Pages: 29 - 39
Abstract: Heavy mineral assemblages from profiles of Upper Cretaceous Gosau sediments of the Apuseni Mts (Romania) help to reveal source areas and to get clues about geodynamic processes leading to erosion of distinct rocks in the surrounding geological units. The samples from the Lower Gosau Subgroup reflect no distinct heavy mineral predominance: metamorphic and magmatic sources are largely balanced. The Upper Gosau Subgroup is characterized by an increase in minerals derived from metamorphic rocks. Increasing amounts of apatite reflect the onset of the banatite magmatism during Campanian time. Cr-spinel was found in most of the profiles and in different stratigraphic horizons, reflecting erosion of obducted oceanic crust situated south and southeast of the Gosau basin (in present-day coordinates). Paleocurrents indicate that sedimentary supply was provided from both sides of the elongated forearc basin. On the basis of paleocurrent indicators and heavy mineral spectra we propose a scenario with erosion of a forearc ridge on the one side of the basin and a crystalline basement on the other. The increase in metamorphic heavy minerals indicates enhanced erosion in the uplifting crystalline hinterland (mainly composed of the Bihor Autochthonous Unit) during sedimentation of the Upper Gosau Subgroup.
Keywords: Eastern Alps, Apuseni Mts, Gosau succession, paleocurrent directions, heavy mineralsDownload PDF document Show Text Version