Depth-to-basement study for the western Polish Outer Carpathians from three-dimensional joint inversion of gravity and magnetic data

[摘要] Results of a depth-to-basement study are presented for the westernmost Polish Outer Carpathians. The gravity data areinverted for the top of the Precambrian basement using horizons from 2–D gravity and magnetic forward models andwell tops as input depth measurements. 2–D models, used in the study, are built upon depth converted seismic profiles.The results are visualized as an isobath map for the top of the Precambrian basement, complemented with the qualitativestructural interpretation of gravity and magnetic anomaly maps. The outcome of 3–D joint inversion of the gravity dataand depth measurements shows the Precambrian crystalline basement deepening southward from c. 1 to almost 7 kmb. s. l. Consequently, an approximately 2 km thick wedge of autochthonous sediments, thickening southward, is embraced between the crystalline basement and a sole detachment of the Carpathian fold-and-thrust belt, imaged by seismicdata. Since the modelled top of the crystalline basement is roughly parallel to the Moho, suggesting no extension-relatedthinning in Mesozoic, the autochthonous sediments are likely of pre-Permian age. A positive magnetic anomaly in thesouth of the study area is presumably associated with the presence of an elongated body of intermediate to mafic rocks inthe basement of the Brunovistulian Terrane. These rocks may represent a relic of a Cadomian magmatic arc comparableto that existing in the Brno Massif of southern Moravia.

[学科分类] 自动化工程

[关键词] Joint inversion;gravity and magnetic data;Outer Western Carpathians;Precambrian basement;Brunovistulian terrane