A study of conditions at the inner core boundary of the earth     

David E. Loper  Paul H. Roberts 《Physics of the Earth and Planetary Interiors》1981,24(4):302-307

A study is made of the thermal and compositional conditions which the liquid outer core must satisfy at the inner core boundary, assuming the inner core to be growing by continual solidification of the heavy component of the liquid alloy in the outer core. It is found that the outer core is strongly destabilized by the compositional gradients driven by the separation process associated with the freezing. Further, it is argued that all the freezing necessary for the growth of the solid inner core cannot occur on a flat interface; most of it must occur above the solid boundary in a region labeled the slurry layer.  相似文献   

A new type of chondritic meteorite found in lunar soil     

Harry Y. McSween 《Earth and Planetary Science Letters》1976,31(2):193-199

A fragment found in soil from the Apollo 12 site (12037, from the rim of Bench Crater) appears to be a unique type of chondrite, petrologically and chemically distinct from other chondrites and lunar rocks. Inclusions consisting of shocked pyroxene rimmed by euhedral troilite crystals are set in a black aphanitic matrix. Abundant magnetite in the matrix exhibits microscopic morphologies (framboids and plaquets) characteristic of C1 chondrites. The bulk composition of this sample has high Mg/Si and low Fe/Si relative to other chondrites, and P and S are strongly enriched. Most compositional differences between this meteorite and other chondrites may be explained by fractionation of Fe phases, such as magnetite and troilite. Low refractory element contents preclude mixing with lunar materials. This sample may be a surviving fragment of the meteoritic component present in the lunar regolith. Its characteristics suggest that ancient meteoritic debris sampled by the moon may be significantly different from that captured by the present-day earth.  相似文献   

Variation in stable carbon isotopes in organic matter from the Gunflint Iron Formation     

Elso S Barghoorn  Andrew H Knoll  Harry Dembicki  Warren G Meinschein 《Geochimica et cosmochimica acta》1977,41(3):425-430

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Resolving climate change in the period 15–23 ka in Greenland ice cores: a new application of spectral trend analysis     

Mat G. G. De Jong  Djin S. Nio  Alain R. Böhm  Harry C. Seijmonsbergen  Leo W. S. de Graaff 《地学学报》2009,21(2):137-143

Northern Hemisphere climate history through and following the Last Glacial Maximum is recorded in detail in ice cores from Greenland. However, the period between Greenland Interstadials 1 and 2 (15–23 ka), i.e. the period of deglaciation following the last major glaciation, has been difficult to resolve in great detail. We here offer a new subdivision of this in the NGRIP, GRIP and GISP2 ice cores, by newly introducing spectral trend analysis to the study of climate-related data series from ice cores. This analysis reveals patterns of change and discontinuity in the waveform properties of a data series, relating to the environmental (including climatic) history of accumulation of the rock or ice record. The application allows high-resolution correlation between the ice cores, and a greatly improved subdivision of the study interval. Nine climatic phases are recognized, within which more identifiable events can also be correlated between the three locations.  相似文献   

Residential Location,Ambient Air Lead Pollution And Lead Absorption In Children*     

Raphael J. Caprio  Harry L. Margulis  Morris M. Joselow 《The Professional geographer》1975,27(1):37-42

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The use of land recorded long-range marine airgun data in crustal reflection-refraction investigations     

C-E. Lund  R.G. Roberts  C. Juhlin  R. Bödvarson  H. Palm 《Geophysical Journal International》1987,89(1):365-370

Summary. During the EUGENO-S field campaign in 1984 a large number of airgun shots were fired at sea in the Skagerrak and Kattegat and in Lake Vänern in southwestern Sweden. The signals were recorded on land by analogue "MARS" and digital "SN-PCM-80" three channel stations, by a digital 48 channel "SERCEL SN348" reflection instrument, and by "Geostore" stations. The airguns were shot about every 300 m along profiles up to 100 km in length. Clear reflected and refracted arrivals were observed from 5 km to 250 km shot-receiver offset. The field and data processing techniques used are briefly described, and two examples of data are discussed.  相似文献   

Similarity of new palaeomagnetic data from the Santa Rosa Mountains with those from Steens Mountain gives wide regional evidence for a two-stage process of geomagnetic field reversal     

Neil Roberts  Mike Fuller 《Geophysical Journal International》1990,100(3):521-526

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MIL 03443, a dunite from asteroid 4 Vesta: Evidence for its classification and cumulate origin     

Andrew W. BECK  David W. MITTLEFEHLDT  Harry Y. McSWEEN Jr  Douglas RUMBLE III  Cin‐Ty A. LEE  Robert J. BODNAR 《Meteoritics & planetary science》2011,46(8):1133-1151

Abstract– The absence of dunite (>90 vol% olivine) in the howardite, eucrite, and diogenite (HED) meteorite suite, when viewed with respect to spectroscopic and petrologic evidence for olivine on Vesta, is problematic. Herein, we present petrologic, geochemical, and isotopic evidence confirming that Miller Range (MIL) 03443, containing 91 vol% olivine, should be classified with the HED clan rather than with mesosiderites. Similarities in olivine and pyroxene FeO/MnO ratios, mineral compositions, and unusual mineral inclusions between MIL 03443 and the diogenites support their formation on a common parent body. This hypothesis is bolstered by oxygen isotopic and bulk geochemical data. Beyond evidence for its reclassification, we present observations and interpretations that MIL 03443 is probably a crustal cumulate rock like the diogenites, rather than a sample of the Vestan mantle.  相似文献   

Bounce Rock—A shergottite‐like basalt encountered at Meridiani Planum,Mars     

Jutta ZIPFEL  Bradley L. JOLLIFF  Ralf GELLERT  Kenneth E. HERKENHOFF  Rudolf RIEDER  Robert ANDERSON  James F. BELL III  Johannes BRÜCKNER  Joy A. CRISP  Philip R. CHRISTENSEN  Benton C. CLARK  Paulo A. De SOUZA Jr.  Gerlind DREIBUS  Claude D’USTON  Thanasis ECONOMOU  Steven P. GOREVAN  Brian C. HAHN  Göstar KLINGELHÖFER  Timothy J. McCOY  Harry Y. McSWEEN Jr.  Douglas W. MING  Richard V. MORRIS  Daniel S. RODIONOV  Steven W. SQUYRES  Heinrich WÄNKE  Shawn P. WRIGHT  Michael B. WYATT  Albert S. YEN 《Meteoritics & planetary science》2011,46(1):1-20

Abstract– The Opportunity rover of the Mars Exploration Rover mission encountered an isolated rock fragment with textural, mineralogical, and chemical properties similar to basaltic shergottites. This finding was confirmed by all rover instruments, and a comprehensive study of these results is reported here. Spectra from the miniature thermal emission spectrometer and the Panoramic Camera reveal a pyroxene‐rich mineralogy, which is also evident in Mössbauer spectra and in normative mineralogy derived from bulk chemistry measured by the alpha particle X‐ray spectrometer. The correspondence of Bounce Rock’s chemical composition with the composition of certain basaltic shergottites, especially Elephant Moraine (EET) 79001 lithology B and Queen Alexandra Range (QUE) 94201, is very close, with only Cl, Fe, and Ti exhibiting deviations. Chemical analyses further demonstrate characteristics typical of Mars such as the Fe/Mn ratio and P concentrations. Possible shock features support the idea that Bounce Rock was ejected from an impact crater, most likely in the Meridiani Planum region. Bopolu crater, 19.3 km in diameter, located 75 km to the southwest could be the source crater. To date, no other rocks of this composition have been encountered by any of the rovers on Mars. The finding of Bounce Rock by the Opportunity rover provides further direct evidence for an origin of basaltic shergottite meteorites from Mars.  相似文献   

Relative motion of satellites exploiting the super-integrability of Kepler’s problem     

K. Uldall Kristiansen  P. L. Palmer  M. Roberts 《Celestial Mechanics and Dynamical Astronomy》2010,106(4):371-390

This paper builds upon the work of Palmer and Imre exploring the relative motion of satellites on neighbouring Keplerian orbits. We make use of a general geometrical setting from Hamiltonian systems theory to obtain analytical solutions of the variational Kepler equations in an Earth centred inertial coordinate frame in terms of the relevant conserved quantities: relative energy, relative angular momentum and the relative eccentricity vector. The paper extends the work on relative satellite motion by providing solutions about any elliptic, parabolic or hyperbolic reference trajectory, including the zero angular momentum case. The geometrical framework assists the design of complex formation flying trajectories. This is demonstrated by the construction of a tetrahedral formation, described through the relevant conserved quantities, for which the satellites are on highly eccentric orbits around the Sun to visit the Kuiper belt.  相似文献