A robust interpolation procedure for producing tidal current ellipse inputs for regional and coastal ocean numerical models   总被引：1，自引：1，他引：0  

Do-Seong Byun  Deirdre E. Hart 《Ocean Dynamics》2017,67(3-4):451-463

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On Robust Multi-Year Tidal Prediction Using T_TIDE     

Byun  Do-Seong  Hart  Deirdre Erin 《Ocean Science Journal》2019,54(4):657-671

Ocean Science Journal - A minimum 19 year tidal prediction dataset covering nodal (satellite) modulation effects is required to determine the Lowest Astronomical Tide (LAT) and Highest Astronomical...  相似文献   

Complex pedostratigraphy of a terrace fragipan at the Memorial Park site,central Pennsylvania     

D. L. Cremeens  J. P. Hart  R. G. Darmody 《Geoarchaeology》1998,13(4):339-359

A fragipan (Bxb horizon) encountered during the excavation of a multicomponent archaeological site buried on an alluvial terrace in central Pennsylvania was evaluated to determine the degree of development, pedostratigraphy, and age. Based on the horizon thickness, and the degree of development of adjacent horizons, we believe that the fragipan was weakly developed. Two to three buried A horizons (Ab) occurred within the Bxb, thus, the fragipan formed in a cumulative, or fluvent, type alluvial landscape and postdates the Ab horizons overprinted by it. The buried soils were associated with stratified cultural remains. Artifact and radiocarbon ages indicate that the fragipan formed in the last 4500 years. Fragipan-containing soils on alluvial terraces should be investigated for buried soils and associated stratified cultural remains overprinted by subsequent pedogenesis. © 1998 John Wiley & Sons, Inc.  相似文献   

The salts of Mars     

Benton C. Clark  Daniel C. Van Hart 《Icarus》1981,45(2):370-378

Salt compounds are apparently an important component of the finite-grained regolith on Mars. Salt enrichment may be explained either as a secondary concentration of chemical weathering products or as direct incorporation of planetary released volatiles. Geochemical measurements and chemical relationships constrain the salt species and resultant physicochemical consequences. A likely assemblage is dominated by (Mg,Na)SO₄, NaCl, and (Mg,Ca)CO₃. Formation of brine in equilibrium with such a salt mixture is unlikely under the temperature and water-vapor restrictions prevalent over most, if not all, of the Martian surface. Acidic conditions, accompanying salt formation, favor the preferential destruction of susceptible igneous minerals.  相似文献   

Reply: Drumlin formation in southern Anglesey and Arvon,northwest Wales     

Jane K. Hart 《第四纪科学杂志》1995,10(4):398-399

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Workshop on the Delphi Method     

G. G. Baxter  S. M. Cargill  A. H. chidester  P. E. Hart  G. M. Kaufman  F. Urquidi-Barrau 《Mathematical Geology》1978,10(5):581-587

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The illegal alien question in South Africa: scope,issues and policy     

Hart GH 《GeoJournal》1996,39(1):27-31

Of the many problems facing South Africa, perhaps one of the most important is that of the illegal alien. The scope, issues and policy implications of the illegal alien problem are examined. Different geographical streams of alien immigration are identified are profiled. Official policy responses are reviewed. The pressures for action to be taken against the rising numbers of illegal aliens in South Africa are discussed. In particular, the cost implications of illegal aliens capturing scarce resources and employment opportunities are set against other pressing demands encapsulated in the Reconstruction and Development Programme.  相似文献   

The tholeiite to alkalic basalt transition at Haleakala Volcano,Maui, Hawaii     

C.-Y. Chen  F. A. Frey  M. O. Garcia  G. B. Dalrymple  S. R. Hart 《Contributions to Mineralogy and Petrology》1991,106(2):183-200

Previous studies of alkalic lavas erupted during the waning growth stages (<0.9 Ma to present) of Haleakala volcano identified systematic temporal changes in isotopic and incompatible element abundance ratios. These geochemical trends reflect a mantle mixing process with a systematic change in the proportions of mixing components. We studied lavas from a 250-m-thick stratigraphic sequence in Honomanu Gulch that includes the oldest (1.1 Ma) subaerial basalts exposed at Haleakaka. The lower 200 m of section is intercalated tholeiitic and alkalic basalt with similar isotopic (Sr, Nd, Pb) and incompatible element abundance ratios (e.g., Nb/La, La/Ce, La/Sr, Hf/Sm, Ti/Eu). These lava compositions are consistent with derivation of alkalic and tholeiitic basalt by partial melting of a compositionally homogeneous, clinopyroxene-rich, garnet lherzolite source. The intercalated tholeiitic and alkalic Honomanu lavas may reflect a process which tapped melts generated in different portions of a rising plume, and we infer that the tholeiitic lavas reflect a melting range of 10% to 15%, while the intercalated alkalic lavas reflect a range of 6.5% to 8% melting. However, within the uppermost 50 m of section. ⁸⁷Sr/⁸⁶Sr decreases from 0.70371 to 0.70328 as eruption age decreased from 0.97 Ma to 0.78 Ma. We infer that as lava compositions changed from intercalated tholeiitic and alkalic lavas to only alkalic lavas at 0.93 Ma, the mixing proportions of source components changed with a MORB-related mantle component becoming increasingly important as eruption age decreased.  相似文献   

Habitable zones about main sequence stars   总被引：1，自引：0，他引：1  

Michael H. Hart 《Icarus》1979,37(1):351-357

Calculations show that a main sequence star which is less massive than the Sun has a continuously habitable zone about it which is not only closer in than the corresponding zone about the Sun, but is also relatively narrower. Let L(t) represent the luminosity after t billion years of a main sequence star of mass M, and let r_inner and r_outer represent the boundaries of the continuously habitable zone about such a star—that is, the zone in which an Earthlike planet will undergo neither a runaway greenhouse effect in the early stages of its history nor runaway glaciation after it develops an oxidizing atmosphere. Then our computer results indicate that $\text{r}{}_{\mathrm{<mtext>outer</mtext>}}\text{r}{}_{\mathrm{<mtext>inner</mtext>}}$ is roughly proportional to $\text{[}\text{L(3.5)}\text{L(1.0)}\text{]}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$. This ratio is smaller for stars less massive than the Sun (because they evolve more slowly), and the width of the continuously habitable zone about a main sequence star is therefore a strong function of the initial stellar mass. Our calculations show that r_inner = r_outer for $\text{M～0.83M?}$ (i.e., K1 stars), and it therefore appears that there is no continuously habitable zone about most K stars, nor any about M stars.  相似文献   

Ocean current intensification during the Cretaceous oceanic anoxic event 2 – evidence from the northern Tethys          下载免费PDF全文

Stephan Wohlwend  Malcolm Hart  Helmut Weissert 《地学学报》2015,27(2):147-155

Mesozoic Oceanic Anoxic Events (OAEs) are expressions of major physical oceanographic changes at times of perturbation of the global carbon cycle. A northern Tethyan record of OAE2 is preserved in expanded Cenomanian–Turonian pelagic limestone sections (Seewen Formation) in Eastern Switzerland. The new carbonate carbon‐isotope stratigraphy extracted from these limestones demonstrates that the OAE2 is condensed in all the studied successions and only the onset of the δ¹³C excursion (5.0‰) is present. The condensed interval is characterized by dissolution features, which are filled by a glauconite quartz sandstone. This bed is overlain by a well‐sorted sandstone with intercalated limestone pebbles (Götzis Member), which can be compared with palimpsest sands forming today along current‐swept shelves. The wide distribution of this thin sandstone layer within OAE2 indicates that an intense, erosive, east‐west trending shelf current was active during the highest sea level and most extreme carbon‐cycle perturbation of the OAE2.  相似文献