999 resultados para Manhattan Project (U.S.)
Resumo:
The Curie temperature and thermomagnetic behavior of wholerock samples were measured in basalts recovered from Sites 442, 443, and 444 of DSDP Leg 58 in the Shikoku Basin, and from Site 446 in the Daito Basin, north Philippine Sea. Chemical composition and microscopic features of opaque oxides in the same samples were also investigated. Degree and mode of oxidation of titanomagnetite vary irrespective of site, lithology, or magnetic polarity, and no systematic correlation has been found between any two of these characteristics. Magnetic properties are systematically different between massive flows recovered at Hole 444A (Shikoku Basin) and Hole 446A (Daito Basin), although the controlling factor is unknown.
Resumo:
Kimmeridgian-Tithonian red marly limestones and Berriasian white limestones were recovered at Site 534 of DSDP Leg 76 in the western North Atlantic. These yielded a well-defined magnetostratigraphy with the characteristic magnetization carried by hematite in red sediments and magnetite in white sediments. The polarity sequence is correlated to the magnetostratigraphy of Kimmeridgian-Tithonian-Berriasian pelagic carbonates of northern Italy and southern Spain, allowing precise biostratigraphic age correlations. The Berriasian/Tithonian boundary occurs within the upper half of Core 90, the late Tithonian/early Tithonian boundary at the base of Core 96, and the Tithonian/Kimmeridgian boundary at the top of Core 102. Correlations are also made to M-16 through M-22 of the marine magnetic anomaly M-sequence. Poor recovery and irregular magnetic properties of the underlying Kimmeridgian-Oxfordian-Callovian marls and claystones prevented determination of a polarity sequence, but the entire interval has mixed polarity. Valanginian gray marly limestones have very weak magnetizations, and preliminary results are inadequate to determine the polarity pattern.
