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991.
992.
R. Jayangondaperumal A. K. Dubey K. Sen 《Journal of the Geological Society of India》2010,75(1):225-238
Kinematic information from deformation structures and magnetic fabrics are used to infer recent tectonics around Kangra and
Dehradun recesses, western Himalaya. Three types of magnetic fabrics (Type I & II, III, and IV) are identified based on the
angle between K3 axis and bedding pole. It was observed that Kangra recess shows more mature fabric type IV as compared to
Dehradun recess, where orientation of K3 axes and tectonic fabric reveals dominance of superposed deformation. In the vicinity
of Dehradun recess, normal faults occur in un-indurated Quaternary fan deposits confirming their recent formation. The observations
are in conformity with earlier studies that during the 1905 Kangra earthquake, the Main Boundary Thrust (MBT) (or one of its
subsidiary thrusts) near Kangra showed thrusting whereas the MBT near Dehradun underwent either normal faulting or post seismic
adjustments characteristic of normal faulting. The thrusting could be a result of subsurface processes whereas the normal
faulting was a result of prevailing surface strains. 相似文献
993.
994.
I. S. Krassivskaya E. V. Sharkov N. S. Bortnikov A. V. Chistyakov N. V. Trubkin T. I. Golovanova 《Petrology》2010,18(3):263-277
Altered variolites described for the first time in the axial zone of the Mid-Atlantic Ridge are represented by rounded globules
of andesite (icelandite) composition with light trachyandesite rim embedded in a picrobasaltic matrix. The globules were transferred
with picrobasaltic melt and then floated to the surface of lava flow, while formation of leucocratic rims was presumably related
to thermodiffusion (Soret effect) in a cooling heterogeneous melt. This heterogeneous melt was formed by penetration of ascending
column of picrobasaltic magma in already existing small intracructsal magmatic chamber filled with residual icelanditetype
andesite melt and involvement of the latter into a general upward movement. The rapid ascent of the melts in the oceanic spreading
zones by means of turbulent flowing caused dispersion of the extragenous melt into small drops in a jet of picrobasaltic magma,
without their interaction. Variolites were formed during cooling of such heterogeneous lava flow. No signs of liquid immiscibility
were found in the studied variolites. 相似文献
995.
996.
997.
This paper reports REE data on resin-asphaltene components of oil from six oil-gas-bearing provinces and on bitumoids from
inferred oil-source rocks (domanikites and bazhenites). It was shown that, regardless of geological-tectonic structure of
the regions, oil composition, depth of reservoirs, and host lithologies, oil exhibits significant REE fractionation, and,
unlike bitumoids, positive Eu anomaly. The (Eu/Sm)n ratio increases from asphaltenes to resins and further to oils. Based on REE distribution in oil, source rocks, and bitumoids,
it was concluded that deep-seated fluids were one of the possible sources that defined the trace element composition of oil. 相似文献
998.
999.
U-Th-Pb systematics of precambrian carbonate rocks: Dating of the formation and transformation of carbonate sediments 总被引:1,自引:0,他引:1
O. K. Kaurova G. V. Ovchinnikova I. M. Gorokhov 《Stratigraphy and Geological Correlation》2010,18(3):252-268
The current state in the Pb-Pb dating of the formation and epigenesis of Precambrian carbonate sediments has been reviewed.
The geochemistry of admixture elements (U, Th, Pb, Rb, Sr, Mn, and Fe) constituting carbonate minerals and the redistribution
of the elements in the course of early diagenesis and epigenesis have been considered. The advantages of choosing samples
for Pb-Pb dating on the basis of geochemical criteria similar to those applied for Sr-isotope stratigraphy and the potentialities
of applying different methods of decontamination of specimens, analyzed from surface contamination and possible epigenetic
carbonate phases, were illustrated. By the example of a series of carbonate formations, distinctions in susceptibility of
U-Pb and Rb-Sr systems of carbonate minerals to secondary transformations have been demonstrated. The prospects for using
the method of step solution allowing noncogenetic carbonate generations to be separated and thus the accuracy and reliability
of Pb-Pb dates to be upgraded were considered. 相似文献
1000.
Studies on the water and suspended matter concentration dynamics were performed for the summer and autumn periods in Kruglaya
Bay, Chupa Inlet (Karelian Coast, the White Sea). The tidal cycle appeared as the major factor defining the water salinity,
temperature, and suspended matter concentration. The water temperature and suspended matter concentration increased during
low tide, and the opposite pattern was observed for water salinity; all the processes were true for both surface and bottom
water layers. Therefore, we conclude that major bulk of the allochtonous suspended matter is carried into the sea by the ebb
stream. 相似文献