L. Henkel 《International Journal of Earth Sciences》1924,15(2):144

Ohne Zusammenfassung  相似文献   

Corrigenda     

V.A. Gostin  C. Herbert 《Australian Journal of Earth Sciences》2013,60(2)

  相似文献   

Dem Andenken Emil Dittlers     

Herbert Haberlandt 《Mineralogy and Petrology》1948,1(2):101-106

Ohne Zusammenfassung  相似文献   

Geochemical exploration for gold in the Nile Valley Block (A) area,Wadi Allaqi,South Egypt     

Mohamed Abdallah Gad Darwish  Herbert Poellmann 《Chemie der Erde / Geochemistry》2010,70(4):353-362

The present work aims to estimate Au-anomalous distribution patterns, the optimum grain size fraction and pathfinder elements for gold placer. The obtained data of analyzed elements (Au, Ag, As, Ba, Cd, Co, Cr, Cu, Fe, Ga, Hg, Li, Mn. Mo, Ni, Pb, Rb, Sb, Se, Sr, Te, Ti, V, Y and Zn) in both the fine (?0.25 mm) and coarse (?1 mm+0.25 mm) grain size fractions of 32 dry stream sediment samples, which have been derived from metamorphosed Island Arc volcanic rocks of Late Proterozoic age, revealed that most of the analyzed elements in both grain size fractions are asymmetrically distributed and did not pass the tests of normality. The coarse grain size fraction appears to be the better size fraction for Au detection and can be considered as the optimum grain size fraction for future application in regional stream sediment surveys. The presence of Au anomalies in the upper part of the stream and beside the mine is either sourced by the main Au-mineralization or new potential extension of the mineralization in the study area. Silver, Cd, Se, Zn and Te can be considered as useful pathfinder elements for Au in the coarse grain size fraction, and they may be used for future geochemical exploration for Au in the area. Recommendation of the authors is pointing to perform lithogeochemical survey in the eastern and western parts of the mine.  相似文献   

Magnetometer survey of the proposed Sirente meteorite crater field,central Italy: Evidence for uplifted crater rims and buried meteorites     

Jens ORM   David Gomez‐Ortiz  Patrick C. McGuire  Herbert Henkel  Goro Komatsu  Angelo Pio Rossi 《Meteoritics & planetary science》2007,42(2):211-222

Abstract— The Sirente crater field consists of a 120 m wide, rimmed main depression flanked to the northwest by about 30 smaller depressions. It has been dated to the first centuries A.D. An impact origin is suggested, but not confirmed. The small size combined with the properties of the target material (carbonate mud) would neither allow shock features diagnostic of impact, nor projectile vaporization. Consequently, a meteoritic component in the sediments would be very localized. At impacts of this size the projectile most likely is an iron meteorite. Any iron meteorites on the ground surface would, in Iron Age Europe, have been removed shortly after the event. However, if the depressions are of impact origin they should contain meteorites at great depth in analogy with known craters. The magnetic properties of iron meteorites differ distinctly from the very low magnetic sediments and sedimentary rocks of the Sirente area. We have used a proton precession magnetometer/gradiometer to produce magnetic anomaly maps over four of the smaller depressions (～8 m diameter), as well as two crossing profiles over a fifth depression (～22 m diameter). All show distinct magnetic anomalies of about 20 nT, the larger depression up to 100 nT. Magnetic modeling shows a best fit for structures with upturned strata below their rims, excluding a karstic origin but supporting an explosive formation. The 100 nT anomaly can only be explained by highly‐magnetic objects at a few meters depth. All together, the magnetic data provides a strong indication for an impact origin of the crater field.  相似文献   

The gentle separation of presolar SiC grains from meteorites     

J. Tizard  I. Lyon  T. Henkel 《Meteoritics & planetary science》2005,40(3):335-342

Abstract— This paper describes the development of a new, effective, and non‐destructive method of SiC isolation from meteorites by freeze‐thaw disaggregation, size, and density separation. This new method is important because there is evidence that current methods, which use strong acids and chemical treatments to dissolve silicates and separate out the interstellar grains, may alter the surfaces of the grains chemically and isotopically. Furthermore, any non‐refractory coating present on the grains would be destroyed. Using our new separation method, SiC grains were enriched from ?6 ppm abundance in Murchison whole rock to 0.67% abundance in the 0.4‐1.4 μm size range and 0.27% abundance in the 1.4–17 μm size range. Individual SiC grains were easily identified using electron probe microanalysis (EPMA) mapping of grains distributed thinly on gold foil; a small aliquot from these fractions has so far yielded >150 SiC grains for isotopic analysis. The method separates out SiC grains efficiently, is applicable to very small or rare samples, and avoids the harsh acid treatments that may alter possible amorphous or non‐refractory coats on the grains. The procedure also preserves the remainder of the original sample and it is hoped that it may be extended to other micron‐sized presolar grains found in meteorites such as corundum, graphite, and silicon nitride.  相似文献   

Evidence for fractional condensation and reprocessing at high temperatures in CH chondrites     

Dominik C. Hezel  Herbert Palme  Frank E. Brenker  Lutz Nasdala 《Meteoritics & planetary science》2003,38(8):1199-1215

Abstract— We performed a detailed study of silica‐rich components (SRC) in the paired CH chondrites Acfer 182 and 207. These SRCs appear either as chondrules or fragments, and they contribute <0.1 vol% to the bulk meteorite. They usually contain a silica and a silicate portion. Both portions are, in most cases, cryptocrystalline and have bulk SiO₂‐concentrations between 65 and 85 wt%. The silicate generally has a pyroxene normative composition. The silica often appears as blebs within the silicate matrix or vice versa. If there are no blebs, silica and silicate still form rounded interfaces. The SRCs are depleted in refractory elements like Ca, Al, and Ti relative to CI. A few SRC‐like objects are extremely rich in Mn and show no depletion in refractory elements. We conducted micro‐Raman studies on the silica portions of the SRCs to determine their structure, and we identified several silica phases: α‐quartz, cristobalite, glass, and a yet unidentified polymorph. The silicate portion is glass when the silica is glass and crystalline when the silica is crystalline. The low contents of Al and Ca make an igneous origin of the SRCs very unlikely, and the absence of metal excludes the formation by reduction of pyroxene. We suggest, instead, a fractional condensation origin of the SRCs from a Si‐enriched gas after removal of gaseous Mg by forsterite condensation. Additional evidence for fractional condensation is provided by a unique layered object with olivine in the core, pyroxene and metal at the rim, and silica at the outermost border; these layers record the condensation sequence. Two chondrules were found with several percent of Mn and high Cr, Na, and K contents, providing further evidence for condensation from a fractionated gas. The texture of the SRCs and the occurrence of cristobalite and silica glass, however, require formation by liquid immiscibility at high temperatures, above 1968 K, and subsequent fast cooling. Therefore, we propose a 2‐stage model for the formation of SRCs in CH chondrites: 1) fractional condensation of forsterite, enstatite, and SiO₂‐rich phases; and 2) reheating of SiO₂‐rich components to temperatures above 1968 K followed by rapid cooling. All other phases identified in CH chondrites can be understood within the framework of this model. Thus, the extremely unequilibrated CH chondrites provide a wealth of evidence for fractional condensation processes in the early solar nebula, in metals (Meibom et al. 1999), and in silicates.  相似文献   

Diurnal precipitation cycle in Austria     

Asma Yaqub  Petra Seibert  Herbert Formayer 《Theoretical and Applied Climatology》2011,103(1-2):109-118

A back-trajectory clustering method was developed to identify synoptic patterns associated with heavy precipitation in Austria. Extending this work from daily precipitation sums to accumulation intervals from 12 to 48 hours, an unexpected problem was encountered related to the observation schedule of data. To modify available data to our specific needs, evening precipitation falling between 19 and 21 LT (Local Time) was studied. Hourly precipitation data for the period of 1950 to 2005 from 132 weather stations over Austria were used. It was found that the evening precipitation fraction has its maxima in the central Alps in all seasons, except in autumn when maxima shift more towards the south of the Alps. These results encouraged us to analyse the variation of diurnal precipitation for different seasons in Austria as well. A total of 119 stations with sixteen years (1990?C2005) of data were used for this purpose. Mean hourly precipitation values were calculated, which were then normalised, smoothed and were finally clustered to find regions with homogeneous diurnal cycles. The diurnal cycles of precipitation of the centres exhibit systematic patterns and seasonal cycles, reflecting intensity and timing of convective activity over these regions. The winter season is relatively dry and summer is associated with the highest precipitation. The areas inside the Alps receive higher amplitudes of precipitation in summer. Interesting features such as bimodal distributions, nocturnal maxima and early morning maxima were also observed in many regions.  相似文献   

运输方式对马氏珠母贝(Pinctada fucata)稚贝存活率、生长、消化及抗氧化性能的影响探究     

李娇妮  廖秀睿  李曦  吕布  杨守国  臧战  VASQUEZ Herbert Ely  王爱民  郑兴  顾志峰 《海洋与湖沼》2022,53(2):414-420

为优化马氏珠母贝苗种运输技术,提高运输效率,以马氏珠母贝(Pinctada fucata)稚贝为研究对象,分别以有水和无水两种运输方式汽运8 h条件下开展实验,比较分析其在运输前后、运输后恢复阶段的生长、消化和抗氧化性能。结果显示:有水运输后存活率达98%,无水运输97%;在恢复期第14 d,有水运输和无水运输存活率分别达97%、96%;有水运输皮质醇含量由(2 607.61±15.27)μg/L显著降低至(1 412.98±5.09)μg/L,无水运输后显著降低至(2 287.36±10.18)μg/L;在恢复期第7 d和14 d皮质醇含量均呈逐渐上升趋势;有水和无水运输后和恢复期淀粉酶活性不断上升,且有水运输酶活性高于无水运输(P<0.05),最高值为(1.43±0.05) U/mg prot;有水和无水运输后及恢复期超氧化物歧化酶酶活性在不断下降,最低下降至(16.00±0.14) U/mg prot,有水运输超氧化物歧化酶活性均高于无水运输(P<0.05);有水运输碱性磷酸酶、谷草转氨酶和谷丙转氨酶活性均上升,无水运输均下降;在恢复阶段,碱性磷酸酶活性在不断下降,谷草转氨酶和谷丙转氨酶活性在不断上升。有水和无水运输会对马氏珠母贝稚贝产生不同的影响,有水运输方式相对无水运输方式可使马氏珠母贝稚贝在后期阶段具有更好的存活效果和生长状态。  相似文献   

Employing airborne multispectral digital imagery to map Brazilian pepper infestation in South Texas     

Reginald Fletcher  James Herbert Everitt  Chenghai Yang 《国际地球制图》2013,28(7):527-536

A study was conducted in south Texas to determine the feasibility of using airborne multispectral digital imagery for differentiating the invasive plant Brazilian pepper (Schinus terebinthifolius) from other cover types. Imagery obtained in the visible, near-infrared, and mid-infrared regions of the light spectrum and a supervised classification approach were employed to develop thematic maps of two areas infested with Brazilian pepper. Map accuracies ranged from 84.2 to 100% for the Brazilian pepper class. Findings support using airborne multispectral digital imagery as a tool for separating Brazilian pepper from associated land cover types and further encourage exploration of airborne multispectral digital imagery and image processing techniques for developing maps of Brazilian pepper infestation in Texas and abroad.  相似文献