Quasar redshifts: the intrinsic component     

Peter M. Hansen 《Astrophysics and Space Science》2016,361(9):303

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Editorial Appreciation     

John Leibacher  Takashi Sakurai  Lidia van Driel-Gesztelyi 《Solar physics》2016,291(2):337-338

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Boron abundances and isotopic ratios of olivine grains on Itokawa returned by the Hayabusa spacecraft          下载免费PDF全文

Wataru Fujiya  Peter Hoppe  Ulrich Ott 《Meteoritics & planetary science》2016,51(9):1721-1729

We report the B abundances and isotopic ratios of two olivine grains from the S‐type asteroid Itokawa sampled by the Hayabusa spacecraft. Olivine grains from the Dar al Gani (DaG) 989 LL6 chondrite were used as a reference. Since we analyzed polished thin sections in both cases, we expect the contribution from the solar wind B (rich in ¹⁰B) to be minimal because the solar wind was implanted only within very thin layers of the grain surface. The Itokawa and DaG 989 olivine grains have homogeneous B abundances (~400 ppb) and ¹¹B/¹⁰B ratios compatible with the terrestrial standard and bulk chondrites. The observed homogeneous B abundances and isotopic ratios of the Itokawa olivine grains are likely the result of thermal metamorphism which occurred in the parent asteroid of Itokawa, which had a similar composition as LL chondrites. The chondritic B isotopic ratios of the Itokawa samples suggest that they contain little cosmogenic B (from cosmic‐ray spallation reactions) rich in ¹⁰B. This observation is consistent with the short cosmic‐ray exposure ages of Itokawa samples inferred from the small concentrations of cosmogenic ²¹Ne. If other Itokawa samples have little cosmogenic B as well, the enrichment in ¹⁰B found previously on the surface of another Itokawa particle (as opposed to the bulk grain study here) may be attributed to implanted solar wind B.  相似文献   

Petrology and oxygen isotopic compositions of clasts in HED polymict breccia NWA 5232          下载免费PDF全文

Katrina D. van Drongelen  Douglas Rumble III  Kimberly T. Tait 《Meteoritics & planetary science》2016,51(6):1184-1200

Northwest Africa (NWA) 5232, an 18.5 kg polymict eucrite, comprises eucritic and exogenic CM carbonaceous chondrite clasts within a clastic matrix. Basaltic clasts are the most abundant eucritic clast type and show a range of textures and grain size, from subophitic to granoblastic. Other eucritic clast types present include cumulate (high‐En pyroxene), pyroxene‐lath, olivine rich with symplectite intergrowths as a break‐down product of a quickly cooled Fe‐rich metastable pyroxferroite, and breccia (fragments of a previously consolidated breccia) clasts. A variable cooling rate and degree of thermal metamorphism, followed by a complex brecciation history, can be inferred for the clasts based on clast rounding, crystallization (and recrystallization) textures, pyroxene major and minor element compositions, and pyroxene exsolution. The range in δ¹⁸O of clasts and matrix of NWA 5232 reflects its origin as a breccia of mixed clasts dominated by eucritic lithologies. The oxygen isotopic compositions of the carbonaceous chondrite clasts identify them as belonging to CM group and indicate that these clasts experienced a low degree of aqueous alteration while part of their parent body. The complex evolutionary history of NWA 5232 implies that large‐scale impact excavation and mixing was an active process on the surface of the HED parent body, likely 4 Vesta.  相似文献   

Examining Fluvial Stratigraphic Architecture Using Ground‐Penetrating Radar at the Fanta Stream Fossil and Archaeological Site,Central Ethiopia     

Peter Lanzarone  Ervan Garrison  Ren Bobe  Assiged Getahun 《Geoarchaeology》2016,31(6):577-591

The Fanta Stream site is an archaeological and paleontological locality in Addis Ababa, Ethiopia. The site contains a rich assemblage of fossil mammals and Acheulean artifacts of approximately 600 ka located in a rare high‐altitude context. A ground‐penetrating radar (GPR) survey was conducted in order to provide three‐dimensional imaging of the subsurface, which the authors use to interpret the geometry and distribution of fossil‐containing stratigraphic units. Utilizing the stream's natural cut bank exposure, we calibrate GPR data to known geologic units through radar facies analysis. Shallow, high‐amplitude coherent reflection geometries are attributed to volcanic tuff deposits, as these units exhibit subparallel continuous reflections consistent with planar stratified sedimentary deposition. Deeper, discontinuous reflection packages are interpreted as conglomeritic, fossil‐containing deposits. The results of the GPR survey outline the location of the Fanta Stream's paleodepositional features as well as suggest the extent of fossiliferous stratigraphic units for use in future excavations.  相似文献   

Editorial: 50 Years of <Emphasis Type="Italic">Solar Physics</Emphasis>     

Paul Charbonneau  John Leibacher  Cristina Mandrini  Lidia van Driel-Gesztelyi  Michael S. Wheatland 《Solar physics》2016,291(12):3461-3465

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Ore Deposits in an Evolving Earth,edited by G.R.T. Jenkin,P.A.J. Lusty,I. McDonald,M.P. Smith,A.J. Boyce and J.J. Wilkinson. Geological Society,London, Special Publication, 393, 2015. No. of pages: 333. Price: UK£110‐00. ISBN 978–1 86239‐626‐5 (hardback).     

Peter W. Scott 《Geological Journal》2016,51(1):161-162

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Runway Wake Vortex,Crosswind, and Visibility Detection with a Scintillometer at Schiphol Airport     

D. van Dinther  O. K. Hartogensis  A. A. M. Holtslag 《Boundary-Layer Meteorology》2015,157(3):481-499

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Direct impacts of alternative energy scenarios on water demand in the Middle East and North Africa   总被引：1，自引：1，他引：0  

Kerstin Damerau  Oscar P. R. van Vliet  Anthony G. Patt 《Climatic change》2015,130(2):171-183

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Climate change,climate justice and the application of probabilistic event attribution to summer heat extremes in the California Central Valley     

Roberto Mera  Neil Massey  David E. Rupp  Philip Mote  Myles Allen  Peter C. Frumhoff 《Climatic change》2015,133(3):427-438

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