Organic matter in Cambrian, Ordovician and Silurian shales of the Baltic-Podlasie-Lublin Basin in Poland

The upper Cambrian-Silurian Piaœnica, Sasino, Udal and Pelplin formations and the Jantar Member include the most organic-rich lower Paleozoic sedimentary rocks in the Baltic-Podlasie-Lublin Basin in Poland. These rocks vary significantly in terms of vertical and lateral organic matter distribution. Generally, the siltstones, mudstones, claystones and shales are characterized by TOC values from 0.1 to as much as 17.4 wt. %. Typically, the maximum TOCvaluesreachabout9wt.%.Rock-Eval,organicmatterpetrologyandbiomarkersdataclearly indicate dominance of type II kerogen. Thermal maturity of organic matter of these rocks is variable and depends mainly on the burial history and depth. In the western slope of the East-European Craton the petroleum prospective formations are located throughout the whole spectrum of thermal maturity zones, from the immature zone (eastern margin of the formations occurrence), through the oil, condensate and gas windows, to the overmature zone dominated by exhausted source rocks in the western margins of the study area