PALAEOCLIMATIC CONDITIONS AND PHYSICOCHEMICAL PROPERTIES OF WATER BODIES IN THE NORTH JIANGSU BASIN DURING THE FUNING GROUP DEPOSITION(PALAEOGENE)

Some speculations upon the palaeoclimatic conditions in the North Jiangsu Basin during the Funing Group deposition(Palaeogene)have been made in the light of the palaeomagnetic, palaeontological and sedimentological methods,and the detailed analyses have also been made on physicochemical properties of the water bodies in the basin at that time with the aid of the indicators of palaeosalinity, palaeotemperature, palaeodepth, pH and Eh values and the degree of oxidation and reduction.
The North Jiangsu Basin lay in the low-to middle-latitude zones(11-23°N), and the palaeoclimates should be tropical or subtropical during the Funing Group deposition. The water bodies in Members 1 and 3 were para-acidic fresh-brackish watet with shallower water depths, suggesting a oxidation-weak reduetion environment, whereas those in Members 2 and 4 were para-alkaline brackish water with deeper water depths, suggesting a reduction-strong reduction environment. The temperatures of the water bodies ranged in general between 23 and 30℃during the Funing Group deposition. It is clear that the results outlined above are of some interest in the study of the Palaeogene sedimentary environments in eastern China and in the search for oil and gas.