Ϊ��ȷ���ư���Ŀǰ����ԭ�͵ij�����Դ��ϵͳ����ȡ���齭����ز�ͬ����ԭ���и��������־��ķֲ���������������ַ�خ��¡�𱱲����켰��خ4 �ݵ�ԭ�;�����ֲ�ȵ� ( ��2. 0)��ָʾ½Դ�л�������İ����麬���еȣ�����ȱ��������֬���׵�˫�����飬�������Ź�����޽�����ϵͣ���ָʾ�����幱�׵� C ₃₀ 4 �� �׻������쳣�ḻ���ص㡣C ₃₀ 4 �� �׻������� C ₂₉ ��������ı�ֵ��2. 1��������������ϵ�� C _{19 ��26} ������ C ₂₁ Ϊ�������̬�ֲ���ָʾ��ԭʼ����ĸ��������Ϊ������������ԭ�����IJ��������Դ�Ҿ��нϺõĿɱ���; ����خ��¡���ϲ����켰���ư��ݵ������;�����ֲ�ȸ� ( ��4. 0)�����Ը����������˫�����飬�������Ź�����޽�麬���ϸߣ�ȱ�� C ₃₀ 4 �� �׻�������ص㣬������������ C_19��26 ���ֽ���״���ν��͵��ص㣬����½Դ�л���������Ҫԭʼ����ĸ�ʣ�����ϰ��ư��ݷ�����ƽ��úϵ��Դ�ҵ�ʯ�͵��ʱ�����

To figure out the origin and sources of crude oils from Baiyun sag of the Pearl ��iver Mouth Basin�� the authors analyzed the distributions and compositions of various biomarkers in two kinds of crude oils from differ- ent tectonic units in the Pearl ��iver Mouth Basin systematically�� It is found that the Pr/Ph ratios of the crude oils from the north structures of the Panyu low uplift and panyu 4 sub-sag are relatively low ( ��2. 0)��which indicates that the terrigenous organic matter input is moderate��and the bicadinanes derived from dammar resin are almost ab- sent��the contents of rearranged steranes and hopanes are low�� However��C ₃₀ 4-methyl steranes related to dinoflagel- lates are abnormally abundant��and the ratio of C ₃₀ 4-methyl steranes and C ₂₉ regular sterane is more than 2.1��and the C _{19 ��26} tricyclic terpanes show a normal distribution while the dominant peak is C ₂₁ ��suggesting that algae has made an important contribution to original hydrocarbon parent material��which is consistent with that of lacustrine source rocks of the Wenchang Formation�� The Pr/Ph ratios of the condensates from the south structures of the Pan- yu low uplift and Baiyun sag are more than 4. 0��with abundant oleanane and bicadinanes��the contents of rear- ranged steranes and hopanes are relatively high��lacking C 30 4-methyl steranes�� While tricyclic terpane C _{19 ��26} presents the characteristics of the trapezium in turn reduce��indicating that terrigenous organic matter is their original parent material��which accords with the petroleum geology background of the development of coal-containing source rocks of the Enping Formation in the Baiyun sag��