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231.
Anton Kearsley Giles Graham Tony McDonnell Phil Bland Rob Hough Paul Helps 《Meteoritics & planetary science》2004,39(2):247-265
Abstract— Understanding the nature and composition of larger extraterrestrial bodies that may collide with the Earth is important. One source of information lies in the record of ancient impact craters, some of which have yielded chemical information as to the impacting body. Many deeply eroded craters have no remaining melt sheet or ejecta yet may contain impactor residue within basement fractures. The emplacement mechanism for fractionated siderophile residues is likely to be gaseous, although, melt droplets and some solid materials may survive. For breccia‐ and melt‐filled fractures to contain extraterrestrial material, they must form very early in the impact process. Most current numerical models do not dwell on the formation and location of early major fractures, although, fractures in and around small craters on brittle glass exposed to hypervelocity impact in low Earth orbit have been successfully simulated. Modelling of fracture development associated with larger craters may help locate impact residues and test the models themselves. 相似文献
232.
Tony Waltham 《Geology Today》2005,21(5):187-190
Silver mining in Bolivia exploited the richest hill on Earth to finance the imperial Spanish in the 16th century. The mines still operate at Potosi today, with primitive conditions underground, but silver production may be boosted by new geological understanding. 相似文献
233.
Anja Strφmme 《极地研究(英文版)》2002,13(1)
1 TheincoherentscattertechniqueTheuseofincoherentscatterradarsasapowerfulground baseddiagnostictoolforstudyingthenear EarthspaceenvironmentbeganwiththefirsttheoreticalpredictionsbyGordon( 1 958) ,andthefirstobservationsbyBowles( 1 958)afewmonthslater .Thereares… 相似文献
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Escudero Christian R. Ramirez Gaytan Alejandro Zamora Camacho Araceli Preciado Adolfo Flores Karen L. Gomez Hernandez Adan 《Natural Hazards》2022,110(1):247-267
Natural Hazards - We performed a seismic vulnerability assessment that involves geotechnical and building structure analysis for Puerto Vallarta, Mexico, a city located along the pacific coast.... 相似文献
238.
Tony Waltham 《Geology Today》2000,16(3):97-101
Yellowstone is justifiably famed for its geysers, but Iceland, New Zealand and Kamchatka all have their own special geothermal features. 相似文献
239.
Javier Ortega Hernandez 《Geology Today》2009,25(2):71-74
Graphoglyptids are trace fossils that are generally acknowledged to have had a deep-sea origin, displaying complex, nutrient gathering strategies in response to stable environments with low productivity. However, two recently discovered graphoglyptids in the Permian of New Mexico seem to challenge previous assumptions. Rather than in deep-sea sediments, Spirorhaphe azteca and Augerinoichnus helicoidalis were discovered in tidal flat palaeoenvironments, showing that these behavioural patterns are also carried out by animals in tidal settings. Fine sediments of the region are recognized as the key factor in the preservation of these trace fossils. Presence of graphoglyptids in a transitional environment demonstrates that behaviour is not solely defined by depth, but many intricate factors are involved. 相似文献
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