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41.
Andrs Folguera Antonio Introcaso Mario Gimnez Francisco Ruiz Patricia Martinez Cynthia Tunstall Ezequiel García Morabito Víctor A. Ramos 《Tectonophysics》2007,439(1-4):129-147
The western retroarc of the Southern Andes between 38° and 40° S is formed by a NNW-elongated ridge not associated with stacked thrust sheets. On the contrary, during the last 4–3 Ma this ridge was affected by extensional deformation, regional uplift and related folding on a very broad scale. Receiver function analysis shows that the drainage divide area and adjacent retroarc lie over an attenuated crust. Expected crustal thickness at these latitudes is around 38 km, whereas in this part of the retroarc the thickness is less than 32 km. The causes for such attenuation have been linked to a moderate steepening of the subducted Nazca plate beneath the South American plate, which is suggested by a westward shift and narrowing of the magmatic arc during the last 4 to 5 Ma. Gravimetric studies show that the upper plate did not react homogeneously to slab steepening, but ancient sutures and lithospheric discontinuities deeply buried under Mesozoic to Cenozoic sequences in the retroarc were locally reactivated. These processes resulted in an asthenospheric anomaly that correlates at the surface with the area of Pliocene to Quaternary doming, widespread extension and three radial troughs. Two of the troughs have accommodated substantial amounts of extension, but the third was probably aborted at an early stage. Moreover, the presence of an anomalous concentration of calderas and large volcanic centers over the proposed asthenospheric anomaly, and their age distribution, may indicate minor migration of the asthenospheric anomaly between 4 and 2 Ma through the western South American plate. 相似文献
42.
Mario Rabinowitz 《Astrophysics and Space Science》1998,262(4):391-410
Small, quiescent black holes can be considered as candidates for the missing dark matter of the universe, and as the core
energy source of ball lightning. By means of gravitational tunneling, unidirectional radiation is emitted from black holes
in a process much attenuated from that of Hawking radiation, P, which has proven elusive to detect. Gravitational tunneling
emission is similar to electric field emission of electrons from a metal in that a second body is involved which lowers the
barrier and gives the barrier a finite rather than infinite width. Hawking deals with a single isolated black hole. The radiated
power here is P ∝ e-2Δγ P, where e-2Δγ is the transmission probability.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
43.
Vincenzo Amico Giuseppe Impellizzeri Giovanna Oriente Mario Piattelli Sebastiano Sciuto Corrado Tringali 《Marine pollution bulletin》1979,10(10):282-284
Concentrations of chlorinated hydrocarbons (DDT and metabolites, PCBs, aldrin, dieldrin, HCB and BHCs) have been determined in the tissues of five species of marine animals sampled in selected areas of the central Mediterranean. 相似文献
44.
Vincenzo Amico Giovanna Oriente Mario Piattelli Corrado Tringali 《Marine pollution bulletin》1979,10(6):177-179
The levels of PCBs, DDT and BHC residues have been determined in thalli of 12 species of marine algae harvested along the east coast of Sicily. The results are discussed in comparison with those obtained earlier with animal species sampled in the same area. 相似文献
45.
Mario Bossolasco Guiseppe Cicconi Ignazio Dagnino Antonio Elena Giuseppe Flocchini 《Pure and Applied Geophysics》1965,62(1):207-214
Summary The relationship, already found by the authors, between sunspot numbers and the solar constant, as deduced from the highest global irradiance values at noon, is here reexamined and confirmed. Some attempts at explanation and further inferences are presented. 相似文献
46.
Abdellatif Chaouti Isabella Colombini Mario Fallaci Elena Gagnarli Lorenzo Chelazzi & Abdellatif Bayed 《Marine Ecology》2008,29(S1):99-107
The effects of the freshwater discharge of the Oued Sebou River on the macroinfauna, was studied on the sandy beach of Mehdia through the analysis of the abiotic parameters and of the macrozoobenthos. In autumn 2002 and spring 2003, three beach sites, each with two transects, localized at 50, 3500 and 5720 m from the river mouth respectively, were studied. Positive correlations were recorded for beach slope and pH whereas negative ones were obtained for organic matter content and salinity at increasing distances from the river mouth. Significant differences between beach sites and seasons occurred for median grain size, organic matter content and pH. For each beach site, mean macroinfauna abundance varied between 30 and 100 ind.·m−2 and in spring there was a significant correlation between this parameter and the increasing distance from the river mouth. No significant correlation was instead found between species richness and the increasing distance, although the farthest beach site from the mouth had the highest number of species during both seasons. The results indicated the importance of organic matter content and salinity for the macrofaunal abundance whereas the diversity indices were more affected by beach slope and grain size. The results showed that there was no clear spatial trend in compound indices of the macrofauna across the sampled sites and the influence of the river discharge of Sebou River did not seem to be significant and consistent on the macrobenthos of this mesotidal shore. Comparison with microtidal shores revealed the influence of the tidal excursion and swell characteristics on the response of the benthic structures of sandy beaches to discharges of freshwater. 相似文献
47.
Mario di Bossolasco 《Pure and Applied Geophysics》1939,1(1):47-51
Riassunto Si segnala la notevole regressione subita dalla linea di spiaggia di Belvedere Marittimo nel periodo 1913–1938 e se ne discutono i possibili fattori, specie l'effetto del vento sull'erosione del fondo marino, accennando alle indagini intraprese dal R. Istituto Geofisico e Geodetico di Messina. 相似文献
48.
Taro Takahashi Stewart C. Sutherland Rik Wanninkhof Colm Sweeney Richard A. Feely David W. Chipman Burke Hales Gernot Friederich Francisco Chavez Christopher Sabine Andrew Watson Dorothee C.E. Bakker Ute Schuster Nicolas Metzl Hisayuki Yoshikawa-Inoue Masao Ishii Takashi Midorikawa Yukihiro Nojiri Arne Krtzinger Tobias Steinhoff Mario Hoppema Jon Olafsson Thorarinn S. Arnarson Bronte Tilbrook Truls Johannessen Are Olsen Richard Bellerby C.S. Wong Bruno Delille N.R. Bates Hein J.W. de Baar 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(11):2075-2076
49.
50.
Mario A. VESCONI Shawn P. WRIGHT Mauro SPAGNUOLO Robert JACOB Carlos CERRUTTI Luciana GARCIA Evangelina FERNANDEZ William A. CASSIDY 《Meteoritics & planetary science》2011,46(7):935-949
Abstract– More craters may be discovered in the future, but as it is currently known, the Campo del Cielo crater field is 18 km long by 4 km at its widest point. Such a distribution of craters suggests that the parent meteoroid entered and traversed the atmosphere at a very low angle relative to horizontal. The crater field contains at least 20 small craters produced by the larger fragments of the parent meteoroid. Four of these are explosion analog craters and the rest are penetration funnels. During four field seasons, we have constructed topographic and magnetic maps of four of the penetration funnels as found, and then dug trenches across them to learn their original structures and recover meteorites preserved within them. Structures of these penetration funnels indicate very low angles of impact, i.e., 9–16° relative to horizontal. This supports the idea that the parent meteoroid traversed the atmosphere at a low angle. Data given here for the four penetration funnels include projectile masses, lengths, widths, depths, and estimates of impact angles and azimuths. One of the penetration funnels described here (No. 6) can almost be classified as an explosion analog crater. 相似文献