Henryk Sechman

Unique Quaternary environment for discoveries of woolly rhinoceroses in Starunia, fore-Carpathian region, Ukraine: Geochemical and geoelectric studies

In 1907, remnants of a mammoth and a woolly rhinoceros were discovered in the Pleistocene clays of an earth-wax mine in Starunia village. Then, in 1929, a nearly fully preserved woolly rhinoceros was found in the same mine. The unique combination of clays, oil, and brine into which the animals had sunk is responsible for their almost perfect preservation. During the late Pleistocene winters, when the ice and snow cover was present in the tundra “paleoswamp,” areas of infl ow of brines, oils, and hydrocarbon gases had a higher temperature, which resulted in melting and cracking of the cover, and large mammals could be trapped. Geoelectric measurements, as well as molecular and stable isotope analyses of gases in the near-surface zone within the “paleoswamp” performed in 2004–2005, reveal a few places favorable to the burial and preservation of Pleistocene vertebrates.

Near-Surface Geochemical Anomalies Integrated with Seismic and Well Data over the Contact of the Outer Carpathians and the Carpathian Foredeep (SE Poland)

The objective of this study is to interpret the regularities in distribution of surface geochemical anomalies observed in a fragment of the contact zone between the Carpathian Fold-and-Thrust Belt and the Carpathian Foredeep (SE Poland). The surface geochemical survey included a total of 670 soil gas samples analyzed by gas chromatography, integrated with seismic cross sections, and supplemented by production data from wells. Maximum concentrations of methane, total alkanes C2-C5, total alkenes C2-C4, H2, and CO2 measured in soil gas samples were 27.1 vol.%, 45.3 ppm, 0.49 ppm, 0.232 vol.%, and 6.29 vol.%, respectively. Traces of alkanes detected in samples are the result of microseepage from a few accumulations of various compositions. Methane and ethane migrate primarily from relative shallow Miocene strata, and higher alkanes from deeper Miocene strata and from Paleozoic-Mesozoic basement. We found relatively high positive correlation between the distribution of surface geochemical anomalies and the relative intensity of hydrocarbon shows recorded in the wells. The location and range of 13 anomalous zones are controlled by the patterns of both the Debno and the Wojnicz slice-folds. Most of the anomalies occur over the Wojnicz Trough, suggesting the presence of conventional accumulations and/or the sites where the Miocene mudstone and heterolithic formations are saturated with gas.

EMISSION MEASUREMENTS OF GEOGENIC GREENHOUSE GASES IN THE AREA OF "PUSTY LAS" ABANDONED OILFIELD (POLISH OUTER CARPATHIANS)

The Carpathians may play a significant role as a supplier of greenhouse gases to the atmosphere. Unfortunately, most of the discovered oil and gas deposits are recently only historical objects. An example is the Sękowa-Ropica Górna-Siary oil deposit located in the marginal part of the Magura Nappe where oil had been extracted in dug wells until the mid XX century. One of such extraction sites is the “Pusty Las” oilfield. In that area, 10 methane and carbon dioxide emission measurement sites were located, among which 4 in dried dug wells and 6 in dig wells still filled with oil and/or water. Dynamics of methane and carbon dioxide concentration changes were measured with the modified static chambers method. Gas samples were collected immediately after the installation of the chamber and again, after 5 and 10 minutes. In the case of reclaimed or dry dug wells, static chamber was installed directly at the ground surface. In wells still filled with oil and/or water the chamber was equipped with an “apron” mounted on special sticks. The dynamics of concentrations changes varied from -0.871 to 119.924 ppm∙min-1 for methane and from -0.005 to 0.053% obj∙min-1 for carbon dioxide. Average methane emission was 1.9 g∙m-2∙d-1 and that of carbon dioxide was 26.95 g∙m-2∙d-1. The measurements revealed that an abandoned oil field supplies significant amounts of greenhouse gases to the atmosphere although the emission of methane is lower than that measured e.g. in mud volcanoes located in various parts of the world.