Algorithm of Calculation of Lyapounov Coefficients for Analysis of Chemical Autooscillations, as Applied to Calcite Crystallization Model

The numerical algorithm of calculation of Lyapounov coefficients (L _k) of any order is developed. The apparatus of analytical calculations is not used in this algorithm. The proposed algorithm is of use for usual computer languages and allows us to find the numerical value of L _k for any k and to make complete qualitative analyses of dynamic models on the plane.     

LIP Reading: Recognizing Oceanic Plateaux in the Geological Record

Basaltic oceanic plateaux are important features in the geologicalrecord. Not only do they record ancient mantle plume activity,but they also are believed to be important building blocks inthe formation of the continental crust. In this paper we reviewthe salient features of two Cretaceous oceanic plateaux (theOntong Java and the Caribbean–Colombian): thick sequencesof predominantly homogeneous basalt; the occurrence of high-MgObasalt, including komatiites; and an apparent absence of sheeteddyke complexes. In addition, pyroclastic deposits may be scarce.We then explore ways of distinguishing plateaux from basalticsequences erupted in different tectonomagmatic settings: continentalflood basalt provinces; island arcs; back-arc basins; oceanislands and mid-ocean ridges. Using these criteria, potentialArchaean and Proterozoic oceanic plateaux are reviewed and identified.Finally, we explore how these remnant oceanic plateaux becameincorporated into the continents, by reviewing the proposedaccretion mechanisms for the Cretaceous Caribbean–Colombianoceanic plateau, on the basis of evidence from South Americaand the tonalites of the southern Caribbean island of Aruba. KEY WORDS: oceanic plateau; basalt geochemistry; large igneous provinces; plumes     

Significance of pteropods in deciphering the late Quaternary sea-level history along the southwestern Indian shelf

The paper evaluates the usefulness of pteropods in palaeobathymetric synthesis along the southwestern continental shelf of India. Core samples collected from the shelf off north Kerala (SW coast of India) were studied for faunal assemblages (pteropods and foraminifers), calcium carbonate contents and lithological characteristics. A fundamental precept for considering any organism as a bathometer is that it should be highly sensitive to changing water depths. To ascertain this, the bathymetric distribution patterns of modern pteropods as well as planktonic and benthic foraminifers were recorded in core-top samples. The results reveal that certain pteropod species (Limacina inflata, Creseis acicula, Creseis virgula, and Creseis chierchiae) are highly depth sensitive. The response of these species to depth changes was assessed in terms of the L. inflata and Creseis spp. abundance ratio. A model for the relationship between water depths and the L. inflata/Creseis spp. ratio is proposed for the southwestern shelf of India. Variations of benthic/planktonic foraminifers (BF/PF) and pteropods/planktonic foraminifers (Pt/PF) in the modern sediments were also found to be depth controlled. Two sediment cores, representing the last 36,000 and 23,000 years, were collected to investigate past sea-level changes. These cores comprised two distinct lithological units, the upper unit corresponding to the Holocene, and the lower unit to the last glacial period. The L. inflata/Creseis spp. model was successfully applied to the fossil record for reconstructing the palaeobathymetry of the shelf study locations. Down-core variations in the BF/PF and Pt/PF ratios support these inferred sea-level changes. Major periods of sea-level oscillations were also found to have a strong influence on the calcium carbonate distribution. For both core sites, the palaeobathymetric curves reflect consistency in terms of changing sea level. The results suggest that the sea level stood around 100 m below the present mean sea level during the last glacial maximum. A rapid rise in sea level was documented between 15 and 10 ka B.P. The sea-level rise has been slower since 7 ka B.P.     

Climate prediction: Progress,problems, and prospects

“Hundred year forecasts are made with the same models, which cannot predict the weather even several days ahead...”     

Revealing the energy sources of alternating intensity regimes of the evolving Alberto tropical cyclone using microwave satellite sensing data

The trajectory characteristics and the intensity evolution of the Alberto tropical cyclone (TC) in the integral water-vapor field are analyzed in detail using a software-algorithmic complex designed for constructing highly detailed global radio-thermal fields of the ocean-atmosphere system based on microwave satellite measurements. This complex was developed by the authors earlier and allows one to obtain global animated radio-thermal fields with a time step of 1.5 h and a spatial resolution of 0.2°. Special attention is paid to the problem of revealing the energy sources of three consecutive intensifications of this TC. The analysis of satellite data with the use of the animation method developed by the authors shows for the first time that these sources are regions with an increased (exceeding the critical level) integral water-vapor content located in different geographical areas lying along the complex trajectory of the TC with a variable intensity. The first region was located in the equatorial intertropical convergence zone, the second was located above the Gulf Stream water area, and the third resided in the area affected by the Azores High.     

Density estimation of two-phase flow with multiscale and randomly perturbed data

In this paper, we describe an efficient approach for quantifying uncertainty in two-phase flow applications due to perturbations of the permeability in a multiscale heterogeneous porous medium. The method is based on the application of the multiscale finite element method within the framework of Monte Carlo simulation and an efficient preprocessing construction of the multiscale basis functions. The quantities of interest for our applications are the Darcy velocity and breakthrough time and we quantify their uncertainty by constructing the respective cumulative distribution functions. For the Darcy velocity we use the multiscale finite element method, but due to lack of conservation, we apply the multiscale finite volume element method as an alternative for use with the two-phase flow problem. We provide a number of numerical examples to illustrate the performance of the method.     

Fossil mammoths from Santa Cruz Island, California

Mammoth remains on Santa Cruz Island, one of the four Northern Channel Islands of California, are very sparse, in marked contrast to those reported from Santa Rosa and San Miguel Islands of the same island group. A probable major reason for this scarcity is that Quaternary deposits are greatly restricted on Santa Cruz Island. It is proposed, contrary to popular opinion, that fossils found on Santa Cruz Island were derived from animals which died on the island, and were not transported there by humans. Reasons for this conclusion are that the size and geological context of the fossils are similar to those of the largest mammoth fossils of Santa Rosa Island, and that, in spite of extensive investigations by many persons, mammoth remains have not been found in middens, either on the islands or on the adjacent mainland.     

Late Mesozoic magmatism and Cenozoic tectonic deformations of the Barents Sea continental margin: Effect on hydrocarbon potential distribution

The paper is focused on the two tectonic-geodynamic factors that made the most appreciable contribution to the transformation of the lithospheric and hydrocarbon potential distribution at the Barents Sea continental margin: Jurassic-Cretaceous basaltic magmatism and the Cenozoic tectonic deformations. The manifestations of Jurassic-Cretaceous basaltic magmatism in the sedimentary cover of the Barents Sea continental margin have been recorded using geological and geophysical techniques. Anomalous seismic units related to basaltic sills hosted in terrigenous sequences are traced in plan view as a tongue from Franz Josef Land Archipelago far to the south along the East Barents Trough System close to its depocentral zone with the transformed thinned Earth’s crust. The Barents Sea igneous province has been contoured. The results of seismic stratigraphy analysis and timing of basaltic rock occurrences indicate with a high probability that the local structures of the hydrocarbon (HC) fields and the Stockman-Lunin Saddle proper were formed and grew almost synchronously with intrusive magmatic activity. The second, no less significant multitectonic stress factor is largely related to the Cenozoic stage of evolution, when the development of oceanic basins was inseparably linked with the Barents Sea margin. The petrophysical properties of rocks from the insular and continental peripheries of the Barents Sea shelf are substantially distinct as evidence for intensification of tectonic processes in the northwestern margin segment. These distinctions are directly reflected in HC potential distribution.     

Station-keeping for a translunar communication station

A translunar communication station is to be kept close to a nominal unstable periodic ‘Halo’ orbit, visible at all times from Earth. The analytically computed nominal orbit is not perfect, requiring an average control acceleration of about 10^?6 g's for tight control. An adjustable quadratic combination of position deviation and control acceleration is minimized to provide an (adjustable) control law with period feedback gains and a periodic bias. The average control acceleration can be reduced to less than 10^?8 g's with an error settling time of less than 21/2 months. The resulting limiting motion provides, in turn, an improved nominal, permitting the same low control cost with much tighter control, corresponding to settling times of the order of one day.