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Late Carboniferous^Early Tertiary apparent polar wander (APW) paths (300^40 Ma) for North America and Europe have been tested in various reconstructions. These paths demonstrate that the 500 fathom Bullard et al. fit is excellent from Late Carboniferous to Late Triassic times, but the continental configuration in northern Pangea changed systematically between the Late Triassic (ca. 214 Ma) and the Mid-Jurassic (ca. 170 Ma) due to pre-drift extension. Best fit North Atlantic reconstructions minimize differences in the Late Carboniferous^Early Jurassic and Late CretaceousT ertiary segments of the APW paths, but an enigmatic difference exists in the paths for most of the Jurassic, whereas for the Early Cretaceous the data from Europe are nearly non-existent. Greenland's position is problematic in a Bullard et al. fit, because of a Late Triassic^Early Jurassic regime of compression ( s 300 km) that would be inherently required for the Norwegian Shelf and the Barents Sea, but which is geologically not defensible. We suggest a radically new fit for Greenland in between Europe and North America in the Early Mesozoic. This fit keeps Greenland`locked' to Europe for the Late Paleozoic^Early Mesozoic and maintains a reconstruction that better complies with the offshore geological history of the Norwegian Shelf and the Barents Sea. Pre-drift (A24) extension amounted to approximately 450 km on the Mid-Norwegian Shelf but with peak extension in the Late Cretaceous.

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Decylammonium chloride dissolved in water at concentrations of 0.5 and 2.0 M has been studied by multifield carbon-13 and deuterium nuclear magnetic relaxation. Carbon-13 longitudinal relaxation times , and nuclear Overhauser effects have been obtained for all carbons in the aliphatic chain, at frequencies ranging from 15 to 90 MHz. Decylammonium chloride has been selectively deuterated at the a position with respect to the polar head. 2H longitudinal relaxation times T[ and, in some instances, transverse relaxation times T2 have been measured from 2 to 55 MHz. At 0.5 M decylammonium chloride forms spherical micelles. The relevant data are consistently analyzed according to the "two-step model" (Halle, B.; Wennerstrom, H. J. Chem. Phys. 1981, 75, 1928, which implies correlation times associated with the local fast motions, ß (/ = 1, 10), a correlation time associated with the slow overall motion of surfactant molecules, rs, and local order parameters S¡. The 2.0 M solution data required a more elaborate analysis (three-step model), which involves two correlation times (corresponding to rotation about the different axes of an ellipsoid) for describing the slow motions. This is because, at this concentration, micelles have nonspherical shape. In both cases, slow correlation times could be interpreted in terms of micelle tumbling and lateral diffusion of surfactant molecules around the curved surface of the aggregate. Quantitative parameters could be deduced. The radius of spherical micelles is identical with the surfactant extended chain length. At 2 M concentration, micelles are rod-shaped. When approximated by an ellipsoid, it is shown that the minor axis is identical with the radius of spherical micelles whereas the major axis is 9 times as large as the latter. The lateral diffusion coefficient is found to be the same in the two types of micelles D = (1.5 ± 0.2) X 10"10 m2 s"1. The fast correlation times confirm the liquidlike character of the micelle interior and the order parameters exhibit the usual profile starting from 0.2 at the a position to very small values at the terminal methyl.

Surfactant and polymer NMR self-diffusion measurements were carried out at different temperatures on gelling and nongelling aqueous systems of ethyl(hydroxyethy1) cellulose (EHEC) in the presence of sodium dodecyl sulfate (SDS) or cetyltrimethylammonium bromide (CTAB). The surfactant self-diffusion experiments revealed strong surfactant-EHEC interactions. By using a two-site model it was demonstrated that the degree of surfactant binding to EHEC, at a given total surfactant concentration, is higher in the presence of CTAB than with SDS. In both cases, the amount of surfactant bound to the polymer is roughly independent of temperature, even when the gel transition region is approached. The results for a more polar EHEC sample show that in the presence of SDS (a nongelling system in the temperature range considered) a significant increase of the binding parameter is observed at elevated temperatures, whereas no change of the parameter is found in solutions containing CTAB. In the analysis of the interaction situation, the interplay between surfactantinduced associations and enhanced polymer-polymer interactions is considered. The polymer self-diffusion results suggest that the decay of the spin-echo attenuation can initially be described by a stretched exponential ("fast" diffusion) followed by a single exponential ("slow" diffusion). The observations indicate that the interactions are stronger in the EHEUSDS system as compared with the corresponding EHEC/CTAB system.

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