THE 44 Ma/42 Ma INTERVAL OF VOLCANIC EVENTS IN NORTHEAST CHINA AND ITS SIGNIFICANCE IN GEOLOGY AND ORE-SEARCHING

According to K-Ar age data, at lease once volcanic event of basaltic magma eruption is recorded in every Ma from 48 Ma to 32 Ma during Paleogene Period in Northeast China, except one interval between 44 Ma and 42 Ma. The age record of 43 Ma±is not found in 60 age data in the whole region. That time was just when the Pacific plate moved from NNW direction turning to NW-NWW direction, as well as the activity of the volcanic chain of the Emperor Ocean Ridge-Hawaiian Seamount turning from NNW to NW-NWW. The stress field in Northeast China continental margin changed from regional pull apart-tension to NW-trending stretch stress field. The marginal rift superimposed on the pull apart-tensioned basin, or formed new rift basin. The ore-bearing rock series of petroleum, oil shale and coal were formed in Late Eocene and performed as the main ore-bearing strata in Paleogene sedimentary basin.