Nikolaos Tougiannidis

Orbital Control on Carbonate-Lignite Cycles in the Ptolemais Basin, Northern Greece - An Integrated Stratigraphic Approach

Establishing the time frame is crucial for most geoscientific investigation. Without proper time control, past geologic processes cannot be inferred appropriately, nor can their dynamics be understood adequately. Rhythmic changes in sedimentary cycles hold the key to establishing precise and high-resolution chronologies. The concept goes back to theoretical considerations first published by Milankovitch (1941). His calculations showed that changes in earth’s orbital geometry lead to changes in the seasonal and latitudinal distribution of incoming solar radiation (insolation). Three main periods are responsible for these insolation changes, eccentricity (the shape of the orbit around the sun; with periods of 413 kyr, 123 kyr, and 95 kyr), obliquity (the tilt of the axis; changing at a period of 41 kyr), and precession (the wobbling spin of the axis with periods of 19 kyr and 23 kyr). He argued that these changes caused the waning and waxing of polar ice sheets. More than three decades later, Hays et al. (1976) and Imbrie et al. (1984) provided proof the cyclic changes of the earth energy budget were large enough to be preserved in marine sediment. Theoretical calculation of Berger (1976) and Berger and Loutre (1991) supported the Milankovitch theory and provided templates for orbital variability for the last couple of million yeas. Henceforth, cyclic changes in sediment strata were used to develop detailed orbital chronologies by assigning sedimentary cycles to orbital cycles.

Combined Electromagnetic and Magnetic Survey To Study The Basement Structure Of The Neogene Philippi Basin (Northern Greece)

During 2009 and 2010 geophysical soundings have been conducted to study the basement structure of the Neogene Philippi Basin in Northern Greece. Primary task was to give an estimate of the top of basement distribution along a 12 km transect through the basin and then to choose the most promising drilling location for a climate change study. Different electromagnetic methods, each sensitive for different exploration depth, were applied to obtain a dataset suitable for a later joint inversion. Those methods are supporting each other to overcome resolution problems laterally and horizontally. During the first campaign we stated that the Time Domain Electromagnetic Soundings (TEM) did not succeed in reaching the basement in the centre of the basin, consequently we used, in a second stage, a combined set of radiomagnetotelluric (RMT) and audiomagnetotelluric soundings (AMT) to estimate a first 2D conductivity model. Since the scalar RMT data are measured solely in TM‐mode configuration, we confine ourselves to...

Mineralogical characterization of the intraseam layers of Lofoi lignite deposits in Florina basin (western Makedonia, northwest Greece)

ABSTRACT The mineralogical composition of intraseam layers from Lofoi lignite deposits (northwest Greece) is the subject of the present study. The samples were examined by means of X-ray diffraction (XRD), thermo-gravimetric (TG/DTG) and differential thermal analysis (DTA), and Fourier transform infrared (FT-IR) spectrometry. The clay minerals prevail in most samples, with illite-muscovite being the dominant phase, and kaolinite and chlorite being the other major clay components. No smectite was found. Quartz and feldspars, dominate in two cases. The studied materials are characterized as clays to clayey sands, showing significant similarities with the intraseam layers of the adjacent Achlada lignite deposits.