GEOPHYSICAL CHARACTERISTICS OF THE TORNQUIST FAN AREA, NORTHWEST TRANS-EUROPEAN SUTURE ZONE - INDICATION OF LATE CARBONIFEROUS TO EARLY PERMIAN DEXTRAL TRANSTENSION

The Tornquist Fan is a northwestward widening splay of late Carbonifer ous-early Permian fault zones in the region of Denmark emanating from the Teisseyre-Tornquist Zone in northern Poland. The crust-mantle boun dary shows an undulating topography which correlates with the main tec tonic features of the area. Zones of high average velocity through the consolidated crust coincide with pronounced positive Bouguer gravity anomalies in the deep basins and in the border zone of the shield. Les s pronounced, similar correlation to gravity is found for the thicknes s of the lower crust, whereas the thickness of the upper crust in part s is inversely related to the gravity anomalies. Some magnetic anomali es appear to be related to the gravity anomalies. The positive feature s are interpreted as magmatic bodies that formed during late Carbonife rous to early Permian transtensional movement along the faults of the Tornquist Fan, which explains pull-apart structures in the area and th e Ringk circle divide bing-Fyn basement High. The magmatism has strong implications for the subsequent formation of the regional Mesozoic ba sins. Localized dextral strike-slip movement on the Teisseyre-Tornquis t Zone became distributed over the Tornquist Fan, which formed part of the rigid Baltic Shield and was situated at the northwestern end of t his major, long-reaching Central European zone. As defined by late Cre taceous-early Tertiary compressional inversion structures, the Sorgenf rei-Tornquist Zone cuts across the Tornquist Fan area.