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21.
A. B. Kotov N. V. Vladykin V. V. Yarmolyuk E. B. Sal’nikova I. A. Sotnikova S. Z. Yakovleva 《Doklady Earth Sciences》2013,453(1):1082-1085
This paper presents the U-Pb zircon age of pulaskite of the main phase (294 ± 1 Ma) and the rare metal syenite (283 ± 8 Ma) of the Burpala alkaline pluton. The geochronological data show that it was formed in the Early Permian. By age, it is comparable with the Synnyr pluton of the Synnyr rift zone, alkaline granitic rocks and bimodal volcanic associations of the Uda-Vitim rift zone, and carbonatites of the Saizhen rift zone of the Central Asian foldbelt. These intraplate igneous complexes were formed almost simultaneously with crustal granitic rocks of the Angara-Vitim batholite. All of this gives ground to suppose that the origination of their parental melts is a result of the influence of the mantle hot spot or mantle plume on the lithosphere that led to extensive crustal anatexis. 相似文献
22.
23.
William C. Mahaney Michael W. Milner Rana Sodhi Ronald I. Dorn Sal Boccia Roelf P. Beukens Pierre Tricart Stphane Schwartz Eva Chamorro‐Perrez Ren W. Barendregt Volli Kalm Randy W. Dirszowsky 《Geoarchaeology》2007,22(7):797-816
Identification of the exact route followed by Hannibal during his invasion of Italia in the Second Punic War is one of the major questions of antiquity and one that historians/archaeologists have long studied. One of the many clues in the ancient literature that can help answer this question is the mention of fired rock, the result of a conflagration Hannibal is reputed to have employed to reduce the size of boulders in a blocking rockslide some distance down from the high col on the Italian side. The only route with evidence of fired rock along the roadway leading into Italia follows the Col du Clapier, one of the possible northern routes discussed by historians. Radiocarbon dating of calcined rocks is not possible, but whereas Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS), Field Emission Scanning Electron Microscope (FESEM‐EDS), backscatter electron scanning microscopy (BSE), High Resolution Transmission Electron Microscope (HRTEM), and Raman Spectroscopic data do not provide an age for the burnt rock, compositional evidence of the conflagration derived from these analyses may shed light on Hannibal's actual route. © 2007 Wiley Periodicals, Inc. 相似文献
24.
A. SalĪtis 《Earth, Moon, and Planets》1996,72(1-3):41-44
We consider the changes of cometary perihelion distances as a process of diffusion in the value of q, due to perturbations by stars. We find more comets at large q values than is observed. This suggests that a large number of long-period comets is not observed. 相似文献
25.
A. Salītis 《Earth, Moon, and Planets》1995,71(3):41-44
We consider the changes of cometary perihelion distances as a process of diffusion in the value of q, due to perturbations by stars. We find more comets at large q values than is observed. This suggests that a large number of long-period comets is not observed. 相似文献
26.
27.
V. V. Yarmolyuk V. I. Kovalenko A. M. Kozlovsky V. P. Kovach E. B. Sal’nikova D. V. Kovalenko A. B. Kotov E. A. Kudryashova V. I. Lebedev G. Eenzhin 《Petrology》2008,16(7):679-709
The paper reports data on the evolutionary history of magmatism, its conditions, and sources in the process of the development
of the Southern Mongolian Hercynides during the pre-accretion, continental-margin, and rifting stages within the time span
from the Silurian to Early Permian. The Hercynian continental crust in the southern Mongolian segment of the Central Asian
Foldbelt (CAFB) was determined to have grown in the environment of ensimatic island arcs, backarc basins, spreading centers,
and oceanic islands or plateaus, with material coming from the depleted and, perhaps, also enriched mantle sources in the
open ocean that surrounded the Siberian paleocontinent on the side of the Caledonian margin. This made it possible to recognize
the Early-Middle Paleozoic epoch of juvenile crustal growth in CAFB and the corresponding isotopic crustal province with a
total area of more than 200 thousand km2. The principal differences between the composition and structure of the blocks surrounding the Hercynian regions (Caledonides
in the Gobi Altai and Grenwillides in the South Gobi microcontinent) testify that the southern margin of the Caledonian Siberian
continent and the Grenvillides of the South Gobi microcontinent had different geological histories and were spatially separated.
The structural complex of the Paleoasian ocean, including the terranes of the South Gobi microcontinent, were transformed
into a continental block in the latest Devonian-earliest Carboniferous, in relation with accretion processes, folding, metamorphism,
and tectonic delamination along the boundaries of structurally heterogeneous domains. The subsequent recycling of the crust
by magmatic processes was related to the development of an active continental margin (ACM). The development of an ACM in the
Hercynides resulted from and was a continuation of the motions of the continental and oceanic lithospheric plates, i.e., processes
that brought about the Hercynian accretion. The evolution history of the ACM was subdivided into two stages: early (a continental-margin
stage proper) and late (rifting stage). The rocks of the early stage were produced at 350–330 Ma and compose a differentiated
basalt-andesite-rhyodacite complex and related massifs of the granodiorite-plagiogranite and banatite (diorite-monzonite-granodiorite)
associations. During the rifting stage at 320–290 Ma, a bimodal basalt-comendite-trachyrhyolite association was formed, along
with accompanying alkali granite massifs. In the southern Mongolian segment of the Hercynides, the rocks of the rifting stage
compose two subparallel rift zones: Gobi-Tien Shan, which extends along the boundaries of the South Gobi microcontinent, and
the Main Mongolian lineament, which marks the boundaries between the Hercynides and Caledonides in the CAFB. The rift structures
are made up of alkali granitoids and normal-alkalinity granitoids, which are atypical of rift zones. Their genesis is thought
to have been related to crustal anatexis, a process that was triggered by rift-related magmas at an unusual combination of
rifting and ACM tectonic setting. The basic rocks of the rift associations have geochemical signatures atypical of continental
rifting. They show Ta and Nb minima and K and Pb maxima, as is typical of rocks generated at convergent plate boundaries.
Nevertheless, the broad variations in the concentrations and ratios of some major and incompatible trace elements and in the
Sr, Nd, and O isotopic composition of the rift basaltoids allowed us to distinguish their high-and low-Ti varieties, which
were produced with the participation of three mantle sources: depleted mantle similar to the source of basalts in midoceanic
ridges, enriched mantle like the source of basalts in oceanic islands, and the mantle material of the metasomatized mantle
wedge. The origin of andesites in the rift zones is explained by the contamination of mantle basaltoid melts with sialic (predominantly
sedimentary) material of the continental crust or the assimilation of anatectic partial granite melts. 相似文献
28.
I. K. Kozakov E. B. Sal’nikova V. P. Kovach V. V. Yarmolyuk I. V. Anisimova A. M. Kozlovskii Yu. V. Plotkina T. A. Myskova A. M. Fedoseenko S. Z. Yakovleva A. M. Sugorakova 《Stratigraphy and Geological Correlation》2008,16(4):360-382
Granitoids and metamorphic rocks of the Baidarik basement block of the Dzabkhan microcontinent are studied in terms of geology, geochronology (U-Pb dating of zircon microfractions and individual grains) and Nd isotopic-geochemical systematics. As is established, the formation history of metamorphic belt (disthene-sillimanite facies) in junction zone of the Baidarik block and Bayankhongor zone of the Late Riphean (~665 Ma) ophiolite association characterizes development of the Vendian (~560–570 Ma) active continental margin. The high-P metamorphic rocks of that time span evidence formation of structures with the Earth’s crust of considerable thickness. In Central Asia, events of the Vendian low-gradient metamorphism are established also in the Tuva-Mongolian massif, Kan block of the East Sayan Mountains, and South Chuya inlier of the Caledonides in the Altai Mountains. Based on these data, it is possible to distinguish the Late Baikalian stage in development of the Early Caledonian superterrane of Central Asia, which antedated the subsequent evolution of this structure during the Late Cambrian-Ordovician. The high-gradient metamorphism that affected most intensively the southeastern part of the Baidarik block can be correlated with the Early Paleozoic (525–540 Ma) evolution of active continental margin and associated development of the Vendian oceanic basins and island arcs of the Ozernaya zone. 相似文献
29.
Ohne Zusammenfassung 相似文献
30.
Sal 《International Journal of Earth Sciences》1916,7(1-2):84-85
Ohne Zusammenfassung 相似文献