High dispersive minerals of the metalliferous sediments from the axial zone of ultra-fast spreading center in the South part of the East Pacific Rise (20°30´-22°00´S) were studied by XRD methods. It is established that the high dispersive part of the studied sediments is almost totally composed of X-ray amorphous Fe and Mn oxihydroxides. Among the crystalline phases of greater importance is the Fe-montmorillonite with different degree of crystallinity. Going away from the rise axis illite of terrigenous origin appears. It is established that during the pulsed hydrothermal processes the degree of Fe-montmorillonite crystallinity changes. The Fe-montmorillonite formed during the low temperature phases of the hydrothermal stages is better crystallized than that one formed during the high temperature phases. The processes of crystallization are most probably controlled by the physicochemical parameters of the venting from the oceanic crust hydrothermal fluids.

In northeastern Bulgaria Upper Paleozoic coals are only found in the Dobroudja Basin. This coal basin belongs to a Variscan foredeep which is at present covered by a thick ( 1300-1500 m) Mesozoic-Cenozoic complex (Moesian platform). The coal seams are associated with alternating sandstones, siltstones and shales deposited under fluvio-deltaic environmental conditions. Previous coalification studies on the basin have recorded high volatile to low volatile bituminous ranks. The construction of coalification profiles (increase ofvitrinite reflectance with depth) in ten wells from the Dobroudja coal basin has enabled us to interpret the paleotemperature regime. The simulation of the burial and thermal history of the Upper Carboniferous formations in the Dobroudja coal basin yielded paleogeothermal gradients between 45 and 71 °C/km. The results show an increase of the paleogeothermal regime from the northwest towards the southeast. The existence of a high paleoheatflow is in accordance with data from other Carboniferous basins in Europe. Due to high vertical paleogeothermal gradients and deep burial, the maturation of the formations was completed during the Late Carboniferous. The relatively large maturation range of the Upper Carboniferous sediments enables comparison among different thermal indicators (vitrinite reflectance, spectral fluorescence maximum, pyrolysis indices, illite crystallinity and bulk clay mineralogy) and their behavior in the course of diagenesis.