The first finds of cretaceous belemnites from the Magellan Rise, Pacific Ocean

The occurrence of belemnites in Mesozoic sediments of the Pacific guyots is established for the first time (rostra Dimitobelidae gen. et sp. indet. from the late Campanian-Maastrichtian detrital limestone of the DVGI Guyot, Belemnitella? sp. from oolitic limestone of the Gelendzhik Guyot, which are presumably of the Santonian-Maastrichtian age, and Belemnitidae? gen. et sp. indet. from the Maastrichtian oolitic limestone of the Butakov Guyot, the Magellan Rise). In recent years, fossil cephalopods important in stratigraphic and paleobiogeographic aspects have been found at five guyots of that rise. New data on fossil invertebrates from the study region suggest breaks in the sedimentation here at the terminal Maastrichtian, Paleogene, and initial Neogene time. Possible limits of vertical migration in the tropical Pacific are estimated for the Late Cretaceous belemnites based on preliminary results of the oxygen isotope analysis.     

Frequency Structure of Radio Scintillations for Several Pulsars

Scintillation times and decorrelation bandwidths for the pulsars B0329+54, B1641–45, B1508+55 and B1919+21 are determined. The results are based on observations made with different instruments and at different radiofrequencies. All objects but the pulsar B1508+55 were detected to have more than one frequency scale. The obtained values of scattering parameters are not contrary in general to the Kkolmogorov form of density fluctuation spectrum. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Procedure for Calculating Extreme Characteristics of the Northern Caspian Sea Level

A procedure is proposed for calculating extreme characteristics of the level of a sea with allowance for positive and negative setups. Analysis is made of past storm events in the Northern Caspian Sea that have caused strong setups. Sixty-three storm weather patterns are chosen from a period of 45 years. Time ring synoptic maps are used to digitize the atmospheric pressure fields and calculate the field of its gradient and the wind near water surface. Based on these data, the sea level values and currents are calculated through two- and three-dimensional hydrodynamic models. A probabilistic model along with computer-aided data treatment procedures are used to calculate the fields of extreme characteristics of the sea level at the Lagan gage with the occurrence of once per N years at the average Caspian Sea level of 27 m below SL.     

Temperature range for magnetization of oceanic spinel peridotites

Petromagnetic studies of a representative spinel peridotite collection from a number of localities along slowly spreading mid-ocean ridges were performed. It was established that oceanic peridotites usually contain two or more generations of ferrimagnetics formed in assemblages with metamorphic silicates at different temperatures. The crystallization of different magnetite (or magnetite-rich spinel) generations in the rocks is manifested by the appearance of inflection points in the thermomagnetic curves. The particular petrographic features of the metamorphism observed in the peridotites correlate well with the temperatures of the inflection points in the thermomagnetic curves. Generally, the serpentinization of primary minerals in oceanic peridotites starts at 210–225°C (green mesh serpentines and bastites) and finishes at 135–190°C (colorless plate serpentines, hourglass-textured serpentines, and colorless homoaxial bastites). Crystallization of ferrimagnetic grains associated with talc, chlorite, and amphibole in the course of medium-grade metamorphism, which precedes the serpentinization, was observed in the major part of the collection examined and occurred at temperatures higher than 370°C. Seprentinization of metamorphic minerals (predominantly talc) with the formation of antigorite and crystallization of ferrimagnetic grains in oceanic peridotites occurred at 250–350°C, previous to the serpentinization of primary silicates. Thus, the petromagnetic thermometry of metamorphic events in oceanic peridotites may provide significant progress in the understanding of the geological process accompanying the formation of the oceanic lithosphere in slowly spreading ocean ridges.     

Multicolor Photometry of Small Bodies of the Solar System: Performance Potential at the Robophot Telescope

Solar System Research - We consider prospects for investigating asteroids with the multicolor photometric method at the Robophot telescope—a robotic telescope of the Dall–Kirkham system...     

On the importance of rock thermal conductivity and heat flow density in basin and petroleum system modelling

Basin and petroleum systems are routinely modelled to provide qualitative and quantitative assessments of a hydrocarbon play. The importance of the rock thermal properties and heat flow density in thermal modelling the history of a basin are well-known, but little attention is paid to assumptions of the thermal conductivity, present-day heat flow density and thermal history of basins. Assumed values are often far from measured values when data are available to check parameters, and effective thermal conductivity models prescribed in many basin simulators require improvement. The reconstructed thermal history is often justified by a successful calibration to present-day temperature and vitrinite reflectance data. However, a successful calibration does not guarantee that the reconstruction history is correct. In this paper, we describe the pitfalls in setting the thermal conductivity and heat flow density in basin models and the typical uncertainties in these parameters, and we estimate the consequences by means of a one-dimensional model of the super-deep Tyumen SG-6 well area that benefits from large amounts of reliable input and calibration data. The results show that the entire approach to present-day heat flow evaluations needs to be reassessed. Unreliable heat flow density data along with a lack of measurements of rock thermal properties of cores can undermine the quality of basin and petroleum system modelling.     

Results of three-frequency monitoring of giant pulses from the crab pulsar

We present the results of long-term, three-frequency monitoring of giant pulses from the Crab pulsar on the 64-m radio telescope in Kalyazin. The total monitoring time was 160 hours. The signal power was recorded simultaneously at 600, 1650, and 4850 MHz via direct sampling of the received signals in the total receiver bandwidth without any compensation for interstellar dispersion. In total, 1117 and 352 giant pulses were detected at 600 and 4850 MHz, respectively. The frequency band centered at 1650 MHz was contaminated by interference, and was used only to identify events found in other frequency bands. The cumulative energy distribution of the giant pulses follows a power law at 600 and 4850 MHz up to the highest energies. A deep modulation in the radio spectra of individual giant pulses was observed on both large (Δv/v ≈ 0.5) and small (Δv/v ≈ (2?4) × 10^?3) frequency scales. The simultaneous appearance of giant pulses at the interpulse longitudes at high (4850 MHz) and low (1650 and/or 600 MHz) frequencies testifies to their common origin, in spite of the observed differences in other parameters.