关键词: 含碱建造, 幔源, 烃碱流体, 泌阳凹陷, 南襄盆地

Abstract: Biyang Sag in Nanxiang Basin is rich in oil and gas resources,and contains the largest natural alkali deposit in Asia,which is also the third largest in the world. In this paper,the problems in the huge material source required for the formation of alkali deposit and the symbiosis of salt(alkali) ore and oil and gas resources are studied through comprehensive geological and geophysical analysis,and the background and genesis of alkali bearing formation,the possible genetic relationship between natural alkali,oil and gas and metal deposits in the adjacent Tongbai ore concentration area are discussed. The result shows that the Nanxiang Basin is a tectonic faulted basin formed on a special geological background with abnormal uplift of deep asthenosphere mantle and development of deep faults in the basin. A large number of hydrothermal minerals and mantlederived materials are found in the alkali bearing formation of Biyang Sag,and their component characteristics show strong deep thermal fluid activity. The main ore-forming materials of the whole alkali bearing formation,including dolomite,salt ( alkali), oil and gas (or oil shale),are mainly derived from mantle-derived hydrocarbon alkali fluids,and the upward migration of these fluids into the basin through regional deep faults results in mineralization. There should be bedrock oil and gas reservoirs in the deep part of the basin. The oil and gas,salt and alkali in the alkali bearing formation of Biyang Sag and the metal minerals of Tongbai ore concentration area may be formed in the same complete mantle-derived fluid metallogenic system.