中国东北44 Ma/42 Ma火山事件的出现及其地质找矿意义

中国东北地区古近纪玄武岩浆喷发火山事件从48 Ma~32 Ma，每1 Ma内至少有一处或数处，以K-Ar测年数据记录了其活动的存在.唯44 Ma/42 Ma间，火山事件间隔时间超过1 Ma，即全区该时段近60个测年数据，未发现有43 Ma±的测年记录.此时，正是太平洋板块由NNW向运动转向NW-NWW向运动，也是太平洋天皇海岭-夏威夷海山火山链活动从NNW向转向NW-NWW向活动的转折时间.东北大陆边缘从拉分-张裂的区域应力场转换为NW向的拉伸（或伸展）应力场.陆缘裂谷或叠加于早期的拉分-张裂盆地之上，或出现新的裂谷盆地，形成了晚始新世石油、油页岩、煤等含矿岩系，并成为古近纪沉积盆地该类资源的主含矿层.

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.