Rozkład głębokościowy temperatury Curie i jego wpływ na pole magnetyczne w Polsce

Abstract

Omówiono metodę określania głębokości występowania temperatury Curie, wykorzystaną do sporządzenia pierwszej mapy tej wielkości dla obszaru Polski. Przeanalizowano jej-rozkład przestrzenny. Ustalono wynikające z tej analizy ograniczenia wieloznaczności interpretacji obrazu magnetycznego Polski. W szczególności rozpatrzono przyczyny braku intensywnych lokalnych anomalii magnetycznych na obszarze Polski zachodniej. Wykorzystano również do tego celu ocenę maksymalnych efektów magnetycznych ciał zaburzających, które mogą tu występować między spągiem nieskonsolidowanych utworów osadowych a izotermą Curie.DEPTH DISTRIBUTION OF CURIE .POINT AND ITS INFLUENCE ON MAGNETIC FIELD OF POLANDThe lack of intense local magnetic anomalies in the western Poland (Wielkopolska Depression) was differently explained by geophysicists which have been studying this problem for 70 years. In order to avoid ambiguous solutions of this problem a map of depth distribution of Curie point in Poland has been prepared for the first time. The map is· accompanied by a description of the mode and premises of its preparation. There are also established maximum values of component Z anomalies of magnetic field; the anomalies can be ewoked by disturbing bodies situated between the base of unconsolidated sedimentary deposits and Curie isotherm in the western Poland.The limitations of ambiguity of interpretation of magnetic picture of Poland, which result from the data gathered, were analysed. Special attention was given to the reasons for the lack of intense local anomalies in the western Poland. It was found that the Curie point is situated between the base of unconsolidated sedimentary rocks and Moho discontinuity throughout the country. It anomalously rises in the zone of. maximum thickness of these rocks and commonly passes within granite layer. The source of magnetic anomalies recorded in Poland is always located .above Moho discontinuity. The lack of intense anomalies in large area of western Poland is connected with the lack of more susceptible rocks below the base of unconsolidated sedimentary rocks. Metasomatic granites may occur beneath these rocks in north-eastern part of that region. Local low-amplitude anomalies recorded in that region presumably result from differentiation in magnetic properties . of Quaternary deposits.