A new detailed map of Bouguer gravity anomalies covers an area of c. 13 500 km² of the Lugian Unit in the Bohemian Massif (Czech Republic, Germany and Poland). It is limited approximately by the towns of Bautzen (NW), Zlotoryja (NE), Cerveny Kostelec (SE) and Roudnice nad Labem (SW). An extensive gravity low about 120 km long (W-E) and 40 km wide (N-S) is the most remarkable feature in the Bouguer gravity map and the maps derived from it. This central Lugian gravity low (CLGL), is adjacent to the Saxothuringian low in the West but it disappears in the gravity high of the Kaczawa Complex and the Intra Sudetic Basin in the East. Five partial gravity lows, i.e., (A) - Ceska Kamenice Low, (B) - Zittau Low, (C) - Jizerske hory Mts. Low, (D) - North Krkonose/Karkonosze Mts. Low and (E) - Straz pod Ralskem Low are identified within the CLGL. The lows (C), (D) and (E) were interpreted quantitatively using a gravity modelling, whereas the lows (A) and (B) were evaluated without modelling. The presented gravity cross-sections show that the Cambrian Rumburk granite is the main source of the lows (A), (B) and (E). On the other hand, the Variscan Krkonose-Jizera granites together with the Cambrian Jizera orthogneisses are the main sources of the lows (C) and (D). Besides that, the sediments of the Czech Cretaceous Basin play an important additional role in the formation of lows (A) and (E) and the Zittau Basin Tertiary sediments are markedly involved in the low (B) amplitude. The gravity cross-sections imply that the granite bodies influencing gravity lows can reach a depth of 7 to 10 km. A hidden mafic body situated in the basement of the South Krkonose Piedmont Late Palaeozoic Basin, producing the gravity high near the town of Vrchlabi, was interpreted to reach a depth of 5 to 6 km beneath the current surface

A new cross-border gravity map on the scale of 1:200,000 covering 14,900 km 2 of the SE Saxony and NW Bohemia was compiled. It is limited by the sites of Grimma (NW), Karlovy Vary (SW), Neratovice (SE) and Bautzen (NE). Three positive gravity regions -(a) Lusatian Anticline, (b) SE part of the North Saxon Syncline and (c) Teplá-Barrandian Unit were delimited. Separation of the Bouguer anomalies into the regional and residual components together with the Linsser filtering provided three types of derived gravity maps (regional, residual and density boundaries) for geological interpretation. Eighteen negative residual anomalies mostly pertaining to partially buried granite or acid volcanic bodies and ten positive residual anomalies mostly caused by metamorphic complexes were identified. The map of the Linsser indications showing the density boundaries at three depth levels (1, 3 and 6 km) introduces not only numerous disjunctions but also indicates an internal structure of the individual regions. A new cross-border magnetic map covering the same area is also presented. A "central" circular gravity low (−61 mGal) delineates the Altenberg-Teplice Caldera extending to 10 km depth. Variscan igneous bodies produce only negative gravity anomalies regardless their size. Pre-Variscan igneous bodies cause either weak negative or positive anomalies. A chain of gravity and magnetic anomalies follows the Litoměřice Deep Fault and a large pronounced magnetic anomaly between Doupov volcanic complex (SW) and the Elbe Zone (NE) delineates the Saxothuringian/Teplá-Barrandian Suture Zone.

A detailed airborne magnetic and gamma-ray spectrometric as well as ground gravity survey in the south-western part of the Moldanubian Zone (Bohemian Massif) provided detailed geophysical characteristics of the principal geological units and large-scale tectonic features. The Knížecí Stolec durbachitic pluton with high contents of natural radioactive elements (Th, U and K) represents a body with no magnetically anomalous response but a pronounced positive gravity anomaly. The Křišťanov granulite massif, which is a host rock of the Knížecí Stolec pluton, exhibits low concentrations of Th and U, high abundances of K, slight magnetic and a negative gravity anomalies. The Plechý composite pluton is characterized by strikingly low gravity and an extremely monotonous magnetic field. One of its petrographic varieties (the Třístoličník granite) is enriched in natural radioactive elements, especially in Th and U. Metamorphic complexes of the Monotonous and Varied groups contain multiple magnetic anomalies mostly related to the intercalated metabasic rocks; they also cause positive gravity anomalies. The Linsser density boundaries at a depth of 0.5 km clearly delimit the Plechý composite pluton and the Lhenice zone and indicate several structurally and/or lithologically different domains within the Křišťanov granulite massif and in the Knížecí Stolec pluton. The 2.5D gravity model indicates an asymmetric shape of the Knížecí Stolec pluton, which is deepest in its SE part (at least 4 km). The joint interpretation of the geophysical and structural data revealed that the maximum depth of the pluton is c. 4.5 km, with gently to moderately dipping intrusive contacts in the north and subvertical orientation in the south. The asymmetric shape of the pluton is consistent with its inferred syn-tectonic emplacement coeval with the regional subvertical contraction and development of regional flat-lying fabric. The gravity model combined with structural analyses also implies a considerable depth of the south Bohemian granulite massifs. This indicates their steep exhumation path and is at variance with the model of the Moldanubian Zone as a sequence of flat-lying nappes. The south-western part of the studied area is reworked by the NE-directed compression, referred to as the ‛Bavarian' deformation phase.

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