摘要
将高精度的钻孔测井数据与三维反射地震数据相结合,对塔里木盆地中部47井区早二叠世大陆溢流玄武岩(CFB)火山机构进行三维地震解释研究。通过时间剖面层位追索和速度分析等方法,对火山机构的形态、结构和岩性组成进行解析,确定塔里木盆地中部47井区火山机构下方存在玄武质高波速侵入体,其平均地震纵波速度为5800 m/s,围岩碎屑岩的平均地震纵波速度为3500 m/s。通过计算两个标志层(二叠系-三叠系界面"P-top"和生屑灰岩顶面"BL-top")的测井深度,确定玄武质侵入体导致上部标志层相对于下部标志层发生了159.1 m的向上抬升,这相当于火山机构处地层的变形抬升量。进一步利用"速度上拉"效应计算得到的玄武质侵入体总厚度为167.7 m,与测井计算的抬升量基本上一致。研究结果表明,塔中47火山机构的地层抬升是由于深部岩浆注入,导致上覆地层发生"强制褶皱"而形成,与Karoo大火成岩省、北大西洋火成岩省等大陆溢流玄武岩在地壳浅部的就位方式一致。
The volcano edifices from Tazhong-47 exploring area in the middle of Tarim basin are interpreted by 3-D seismological reflection data coupled with physical drilling well logs. Based on seismic profile interpretation and velocity analysis, the structure of the volcano edifices of continental flood basalt（CFB） are studied. The result shows that reflectors beneath the Tazhong-47 volcanic edifice are corresponding to basaltic intrusions, which have average velocity of 5800 m/s, and the clastic wall rocks have average velocity of 3500 m/s. Based on the calculation of the stratigraphical thickness between the two horizontal markers（Permian-Triassic boundary as named ＂P-top＂ and top of bioclastic limestone as named ＂BL-top＂） at drilling well, it is found that the basaltic intrusions make the upper layer relative to the lower layer marks move the 159.1 m upward. This is equal to the uplift extent. By using the ＂velocity pull-up（VPU）＂ effect, the total thickness of the basaltic sills is calculated to be 167.7 m, which is similar to the uplift extent. This similarity suggests that the uplift at the volcanic center was the result of ＂forced folding＂ caused by the intrusion of the magma. This emplacement style is the same as that of the Karoo large igneous province and the North Atlantic igneous province.
作者
高中博
王磊
田伟
弓明月
GAO Zhongbo1, WANG Lei2, TIAN Wei1, GONG Mingyue1(1. School of Earth and Space Sciences, Peking University, Beijing 100871;2. College of Engineering, Peking University, Beijing 10087)
出处
《北京大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2018年第3期555-562,共8页
Acta Scientiarum Naturalium Universitatis Pekinensis
基金
国家自然科学基金(41702360
41272368
41630205)资助
