High resolution Th_ex stratigraphy of sediments from high-latitude areas (Norwegian Sea, Fram Strait)     

Jan C. Scholten  Reiner Botz  Augusto Mangini  Hanno Paetsch  Peter Stoffers  Elke Vogelsang 《Earth and Planetary Science Letters》1990,101(1)

We present data on the average sedimentation rates (ranging from 1.6 cm/kyr to 3 cm/kyr) for the last 300.000 years based on δ¹⁸O analyses of foraminifera in a core from the Norwegian Sea and ²³⁰Th_ex measurements in cores from the Norwegian Sea and the Fram Strait (Arctic Ocean). Furthermore, we relate ²³⁰Th_ex variations downcore to the various oxygen isotope stages. This correlation is tentatively interpreted as being a result of the paleoceanographic and paleoclimatic control of bioproductivity. It is shown that based on the average sedimentation rates and characteristic ²³⁰Th_ex variations carbonate-poor sediment cores from northern latitudes can be correlated.  相似文献   

Indirect determination of the heat budget of tidal flats     

Reiner Onken  Ulrich CalliesBernd Vaessen  Rolf Riethmüller 《Continental Shelf Research》2007

A method is presented to calculate indirectly the heat budget of a tidal flat area from downstream observations of temperature and horizontal velocity in a tidal channel. It is only necessary to establish a relationship between the velocity and the volume flux. Then the heat budget of the upstream region is determined by integrating the heat flux over one tide. The proposed method is applied to long-term measurements obtained in 2004 at two sites in a tidal channel in the Hörnum Basin, German Wadden Sea. At the site located farther downstream in the channel, the upstream catchment area is diagnosed to export heat (heat gain in the interior) from March to August, while import is diagnosed for the same period of time at the other upstream site. From September to November the situation is reversed. An analytical estimate suggests that the sign of the budget is controlled by the tidal prism and the length of the dry-falling period of the flats in the respective upstream region. In addition, a simple model is developed which can be used to determine the integral bottom heat flux of the tidal flats.  相似文献   

Methane Production, Emission and Possible Control Measures in the Rice Agriculture   总被引：19，自引：0，他引：19  

Wang Mingxing  Shangguan Xingjian  Shen Renxing  Wassmann Reiner  Seiler Wolfgang 《大气科学进展》1993,10(3):307-314

In the rice field methane is produced in the soil layer with depths of 2-25 cm. The vertical profile of methane production rate in the paddy soil during the water covering period differs from that in the paddy soil in dry phase. Only a small part, about 30%. of the produced methane is emitted to the atmosphere through rice plant, air bubbles, and molecular diffusion. Therefore, the methane emission rate from the rice field depends not only on the methane production rate in the soil, but also on the transport efficiency of the rice plant, air bubble formation that in turn depends on the production rate, and molecular diffusion.Field measurements show that methane emission rates from a particular rice field have very large diurnal, seasonal and interannual variations, which are related to soil characteristics, water regime, farming procedure, local climate, and rice growing activities. The relationship between the methane emission rate and the above mentioned factors is very complicated. The emission rate  相似文献   

Archaean to Proterozoic Crustal Evolution in the Central Zone of the Limpopo Belt (South Africa-Botswana): Constraints from Combined U-Pb and Lu-Hf Isotope Analyses of Zircon   总被引：5，自引：0，他引：5  

Zeh  Armin; Gerdes  Axel; Klemd  Reiner; Barton  Jackson M.  Jr 《Journal of Petrology》2007,48(8):1605-1639

A combined set of U–Pb and Lu–Hf in situ laser ablationICP-(MC)-MS zircon analyses were obtained from orthogneissesand granitoids in the Central Zone of the Limpopo Belt, whichcomprises the Beit Bridge and Mahalapye complexes. The resultsindicate that by combining the two isotope systems primary magmaticzircon domains can be distinguished from those formed duringlater metamorphic events, even if the distinct zircon domainsunderwent multiple Pb loss and the texture–age relationships,as obtained by cathodoluminescence images and U–Pb analyses,are ambiguous. Furthermore, the applied technique allows distinctionof zircon grains formed in juvenile magmas from those generatedby melting of older continental crust or affected by substantialcrustal contamination. The combined U–Pb and Lu–Hfdata reveal that the Sand River gneiss suite of the Beit BridgeComplex was emplaced at 3283 ± 8 Ma and formed from meltingof an older Archaean crust, which was derived from a depletedmantle source at around 3·65 Ga. The hafnium model age(T_DM^Hf) is significantly older than those obtained from zirconsfrom numerous Neoarchaean granitoids of the Beit Bridge Complex,comprising the Singelele gneiss (2647 ± 12 Ma), the Bulaigranite (2612 ± 7 Ma), the Regina gneiss (2649 ±9 Ma) and two samples of the Zanzibar gneiss (2613 ±6 Ma). These granitoids show initial Hf(t) values between +0·5 and –7·1, which correspond to initialT_DM^Hf between 3·46 and 3·01 Ga. These variableT_DM^Hf_initial and Hf(t)_initial values are interpreted to be theresult of different mixtures of reworked 3·65 Ga Palaeoarchaeancrust with juvenile magmas extracted from the depleted mantleduring the Neoarchaean at 2·65 Ga. This conclusion issupported by results obtained from the Mahalapye Complex, whichwas affected by migmatization and granite intrusions duringthe Palaeoproterozoic at 2·02–2·06 Ga. TheMokgware granite (2019 ± 9 Ma) contains zircon xenocrystswith Pb–Pb ages of 2·52–2·65 Ga and2·93 Ga and hafnium model ages of 3·0–3·4Ga, indicating that this granite is derived from remelting ofArchaean crust. In contrast, uniform T_DM^Hf_initial ages of 2·61–2·67Ga obtained from a diorite gneiss (2061 ± 6 Ma) of theMahalapye Complex indicate that its protolith may have beenformed from remelting of a Neoarchaean juvenile crust. VariableHf(t)_initial values from –3·7 to +6·3 ofzircon cores (2711 ± 11 Ma) in an adjacent leucosomealso support a model of mixing of juvenile mantle derived matterwith older crust in the Neoarchaean. KEY WORDS: Archaean; Palaeoproterozoic; Limpopo Belt; zircon, U–Pb dating; Lu–Hf isotopes; LA-ICP-MS  相似文献   

Fluid Inclusions and Stable Isotopic Characteristics of the Yaoling Tungsten Deposit in South China: Metallogenetic Constraints     

Feng Yang  Wei Zhai  Xiaoming Sun  Reiner Klemd  Yanyan Sun  Yunshan Wu  Renmin Hua  Siqi Zheng 《Resource Geology》2019,69(1):107-122

The Yaoling tungsten deposit is a typical wolframite quartz vein‐type tungsten deposit in the South China metallogenic province. The wolframite‐bearing quartz veins mainly occur in Cambrian to Ordovician host rocks or in Mesozoic granitic rocks and are controlled by the west‐north‐west trending extensional faults. The ore mineralization mainly comprises wolframite and variable amounts of molybdenite, chalcopyrite, pyrite, fluorite, and tourmaline. Hydrothermal alteration is well developed at the Yaoling tungsten deposit, including greisenization, silicification, fluoritization, and tourmalinization. Three types of primary/pseudosecondary fluid inclusions have been identified in vein quartz, which is intimately intergrown with wolframite. These include two‐phase liquid‐rich aqueous inclusions (type I), two‐ or three‐phase CO₂‐rich inclusions (type II), and type III daughter mineral‐bearing multiphase high‐salinity aqueous inclusions. Microthermometric measurements reveal consistent moderate homogenization temperatures (peak values from 200 to 280°C), and low to high salinities (1.3–39 wt % NaCl equiv.) for the type I, type II, and type III inclusions, where the CO₂‐rich type II inclusions display trace amounts of CH₄ and N₂. The ore‐forming fluids are far more saline than those of other tungsten deposits reported in South China. The estimated maximum trapping pressure of the ore‐forming fluids is about 1230–1760 bar, corresponding to a lithostatic depth of 4.0–5.8 km. The δD_H2O isotopic compositions of the inclusion fluid ranges from ?66.7 to ?47.8‰, with δ¹⁸O_H2O values between 1.63 and 4.17‰, δ¹³C values of ?6.5–0.8‰, and δ³⁴S values between ?1.98 and 1.92‰, with an average of ?0.07‰. The stable isotope data imply that the ore‐forming fluids of the Yaoling tungsten deposit were mainly derived from crustal magmatic fluids with some involvement of meteoric water. Fluid immiscibility and fluid–rock interaction are thought to have been the main mechanisms for tungsten precipitation at Yaoling.  相似文献   

A Geodetic View on Isostatic Models   总被引：1，自引：0，他引：1  

Franziska Göttl  Reiner Rummel 《Pure and Applied Geophysics》2009,166(8-9):1247-1260

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Analysis of the photometric and spectroscopic period of the symbiotic star AG Pegasi with consequences for the model     

Reiner Luthardt 《Astronomische Nachrichten》1990,311(2):141-141

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德国4站点极端降水频数和强度趋势变化分析   总被引：1，自引：0，他引：1  

杨靖文  孙即霖  Reiner Schlitzer 《中国海洋大学学报(自然科学版)》2010,(Z1)

根据不莱梅、波茨坦、卡尔斯鲁厄和楚格峰1901—2007年逐日降水量分析了各站极端降水的频数和强度趋势变化。结果表明:山区(楚格峰)出现的极端降水数量呈上升趋势,且强度显著增强,在冬、夏2季亦如此。这与全球变暖背景下,山区的积雪融化导致对流活动增强以及大气环流影响水汽输送增强有关;在超过绝对阈值的极端降水方面,北方地区(不莱梅和波茨坦)发生频数保持稳定,无显著趋势变化,南方地区(卡尔斯鲁厄)有显著减少的趋势,且不莱梅的频数变化趋势与波茨坦相似,具有强正相关,而此2站与卡尔斯鲁厄的频数变化趋势呈反位相,有较强的负相关;除楚格峰外,极端降水强度变化无显著趋势。低海拔地区在冬季极端降水的频数和强度上,大部分有显著上升的趋势,而夏季,在2方面均出现不同程度的下降;极端降水频数和强度呈强正相关。  相似文献   

On the spectral consistency of the altimetric ocean and geoid surface: a one-dimensional example     

Alberta Albertella  Reiner Rummel 《Journal of Geodesy》2009,83(9):805-815

Geoid models from the new generation of satellite gravity missions, such as GRACE and GOCE, in combination with sea surface from satellite altimetry allow to obtain absolute dynamic ocean topography with rather high spatial resolution and accuracy. However, this implies combination of data with fundamentally different characteristics and different spatial resolutions. Spectral consistency would imply the removal of the short-scale features of the altimetric sea surface height by filtering, to provide altimetric data consistent with the resolution of the geoid field. The goal must be to lose as little as possible from the high precision of the altimetric signal. Using a one-dimensional example we show how the spectrum is changing when a function defined only on a limited domain (ocean in the real case) is extended or not as to cover the complete domain (the whole sphere in the real case). The results depend on the spectral characteristics of the altimetric signal and of the applied filter. Referring to the periodicity condition, as it is requested in the case of Fourier analysis, the action of the two classical filters (Ideal Low Pass and Gauss filter) and of two alternative procedures (wavelets and Slepian) is studied.  相似文献   

On the computation of the geoid–quasigeoid separation     

Jakob Flury  Reiner Rummel 《Journal of Geodesy》2011,85(3):185-186

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