松辽盆地徐家围子断陷营城组火山岩相和火山机构分析

ANALYSIS OF VOLCANIC FACIES AND APPARATUS OF YINGCHENG FORMATION IN XUJAWEIZI FAULTING DEPRESSION,SONGLIAO BASIN NORTHEAST CHINA

徐家围子断陷营城组火山岩极为发育。文章通过对火山岩的岩芯观察、薄片鉴定、岩芯测试及测井资料、二维、三维地震资料的综合分析 ,将营城组火山岩盆地分为 3大相区 ,即火山喷发区、过渡区和沉积区。火山喷发区岩性由各种熔岩、火山碎屑岩和少量砂砾岩组成 ;过渡区岩性以火山碎屑岩与沉积岩互层为特征 ,夹少量火山熔岩 ;沉积区岩性包括砂砾岩、砂岩、粉砂岩和泥岩。火山喷发区内可识别出 8种类型的火山岩相 (空落相、溢流相、基底涌流相、火山碎屑流相、火山泥石流相、火山沉积相、次火山相、隐爆角砾岩相 )和 3种类型的火山机构 (层火山、微型盾火山和渣锥火山 )。不同类型的火山机构具有不同火山作用、岩相分布特征和含油气性。因此火山岩相及火山机构分析对火山作用研究和油气勘探均有重要意义。

Yingcheng formation in Xujaweizi faulting depression, Songliao Basin, is rich in volcanic rock. Based on core observation, thin sections identification and integration of well log and 2D/3D seismic data, 3 facies zones are identified in Yingcheng Formation in this basin, which is the eruption zone of volcanic, transitional zone and sedimentary zone. The eruption zone consists of lava, pyroclastic and limited sandy conglomerate. The transitional zone is characterized by interbedding of pyroclastic and sedimentary rocks,and a little volcanic lava rocks was also found in the strata. Sandy conglomerate, sandy stone and siltstone are developed in the sedimentary zone. Moreover, 8 types of volcanic lithofacies such as fallout facies, effusion facies, base surges facies, pyroclastics flow facies, lahar facies, eruption\|sedimentary facies, sub\|volcanic rock facis and sub\|explosive breccia facies, and three kinds of volcanic apparatus such as layered volcano, micro\|shield volcano and cone Volcano can be identified in the eruption zone. Analysis of volcanic lithofacies and apparatus are very important for both volcanism study and oil and gas exploration, because they are different from each other in that of features of volcanism, distribution of lithofacies and oil\|bearing.