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Showing 1 to 20 of 37 for “"isochron"”.
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Isochron geometry in the presence of saddle objects
… which orbits converge to an oscillation, and its isochrons —each consisting of all points with the same asymptotic phase. From a dynamical systems perspective; isochrons are (𝑛−1)-dimensional manifolds (curves or (hyper-)surfaces) that foliate an 𝑛-dimensional basin of attraction. This thesis …
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Geochemical Implications of Stirring and Mixing in the Earth's Mantle
… interpretation of the 2.0 Ga lead-lead pseudo-isochron age in terms of an age distribution of mantle material. Simple equations relate the pseudo-isochron age to the rate of melting and decay constants. These equations are different from, but related to and more general than, those found …
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Application of the 190Pt-186Os isotope decay system to dating platinum-group minerals
… Ma is widely accepted. We present an accurate isochron age of 2012 ± 47 Ma (2σ, n = 50, MSWD = 1.19) for in situ Bushveld PGM, demonstrating the validity of multi-grain Pt-Os ages. Precision on the Bushveld LA-MC-ICPMS Pt-Os age is comparable to the Re-Os and Rb-Sr ages but data acquisition is …
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The Geometry of Isochrons in Planar Systems
… these responses by finding the so-called isochrons of the underlying periodic orbit. Each isochron is the set of points that converge to the periodic orbit in phase with each other. In this thesis, we investigate planar systems, for which isochrons are curves that can have very complex …
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Re-Os dating of algal laminites : reduction-enrichment of metals in the sedimentary environment and evidence for new geoporphyrins
… Devonian Keg River algal laminites produced an isochron date (382.2 ± 6.9 Ma) consistent with the expected age of about 388 Ma, and showed a lower degree of sample scatter than comparable dating studies of black shales. Ordovician kukersites from the Yeoman Fm. also produced a consistent age …
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Mesozoic alkaline volcanism and mantle evolution of the southwestern São Francisco craton, Brazil
… from the Araxa Group define a 711 Ma Rb-Sr isochron. This latter age is interpreted as a Sr-isotope rehomogenization related to the development of the Brasilia orogenic and foreland thrust belt. A 823 Ma Sm-Nd errorchron indicate that these rocks may be coeval to the felsic volcanism of the …
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Sociogenetic investigation of the southern harvester termite, Microhodotermes viator, via genetic and behavioural bioassays
… to mitigate these challenges, such as U-series isochron dating, is suggested for future research.
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Paleotectonic Investigation by Successive 3D Seismic Horizon Flattening in the Pennsylvanian Interval of Western Osage County, Oklahoma
… 3D seismic data volume. Paleostructure maps and isochron, or time-thickness, maps created in conjunction with the flattened horizons highlight contemporaneous structural features that may be related to regional orogenic events. Paleostructure maps also help determine the sedimentological …
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Mantle plume-midocean ridge interaction : geophysical observations and mantle dynamics
… hot, thus low-density mantle. Along Cocos-plate isochrons, bathymetric and MBA variations increase with increasing isochron age, suggesting the subaxial mantle temperature anomaly was greater in the past when the plume was closer, to the ridge axis. In addition to the Galapagos plume-ridge …
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Major element and isotopic studies on the James Run/Port Deposit association, Maryland: tectonic analogues and Taconic deformation
… Deposit is 525 ± 10 Ma, the Rb-Sr whole rock isochron age is 467 ± 21 Ma, and Rb-Sr model biotite ages are 400 and 300 Ma. Regional and theoretical considerations indicate the 525 zircon age may represent the time of igneous consolidation. Detailed petrographic observations in the Port Deposit …
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A geophysical investigation of geologic structure and regional tectonic setting at the Savannah River site, South Carolina
Time-structure, isochron, and reflection amplitude maps were constructed from 270 km of reprocessed seismic reflection data recorded at the Savannah River Site (SRS), South Carolina. These maps indicate the presence of three major basement blocks bounded by northeast trending faults that penetrate …
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Offshore El Salvador: the first interpretation of a unique 2-D seismic dataset and implications for a working petroleum system in a forearc basin setting
… Pleistocene intervals. Structure contour and isochron maps are generated on mapped sequence boundaries correlated from adjacent regional well-tied seismic surveys offshore Nicaragua and Guatemala. Significant truncation and structural dip reversals have been mapped across the research area …
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The geochemistry and geochronology of the barby formation in the sinclair area, Southern Namibia
… ±3 Ma and an indistinguishable Rb-Sr biotite isochron age of 1238 ±20 Ma, showing that there was no regional metamorphic event. Subduction zone assemblages are generally made of high potassium basalts or calc-alkaline association. The Barby Formation records such assemblages. The Barby …
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ΠΕΤΡΟΛΟΓΙΑ ΚΑΙ ΓΕΩΧΗΜΕΙΑ ΤΟΥ ΠΛΟΥΤΩΝΙΤΗ ΤΗΣ ΕΛΑΤΙΑΣ (ΚΕΝΤΡΙΚΗ ΡΟΔΟΠΗ)
… CHARACTER. USING THE WHOLE-ROCK RB-SR ISOCHRON METHOD AN AGE OF 86,7+27,0 M.A.-MIDDLE CRETACEOUS(?)-AND AN INITIAL 87SR/86SR RATIO OF 0,7060+0.0002 HAVE BEEN DEFINED. FROM ESTIMATES IN THE SYSTEM Q-OR-AB-AN-H2O A CONFINING PRESSURE OF ABOUT 6 KB FOR THE CRYSTALLIZATION ROCKS (SENSU …
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NEW TECHNIQUES FOR TRACE ELEMENT AND RADIOGENIC ISOTOPE MEASUREMENT OF DIAMONDS: THEIR APPLICATION TO DIAMOND PETROGENESIS AND SOURCE TRACING
… The isotope data show no defined isochron systematics that could be used for dating purposes. The parental fluids of fibrous and monocrystalline diamonds are thought to be derived through a similar multi-component mechanism. Diamond formation will result from the interaction …
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Advanced geophysical studies of accretion of oceanic lithosphere in Mid-Ocean Ridges characterized by contrasting tectono-magmatic settings
… (representing both a frozen isotherm and an isochron) dips away from the ridge axis along the Kane transform fault scarp, with a west-dipping angle of ~45° in the shallow (<1 km) crust and <20° in the deeper crust.
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Seismic and Well Log Attribute Analysis of the Jurassic Entrada/Curtis Interval Within the North Hill Creek 3D Seismic Survey, Uinta Basin, Utah, A Case History
… dune complexes. Time structure maps as well as isochron maps have proven useful in delineating the thickest and/or gas prone portions of the Entrada/Curtis interval as well as areas with structural and stratigraphic relief. We have observed that the zones of best production are associated with …
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Advanced geophysical studies of accretion of oceanic lithosphere in Mid-Ocean Ridges characterized by contrasting tectono-magmatic settings
… (representing both a frozen isotherm and an isochron) dips away from the ridge axis along the Kane transform fault scarp, with a west-dipping angle of ~45° in the shallow (<1 km) crust and <20° in the deeper crust.
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The Middle Fork Plutonic Complex: a plutonic association of coeval peralkaline and metaluminous magmas in the north-central Alaska Range
… Hypersolvus syenites and AF granites form an isochron with initial ⁸⁷Sr/⁸⁶Sr of 0.70965. These groupings suggest that at least three different magmas formed the MFPC; scatter of isotopic data reflects mu- tual contamination and assimilation. Trends in whole rock and mineral chemistry also …
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Determination of Heterogeneity by High-Resolution Seismic Reservoir Characterization in the Heavy Oil Temblor Reservoir of Coalinga Field, California
… and Interpretation, and structure and isochron maps brought out two prominent channel-systems, recut and restacked in the central part of the area. These deposits were identified on seismic data and correlated to high-gamma coarsening-upward sands on logs and cores. The deeper one, …
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