The significance of fixed ammonium in Palaeozoic sediments for the generation of nitrogen-rich natural gases in the North German Basin     

Birgit Mingram  Peer Hoth  Volker Lüders  Daniel Harlov 《International Journal of Earth Sciences》2005,94(5-6):1010-1022

In contrast to predominantly hydrocarbon-rich natural gases in the western part of the Central European Basin (CEB), accumulations of natural gases from the eastern part of the North German Basin (NGB) are nitrogen-rich with up to 90% N₂. This study is focused on the behaviour of fixed ammonium in clay minerals of organic-rich Palaeozoic sediments in the eastern part of the NGB as a major source of nitrogen-rich natural gases. Carboniferous shales have been investigated for a better understanding of nitrogen fixing during diagenesis, storage during burial and release during devolatilization processes or fluid–rock interactions. The total nitrogen contents in the studied Carboniferous shales of the NGB reach up to 2700 ppm with an inorganic fixed portion (in the form of NH₄ ⁺–N) of more than 60%. The results of this study indicate an increasing proportion of the mineralogically fixed ammonium with increasing thermal maturity and storage up to catagenetic conditions. The isotopic composition of fixed-NH₄ is relatively homogeneous in the majority of the shales and ranges from +1 to +3.5‰. In contrast, samples from the basin centre show a significant decrease in ammonium contents down to 460 ppm coupled with a shift in δ¹⁵N up to +5.6‰ suggesting a release of nitrogen on a large scale. Calculation of nitrogen loss and isotopic fractionation indicate that more than 30% of nitrogen was released as ammonium probably as a consequence of fluid-rock interaction with highly saline brines.  相似文献   

Isolation of atmospheric effects on rapid polar motion through Wiener filtering     

Susan M. di Leonardo  S. R. Dickman 《Geophysical Journal International》2004,159(3):863-873

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Nitrate temporal and spatial patterns in 12 water-supply wells, Yucatan, Mexico     

J. Pacheco  Luis Marín  Armando Cabrera  Birgit Steinich  Oscar Escolero 《Environmental Geology》2001,40(6):708-715

 The nitrate concentration in 12 water-supply wells were monitored for the period April 1992 to March 1993. Each water-supply well was sampled once a month. The nitrate concentrations in the 12 wells ranged from 7 to 156 mg/l. Two water-supply wells (Chacsinkin and Peto) showed concentrations that reached 3.5 times the maximum permissible limit for the Drinking Water Standard (45 mg/l). A third water-supply well (Akil) exceeds the norm for 7 out of 12 months. The use of nitrogen-rich fertilizers are responsible for high nitrate concentrations in groundwater in the southern part of Yucatan, Mexico where intensive agricultural practices exist. Received: 14 December 1999 · Accepted: 2 May 2000  相似文献   

A case study of Kelvin-Helmholtz waves within an off-shore stable boundary layer: Observations and linear model     

Birgit Busack  Burghard Brümmer 《Boundary-Layer Meteorology》1988,44(1-2):105-135

A case study of Kelvin-Helmholtz waves which were observed by two aircraft in a warm off-shore stable boundary-layer flow over the North Sea is presented. During the one-hour flight mission within an area of 40 × 40 km², the waves were intermittent both in space and time. They were centered around two levels, at 90 and 330m, where inflection points in the mean profile of the cross-wave wind component occurred together with Richardson numbers smaller than the critical value of 0.25. Observed wave amplitudes were on the order of 0.1 K for the potential temperature, 0.15ms^-1 for the vertical wind component, 0.3ms^-1 for the cross-wave wind component and 0.15ms^-1 for the along-wave wind component. Horizontally averaged vertical wave transports were down-gradient.Based on the observed wind and temperature profiles, wave simulations with a linear model are performed. Different diffusion coefficient estimates are tested. The model produces two types of Kelvin-Helmholtz waves with maximum amplitudes at the above mentioned two heights. The modeled wavelengths are about 30% shorter than the observed ones. Adjusting the modeled to the observed temperature variations, the modeled vertical wind variance and the vertical transports agree well with the observations, whereas the modeled horizontal wind variances are smaller than the observed ones.  相似文献   

Magmatic character and geotectonic setting of some tertiary-quaternary Italian volcanic rocks: Orogenic,anorogenic and «Transitional» association — A review     

P. di Girolamo 《Bulletin of Volcanology》1984,47(3):421-432

Discrimination functions based on major element distribution (Pearce, 1976) can be used to define the different basalt types of the Tyrrhenian and Perityrrhenian areas in an attempt to clarify their geodynamic significance.The future Tyrrhenian and Perityrrhenian areas have been affected since Oligocene by either compressional (subduction related) or transitional processes which produced well-defined orogenic and anorogenic magmas. A local development of «transitional» magma types, characteristic of «anomalous» volcanic arcs, also occurred with geochemical features that are intermediate between within-plate and orogenic magmas.The eruption of orogenic rock suites (calcalkaline, shoshonitic and leucite-bearing rocks) took place along the Apennine border on the east and southeast of the Tyrrhenian basin from Upper Miocene to Quaternary (Aeolian and neighbouring seamounts; Campania; Latium; Capraia Island). Absence of spatial zonation and interlayering of products with a various potassic character are the peculiar features of these rocks that appear to be originated from a heterogeneous and variously metasomatized mantle source by the influx of fluids (H₂O andLile enrichment) from the subduction zone affecting the Apennine-Maghrebides collisional front during Tertiary times.In the central Tyrrhenian area oceanic tholeiitic magmatism and creation of a new oceanic crust occurred from Upper Miocene. This activity was probably accomplished by Lower Pliocene when a within-plate volcanism produced the seamounts of the Batial Plain (Magnaghi, Vavilov, base of the Marsili Smts.).Etna and Ustica volcanisms occurring along the Perityrrhenian border on the south and west the Aeolian volcanism respectively, show geochemical characteristics that are transitional between anorogenic and orogenic magmas which could indicate some influence of fluids subduction-related to their mantle sources.The complex magmatic situation of the Tyrrhenian and Perityrrhenian areas may be caused by magma-producing events either from unmodified (anorogenic) or variously modified mantle sources (transitional to orogenic) depending on their proximity to and influenced by the Cainozoic subduction zone which developed along the Apennines-Maghrebides collisional front.  相似文献   

Caractérisation géométrique et cinématique des structures liées aux phases compressives de l'Éocène au Quaternaire inférieur en Tunisie : exemple de la Tunisie nord-orientale     

Houcem Mzali  Hédi Zouari 《Comptes Rendus Geoscience》2006,338(10):742-749

During Eocene to Early Quaternary period, three compressive tectonic phases are recognized in Northeast Tunisia: a NW–SE to north–south phase during the Late Eocene, a N120-to-N140 phase in the Late Miocene, and a NW–SE to north–south phase in the Plio-Early Quaternary. The first Eocene phase has built NE–SW folds and remobilised east–west-to-N120 and NE–SW faults with a reverse component. The second Miocene phase is characterized by east–west-to-N120 faults with a normal component and NE–SW folds. The third phase occurred during the Plio-Early Quaternary has edified NE–SW folds associated with east–west-to-N120 dextral reverse strike-slip faults and NE–SW faults with a reverse component. To cite this article: H. Mzali, H. Zouari, C. R. Geoscience 338 (2006).  相似文献   

On the relationship between hydrocarbon migration pathways and carbonate mound occurrence in the Porcupine Basin     

J. Naeth  R. di Primio  B. Horsfield  R. G. Schaefer  B. M. Krooss 《International Journal of Earth Sciences》2007,96(1):199-200

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New insights into lake responses to rapid climate change: the Younger Dryas in Lake Gościąż, central Poland     

Daniela Müller  Rik Tjallingii  Mateusz Płóciennik  Tomi P. Luoto  Bartosz Kotrys  Birgit Plessen  Arne Ramisch  Markus J. Schwab  Mirosław Błaszkiewicz  Michał Słowiński  Achim Brauer 《Boreas: An International Journal of Quaternary Research》2021,50(2):535-555

The sediment profile from Lake Gościąż in central Poland comprises a continuous, seasonally resolved and exceptionally well-preserved archive of the Younger Dryas (YD) climate variation. This provides a unique opportunity for detailed investigation of lake system responses during periods of rapid climate cooling (YD onset) and warming (YD termination). The new varve record of Lake Gościąż presented here spans 1662 years from the late Allerød (AL) to the early Preboreal (PB). Microscopic varve counting provides an independent chronology with a YD duration of 1149+14/–22 years, which confirms previous results of 1140±40 years. We link stable oxygen isotopes and chironomid-based air temperature reconstructions with the response of various geochemical and varve microfacies proxies especially focusing on the onset and termination of the YD. Cooling at the YD onset lasted ~180 years, which is about a century longer than the terminal warming that was completed in ~70 years. During the AL/YD transition, environmental proxy data lagged the onset of cooling by ~90 years and revealed an increase of lake productivity and internal lake re-suspension as well as slightly higher detrital sediment input. In contrast, rapid warming and environmental changes during the YD/PB transition occurred simultaneously. However, initial changes such as declining diatom deposition and detrital input occurred already a few centuries before the rapid warming at the YD/PB transition. These environmental changes likely reflect a gradual increase in summer air temperatures already during the YD. Our data indicate complex and differing environmental responses to the major climate changes related to the YD, which involve different proxy sensitivities and threshold processes.  相似文献   

Different carbon reservoirs of auriferous fluids in African Archean and Proterozoic gold deposits? Constraints from stable carbon isotopic compositions of quartz-hosted CO2-rich fluid inclusions     

Volker Lüders  Reiner Klemd  Thomas Oberthür  Birgit Plessen 《Mineralium Deposita》2015,50(4):449-454

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Sediment sequences and paleosols in the Kyichu Valley, southern Tibet (China), indicating Late Quaternary environmental changes   总被引：1，自引：0，他引：1  

Knut  Kaiser  Zhongping  Lai  Birgit  Schneider  Werner H.  Schoch  Xuhui  Shen  Georg  Miehe  Helmut  Brückner 《Island Arc》2009,18(3):404-427

Abstract The Tibetan Plateau is highly sensitive to environmental changes and affects the settings of a far larger territory in Central Asia and beyond. Thus, knowledge on past environmental changes in that area is essential. Even though the Kyichu (Lhasa River) Valley and its tributaries is an easily accessible area, the Late Quaternary landscape evolution of southern Tibet is in general scarcely known. Therefore, 12 sedimentary sections in the middle and lower catchment were subjected to multidisciplinary analyses (sedimentology, paleopedology, AMS ¹⁴C and luminescence dating, and charcoal determination) aiming at results on regional paleoenvironmental changes. At the altitude studied (3600–4000 m above sealevel), no glacial relics could be detected, indicating that the valley positions have been unglaciated since the Last Interglacial. The lack of fluvial–lacustrine structures above the floodplain is due to the aggradational character of this tectonically (sub‐)active valley, which caused an alluvial burying of older valley bottoms. During the Late Pleistocene the mouth area of the Kyichu was occupied by a lake which was part of a larger dam‐lake in the superordinate Yarlung Zhangbo Valley. On the valley flanks, loesses were predominantly deposited before the Last Glacial Maximum (LGM), whereas eolian sands were predominantly deposited around and after the LGM. Paleosols of Last Interglacial, Last Glacial and Holocene ages regularly occur at terrestrial sites representing temperate to cool and humid to semiarid conditions during soil formation. Ages of colluvial sediments indicate that the widespread barren valley slopes were primarily formed by Late Pleistocene erosion followed by a secondary Holocene erosion phase. Charcoal spectra indicate a Late Holocene change from a forest environment to a pastoral environment with sparse grasses, herbs and dwarf shrubs. It is assumed that the Late Holocene environmental changes, such as loss of forests/woodlands and erosion, have at least been reinforced by humans, enhancing a regional climatic aridification and cooling trend.  相似文献