胜利油田火山岩类、盆地演化及其CO_2-Au成藏成矿效应

VOLCANIC ROCKS, BASIN EVOLUTION AND RELATED CO_2-Au MINERALIZATION IN SHENGLI OILFIELD, CHINA

将胜利油田盆地内火山岩类分为石英拉斑玄武岩、橄榄拉斑玄武岩和碱性橄榄玄武岩 3类。其中 ,碱性橄榄玄武岩多分布于盆地边部、出现较晚并受深断裂控制 ,其成分中明显更富碱、富轻稀土、富大离子亲石元素而贫铬、镍等相容元素和挥发分 ,深度大而熔融程度不高 ,应源于富集地幔。二氧化碳气藏与碱性橄榄玄武岩有空间、时间和成因上的关系 ;二氧化碳气藏区的火山岩中含有高含量的金。二氧化碳和金是盆地和火山岩类演化一定阶段的产物 ,源于富集地幔的岩浆去气是其形成的主要机制。

According to geological and geochemical characteristics, the volcanic rocks from the Shengli Oilfield can be divided into three major types. The quartz tholeiite basalt erupted in the initial stage of the basin openning, which underwent an obvious contamination by materials derived from continental crust. The olivine tholeiite occurred in the inner part of the basin, accompanied with the main extension of the basin. The alkali olivine basalt occurred, along the boundary faults, in the later stage of the basin evolution, namely, the down depressing stage, which was controlled by deep fractures. From the guartz tholeiite through the olivine tholeiite to the alkali olivine basalt, the magma chamber must have migrated from the shallower to the deeper. The alkali olivine basalt is highly enriched in CO 2, Au,alkali, LREE , LILE and relatively depleted in Cr and Ni, which may be derived from the enriched and replaced mantle, so as to have closely space temporal genetic relations with the CO 2 gas fields and Au mineralization.