Podrobnosti záznamu

    The Neogene remagnetization and petromagnetic study of the Early Cretaceous limestone beds from the Río Argos (Caravaca, Province of Murcia, SE Spain)
Údaj o odpovědnosti
    Philip J. Hoedemaeker, Miroslav Krs, Otakar Man, Josep M. Parés, Petr Pruner, Daniela Venhodová
Další názvy
    New Trends in Geomagnetism (Variant.)
    Hoedemaeker, Philip J.
    Krs, Miroslav, 1928-
    Man, Otakar
    Parés, Josep M.
    Pruner, Petr
    Venhodová, Daniela
Zdrojový dokument - seriál
    Geologica carpathica
    Vol. 49, no. 1
    p. 15-32
    16 obr., 3 tab., 21 bibl.
    Zkr. název ser.: Geol. carpath.
Předmětová skupina
    geologie strukturní
    vlastnosti magnetické
    vrásnění alpinské
Geografické jméno
Klíčové slovo
Abstrakt (anglicky)
   The Early Cretaceous limestone strata around the Rio Argos (Caravaca Region, Province Murcia, SE Spain) were selected for magnetostratigraphic investigations. This section was chosen due to its importance, detailed geological and paleontological documentation and good outcrops of individual strata. Altogether 361 oriented hand samples were collected covering the Berriansian, Valangian, Hautevirian, Barremian and the Early Aptian sequence strata. The laboratory specimens were subjected to both the alternating-field and thermal demagnetization procedures, while the thermal treatment by means of the MAVACS apparatus was carried out at relatively dense temperature steps up to 590°C, in many cases up to 690°C. Twenty pilot samples were tested for the anisotropy of magnetic susceptibility.
   Fifteen samples were selected for detailed analysis with the aim of determining the unblocking temperatures with higher precision and veryfying the possible occurrence of self-revelsal phenomena of remanence during laboratory thermal treatments. All the 361 collected samples were subjected to systematic thermal or comoned demagnetization procedures. Multi-component analysis was applied to separation remanent magnetization components, Fisher's (1953) statistics were used for the calculation of the separated remanence component combined with fold tests. - Few samples were found totally weathered, these are charcterized by low unblocking temperatures (below 100°C), and their magnetic susceptibility is markedly lower. The vast majority of samples showed three components of remanence, A-, B-, and C-components.
   It was clearly proved that the studied un-weathered limestones can be divided into two groups of rocks, the first group with syn-tectonic magnetization, and the second group of limestones totally remagnetized in the Neogene. This way, the Early Cretaceous limestones from the Rio Argos were found unsuitable for derivation of a magnetostratigraphic scale. Apart from totally weathered limestones, magnetite with a well defined unblocking temperature (around 540°C) was found as the carrier of remanent magnetization in the majority of massive and fresh-looking limestone samples. From the study of the anisotropy of magnetic suscpetibility it could be concluded that the fabric of the limestones in both the groups of totally and partially remagnetized samples showed the same features. It is of interest that the limestones under study display no signs of thermal, hydrothermal, chemical, dynamometamorphic or other alterations.
   The principal aim of the paper is to demonstrate typical case histories aimed at methodological problems since similar rocks may be selected for magnetostratigraphic studies in other regions of the Tethyan realm and similar remagnetization phenomena may be encountered as already descibed in the papers by Villalain et al. (1196), Parés
    Česká geologická služba
Kód přispěvatele
    ČGS (UNM)
Zdrojový formát
Datum vložení
    18. 2. 2008
Datum importu
    8. 8. 2012