Complex sentence: Tar sand contains asphaltic oil rich in asphaltenes and resinsm it has a high content of aromatics and napthenes compared to paraffin and a high content of nitrogen, sulphur and oxygen.
Split into simpler sentences: Tar sand contains asphaltic oil rich in asphaltenes and resins. It has a high content of aromatics and napthenes compared to paraffin and a high content of nitrogen, sulfur and oxygen.