Tidal response to sea level rise and bathymetric changes in the German Wadden Sea     

Wachler  Benno  Seiffert  Rita  Rasquin  Caroline  Kösters  Frank 《Ocean Dynamics》2020,70(8):1033-1052

Ocean Dynamics - Tidally dominated coasts are directly affected not only by projected rise in mean sea level, but also by changes in tidal dynamics due to sea level rise and bathymetric changes. By...  相似文献   

Deciphering late Devonian–early Carboniferous P–T–t path of mylonitized garnet-mica schists from Prins Karls Forland,Svalbard     

Karolina Kośmińska  Frank S. Spear  Jarosław Majka  Karol Faehnrich  Maciej Manecki  Karsten Piepjohn  Winfried K. Dallmann 《Journal of Metamorphic Geology》2020,38(5):471-493

Quartz-in-garnet inclusion barometry integrated with trace element thermometry and calculated phase relations is applied to mylonitized schists of the Pinkie unit cropping out on the island of Prins Karls Forland, western part of the Svalbard Archipelago. This approach combines conventional and novel techniques and allows deciphering of the pressure–temperature (P–T) evolution of mylonitic rocks, for which the P–T conditions could not have been easily deciphered using traditional methods. The results obtained suggest that rocks of the Pinkie unit were metamorphosed under amphibolite facies conditions at 8–10 kbar and 560–630°C and mylonitized at ~500 to 550°C and 9–11 kbar. The P–T results are coupled with in-situ Th–U-total Pb monazite dating, which records amphibolite facies metamorphism at c. 359–355 Ma. This is the very first evidence of late Devonian–early Carboniferous metamorphism in Svalbard and it implies that the Ellesmerian Orogeny on Svalbard was associated with metamorphism up to amphibolite facies conditions. Thus, it can be concluded that the Ellesmerian collision between the Franklinian margin of Laurentia and Pearya and Svalbard caused not only commonly accepted brittle deformation and weak greenschist facies metamorphism, but also a burial and deformation of rock complexes at much greater depths at elevated temperatures.  相似文献   

Neogene upper‐crustal cooling of the Olympus range (northern Aegean): major role of Hellenic back‐arc extension over propagation of the North Anatolia Fault Zone     

Isabelle Coutand  Michael Walsh  Bertha Louis  Frank Chanier  Jacky Ferrière  Jean‐Yves Reynaud 《地学学报》2014,26(4):287-297

The North Anatolian Fault Zone (NAFZ) is one of the most hazardous active faults on Earth, yet its Pliocene space‐time propagation across the north Aegean domain remains poorly constrained. We use low‐temperature multi‐thermochronology and inverse thermal modelling to quantify the cooling history of the upper crust across the Olympus range. This range is located in the footwall of a system of normal faults traditionally interpreted as resulting from superposed Middle–Late Miocene N–S stretching, related to the back‐arc extension of the Hellenic subduction zone, and a Pliocene‐Quaternary transtensional field, attributed to the south‐westward propagation of the NAFZ. We find that accelerated exhumational cooling occurred between 12 and 6 Ma at rates of 15–35 °C Ma^?1 and decreased to <3 °C Ma^?1 by 8–6 Ma. The absence of significant Plio‐Pleistocene cooling across Olympus suggests that crustal exhumation there is driven by late Miocene back‐arc extension, while the impact of the NAFZ remains limited.  相似文献   

Petrography and geochemistry of manganiferous rocks in the Mankwadzi area in the southern Kibi‐Winneba metavolcanic belt,Ghana: Implications for genesis of Mn formations in the Birimian of West Africa     

Kwabina Ibrahim  Frank K. Nyame  Thomas Armah  Johnson Manu  Jeff Baah‐Acheamfour  Jacob Tigme 《Island Arc》2020,29(1)

Manganiferous rocks in the Mankwadzi area in the southernmost portion of the Kibi‐Winneba metavolcanic belt, one of several Mn occurrences in the Paleoproterozoic Birimian of Ghana, are hosted in hornblende schist and amphibolite. These rocks are, in places, intruded by hornblende dyke. In outcrop, the manganiferous rocks appear to be conformable with the host schist and amphibolite, are macroscopically dark, fine‐grained and structurally massive to distinctly banded. Observed alternating light and dark occasionally macro‐folded bands suggest post‐depositional deformation of both light and dark bands. Microscopic observations revealed that the light bands are dominantly Si‐rich and the dark bands mainly of opaque minerals. Whole rock analyses of the manganiferous rocks show high contents of MnO (16.75–27.4 wt%) suggesting that the opaque minerals are likely rich in Mn. The analyzed rock samples show moderate to strong enrichments in light rare earth elements compared to heavy rare earth elements. Whereas the manganiferous rocks show perceptibly negative Eu anomaly, host hornblende schist and hornblende dyke do not. Eu anomaly in amphibolite samples is, however, uncertain as the three samples analyzed gave positive, negative and no Eu anomalies. Based on the field characteristics, microscopic and geochemical features, we suggest that the Mn occurrence in the Mankwadzi area originated via sedimentary deposition and was later modified by metamorphism, hydrothermal and/or supergene processes similar to manganiferous occurrences at Nsuta and Tambao in the Birimian of West Africa.  相似文献   

Correction to: Hydro-geochemical characteristics of the groundwater resources in the southern part of the Red River’s Delta plain,Vietnam     

Hoan V. Hoang  Lam V. Nguyen  Nhan D. Dang  Frank Wagner  Nhan Q. Pham 《Environmental Earth Sciences》2018,77(20):714

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Satellite altimetry for measuring river stages in remote regions     

Ganming Liu  Frank Schwartz  Kuo-Hsin Tseng  C. K. Shum  Sangsuk Lee 《Environmental Earth Sciences》2018,77(18):639

The advent in satellite altimetry with the most accurate satellite radar altimeter since 1992 and its successive missions have enabled the routine global monitoring of water-level (or stage) for surface waters and changes in the quantities of dammed water reservoirs. However, satellite altimeter measurements typically have spatial resolution capable of observing only large water bodies, such as major lakes and rivers. This paper addresses the challenges of how to investigate water levels in medium (~?1 km in width) to small (~?100 m and narrower) rivers. Comparisons between the ENVISAT altimetry ICE-1 waveform retracking height and standard water-level measurements for multiple sections of Ohio River, Columbia River, and Red River of the North in the United States (US) reveals that the satellite altimetry measured water levels agree well with those observed at nearby US Geological Survey gaging stations over the 10-year period starting from 2002. The significant results include those obtained at Thompson, North Dakota (ND, correlation coefficient or R value of 0.76 between satellite and in situ water-level measurements) and Fargo, ND (R?=?0.74), where the stream channels of Red River are merely?~?50 m and ~?40 m wide, respectively, under normal climatic conditions. In addition, demonstrations of the approach over largely inaccessible portions of Tigris–Euphrates Rivers and Helmand River in the Middle East aided in understanding hydrology in these systems. This study demonstrates the ability of satellite radar altimetry to characterize rivers in these study regions which are much narrower than 100 m in width.  相似文献   

Calibration of cyclic constitutive models by oscillating functions     

Muyiwa Ebenezer Alalade  Binod Kafle  Frank Wuttke  Tom Lahmer 《Geomechanics and Geoengineering》2018,13(2):146-157

Most structures are subjected to more cyclic loads during their life time than static loads. These cyclic action could be a result of either natural or man-made activities and may lead to soil failure. In order to understand the response of the foundation and its interaction with these complex cyclic loadings, various researchers have over the years developed different constitutive models. Although a lot of research is being carried out on these relatively new models, little or no details exist in literature about the model-based identification of the cyclic constitutive parameters which to a large extent govern the quality of the model output. This could be attributed to the difficulties and complexities of the inverse modeling of such complex phenomena. A variety of optimisation strategies are available for the solution of the sum of least-squares problems as usually done in the field of model calibration. However, for the back analysis (calibration) of the soil response to oscillatory load functions, this article gives insight into the model calibration challenges and also puts forward a method for the inverse modeling of cyclic loaded foundation response such that high-quality solutions are obtained with minimum computational effort.  相似文献   

Experimental study of quartz inclusions in garnet at pressures up to 3.0 GPa: evaluating validity of the quartz-in-garnet inclusion elastic thermobarometer     

Jay?B.?ThomasEmail authorView author&#;s OrcID profile  Frank?S.?Spear 《Contributions to Mineralogy and Petrology》2018,173(5):42

Garnet crystals with quartz inclusions were hydrothermally crystallized from oxide starting materials in piston–cylinder apparatuses at pressures from 0.5 to 3 GPa and temperatures ranging from 700 to 800 °C to study how entrapment conditions affect remnant pressures of quartz inclusions used for quartz-in-garnet (QuiG) elastic thermobarometry. Systematic changes of the 128, 206 and 464 cm^?1 Raman band frequencies of quartz were used to determine pressures of quartz inclusions in garnet using Raman spectroscopy calibrations that describe the P–T dependencies of Raman band shifts for quartz under hydrostatic pressure. Within analytical uncertainties, inclusion pressures calculated for each of the three Raman band frequencies are equivalent, which suggests that non-hydrostatic stress effects caused by elastic anisotropy in quartz are smaller than measurement errors. The experimental quartz inclusions have pressures ranging from ??0.351 to 1.247 GPa that span the range of values observed for quartz inclusions in garnets from natural rocks. Quartz inclusion pressures were used to model P–T conditions at which the inclusions could have been trapped. The accuracy of QuiG thermobarometry was evaluated by considering the differences between pressures measured during experiments and pressures calculated using published equation of state parameters for quartz and garnet. Our experimental results demonstrate that Raman measurements performed at room temperature can be used without corrections to estimate garnet crystallization pressures. Calculated entrapment pressures for quartz inclusions in garnet are less than ~?10% different from pressures measured during the experiments. Because the method is simple to apply with reasonable accuracy, we expect widespread usage of QuiG thermobarometry to estimate crystallization conditions for garnet-bearing silicic rocks.  相似文献   

Opportunities provided by geographic information systems and volunteered geographic information for a timely emergency response during flood events in Cologne,Germany     

Katerina Tzavella  Alexander Fekete  Frank Fiedrich 《Natural Hazards》2018,91(1):29-57

The occurrence of disasters such as extreme flooding in urban environments has severe consequences, not only on the human population but also on critical infrastructures such as the road networks, which are of vital importance for everyday living and particularly for emergency response. In this article, our main goal is to present-conceptually and in praxis-a model that could be used from the emergency responders for timely and efficient emergency management and response in an urban complex environment. For the city of Cologne in Germany, we aim to indicate possible ways to decrease the emergency response time during an extreme flood scenario through the development of an accessibility indicator, which consists of different components. Therefore, we will investigate the opportunities that occur, in a flood risk scenario, from the use of geographic information in different forms such as Volunteered Geographic Information (VGI) and open-source data in an ArcGIS environment, to increase urban resilience through the decreasing emergency response time. We will focus on network analysis for the fire brigades (first acting emergency responders) during a flood scenario to calculate their emergency response ranges and emergency response routes through flooded road networks, for the assistance of the possibly affected hospitals, refugee homes and fire brigades, which can be flooded. At the end of the paper, we suggest that the vulnerable community of the refugees could be taken into consideration as a new source of VGI, as an additional component that would lead to the decrease in the emergency response time. The geo-located information that could be provided by the refugee community can be very useful in emergency situations, such as those examined in this article where timely information can be forwarded to the proper authorities for a more focused and timely emergency response, increasing the resilience of the urban population and their community.  相似文献   

Changes in tidal asymmetry in the German Wadden Sea     

Hagen  Robert  Winter  Christian  K&#;sters  Frank 《Ocean Dynamics》2022,72(5):325-340

Ocean Dynamics - The recent morphological development of the German Wadden Sea (North Sea, Europe) has been characterized by expanding intertidal flats and deepening, narrowing tidal channels at...  相似文献