排序方式： 共有79条查询结果，搜索用时 171 毫秒
31.
Sokol E. V. Deviatiiarova A. S. Kokh S. N. Reverdatto V. V. Artemyev D. A. Kolobov V. Yu. 《Doklady Earth Sciences》2019,489(1):1326-1329
Doklady Earth Sciences - Marbles of the Kochumdek complex contain pyrrhotite, rasvumite, alabandine, würtzite, galena, and acanthite. The diversity of sulfides is caused by efficient crystal... 相似文献
32.
Doklady Earth Sciences - The petrological–geochemical and isotopic–geochronological studies of contrasting rocks of the Yenisei Regional Tectonic Zone of the Yenisei Ridge allowed... 相似文献
33.
Polyansky O. P. Korobeynikov S. N. Babichev A. V. Reverdatto V. V. Sverdlova V. G. 《Doklady Earth Sciences》2009,429(1):1380-1384
A new point of view describing processes of partial melting and development of gravitational instability in a thickening crust
with increased thickness of the granite layer is suggested. Numeral experiments support the following main conclusions. The
critical volume of partially melted material should be formed for the beginning of flotation in a gravitational field. Due
to model estimations, the height of the melting area in the granite crust should be not less than 6–7 km. A mushroom-shaped
form of the floating body was observed in all models regardless of the thermal source size (fixed or variable width): the
high temperature channel (magma leader) and head body of the diapir are formed. The height of diapir floating depends on rheological
features of the surrounding crust: 10 times increase in the yield strength (from 1 to 10 MPa) while temperature decrease confines
the possible level of rising to a depth of 15–16 km. An elevation of about 750 m is formed in the day surface relief above
the axis part of the diapir. 相似文献
34.
Prokopiev A. V. Polyansky O. P. Koroleva O. V. Vasiliev D. A. Tomshin M. D. Reverdatto V. V. Novikova S. A. 《Doklady Earth Sciences》2020,490(1):4-7
Doklady Earth Sciences - The paper presents the results from the first 40Ar/39Ar isotope dating of eleven mafic sills recovered by deep boreholes in the eastern Siberian Platform. Most of the dates... 相似文献
35.
36.
The mineralogical, petrological, geochemical and geochronological data on the Garevka metamorphic complex (GMC) of the Yenisey Ridge were used to evaluate the age, nature, and provenance of their protoliths. The evolution of the GMC occurred in two stages with different ages, thermodynamic regimes, and metamorphic field gradients. The final emplacement of granitoids was marked by high-pressure (HP) amphibolite facies regional metamorphism (970 Ma). At the second stage, these rocks experienced Late Riphean (900–870 Ma) retrograde epidote-amphibolite facies metamorphism accompanied by the formation of blastomylonitic complexes within narrow zones of brittle-ductile deformation. The metamorphism of migmatites (850 Ma) is coeval with the collisional medium-pressure metamorphism of the kyanite-sillimanite type. The GMC is different from the other rock complexes of the Yenisey Ridge in the presence of rapakivi-type granites. The geochemistry of these rocks, which is characterized by stronger enrichment in K2O, FeO, Y, Th, U, Zr, Hf, Nb, Ta, and REE relative to the other mineral assemblages of the GMC, is typical of anorogenic (A-type) within-plate granites. Among other distinctive features of these rocks are the strong iron enrichment of the melanocratic minerals, the presence of ilmenite as the sole Fe-Ti oxide, and crystallization from higher temperature (T = 825°C vs. T = 750°C) water-poor magmas under reducing conditions below the FMQ buffer. Significant variations in the geochemical and petrological characteristics of the GMC rocks suggest that they could not be derived from a single source. The main volume of the high-K rocks varying in composition from A-type to S-type granites was generated by melting of mixed mantlecrustal sources. The products of melting of the Late Archean-Early Proterozoic infracrustal gneisses of the Siberian Craton could be a possible source for the least oxidized rocks. 相似文献
37.
38.
39.
I. I. Likhanov V. V. Reverdatto P. S. Kozlov A. E. Vershinin 《Doklady Earth Sciences》2011,436(2):213-218
Two successive phases of metamorphism can be recognized based on mineralogical and petrological observations coupled with
geothermobarometric estimates for chemical zoning in Fe- and Al-rich metapelites from the Teya crystalline rocks of the Transangarian
Yenisei Ridge. The first phase is marked by the formation of low-pressure regional metamorphic complexes of the andalusite-sillimanite
type (P = 3.9–5.1 kbar; T = 510–640°C), which were most likely related to the Middle Riphean Grenville events. In the second phase, metapelitic rocks
underwent Late Riphean medium-pressure collisional metamorphism of the kyanite-sillimanite type (P = 5.7–7.2 kbar, T = 660–700°C), which resulted locally in an increase in pressure in the vicinity of thrusts. These results suggest that medium-pressure
kyanite-bearing metapelitic rocks were formed as a result of collision-related metamorphism caused by thrusting of the Siberian
cratonal blocks onto the Yenisei Ridge in the vicinity of the Tatarka deep fault. 相似文献
40.
I. I. Likhanov V. V. Reverdatto P. S. Kozlov V. V. Khiller V. P. Sukhorukov 《Petrology》2013,21(6):561-578
A study of gneisses and schists from the Yenisey regional shear zone (Garevka complex) at the western margin of the Siberian Craton has provided important constraints on the tectonothermal events and geodynamic processes in the Yenisey Ridge during the Riphean. In situ U-Th-Pb geochronology of monazite and xenotime from different garnet growth zones and the calculation of P-T path derived from chemical zoning pattern in garnet were used to distinguish three metamorphic events with different ages, thermodynamic regimes and metamorphic field gradients. The first stage occurred as a result of the Grenville orogeny during late Meso-early Neoproterozoic (1050–850 Ma) and was marked by low-pressure zoned metamorphism at ～4.8–5.0 kbar and 565–580°C and a metamorphic field gradient with dT/dH = 20–30°C/km typical of orogenic belts. At the second stage, the rocks experienced Late Riphean (801–793 Ma) collision-related medium-pressure metamorphism at ～7.7–7.9 kbar and 630°C with dT/dH ≤ 10°C/km. The final stage evolved as a syn-exhumation retrograde metamorphism (785–776 Ma) at ～4.8–5.4 kbar and 500°C with dT/dH ≤ 12°C/km and recorded a relatively fast uplift of the rocks to upper crustal levels in shear zones. The range of exhumation rates at the post-collisional stage (500–700 m/Ma) correlates with the duration of exhumation and the results of thermophysical numerical modeling of metamorphic rocks within orogenic belts. The final stages of collisional orogeny are marked by the development of rift-related bimodal dyke swarms associated with Neoproterozoic extension (797 ± 11 and 7.91 ± 6 Ma; U-Pb SHRIMP II zircon data) along the western margin of the Siberian craton and the beginning of the breakup of Rodinia. Post-Grenville metamorphic episodes of regional evolution are correlated with the synchronous succession and similar style of the later tectono-metamorphic events within the Valhalla orogen along the Arctic margin of Rodinia and support the spatial proximity of Siberia and North Atlantic cratons at about 800 Ma, as indicated by the latest paleomagnetic reconstructions. 相似文献