Gravity Anomalies and Flexure of the Lithosphere along the Hawaiian-Emperor Seamount Chain   总被引：1，自引：0，他引：1  

A. B. Watts  J. R. Cochran 《Geophysical Journal International》1974,38(1):119-141

Simple models for the flexure of the lithosphere caused by the load of the Hawaiian-Emperor Seamount Chain have been determined for different values of the effective flexural rigidity of the lithosphere. The gravity effect of the models have been computed and compared to observed free-air gravity anomaly profiles in the vicinity of the seamount chain. The values of the effective flexural rigidity which most satisfactorily explain both the amplitude and wavelength of the observed profiles have been determined. Computations show that if the lithosphere is modelled as a continuous elastic sheet, a single effective flexural rigidity of about 5 × 10²⁹ dyne-cm can explain profiles along the Hawaiian-Emperor Seamount Chain. If the lithosphere is modelled as a discontinuous elastic sheet an effective flexural rigidity of about 2 × 10³⁰ dyne-cm is required. Since the age of the seamount chain increases from about 3 My near Hawaii to about 70 My near the northernmost Emperor seamount these results suggest there is apparently little decrease in the effective flexural rigidity of the lithosphere with increase in the age of loading. This suggests the lithosphere is rigid enough to support the load of the seamount chain for periods of time of at least several tens of millions of years. Thus the subsidence of atolls and guyots along the chain is most likely to be regional in extent and is unlikely to be caused by an inelastic behaviour of the lithosphere beneath individual seamounts.  相似文献   

Free–air gravity anomalies in the world's oceans and their relationship to residual elevation     

James R. Cochran  Manik Taiwan 《Geophysical Journal International》1977,50(3):495-552

  相似文献   

Northern hemisphere atmospheric response to changes of atlantic ocean SST on decadal time scales: a GCM experiment     

Andreas Hense  Rita Glowienka-Hense  Hans von Storch  Ursula Stähler 《Climate Dynamics》1990,4(3):157-174

Analyses indicate that the Atlantic Ocean seasurface temperature (SST) was considerably colder at the beginning than in the middle of the century. In parallel, a systematic change in the North Atlantic sea-level pressure (SLP) pattern was observed. To find out whether the SST and SLP changes analyzed are consistent, which would indicate that the SST change was real and not an instrumental artifact, a response experiment with a low-resolution (T21) atmospheric GCM was performed. Two perpetual January simulations were conducted, which differ solely in the Atlantic Ocean (40° S-60° N) SST: the cold simulation utilizes the SSTs for the period 1904–1913; the warm simulation uses the SSTs for the period 1951–1960. Also, a control run with the model's standard SST somewhat between the cold and warm SST was made. For the response analysis, a rigorous statistical approach was taken. First, the null hypothesis of identical horizontal distributions was subjected to a multivariate significance test. Second, the level of recurrence was estimated. The multivariate statistical approaches are based on hierarchies of test models. We examined three different hierarchies: a scale-dependent hierarchy based on spherical harmonics (S), and two physically motivated ones, one based on the barotropic normal modes of the mean 300 hPa flow (B) and one based on the eigenmodes of the advection diffusion operator at 1000 hPa (A). The intercomparison of the cold and warm experiments indicates a signal in the geostrophic stream function that in the S-hierarchy is significantly nonzero and highly recurrent. In the A-hierarchy, the low level temperature field is identified as being significantly and recurrently affected by the altered SST distribution. The SLP signal is reasonably similar to the SLP change observed. Unexpectedly, the upper level stream-function signal does not appear to be significantly nonzero in the B-hierarchy. If, however, the pairs of experiments warm versus control and cold versus control are examined in the B-hierarchy, a highly significant and recurrent signal emerges. We conclude that the cold versus warm response is not a small disturbance that would allow the signal to be described by eigenmodes of the linear system. An analysis of the three-dimensional structure of the signal leads to the hypothesis that two different mechanisms are acting to modify the model's mean state. At low levels, local heating and advection are dominant, but at upper levels the extratropical signal is a remote responce to modifications of the tropical convection.This paper was presented at the International Conference on Modelling of Global Climate Change and Variability, held in Hamburg 11–15 September 1989 under the auspices of the Meteorological Institute of the University of Hamburg and the Max Planck Institute for Meteorology. Guest Editor for these papers is Dr. L. Dilmenil.AWI Publication no. 254  相似文献   

A saturation model of the atmosphere of Uranus     

Robert E. Danielson  William D. Cochran  Peter G. Wannier  Edward S. Light 《Icarus》1977,31(1):97-109

A model of the atmospheric structure of Uranus is presented which differs from previous types of models in two important respects: (1) The CH₄/H₂ ratio is sufficiently large that CH₄ is saturated to large depths in the Uranian atmosphere. (2) The internal energy flux is small compared with that due to solar heating. Because of the small internal flux, the thermal flux decreases rapidly with depth and the atmosphere is radiative to large optical depths. A CH₄ droplet cloud forms where the atmosphere finally becomes convective due to the internal flux. The model is shown to be in reasonable agreement with published observations of the H₂ quadrupole 3-0 and 4-0 bands, the visible (4000–6000 Å) CH₄ bands, and the infrared emission spectrum.  相似文献   

New calibration data for the Fe–Ti oxide thermo-oxybarometers from experiments in the Fe–Ti–O system at 1 bar, 1,000–1,300°C and a large range of oxygen fugacities     

Dominique?LattardEmail author  Ursula?Sauerzapf  Martin?K?semann 《Contributions to Mineralogy and Petrology》2005,149(6):735-754

The current formulations of the Fe–Ti oxide thermobarometer (titanomagnetite–ilmenite_ss) fail to reproduce experimental results, in particular at the high temperatures that are relevant for basaltic assemblages. With the aim of improving the experimental basis of the calibration in the Fe–Ti–O system, we have synthesised assemblages of titanomagnetite–ilmenite_ss (Tmt–Ilm_ss), ilmenite_ss–pseudobrookite_ss (Ilm_ss–Psb_ss) and single-phase samples under a wide range of fO₂ (fixed with CO/CO₂ mixtures or by solid oxygen buffers) in sub-solidus conditions (1,000–1,300°C) at 1 bar. Runs lasted 24 h at 1,300°C and up to 240 h at 1,000°C and were terminated by quenching in water. All run products are polycrystalline, roughly equigranular aggregates, with grain sizes of 10–50 m. They were examined and analysed with the SEM and EMP. Tmt compositions are broadly in accordance with the current models at moderate fO₂, but significantly richer in Ti at low fO₂ and high T, due to cationic vacancies. Ilm_ss compositions depart from the predicted values practically at all fO₂ and T conditions, which is related to unsatisfactory thermodynamic models for the rhombohedral oxide. For Ilm_ss–Psb_ss assemblages the best agreement between our data and current calculations is at 1,000°C and moderately high fO₂. Otherwise, experimental and calculated data strongly disagree. The experimental data set on the three Fe–Ti oxide solid solutions presented here is intended to support new versions of both the titanomagnetite–ilmenite_ss thermo-oxybarometer and the ilmenite_ss–pseudobrookite_ss oxybarometer.  相似文献   

Chemical Flux Associated with Spatially and Temporally Variable Submarine Groundwater Discharge,and Chemical Modification in the Subterranean Estuary at Gloucester Point,VA (USA)     

Aaron J. Beck  Alex A. Kellum  Jenna L. Luek  Michele A. Cochran 《Estuaries and Coasts》2016,39(1):1-12

  相似文献   

Geology of London,UK     

Katherine R. Royse  Mike de Freitas  William G. Burgess  John Cosgrove  Richard C. Ghail  Phil Gibbard  Chris King  Ursula Lawrence  Rory N. Mortimore  Hugh Owen  Jackie Skipper 《Proceedings of the Geologists' Association. Geologists' Association》2012,123(1):22-45

The population of London is around 7 million. The infrastructure to support this makes London one of the most intensively investigated areas of upper crust. However construction work in London continues to reveal the presence of unexpected ground conditions. These have been discovered in isolation and often recorded with no further work to explain them. There is a scientific, industrial and commercial need to refine the geological framework for London and its surrounding area. This paper reviews the geological setting of London as it is understood at present, and outlines the issues that current research is attempting to resolve.  相似文献   

Nanoparticles and their influence on radionuclide mobility in deep geological formations     

Thorsten Schäfer  Florian Huber  Holger Seher  Tiziana Missana  Ursula Alonso  Michael Kumke  Sascha Eidner  Francis Claret  Frieder Enzmann 《Applied Geochemistry》2012

  相似文献   

A professor,a president,and a meteor     

Ursula B. Marvin 《Meteoritics & planetary science》2011,46(10):1608-1616

  相似文献   

Observations of Comet 9P/Tempel 1 with the Keck 1 HIRES instrument during Deep Impact     

Anita L. Cochran  William M. Jackson  Micah Glaz 《Icarus》2007,187(1):156-166

We report high-spectral resolution observations of Comet 9P/Tempel 1 before, during and after the impact on 4 July 2005 UT of the Deep Impact spacecraft with the comet. These observations were obtained with the HIRES instrument on Keck 1. We observed brightening of both the dust and gas, but at different rates. We report the behavior of OH, NH, CN, C₃, CH, NH₂ and C₂ gas. From our observations, we determined a CN outflow velocity of at least 0.51 km s⁻¹. The dust color did not change substantially. To date, we see no new species in our spectra, nor do we see any evidence of prompt emission. From our observations, the interior material released by the impact looks the same as the material released from the surface by ambient cometary activity. However, further processing of the data may uncover subtle differences in the material that is released as well as the time evolution of this material.  相似文献