EARLY PROTEROZOIC PALEOMAGNETIC DATA FROM THE PECHENGA ZONE (NORTH-WEST RUSSIA) AND THEIR BEARING ON EARLY PROTEROZOIC PALEOGEOGRAPHY

An Early Proterozoic palaeomagnetic signature (c. 2125 Ma), verified b y a positive conglomerate test, is recorded in the Kuetsyarvi Formatio n, Pechenga Group (north-west Russia), but the majority of the palaeom agnetic directions observed in the Pechenga Group lithologies reflect a low-grade remagnetization event probably linked with the Late Precam brian Baikalian Orogeny which affected north-west Russia and northern Norway. Secondary pyrrhotite is the dominant remanence carrier in the uppermost formations of the Pechenga Group. Palaeomagnetic poles from the Kuetsyarvi Formation differ somewhat or partially overlap with coe val palaeomagnetic poles from other tectonomagmatic provinces in north ern Fennoscandia, but it is premature at this stage to speculate on in traplate movements during the Early Proterozoic. Besides, the Kuetsyar vi Formation probably developed during an early phase of intracontinen tal rifting along the northern margin of Fennoscandia, similar to the present-day East African rift. Hence younger intercontinental rifting, possible seafloor-spreading and subsequent convergence would remain u ndetected by our palaeomagnetic data. Palaeolatitude estimates from th e Kuetsyarvi Formation suggest that the Pechenga region was located in latitudes of around 20 degrees to 30 degrees during the 2100-2200 Ma interval. These low-latitude estimates are supported by the sedimentar y record in the Pechenga region which is characterized by red beds and evaporites. Comparison of Fennoscandian palaeomagnetic poles with coe val poles from the Slave and Superior cratons (Laurentia) questions pr eviously publicized supercontinental configurations. A close relations hip between Fennoscandia and Early Proterozoic Laurentian Provinces is conceivable from palaeomagnetic data, but, given the lack of longitud inal control as well as the choice of hemisphere, such postulates are tentative at best on purely palaeomagnetic grounds.