利用物探资料对西安凹陷和固市凹陷基底结构特征的研究  

Study on the characteristics of the basement structure of the geophysical data in Xi'an and Gushi depression

作　　者：张瑾爱 张林 江桂 周少伟 凌丹丹 ZHANG Jin-ai;ZHANG Lin;JIANG Gui;ZHOU Shaowei;LING Dandan(Shaanxi Center of Geological Survey,Xi'an 710068,China)

机构地区：[1]陕西省地质调查中心,西安710068

出　　处：《物探化探计算技术》2018年第5期667-673,共7页Computing Techniques For Geophysical and Geochemical Exploration

基　　金：中国地质调查局项目(12120113040500)

摘　　要：为了探测渭河新生代盆地的基底组成和结构构造,调查渭河盆地主要地层厚度、埋深和构造特征,在渭河盆地开展二维地震勘探测量,在全面收集渭河盆地以往物探和钻孔资料的基础上,通过实测地震剖面,划分渭河盆地新生界地层,得到固市凹陷基底深约8 100km,西安凹陷基底深约6 600km,固市凹陷明显比西安凹陷基底深,这是本次工作最大的成果之一。再结合收集的重力数据,经过消除莫霍面影响后,分析渭河盆地西安凹陷和固市凹陷整体重力场变化特征,结果表明造成西安凹陷重力低,但基底浅;固市凹陷重力高,但基底深。这种实际地质情况是由于西安凹陷新近系沉积地层比固市凹陷沉积地层厚且深,而古近系地层却较之薄而浅,这种"跷跷板"式的地层分布特征能够引起重力异常"非常规"现象出现。通过此次工作实践,对渭河新生代盆地的基底组成和结构构造有清楚认识,对评价重点勘查区的成藏条件,为渭河盆地氦气资源远景调查提供借鉴。In order to investigate the basal composition and structural structure of the Weihe Cenozoic basins,the main strata thickness,depth and tectonic characteristics of the Weihe basin,the 2D seismic survey was carried out in the Weihe basin.And the past geophysical and borehole data of the Weihe Basin was collected.According to the measured seismic section,the cenozoic strata of Weihe basin are divided.The base of Gushi and Xi'an depressions is about 8 100 km 6 600 km deep,respectively.This suggests that the Gushi depression is deeper than that of Xi'an depression,which is inconsistent with previous understanding.This is one of the greatest achievements.Combined with the collected gravity data and elimination the influence of Moho have been used to analyze the gravity field variation in Weihe basin.The results show that the gravity is low in the Xi'an depression,but the base is shallow.The gravity of the Gushi depression is high,but the basement is deep.This practical geological condition is due to the thick and deep sedimentary strata of the Neogene sedimentary strata in the Xi'an depression,which is thicker and shallow than the sedimentary strata in the Gushi depression.And so the characteristics of the distribution of the"seesaw"type can cause gravity"unconventional"phenomenon.Through the practice of this work,the basal composition and structure of the Weihe cenozoic basins have a clear understanding,and evaluation of reservoir formation conditions in the key exploration areas,and provide the geophysical basis for the helium resource prospecting survey in the Weihe basin.

关 键 词：西安凹陷 固市凹陷 地震勘探 重力场特征 基底深度 

分 类 号：P631.4[天文地球—地质矿产勘探]