【摘要】 <正> 三水盆地位于珠江三角洲,是一个小型白垩纪至早第三纪拉张型断陷盆地。在生油岩沉积时期和油气生成、运移时期皆有强烈的火山活动。一、火山活动特点在三水盆地地表和钻井中普遍发现岩浆岩和火山碎屑岩。白垩纪—早第三纪的火山活动可归纳为3个旋回、13个喷发期。喷发次数超过100次,火山岩累计厚度逾2000米(表1)。更多还原

【Abstract】 The Eogene volcanism were quite often in Sanshui Basin.Various lavas and volcanic clastics,totalling about 2,000m thick,were formed in more than one hundred times of volcanic eruption.They distribute mainly in the central partof the basin which measures 45 km long NS and 8-12 km wide EW,and formedin the process of deposition of the Buxin Formation(E₁₂b),the source rock,and also in the generation and migration process of oil and gas in it.As a result,they have exerted great influence both on the accumulation and preserva-tion of oil and gas.The high ancient geotherm derived from the volcanism had accelerated theevolution of source rocks,so the depth of oil generating threshold is 800-1,200mshallower than that in basins elsewhere in the eastern part of China.The abundance of organic matters,such as organic carbon,chloroform asphalt and hydrocarbon,decreased remarkably due to volcanism within this area,resulting inpoor oil and gas showing.Rocks rich in organic matters are distributed in ahorse-shoe belt surrounding the centre of volcanics,showing clear relationshipto the distance away from the area of volcanic eruption centres or subvolcanicintrusions and also to the shape and volume of lavas.In fact,almost all oil and gas fields and wells with good showings are located around the area of volcanic activities.Volcanism occurred during the stage of oii and gas migra- tion,for example,formed in the deposition process of the Huayong Formation (E₂₃b),had brought serious damage to oil and gas.Diapiric and draping structures were formed due to volcanic activities in San-shui Basin,but they bear no significance for oil and gas accumulation,because of their delay in formation.The highly pure carbon dioxide（99.5%）pools discovered in the present area are closely related to volcanism,they distribute in or close to the terrain of volcanic rocks.更多还原