Hydrographische Untersuchungen im Westeuropäischen Becken im Frühjahr 1984 während NOAMP II     

Dr. Gerd Axel Becker  Ingrid Bork  Dr. Ursula Schauer 《Ocean Dynamics》1984,37(4):157-164

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Hydration swelling of crystalline rocks     

Axel Schult  Ge Shi 《Geophysical Journal International》1997,131(1):179-186

Long-duration deformation experiments at room temperature have shown that crystalline rocks with low porosities, such as granites, diorites, gneisses and metabasites, swell when saturated with water and shrink when dried out. The effect is reversible and reproducible. The swelling cannot be completely hindered by confining pressures up to 15 MPa. The volume strain (from the dry to the saturated state) is of the order of a tenth of the porosity. The volume strain is decreased in brine with increasing molarity and becomes much smaller by saturation with heptane. Swelling and shrinking can also be observed with sorption and desorption of water, that is a change in the relative humidity of the air. It is proposed that the swelling effect is due to surface forces, that is van der Waals attraction and electrostatic double-layer and solvation repulsion. The pore pressure causing the swelling was estimated to be of the order of 15 MPa. This indicates the presence of very flat pores with distances between the surfaces of about 1 nm. The surface forces probably also play an important role in determining the seismic properties of the rocks at low confining pressures.  相似文献   

Textural evidence of magma decompression, devolatilization and disequilibrium quenching: an example from the Western Krušné hory/Erzgebirge granite pluton     

Miroslav Štemprok  David Dolejš  Axel Müller  Reimar Seltmann 《Contributions to Mineralogy and Petrology》2008,155(1):93-109

We report new occurrences of “two-phase” granitic textures from the Western Krušné hory/Erzgebirge pluton (central Europe) and use crystal-size distribution data and thermodynamic modeling to interpret their crystallization conditions. The two-phase texture consists of (1) early phenocrysts of quartz, plagioclase, K-feldspar and biotite, (2) medium-grained matrix of the same phases and (3) interstitial channels and patches of a late-stage, very fine-grained matrix. The porphyritic two-mica microgranites, which host two-phase textures, occur as minor intrusions in early low-F biotite granites or as marginal parts of evolved high-F Li-mica granites. Measurements of the crystal-size distribution of quartz revealed three grain populations: (1) early phenocrysts (0.5–3.0 mm) showing partial resorption by residual melt, (2) a medium-grained population of the equigranular rock matrix (0.05–0.50 mm) that experienced minor coarsening by subsolidus annealing and (3) a fine-grained population (<0.03 mm) in the interstitial channels and patches formed during rapid devolatilization; this quartz group shows no or poor grain coarsening. All samples exhibit similar fraction of the fine-grained population (44–52%) but proportions of phenocrysts to medium-grained matrix vary significantly. Thermodynamic modeling of liquidus equilibria and experimental data in the hydrous haplogranite system require: (1) ascent of a granitic suspension (15–25% phenocrysts) under H₂O-undersaturated conditions at 25–45 bar/°C and a cooling rate of 40 J/(g kbar) in order to produce partial resorption of quartz phenocrysts and continued growth of feldspar phenocrysts, followed by (2) emplacement as discrete intrusions or bodies along pluton roof accompanied by sudden devolatilization. At the onset of matrix nucleation, disequilibrium undercooling of 70–85°C was inferred from the presence of micrographic intergrowths of quartz and K-feldspar. The two-phase granites in the Western Krušné hory/Erzgebirge pluton and in the Southeast Asian batholith form compositionally narrow groups with high-silica and moderate volatile enrichments but they differ in peraluminosity and phosphorus concentrations. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

Preliminary Estimation of Paleoproductivity via TOC and Habitat Types： Which Method Is More Reliable？ -A Case Study on the Ordovician-Silurian Transitional Black Shales of the Upper Yangtze Platform, South China     

苏文博  王永标  Bradley  D  Cramer  AxelMunnecke  李志明  傅力浦 《中国地质大学学报(英文版)》2008,19(5):534-548

New total organic carbon (TOC) data from the two Ordovician-Silurian transitional graptolite-bearing black shale intervals, the Wnfeng (五峰) Formation and the Longmaxi (龙马溪) Formation in Central Guizhou (贵州) and West Hubei (湖北), respectively, as well as previously reported TOC data from the same intervals in other places on the Yangtze platform of South China, have been used to produce an initial estimate of the primary paleoproductivity via a conventional inverse method (i.e., Rpp-inverse). The values of the Rpp-inverse are estimated to be 32 (43-21) gC/(m2·a) (Wufeng Formation) and 21 (27-16) gC/(m2·a) (Longmaxi Formation). Also, simultaneously, the habitat types (i.e., HT; cf., BA: benthic assemblage) and their temporal and spatial changes have been documented from the same succession, and an initial estimate of the primary paleoproductivity has been produced using a forward method (i.e., Rpp.forward). Being bounded mainly by the peritidai to inner-shelf environment shelly-facies or mixed-facies successions with BAI to BA3 faunas both at the top and the base, which indicates the habitat types from HT Ⅱ1 to HT Ⅲ2, the biohabitat type of the two graptolite-bearing black shale intervals can be limited to HT Ⅲ to HT Ⅳ, corresponding to the inner shelf to the outer shelf, with depths from roughly 60 m to 200-300 m. Based on the current data from the South China Sea and the southern part of the East China Sea, values of Rpp-forward should be about 100 to 400 gC/(m2·a). The difference in the results via the two methods suggests that paleoproductivity estimates from the geological strata need to be made cautiously, with particular attention paid to the paleogeographic setting, oxic-anoxic conditions, as also the preservation factor of organic carbon.  相似文献   

The impact of errors in polar motion and nutation on UT1 determinations from VLBI Intensive observations   总被引：2，自引：2，他引：0  

Axel Nothnagel  Dorothee Schnell 《Journal of Geodesy》2008,82(12):863-869

The earth’s phase of rotation, expressed as Universal Time UT1, is the most variable component of the earth’s rotation. Continuous monitoring of this quantity is realised through daily single-baseline VLBI observations which are interleaved with VLBI network observations. The accuracy of these single-baseline observations is established mainly through statistically determined standard deviations of the adjustment process although the results of these measurements are prone to systematic errors. The two major effects are caused by inaccuracies in the polar motion and nutation angles introduced as a priori values which propagate into the UT1 results. In this paper, we analyse the transfer of these components into UT1 depending on the two VLBI baselines being used for short duration UT1 monitoring. We develop transfer functions of the errors in polar motion and nutation into the UT1 estimates. Maximum values reach 30 [μs per milliarcsecond] which is quite large considering that observations of nutation offsets w.r.t. the state-of-the-art nutation model show deviations of as much as one milliarcsecond.  相似文献   

Tectono‐sedimentary evolution of the northern Iranian Plateau: insights from middle–late Miocene foreland‐basin deposits          下载免费PDF全文

Paolo Ballato  Francesca Cifelli  Ghasem Heidarzadeh  Mohammad R. Ghassemi  Andrew D. Wickert  Jamshid Hassanzadeh  Guillaume Dupont‐Nivet  Philipp Balling  Masafumi Sudo  Gerold Zeilinger  Axel K. Schmitt  Massimo Mattei  Manfred R. Strecker 《Basin Research》2017,29(4):417-446

Sedimentary basins in the interior of orogenic plateaus can provide unique insights into the early history of plateau evolution and related geodynamic processes. The northern sectors of the Iranian Plateau of the Arabia–Eurasia collision zone offer the unique possibility to study middle–late Miocene terrestrial clastic and volcaniclastic sediments that allow assessing the nascent stages of collisional plateau formation. In particular, these sedimentary archives allow investigating several debated and poorly understood issues associated with the long‐term evolution of the Iranian Plateau, including the regional spatio‐temporal characteristics of sedimentation and deformation and the mechanisms of plateau growth. We document that middle–late Miocene crustal shortening and thickening processes led to the growth of a basement‐cored range (Takab Range Complex) in the interior of the plateau. This triggered the development of a foreland‐basin (Great Pari Basin) to the east between 16.5 and 10.7 Ma. By 10.7 Ma, a fast progradation of conglomerates over the foreland strata occurred, most likely during a decrease in flexural subsidence triggered by rock uplift along an intraforeland basement‐cored range (Mahneshan Range Complex). This was in turn followed by the final incorporation of the foreland deposits into the orogenic system and ensuing compartmentalization of the formerly contiguous foreland into several intermontane basins. Overall, our data suggest that shortening and thickening processes led to the outward and vertical growth of the northern sectors of the Iranian Plateau starting from the middle Miocene. This implies that mantle‐flow processes may have had a limited contribution toward building the Iranian Plateau in NW Iran.  相似文献   

Mineralogy and mineral chemistry of detrital heavy minerals from the Rhine River in Germany as evidence to their provenance,sedimentary and depositional history: focus on platinum-group minerals and remarks on cassiterite,columbite-group minerals and uraninite     

Thomas Oberthür  Frank Melcher  Simon Goldmann  Hermann Wotruba  Axel Gerdes  Arjan Dijkstra  Christopher W. Dale 《International Journal of Earth Sciences》2016,105(2):637-657

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Predictors of national CO2 emissions: do international commitments matter?     

Axel Franzen  Sebastian Mader 《Climatic change》2016,138(3-4):491-504

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On the relation between the synodic and sidereal rotation period of the Sun     

Axel D. Wittmann 《Solar physics》1996,168(1):211-213

It is pointed out that by taking Kepler's second law into account, the sidereal correction, i.e., the correction to be added to the observed synodic rotation rate of the Sun in order to get the sidereal rate, can be calculated more directly than described in a recent paper by Roa et al. (1995).  相似文献   

CCD-Doppler measurements of solar differential rotation     

Axel D. Wittmann 《Solar physics》1996,167(1-2):441-444

Using the AT1 CCD camera at the Echelle spectrograph of the GCT at Tenerife, solar Doppler rotation measurements in the photospheric lines Fe I 6301.5 Å and 6302.5 Å and in the chromospheric line Na-D₂ 5890.0 Å have been made. The line shifts measured at different heliographic latitudes around the limb were corrected for observer motion and converted into sidereal rotation rates. At the equator the observed chromospheric rotation rate is about 8 % larger than the photospheric rate, and the average observed Doppler rotation rate is not very much different from the mean rotation rates deduced from all published tracer works and all published Doppler works. Near the poles (where tracer methods rely on extrapolation) both the chromospheric and the photospheric rotation rate are slightly smaller than the all Doppler rate and are considerably smaller than the extrapolated all tracer rate. If all previous measurements of solar rotation are taken into account, a surface rotation law with lower error bounds than previously possible can be derived.  相似文献