not only the field surveying of fold structures, especially in view of their quantification in three dimensions with the classical tools as measuring tape, grid mapping with measuring tapes, geological compass, field book and camera is a time consuming and laborious job, but also the construction of a georeferenced 3D-model of fold structures based on classical data. Another crucial aspect of the classical field surveying of folds is the limitation by poor outcrop conditions. Reasons might be restricted or no accessibility due to high outcrop walls, water or fences, limited visibility because of vegetation, difficult measurability due to very smooth walls or complexity as a result of irregular outcrop walls or distant outcrops. Furthermore, inappropriate oriented outcrop surfaces in respect to the fold geometry can make a survey even worse. Over the past years modern 3D surveying techniques like terrestrial Lidar and digital photogrammetry became progressively affordable for geological field work and now start to complement or replace traditional methods. We started to utilize these techniques on fold structure surveying and to apply quantitative fold structure analysis on different outcrop settings in Central Germany. Different workflows were developed and tested to optimize data conversion, handling and representation. We applied a laser scanner and a single lens reflex camera, complemented by a differential GPS device and laser tachymeter. Data conversion, correction and analysis were done by means of different free as well as commercial software packages. To test different outcrop situations, different quarries, salt mines and steep cliffs, exposing from single fold to complex folds in limestone, greywacke, cherts, rock salt or potassium salt, were selected. As a result, exact 3D point clouds of all exposed folds could be generated by the use of both techniques. The resultant point clouds are suited as excellent visualisation objects as well as base for accurate geometrical measurements in the range of mm or cm of single and complex folds. In addition, the point clouds serve as input dataset for the construction of detailed geological 3D models comprising punctual, linear and plane fold elements. In summary, terrestrial Lidar and digital photogrammetry are excellent field techniques to survey and document exposed folds in the range of few meters to tens of meters, especially under poor outcrop conditions. Different fold sections can now easily be correlated in 3D space to construct complete fold structures with their 3D-fold geometry. Certain fold elements, e.g. axial planes, can be reconstructed much faster and much more accurate compared to the classical approach. The only limiting factor are the very large datasets and the processing power. As next steps, we seek (1) to involve drones for completing data sets from inaccessible areas and perspectives and (2) to incorporate 3D-microfabric analysis data in the fold models as e.g. grain shape an crystallographic preferred orientations to better understand stain paths and deformation mechanisms.

Description: poster

Description: Under certain conditions, ocean surface gravity waves (SGW) interact with the seafloor underneath to trigger relatively faint but measurable seismic waves known as ocean microseisms. Cyclonic storms (e.g. hurricanes, typhoons) wandering over the ocean are major (non-stationary) sources of the former, thus opening the possibility of tracking and studying cyclones by means of their corresponding microseims. For this purpose, we identified storm-related microseisms hidden in the ambient seismic wavefield via array processing. Polarization beamforming, a robust and well-known technique is implemented. The analyses hinge on surface waves (Love and Rayleigh) which, in contrast to P-waves, are stronger but only constrain direction of arrival (without source remoteness). We use a few land-based virtual seismic arrays surrounding the North Atlantic to investigate the signatures of major hurricanes in the microseismic band (0.05-0.16 Hz), in a joint attempt to continuously triangulate their tracks. Our findings show that storm microseisms are intermittently excited with modulated amplitude at localized oceanic regions, particularly over the shallow continental shelves and slopes, having maximum amplitudes virtually independent of storm category. In most cases no detection was possible over deep oceanic regions, nor at distant arrays. Additionally, the rear quadrants and trailing swells of the cyclone provide the optimum SGW spectrum for the generation of microseisms, often shifted more than 500 km off the "eye". As a result of the aforementioned and added to the strong attenuation of storm microseisms, the inversion of tracks or physical properties of storms using a few far-field arrays is discontinuous in most cases, being reliable only if benchmark atmospheric and/or oceanic data is available for comparison. Even if challenging due to the complexity of the coupled phenomena responsible for microseisms, the inversion of site properties, such as bathymetric parameters (e.g. depth, seabed geomorphology), near- bottom geology or SGW spectrum might be possible if storms are treated as natural sources in time-lapse ambient noise investigations. This will likely require near-field (land and underwater) observations using optimal arrays or dense, widespread sensor networks. Improved detection and understanding of ocean microseisms carries a great potential to contribute to mechanically coupled atmosphere-ocean-earth models.

Description: Universität Hamburg

Description: poster

Description: Stable organic carbon and nitrogen isotopes can be used to interpret past vegetation patterns and ecosystem qualities. Here we present these proxies for two loess-palaeosol sequences from the southern Carpathian Basin to reconstruct the palaeoenvironment during the past 350 ka and establish regional commonalities and differences. Until now, isotopic studies on loess sequences from this region were only conducted on deposits from the last glacial cycle. We conducted methodological tests concerning the complete decalcification of the samples prior to stable isotope analyses. Two decalcification methods (fumigation method and wet chemical acidification), different treatment times, and the reproducibility of carbon isotope analyses were tested. Obtained results indicate that the choice of the decalcification method is essential for organic carbon stable isotope analyses of loess-palaeosol sequences because ratios vary by more than 10‰ between the wet chemical and fumigation methods, due to incomplete carbonate removal by the latter. Therefore, we suggest avoiding the fumigation method for studies on loess-palaeosol sequences. In addition, our data show that samples with TOC content 〈0.2% bear increased potential for misinterpretation of their carbon isotope ratios. For our sites, C3-vegetation is predominant and no palaeoenvironmental shifts leading to a change of the dominant photosynthesis pathway can be detected during the Middle to Late Pleistocene. Furthermore, the potential for further stable nitrogen isotope studies is highlighted, since this proxy seems to reflect especially past precipitation patterns and reveals favourable conditions in the southern Carpathian Basin, especially during interstadials.

Description: In Antarctic and Subantarctic environments, 14C-based age determination is often challenging due to unknown reservoir effects, low organic carbon contents of sediments, and high contributions of petrogenic (14C-free) carbon in ice marginal settings. In this study, we evaluate possible benefits and challenges of compound-specific radiocarbon analysis (CSRA) as a tool for age determination of marine Antarctic and Subantarctic sediment sequences. We present a comprehensive data set of 14C ages obtained on bulk organic carbon, carbonates, and on fatty acids (FA) from three coastal marine sediment cores from Subantarctic South Georgia and East Antarctica. Low molecular weight (LMW) FA represent the least 14C-depleted fraction, indicating that the phytoplankton-derived compounds can be a means of dating sediments. In contrast, vascular plant-derived high molecular weight FA are systematically depleted in 14C relative to the low molecular weight homologues, reflecting processes such as soil formation/erosion in the catchment. Comparative age-depth models show significant differences, depending on the material used for the respective models. While the land plant-derived FA may lead to an overestimation of the actual sediment age, LMW FA reveal complex aquatic reservoir effects. Bulk sedimentary organic carbon 14C ages likely provide appropriate age estimates in settings with low petrogenic carbon input in the Antarctic, whereas CSRA has the potential to produce improved age control in settings with high contributions of petrogenic carbon.

Description: It is widely assumed that the ventilation of the Southern Ocean played a crucial role in driving glacial-interglacial atmospheric CO2 levels. So far, however, ventilation records from the Indian sector of the Southern Ocean are widely missing. Here we present reconstructions of water residence times (depicted as ΔΔ14C and Δδ13C) for the last 32,000 years on sediment records from the Kerguelen Plateau and the Conrad Rise (~570- to 2,500-m water depth), along with simulated changes in ocean stratification from a transient climate model experiment. Our data indicate that Circumpolar Deep Waters in the Indian Ocean were part of the glacial carbon pool. At our sites, close to or bathed by upwelling deep waters, we find two pulses of decreasing ΔΔ14C and δ13C values (~21–17 ka; ~15–12 ka). Both transient pulses precede a similar pattern in downstream intermediate waters in the tropical Indian Ocean as well as rising atmospheric CO2 values. These findings suggest that 14C-depleted, CO2-rich Circumpolar Deep Water from the Indian Ocean contributed to the rise in atmospheric CO2 during Heinrich Stadial 1 and also the Younger Dryas and that the southern Indian Ocean acted as a gateway for sequestered carbon to the atmosphere and tropical intermediate waters.

Description: There is a converging body of evidence supporting a measurable slowdown of the Atlantic Meridional Overturning Circulation (AMOC) as climate warms and Northern Hemisphere ice sheets inexorably shrink. Within this context, we assess the variability of the AMOC during the Holocene based on a marine sediment core retrieved from the deep northwest Atlantic, which sensitively recorded large-scale deglacial transitions in deep water circulation. While there is a diffuse notion of Holocene variability in Labrador and Nordic Seas overturning, we report a largely invariable deep water circulation for the last ~11,000 years, even during the meltwater pulse associated with the 8.2-ka event. Sensitivity tests along with high-resolution 231Pa/230Th data constrain the duration and the magnitude of possible Holocene AMOC variations. The generally constant baseline during the Holocene suggests attenuated natural variability of the large-scale AMOC on submillennial timescales and calls for compensating effects involving the upstream components of North Atlantic Deep Water.

Description: Tunnel valleys are major features of glaciated margins and they enable meltwater expulsion from underneath a thick ice cover. Their formation is related to the erosion of subglacial sediments by overpressured meltwater and direct glacial erosion. Yet, the impact of pre-existing structures on their formation and morphology remains poorly known. High-quality 3D seismic data allowed the mapping of a large tunnel valley that eroded underlying preglacial delta deposits in the southern North Sea. The valley follows the N–S strike of crestal faults related to a Zechstein salt wall. A change in downstream tunnel valley orientation towards the SE accompanies a change in the strike direction of salt-induced faults. Fault offsets indicate important activity of crestal faults during the deposition of preglacial deltaic sediments. We propose that crestal faults facilitated tunnel valley erosion by acting as high-permeability pathways and allowing subglacial meltwater to reach low-permeability sediments in the underlying Neogene deltaic sequences, ultimately resulting in meltwater overpressure build-up and tunnel valley excavation. Active faults probably also weakened the near-surface sediment to allow a more efficient erosion of the glacial substrate. This control of substrate structures on tunnel valley morphology is considered as a primary factor in subglacial drainage pattern development in the study area.

Description: The timing and mechanisms of the Cretaceous sea incursions into Central Asia are still poorly constrained. We provide a new chronostratigraphic framework based on biostratigraphy and magnetostratigraphy together with detailed paleoenvironmental analyses of Cretaceous records of the proto-Paratethys Sea fluctuations in the Tajik and Tarim basins. The Early Cretaceous marine incursion in the western Tajik Basin was followed by major marine incursions during the Cenomanian (ca. 100 Ma) and Santonian (ca. 86 Ma) that reached far into the eastern Tajik and Tarim basins. These marine incursions were separated by a Turonian-Coniacian (ca. 92–86 Ma) regression. Basin-wide tectonic subsidence analyses imply that the Early Cretaceous sea incursion into the Tajik Basin was related to increased Pamir tectonism. We find that thrusting along the northern edge of the Pamir at ca. 130–90 Ma resulted in increased subsidence in a retro-arc basin setting. This tectonic event and coeval eustatic highstand resulted in the maximum observed geographic extent of the sea during the Cenomanian (ca. 100 Ma). The following Turonian-Coniacian (ca. 92–86 Ma) major regression, driven by eustasy, coincides with a sharp slowdown in tectonic subsidence during the late orogenic unloading period with limited thrusting. The Santonian (ca. 86 Ma) major sea incursion was likely controlled by eustasy as evidenced by the coeval fluctuations in the west Siberian Basin. An early Maastrichtian cooling (ca. 71–70 Ma), potentially connected to global Late Cretaceous trends, is inferred from the replacement of mollusk-rich limestones by bryozoan- and echinoderm-rich limestones.

Description: Columnar jointed lava is an important facies in many geothermal reservoir systems. The permeability of jointed lavas is dominated by the contribution from fracture networks. We use a scaling for the permeability of a set of fractures in a solid or porous mass and extend this to arrays of hexagonal intercolumn fractures. To validate our analytical results, we create numerical domains with relevant geometries and extract system-scale permeability using the LBflow lattice-Boltzmann fluid flow simulation tool. Finally, we model the cooling contraction of columns to extend our results so that they predict the permeability with time after lava emplacement. Importantly, we use these results to estimate the range of permeabilities typical of columnar joints that form during cooling from high temperature and are preserved in the crust at moderate to low temperatures.

Description: Detailed organic geochemical and carbon isotopic (δ13C and Δ14C) analyses are performed on permafrost deposits affected by coastal erosion (Herschel Island, Canadian Beaufort Sea) and adjacent marine sediments (Herschel Basin) to understand the fate of organic carbon in Arctic nearshore environments. We use an end-member model based on the carbon isotopic composition of bulk organic matter to identify sources of organic carbon. Monte Carlo simulations are applied to quantify the contribution of coastal permafrost erosion to the sedimentary carbon budget. The models suggest that ~40% of all carbon released by local coastal permafrost erosion is efficiently trapped and sequestered in the nearshore zone. This highlights the importance of sedimentary traps in environments such as basins, lagoons, troughs, and canyons for the carbon sequestration in previously poorly investigated, nearshore areas.

Description: The transition from the Pliocene to the Pleistocene was accompanied by major tectonic reorganizations of key oceanic gateways. In particular, the gradual closure of the Panama Gateway and the constriction of the Indonesian Gateway significantly affected the structure of the Pacific thermocline. In the East Pacific, the thermocline shoaled from an early Pliocene El Niño-like depth to its modern state, which had significant implications for global climate. Here we use Mg/Ca temperature estimates from subsurface and thermocline dwelling foraminifera to reconstruct the meridional Plio-Pleistocene evolution of the Southeast Pacific thermocline, in relation to atmospheric circulation changes. In combination with similar reconstructions from the north-equatorial Pacific, our data indicate a change in the thermocline, responding to the northward displacement of the Intertropical Convergence Zone/South Pacific High system between ~3.8 and 3.5 Ma. After 3.5 Ma, we record a second major phase of thermocline shoaling, which points to the Intertropical Convergence Zone/South Pacific High-system movement toward its modern position along with the gradual cooling of the Northern Hemisphere and its associated glaciation. These findings highlight that a warming globe may affect equatorial regions more intensively due to the potential temperature-driven movement of the Intertropical Convergence Zone/South Pacific High and their associated oceanic systems.

Description: The brittle-ductile transition is a domain of finite extent characterized by high differential stress where both brittle and ductile deformation are likely to occur. Understanding its depth location, extent, and stability through time is of relevance for diverse applications including subduction dynamics, mantle-surface interactions, and, more recently, proper targeting of high-enthalpy unconventional geothermal resources, where local thermal conditions may activate ductile creep at shallower depths than expected. In this contribution, we describe a thermodynamically consistent physical framework and its numerical implementation, therefore extending the formulation of the companion paper Jacquey and Cacace (2020, https://doi.org/10.1029/2019JB018474) to model thermo-hydro-mechanical coupled processes responsible for the occurrence of transitional semi-brittle, semi-ductile behavior in porous rocks. We make use of a damage rheology to account for the macroscopic effects of microstructural processes leading to brittle-like material weakening and of a rate-dependent plastic model to account for ductile material behavior. Our formulation additionally considers the role of porosity and its evolution during loading in controlling the volumetric mechanical response of a stressed rock. By means of dedicated applications, we discuss how our damage poro-visco-elasto-viscoplastic rheology can effectively reconcile the style of localized deformation under different confining pressure conditions as well as the bulk macroscopic material response as recorded by laboratory experiments under full triaxial conditions.

Description: This paper presents evidence for a limnological response to the Laacher See eruption (LSE) as detected in lake sediments from Nahe, northern Germany. The sediment section of the Allerød period dating to between 13 422 and 12 708 cal. a BP is preserved in annual laminations. Within this section, the LSE was identified as a cryptotephra layer (12 944±44 cal. a BP). Microfacies analysis, continuous high-resolution geochemical measurements and pollen analyses enabled a high-resolution reconstruction of environmental change. The older part of the Allerød (c. 13 422 to 12 943 cal. a BP) was characterized by relatively stable sedimentation conditions. Evidence for windier conditions dating to c. 13 160 to 13 080 cal. a BP probably reflects the Gerzensee oscillation. Pronounced changes of the lake sedimentation followed the LSE. Four unusually thick varves with increased amounts of allochthonous material indicate serious disturbance of the local environment immediately after the LSE, related to increased storminess and/or the occurrence of high intensity rainfall events. A pronounced reduction of biogenic silica accumulation for c. 60 years after the LSE could reflect a period of acidification. Indications of a simultaneous lake level increase until c. 60 years after the LSE are in line with the supposed reduced evapotranspiration associated with cooler conditions. About 120 years after the LSE, increased oxygen access at the lake bottom, allochthonous input and Cl fluxes point to an onset of increasingly stronger westerly winds, probably as a long-term response to the LSE. This supports the idea of a southward shift of the mid-latitude westerlies wind system within the interval between the LSE and the beginning of the Younger Dryas. The pace of the southwards shift of this wind system decreased from 10 km a−1 in the initial phase (40–120 years after LSE) to 6 km a−1 in the later phase (120–200 years after LSE).

Description: Upwelling ocean currents associated with oxygen minimum zones (OMZs) supply nutrients fuelling intense marine productivity. Perturbations in the extent and intensity of OMZs are projected in the future, but it is currently uncertain how this will impact fluxes of redox-sensitive trace metal micronutrients to the surface ocean. Here we report seawater concentrations of Fe, Mn, Co, Cd, and Ni alongside the redox indicator iodide/iodate in the Peruvian OMZ during the 2015 El Niño event. The El Niño drove atypical upwelling of oxygen-enriched water over the Peruvian Shelf, resulting in oxidized iodine and strongly depleted Fe (II), total dissolved Fe, and reactive particulate Fe concentrations relative to non-El Niño conditions. Observations of Fe were matched by the redox-sensitive micronutrients Co and Mn, but not by non-redox-sensitive Cd and Ni. These observations demonstrate that oxygenation of OMZs significantly reduces water column inventories of redox-sensitive micronutrients, with potential impacts on ocean productivity.

Description: Heat transport in natural porous media, such as aquifers or streambeds, is generally modeled assuming local thermal equilibrium (LTE) between the fluid and solid phases. Yet, the mathematical and hydrogeological conditions and implications of this simplification have not been fully established for natural porous media. To quantify the occurrence and effects of local thermal disequilibrium during heat transport, we systematically compared thermal breakthrough curves from a LTE with those calculated using a local thermal nonequilibrium (LTNE) model, explicitly allowing for different temperatures in the fluid and solid phases. For the LTNE model, we developed a new correlation for the heat transfer coefficient representative of the conditions in natural porous aquifers using six published experimental results. By conducting an extensive parameter study (〉50,000 simulations), we show that LTNE effects do not occur for grain sizes smaller than 7 mm or for groundwater flow velocities that are slower than 1.6 m day−1. The limits of LTE are likely exceeded in gravel aquifers or in the vicinity of pumped bores. For such aquifers, the use of a LTE model can lead to an underestimation of the effective thermal dispersion by a factor of up to 30 or higher, while the advective thermal velocity remains unaffected for most conditions. Based on a regression analysis of the simulation results, we provide a criterion which can be used to determine if LTNE effects are expected for particular conditions.

Description: Tunnel valleys are assumed to form near the margin of ice sheets. Hence, they can be used to reconstruct the dynamics of former ice margins. The detailed formation and infill of tunnel valleys, however, are still not well understood. Here, we present a dense grid of high-resolution 2D multi-channel reflection seismic data from the German sector of the southeastern North Sea imaging tunnel valleys in very great detail. Three tunnel valley systems were traced over distances ranging between 11 and 21 km. All tunnel valleys are completely filled and buried. They differ in incision depth, incision width and number of incisions. The tunnel valleys cut 130–380 m deep into Neogene, Palaeogene and Cretaceous sediments; they show a lower V-shaped and an upper U-shaped morphology. For individual tunnel valleys, the overall incision direction ranges from east–west to northeast–southwest. Two tunnel valleys intersect at an oblique angle without reuse of the thalweg. These valleys incise into a pre-existing glaciotectonic complex consisting of thrust sheets in the northwest of the study area. The analysis of the glaciotectonic complex and the tunnel valleys leads us to assume that we identified several marginal positions of (pre-)Elsterian ice lobes in the southeastern North Sea.

Description: The climate of the western Mediterranean was characterized by a strong precipitation gradient during the Holocene driven by atmospheric circulation patterns. The scarcity of terrestrial paleoclimate archives has precluded exploring this hydroclimate pattern during Marine Isotope Stages 5 to 3. Here we present stable carbon and oxygen isotope records from three flowstones from southeast Iberia, which show that Dansgaard/Oeschger events were associated with more humid conditions. This is in agreement with other records from the Iberian Peninsula, the Mediterranean, and western Europe, which all responded in a similar way to millennial-scale climate variability in Greenland. This general increase in precipitation during Dansgaard/Oeschger events cannot be explained by any present-day or Holocene winter atmospheric circulation pattern. Instead, we suggest that changes in sea surface temperature played a dominant role in determining precipitation amounts in the western Mediterranean.

Description: The Middle Eocene Climatic Optimum (MECO) was a gradual warming event and carbon cycle perturbation that occurred between 40.5 and 40.1 Ma. A number of characteristics, including greater-than-expected deep-sea carbonate dissolution, a lack of globally coherent negative δ13C excursion in marine carbonates, a duration longer than the characteristic timescale of carbon cycle recovery, and the absence of a clear trigger mechanism, challenge our current understanding of the Earth system and its regulatory feedbacks. This makes the MECO one of the most enigmatic events in the Cenozoic, dubbed a middle Eocene “carbon cycle conundrum.” Here we use boron isotopes in planktic foraminifera to better constrain pCO2 changes over the event. Over the MECO itself, we find that pCO2 rose by only 0.55–0.75 doublings, thus requiring a much more modest carbon injection than previously indicated by the alkenone δ13C-pCO2 proxy. In addition, this rise in pCO2 was focused around the peak of the 400 kyr warming trend. Before this, considerable global carbonate δ18O change was asynchronous with any coherent ocean pH (and hence pCO2) excursion. This finding suggests that middle Eocene climate (and perhaps a nascent cryosphere) was highly sensitive to small changes in radiative forcing.

Description: Millennial-scale reductions in monsoon precipitation, so-called Weak Monsoon Intervals (WMIs), have been identified in numerous paleoclimate records across the Afro-Asian monsoon domain throughout the last glacial-interglacial cycle. These are considered the regional response to cooling during Heinrich events in the North Atlantic realm and several mechanisms have been suggested to explain this hemisphere-scale climatic teleconnection. In particular, reductions in Indian Ocean sea surface temperature (SST) have been proposed as the linking element between Heinrich events and WMIs. However, the validity of this relationship has only been demonstrated for the last ~20 kyr, leaving unresolved whether it also holds on longer time scales. Here we present a new paired record of planktonic foraminifera-based δ18Osw-ivc and UK'37-based SST from the northern Bay of Bengal, covering the last ~130 kyr. The δ18Osw-ivc record clearly reflects orbitally paced changes of Indian Summer Monsoon intensity superimposed by centennial- to millennial-scale WMIs that occurred synchronously to North Atlantic Heinrich events. Comparison with the UK'37-based SST reconstruction reveals, however, that WMIs in most cases were not paralleled by ocean surface cooling, questioning whether Indian Ocean SST lowering was the linking element between Heinrich events and reductions in monsoon precipitation in Asia also during the last glacial period.

Description: Vertical and horizontal components of GNSS displacements in the Long Valley Caldera and adjacent Sierra Nevada range show a clear correlation with hydrological trends at both multiyear and seasonal time scales. We observe a clear vertical and horizontal seasonal deformation pattern primarily attributable to the solid earth response to hydrological surface loading at large-to-regional (Sierra Nevada range) scales. Several GNSS sites, located at the eastern edge of the Sierra Nevada along the southwestern rim of Long Valley Caldera, also show significant horizontal deformation that cannot be explained by elastic deformation from surface loading. Due to the location of these sites and the strong correlation between their horizontal displacements and spring discharge, we hypothesize that this deformation reflects poroelastic processes related to snowmelt runoff water infiltrating into the Sierra Nevada slopes around Long Valley Caldera. Interestingly, this is also an area where water infiltrates to feed the local hydrothermal system, and where snowmelt-induced earthquake swarms have been recently detected.

Description: On interannual timescales the growth rate of atmospheric CO2 is largely controlled by the response of the land and ocean carbon sinks to climate variability. Yet, it is unknown to what extent this variability limits the predictability of atmospheric CO2 variations. Using perfect-model Earth System Model simulations, we show that variations in atmospheric CO2 are potentially predictable for 3 years. We find a 2-year predictability horizon for global oceanic CO2 flux with longer regional predictability of up to 7 years. The 2-year predictability horizon of terrestrial CO2 flux originates in the tropics and midlatitudes. With the predictability of the isolated effects of land and ocean carbon sink on atmospheric CO2 of 5 and 12 years respectively, land dampens the overall predictability of atmospheric CO2 variations. Our research shows the potential of Earth System Model-based predictions to forecast multiyear variations in atmospheric CO2.

Description: Understanding hemisphere-wide millennial-scale temperature variability during past glacials in response to ice sheet dynamics and orbital forcing is one of the key targets for Quaternary climate research. While an inland propagation of abrupt temperature changes into Eurasia from the North Atlantic realm during the last glacial (Weichselian) receives increasingly broad support, much less is known regarding the penultimate glacial (Saalian) temperature variability, especially from a continental interior perspective. Here, we present a TEX86-derived lake surface temperature (LST) record from the former Black Sea “Lake” covering nearly the entire Marine Isotope Stage (MIS) 6. While orbital-scale LST cooling likely relates to meltwater discharge from the retreating Eurasian Ice Sheet during insolation maxima, millennial-scale LST variability suggests interstadial warming in phase with Greenland and northern Mediterranean Sea temperature records during the first half of MIS 6. Although summer insolation reached an interglacial-like level during this period, we propose that the reduced extent of the Eurasian Ice Sheet associated with northward shifted atmospheric fronts was ultimately responsible for the inland propagation of Dansgaard-Oeschger-like temperature variability. During the second half of MIS 6, temperature patterns across the North Atlantic-Eurasian corridor were more variable and less comparable with each other, likely because of the larger continental ice sheet weakening northern hemisphere atmospheric teleconnections. Temperature records across the North Atlantic-Eurasian realm suggest a weaker atmospheric teleconnection during MIS 6 compared to MIS 3, likely related to a stronger imprint of the Eurasian Ice Sheet on the continental and regional climate.

Description: We present a local earthquake tomography to illuminate the crustal and uppermost mantle structure beneath the southern Puna plateau and to test the delamination hypothesis. Vp and Vp/Vs ratios were obtained using travel time variations recorded by 75 temporary seismic stations between 2007 and 2009. In the upper crust, prominent low Vp anomalies are found beneath the main volcanic centers, indicating the presence of magma and melt beneath the southern Puna plateau. Beneath the Moho at around 90-km depth, a strong high Vp anomaly is detected just west of the giant backarc Cerro Galan ignimbrite caldera. This high Vp anomaly is only resolved if earthquakes with an azimuthal gap up to 300° are included in the inversion. However, we show through data subset and synthetic tests that the anomaly is robust due to our specific station-event geometry and interpret it as a delaminated block of lower crust and uppermost mantle lithosphere under the southern Puna plateau. The low velocities in the crust are interpreted as a product of the delamination event that triggered the rise of fluids and melts into the crust and induced the high topography in this part of the plateau. The tomography also reveals the existence of low-velocity anomalies that link arc magmatism at the Ojos del Salado volcanic center with slab seismicity clusters at depths of about 100 and 150 km and support fluid transport in the mantle wedge due to dehydration reaction within the subducted slab.

Description: Geophysical and geochemical data indicate there is abundant fluid expulsion in the Nootka fault zone (NFZ) between the Juan de Fuca and Explorer plates and the Nootka continental slope. Here we combine observations from 〉20 years of investigations to demonstrate the nature of fluid-flow along the NFZ, which is the seismically most active region off Vancouver Island. Seismicity reaching down to the upper mantle is linked to near-seafloor manifestation of fluid flow through a network of faults. Along the two main fault traces, seismic reflection data imaged bright spots 100–300 m below seafloor that lie above changes in basement topography. The bright spots are conformable to sediment layering, show opposite-to-seafloor reflection polarity, and are associated with frequency reduction and velocity push-down indicating the presence of gas in the sediments. Two seafloor mounds ~15 km seaward of the Nootka slope are underlain by deep, nonconformable high-amplitude reflective zones. Measurements in the water column above one mound revealed a plume of warm water, and bottom-video observations imaged hydrothermal vent system biota. Pore fluids from a core at this mound contain predominately microbial methane (C1) with a high proportion of ethane (C2) yielding C1/C2 ratios 〈500 indicating a possible slight contribution from a deep source. We infer the reflective zones beneath the two mounds are basaltic intrusions that create hydrothermal circulation within the overlying sediments. Across the Nootka continental slope, gas hydrate-related bottom-simulating reflectors are widespread and occur at depths indicating heat flow values of 80–90 mW/m2.

Description: Estuarine CO2 emissions are important components of regional and global carbon budgets, but assessments of this flux are plagued by uncertainties associated with gas transfer velocity (k) parameterization. We combined direct eddy covariance measurements of CO2 flux with waterside pCO2 determinations to generate more reliable k parameterizations for use in small estuaries. When all data were aggregated, k was described well by a linear relationship with wind speed (U10), in a manner consistent with prior open ocean and estuarine k parameterizations. However, k was significantly greater at night and under low wind speed, and nighttime k was best predicted by a parabolic, rather than linear, relationship with U10. We explored the effect of waterside thermal convection but found only a weak correlation between convective scale and k. Hence, while convective forcing may be important at times, it appears that factors besides waterside thermal convection were likely responsible for the bulk of the observed nighttime enhancement in k. Regardless of source, we show that these day-night differences in k should be accounted for when CO2 emissions are assessed over short time scales or when pCO2 is constant and U10 varies. On the other hand, when temporal variability in pCO2 is large, it exerts greater control over CO2 fluxes than does k parameterization. In these cases, the use of a single k value or a simple linear relationship with U10 is often sufficient. This study provides important guidance for k parameterization in shallow or microtidal estuaries, especially when diel processes are considered.

Description: research

Description: The Tajik basin archives the orogenic evolution of the Pamir hinterland. Stratigraphic-sedimentologic observations from Cretaceous-Pliocene strata along its eastern margin describe the depositional environment and basin-formation stages in reaction to hinterland exhumation and basin inversion. During the Late Cretaceous-Eocene (preorogenic stage: ~100–34 Ma), a shallow-marine to terrestrial basin extended throughout Central Asia. An alluvial plain with influx of conglomerate bodies (Baljuvon Formation) indicates a first pulse of hinterland erosion and foreland-basin formation in the late Oligocene-early Miocene (synorogenic stage Ia: ~34–23 Ma). Further hinterland exhumation deposited massive alluvial conglomerates (Khingou Formation) in the early-middle Miocene (synorogenic stage Ib: ~23–15 Ma). Westward thickening growth strata suggest transformation of the Tajik basin into the Tajik fold-thrust belt in the middle-late Miocene (synorogenic stage IIa: ~15–5 Ma). Increased water supply led to the formation of fluvial mega-fans (Tavildara Formation). Latest Miocene-Pliocene shortening constructed basin morphology that blocked sediment bypass into the central basin from the east (Karanak Formation), triggering drainage-system reorganization from transverse to longitudinal sediment transport (synorogenic stage IIb: 〈 ~5 Ma). Accelerated shortening (~27–20 Ma) and foreland-directed collapse (~23–12 Ma) of Pamir-plateau crust loaded the foreland and induced synorogenic stages Ia and Ib. Coupling of Indian and Asian cratonic lithospheres and onset of northward and westward delamination/rollback of Asian lithosphere (i.e., lithosphere of the Tajik basin) beneath the Pamir at ~12–11 Ma transformed the Tajik basin into the Tajik fold-thrust belt (synorogenic stage IIa). The timing of the sedimentologically derived basin reconfiguration matches the thermochronologically derived onset of Tajik-basin inversion at ~12 Ma.

Description: Geophysical length scales defined from induced-polarization measurements can be used in models of permeability (k) prediction. We explore the relative merit of different induced-polarization parameters as proxies of an effective hydraulic radius (reff) that can be used to predict permeability from a modified Hagen–Poiseuille equation. Whereas geometrical measures of the hydraulic radius are good proxies of reff, the induced-polarization measures are not well correlated with reff. However, a new proxy of reff that considers both imaginary conductivity and formation factor shows an improved correlation with reff. The resulting model enables a better quality of permeability prediction compared with the other geophysical length scales, but does not reach the predictive quality of the models based on geometrical length scales. The specific polarizability defined when incorporating the effect of the formation factor on imaginary conductivity appears to be independent of pore geometry, indicating that it is the correct parameter representing the role of the surface electrochemistry on the induced-polarization effect. However, the joint dependence of induced-polarization measurements on both the pore radius and the tortuosity and porosity of the interconnected pore network is a limitation to the widely explored use of induced-polarization measurements to isolate surface properties from volumetric properties of the interconnected pore network.

Description: New marine geophysical data acquired across the partly ice-covered northern East Greenland continental margin highlight a complex interaction between tectonic and magmatic events. Breakup-related lava flows are imaged in reflection seismic data as seaward dipping reflectors, which are found to decrease in size both northward and southward from a central point at 75°N. We provide evidence that the magnetic anomaly pattern in the shelf area is related to volcanic phases and not to the presence of oceanic crust. The remnant magnetization of the individual lava flows is used to deduce a relative timing of the emplacement of the volcanic wedges. We find that the seaward dipping reflectors have been emplaced over a period of 2–4 Ma progressively from north to south and from landward to seaward. The new data indicate a major post-middle Eocene magmatic phase around the landward termination of the West Jan Mayen Fracture Zone. This post-40-Ma volcanism likely was associated with the progressive separation of the Jan Mayen microcontinent from East Greenland. The breakup of the Greenland Sea started at several isolated seafloor spreading cells whose location was controlled by rift structures and led to the present-day segmentation of the margin. The original rift basins were subsequently connected by steady-state seafloor spreading that propagated southward, from the Greenland Fracture Zone to the Jan Mayen Fracture Zone.

Description: We combine numerical modeling of lithospheric extension with analysis of seismic moment release and earthquake b-value in order to elucidate the mechanism for deep crustal seismicity and seismic swarms in the Main Ethiopian Rift (MER). We run 2-D numerical simulations of lithospheric deformation calibrated by appropriate rheology and extensional history of the MER to simulate migration of deformation from mid-Miocene border faults to ∼30 km wide zone of Pliocene to recent rift floor faults. While currently the highest strain rate is localized in a narrow zone within the rift axis, brittle strain has been accumulated in a wide region of the rift. The magnitude of deviatoric stress shows strong variation with depth. The uppermost crust deforms with maximum stress of 80 MPa, at 8–14 km depth stress sharply decreases to 10 MPa and then increases to a maximum of 160 MPa at ∼18 km depth. These two peaks at which the crust deforms with maximum stress of 80 MPa or above correspond to peaks in the seismic moment release. Correspondingly, the drop in stress at 8–14 km correlates to a low in seismic moment release. At this depth range, the crust is weaker and deformation is mainly accommodated in a ductile manner. We therefore see a good correlation between depths at which the crust is strong and elevated seismic deformation, while regions where the crust is weaker deform more aseismically. Overall, the bimodal depth distribution of seismic moment release is best explained by the rheology of the deforming crust.

Description: Loess sediments are windblown silt deposits with, in general, a carbonate grain content of up to 30%. While regionally, loess was reported to increase weathering fluxes substantially, the influence on global weathering fluxes remains unknown. Especially on glacial-interglacial time scales, loess weathering fluxes might have contributed to land-ocean alkalinity flux variability since the loess areal extent during glacial epochs was larger. To quantify loess weathering fluxes, global maps representing the loess distribution were compiled. Water chemistry of rivers draining recent loess deposits suggests that loess contributes over-proportionally to alkalinity concentrations if compared to the mean of alkalinity concentrations of global rivers (~4,110 µeq L−1 for rivers draining loess deposits and ~1,850 µeq L−1 for the total of global rivers), showing comparable alkalinity concentration patterns in rivers as found for carbonate sedimentary rocks. Loess deposits, covering ~4% of the ice- and water-free land area, increase calculated global alkalinity fluxes to the coastal zone by 16%. The new calculations lead to estimating a 4% higher global alkalinity flux during the Last Glacial Maximum (LGM) compared to present fluxes. The effect of loess on that comparison is high. Alkalinity fluxes from silicate-dominated lithological classes were ~28% and ~30% lower during the LGM than recent (with loess and without loess, respectively), and elevated alkalinity fluxes from loess deposits compensated for this. Enhanced loess weathering dampens due to a legacy effect changes in silicate-dominated lithologies over the glacial-interglacial time scale.

Description: In contrast to seamount chains, small solitary seamounts/seamount groups have rarely been sampled despite their large number and therefore their origins remain enigmatic. Here we present new 40Ar/39Ar, trace element and Nd-Hf-Pb isotope data from the solitary Demenitskoy Seamount, the isolated Tolkien seamount group and the Krylov Seamount and Ridge in the Canary Basin, Central Atlantic Ocean. Their chemical compositions range from intraplate ocean-island-basalt (Demenitskoy) to mid-ocean-ridge-basalt (Tolkien and Krylov) types. Lavas from all three seamount groups, however, show geochemical evidence for involvement of enriched Canary/Cape Verde plume material. Seismic tomography shows that large areas around these mantle plumes consist of dispersed low-velocity material, which could represent diffusely-upwelling plume mantle. Melts from such upwelling mantle could form isolated seamounts. Diffuse upwelling of plume material is likely to be extremely widespread but has been poorly studied to date. Significance Statement A fundamental question concerns the origin of the hundreds of thousands of solitary seamounts and small isolated clusters of such seamounts on the seafloor of the world's ocean basins. Most of them do not fit into any currently accepted models (e.g. they are not associated with a linear hotspot track or plate boundary processes). Their formation could therefore represent a new kind of intraplate volcanism that in fact could be extremely widespread but has been thus far largely neglected. In this manuscript, we report geochemical data from three isolated seamount sites in the Canary Basin and propose a provocative model for their formation that can also be applied to isolated seamounts elsewhere. Our study is therefore also a plea for the long overdue systematic investigation of small seamount volcanism in the world's ocean basins. I hereby confirm that all the data and interpretations are new and have not been published elsewhere. All co-authors have been actively involved in this work, have approved the manuscript and agreed to this submission.

Description: The Indonesian Throughflow (ITF) operates as an important link in global thermohaline circulation, and ITF variability probably modulated Pliocene climate change. Yet, whether ITF variability accounted for oceanographic change south of Northwest Cape remains controversial. Here, we present a multiproxy oceanographic reconstruction from the Perth Basin and reconstruct the Pliocene history of the Leeuwin Current (LC). We show that the LC was active throughout the Pliocene, albeit with fluctuations in intensity and scope. Three main factors controlled LC strength. First, a tectonic ITF reorganization caused an abrupt and permanent LC reduction at 3.7 Ma. On shorter timescales, eustatic sea level and direct orbital forcing of wind patterns hampered or promoted the LC. At 3.3 Ma, for instance, LC intensity plunged in response to a eustatic ITF restriction. Site U1459 then fell outside the extent of a weakened LC, and the latitudinal sea surface temperature gradient along West Australia doubled its steepness.

Description: Molecular hydrogen (H2) released during serpentinization of mantle rocks is one of the main fuels for chemosynthetic life. Processes of H2 production at slow-spreading mid-ocean ridges (MORs) have received much attention in the past. Less well understood is serpentinization at passive continental margins where different rock types are involved (lherzolite instead of harzburgite/dunite at MORs) and the alteration temperatures tend to be lower (〈200°C vs. 〉200°C). To help closing this knowledge gap we investigated drill core samples from the West Iberia margin. Lherzolitic compositions and spinel geochemistry indicate that the exhumed peridotites resemble sub-continental lithospheric mantle. The rocks are strongly serpentinized, mainly consist of serpentine with little magnetite, and are generally brucite-free. Serpentine can be uncommonly Fe- rich, with XMg Mg/(Mg + Fe) 〈 0.8, and shows distinct compositional trends toward a cronstedtite endmember. Bulk rock and silicate fraction Fe(III)/ Fe ratios are 0.6–0.92 and 0.58–0.8, respectively; our data show that 2/3 of the ferric Fe is accounted for by Fe(III)- serpentine. Mass balance and thermodynamic calculations suggest that the sample’s initial serpentinization produced ∼120 to 〉300 mmol H2 per kg rock. The cold, late-stage weathering of the serpentinites at the seafloor caused additional H2 formation. These results suggest that the H2 generation potential evolves during the transition from continental break-up to ultraslow and, eventually, slow MOR spreading. Metamorphic phase assemblages systematically vary between these settings, which has consequences for H2 yields during serpentinization. At magma-poor rifted margins and ultraslow- spreading MORs, serpentine hosts most Fe(III). Hydrogen yields of 120 to 〉300 mmol and 50–150 mmol H2 per kg rock, respectively, may be expected at temperatures of 〈200°C. At slow-spreading MORs, in contrast, serpentinization may produce 200–350 mmol H2, most of which is related to magnetite formation at 〉200°C. Since, in comparison to slow-spreading MORs, geothermal gradients at magma-poor margins and ultraslow-spreading MORs are lower, larger volumes of low-temperature serpentinite should form in these settings. Serpentinization of lherzolitic rocks at magma-poor margins should produce particularly high amounts of H2 under conditions within the habitable zone. Magma-poor margins may hence be more relevant environments for hydrogenotrophic microbial life than previously thought.

Description: research

Description: https://doi.org/10 .1594/PANGAEA.920208

Description: research

Description: Few data exist that provide insight into pro- cesses affecting the long-term carbon cycle at shallow fore- arc depths. To better understand the mobilization of C in sediments and crust of the subducting slab, we investigated carbonate materials that originate from the subduction chan- nel at the Mariana forearc (〈 20 km) and were recovered during International Ocean Discovery Program Expedition 366. Calcium carbonates occur as vein precipitates within metavolcanic and metasedimentary clasts. The clasts repre- sent portions of the subducting lithosphere, including ocean island basalt, that were altered at lower blueschist facies conditions and were subsequently transported to the fore- arc seafloor by serpentinite mud volcanism. Euhedral arag- onite and calcite and the lack of deformation within the veins suggest carbonate formation in a stress-free environ- ment after peak metamorphism affected their hosts. Inter- growth with barite and marked negative Ce anomalies in car- bonate attest the precipitation within a generally oxic envi- ronment, that is an environment not controlled by serpen- tinization. Strontium and O isotopic compositions in car- bonate (87Sr/86Sr = 0.7052 to 0.7054, δ18OVSMOW = 20 to 24 ‰) imply precipitation from slab-derived fluids at tem- peratures between ∼ 130 and 300 ◦C. These temperature es- timates are consistent with the presence of blueschist facies phases such as lawsonite coexisting with the carbonates in some veins. Incorporated C is inorganic (δ13CVPDB = −1 ‰ to +4 ‰) and likely derived from the decarbonation of cal- careous sediment and/or oceanic crust. These findings pro- vide evidence for the mobilization of C in the downgoing slab at depths of 〈 20 km. Our study shows for the first time in detail that a portion of this C forms carbonate precipitates in the subduction channel of an active convergent margin. This process may be an important asset in understanding the deep carbon cycle since it highlights that some C is lost from the subducting lithosphere before reaching greater depths.

Description: research

Description: Changes in penguin populations on the Antarctic Peninsula have been linked to several environmental factors, but the potentially devastating impact of volcanic activity has not been considered. Here we use detailed biogeochemical analyses to track past penguin colony change over the last 8,500 years on Ardley Island, home to one of the Antarctic Peninsula’s largest breeding populations of gentoo penguins. The first sustained penguin colony was established on Ardley Island c. 6,700 years ago, pre-dating sub-fossil evidence of Peninsula- wide occupation by c. 1,000 years. The colony experienced five population maxima during the Holocene. Overall, we find no consistent relationships with local-regional atmospheric and ocean temperatures or sea-ice conditions, although the colony population maximum, c. 4,000–3,000 years ago, corresponds with regionally elevated temperatures. Instead, at least three of the five phases of penguin colony expansion were abruptly ended by large eruptions from the Deception Island volcano, resulting in near-complete local extinction of the colony, with, on average, 400–800 years required for sustainable recovery.

Description: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3080_ESM.xlsx

Description: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3081_ESM.xlsx

Description: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3082_ESM.xlsx

Description: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3083_ESM.xlsx

Description: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3084_ESM.xlsx

Description: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3085_ESM.xlsx

Description: https://static-content.springer.com/esm/art%3A10.1038%2Fncomms14914/MediaObjects/41467_2017_BFncomms14914_MOESM3086_ESM.xlsx

Description: research

Description: Estimates of flood susceptibility and land loss in the world's coastal regions depend on our knowledge of sea level rise (SLR) from increases in ocean mass and volume, as well as knowledge of vertical land motion. Conventional approaches to the latter include tide-gauge and Global Positioning System (GPS) measurements relative to well-anchored monuments few meters below the surface. However, in regions of rapid Holocene sedimentation, compaction of this material can add a significant component to the surface lowering. Unfortunately, this process has been difficult to quantify, especially for the shallowest material above the monument. Here we use a new technique, GPS interferometric reflectometry, to estimate the rate of this process in the Mississippi Delta and the eastern margin of the North Sea. We show that the rate of shallow compaction is comparable to or larger than the rate of global SLR, adding 35% and 65%, respectively, to the rate of relative SLR by 2100.