Elemental abundances in chondrules from unequilibrated chondrites: Evidence for chondrule origin by melting of pre-existing materials     

James L. Gooding  Klaus Keil  Takaaki Fukuoka  Roman A. Schmitt 《Earth and Planetary Science Letters》1980,50(1):171-180

Bulk abundances of Na, Mg, Al, Ca, Sc, V, Cr, Mn, Fe, Co, Ni, Zn, La, Sm, Eu, Yb, Lu, Ir, and Au were determined by neutron activation analysis of chondrules separated from unequilibrated H-, L-, and LL-chondrites (Tieschitz, Hallingeberg, Chainpur, Semarkona) and correlated with chondrule petrographic properties. Despite wellknown compositional differences among the whole-rock chondrites, the geometric mean compositions of their respective chondrule suites are nearly indistinguishable from each other for many elements. Relative to the condensible bulk solar system (approximated by the Cl chondrite Orgueil), chondrules are enriched in lithophile and depleted in siderophile elements in a pattern consistent with chondrule formation by melting of pre-existing materials, preceded or attended by silicate/metal fractionation. Relative to nonporphyritic chondrules, porphyritic chondrules are enriched in refractory and siderophile elements, suggesting that these two chondrule groups may have formed from different precursor materials.  相似文献   

Echo sounding on suspended particulate matter in the elbe estuary     

Jobst Hülsemann  Hendrik Eden  Klaus Ricklefs 《Ocean Dynamics》1995,47(1):23-45

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High-Precision Trace Element Data for the USGS Reference Materials BCR-1, BCR-2, BHVO-1, BHVO-2, AGV-1, AGV-2, DTS-1, DTS-2, GSP-1 and GSP-2 by ID-TIMS and MIC-SSMS   总被引：2，自引：0，他引：2  

Ingrid Raczek  Brigitte Stoll  Albrecht W. Hofmann  Klaus Peter Jochum 《Geostandards and Geoanalytical Research》2001,25(1):77-86

Different batches of the new US Geological Survey (USGS) reference materials (RMs) BCR-2, BHVO-2, AGV-2, DTS-2 and GSP-2 and the original USGS RMs BCR-1, BHVO-1, AGV-1, DTS-1 and GSP-1 have been analysed by isotope dilution using thermal ionisation mass spectrometry (ID-TIMS) and by multi-ion counting spark source mass spectrometry (MIC-SSMS). The concentrations of K, Rb, Sr, Ba and the rare earth elements were determined with overall analytical uncertainties of better than 1% (ID-TIMS) and 3% (MIC-SSMS). The analyses of different aliquots and batches of BCR-2, BHVO-2, AGV-2 and GSP-2, respectively, agree within 1%, i.e. approximately the analytical uncertainties of the data. This indicates an homogeneous distribution of the trace elements in these RMs. Differences in element concentrations of up to 17% in different aliquots of the depleted RM DTS-2 are outside the analytical uncertainty of our data. They may be attributed to a slightly heterogeneous distribution of trace elements in this dunite sample. Our trace element data for BCR-2, BHVO-2, AGV-2 and GSP-2 agree within about 3% with preliminary reference values published by the USGS. They also agree within 1-6% with those of the original RMs BCR-1, BHVO-1, AGV-1 and GSP-1. Large compositional differences are found between DTS-2 and DTS-1, where the concentrations of K, Rb, Sr and the light REE differ by factors of 2 to 24.  相似文献   

On the ice age glaciation of the Tibetan highlands and its transformation into a 3-D model     

Prof. Matthias Kuhle Dr.  Klaus Herterich Dr.  R. Calov 《GeoJournal》1989,19(2):201-206

We present an interdisciplinary study on data and modeling intercomparison, concerning the possible existence of a Tibetan ice sheet and its climatological implications during the ice age. In the ice sheet model the fields of ice flow and temperature are calculated, and a highly parameterized formulation of the yearly snow balance is used, defining the forcing at the surface of the ice sheet. The data set used, supplies the height of the equilibrium line of the glaciers (=ELA) and documents the maximum extension of the glaciated areas. With prescribed snow accumulation above the ELA and melting below, the model is integrated for 10 000 model years and the model glaciation is then compared with the data.The main results are: Provided the height of the glacial equilibrium line has been reconstructed correctly, a Tibetan ice sheet can be bult up within 10 000 model years, using moderate rates of precipitation (maximum snow fall: 100 mm/year). Comparison of data and model glaciation suggests an increase of precipitation from the NW to the E of Tibet and from the S to the NE, which reflects the presently observed pattern of the monsoon circulation.  相似文献   

The spatial variability of Amazonian soils under natural forest and pasture     

José C. Correa  Prof. Dr. Klaus Reichardt 《GeoJournal》1989,19(4):423-427

Spatial variability of physical and chemical properties in Amazonian soils is evaluated on sites of natural rain forest and pastures of different age in the Amazon region. The sampling scheme was regionalized using transects of fifty points 3 m apart each. Variables analysed were: soil bulk density; resistance to penetration; soil water content; available water; pH and extractable ions such as Ca, K, Al, P and Zn. Geostatistical analyses show that most variables are space independent for the 3 m spacing used. Variances indicate a much lower variability of the measured properties in the forest as compared to pastures.  相似文献   

Gravity interpretation of a unified 2-D acoustic image of the central Alpine collision zone   总被引：1，自引：0，他引：1  

Klaus Holliger  Edi Kissling 《Geophysical Journal International》1992,111(2):213-225

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Announcements     

Stephan Schuhmann  Klaus Herrmann  Kurt Rothermel  Jan Blumenthal  Dirk Timmermann 《Stochastic Hydrology and Hydraulics》1993,7(1):83

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Neuere Veröffentlichungen     

Klaus Figge 《Ocean Dynamics》1993,45(1):55-56

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Seismic structure of gneissic/granitic upper crust: geological and petrophysical evidence from the Strona-Ceneri Zone (northern Italy) and implications for crustal seismic exploration   总被引：2，自引：0，他引：2  

Klaus Holliger  Alan Levander 《Geophysical Journal International》1994,119(2):497-510

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The Chassigny meteorite: a cumulate dunite with hydrous amphibole-bearing melt inclusions     

R.J. Floran  Martin Prinz  P.F. Hlava  Klaus Keil  C.E. Nehru  J.R. Hinthorne 《Geochimica et cosmochimica acta》1978,42(8):1213-1229

The Chassigny meteorite is a moderately shocked olivine achondrite or chassignite with features indicative of a cumulate origin with some subsolidus annealing. Chassigny is an iron-rich dunite (Fo₆₈) with minor amounts of Ca-rich and Ca-poor pyroxene, alkalic feldspar, chromite, and melt inclusions in olivine. Accessory phases include chlorapatite, troilite, marcasite, kaersutite amphibole, pentlandite, ilmenite, rutile and baddeleyite. The meteorite experienced shock pressures of ~150–200 kbar as evidenced by planar and irregular fractures in olivine, local recrystallization in pyroxene and reduced birefringence and rare deformation lamallae in feldspar. Kaersutitic amphibole (K_0.05 Na_0.45)_0.50 (Ca_1.71 Na_0.29)_2.00 (Mg_2.73 ‘Fe’_1.19 Ti_0.73 A1_0.23 Cr_0.08 Mn_0.03)_4.99 (Si_6.05Al_1.95)_8.00 O₂₂ (OH, F)₂ containing hydrogen and lesser amounts of fluorine represents the first extraterrestrial occurrence of hydrous amphibole and the first meteoritic amphibole type other than fluorichterite. Kaersutite is found only in melt inclusions.Melt inclusion bulk compositional data suggest crystallization from a low-Ca melt that may have been similar in major element abundances to the silicate portion of LL group chondrites. However, Chassigny has a fractionated pattern for REE and the lack of metallic iron, possible presence of minor Ni in the olivine and Fe³⁺ in the chromites indicates that Chassigny formed under relatively more oxidizing conditions than most other achondrites. Therefore its parental melt could not have been directly derived from a chondritic composition in a simple single-stage process. The iron-rich bulk composition, cumulate texture and abundance as well as alkalic nature of the interstitial feldspar indicate that Chassigny could not have generated eucritic magmas. This places further constraints on its relationship to other meteorites and the parent body from which it is derived. The Brachina meteorite is similar to Chassigny except that it is finer grained, more feldspathic and is unshocked. It extends the fractionation range of this group which now represents two unusual meteorites.  相似文献