四川盆地东南缘中新生代构造隆升的裂变径迹证据  

Fission track evidence for Mesozoic-Cenozoic uplifting in the southeastern margin of Sichuan basin

作　　者：李双建[1] 李建明[2] 周雁[1] 沃玉进 汪新伟 

机构地区：[1]中国石油化工股份有限公司石油勘探开发研究院,北京100083 [2]延长石油集团研究院,陕西西安710075

出　　处：《岩石矿物学杂志》2011年第2期225-233,共9页Acta Petrologica et Mineralogica

基　　金：国家重点基础研究发展计划973项目(2008CB425703);国家重大科技专项资助项目(2008ZX05005-001-001);国家自然科学基金委员会-中国石油化工股份有限公司联合研究基金(石油化工联合基金)项目(40739904)

摘　　要：通过对四川盆地东南缘8件不同层位的磷灰石样品裂变径迹的分析,获得了该区中新生代构造隆升的时限,并分析了其构造和油气地质意义。磷灰石裂变径迹分布形态总体具有单峰特征,部分具有双峰特征,平均径迹长度在10～13μm,标准偏差在1.5～2.5μm,反映了磷灰石在地质历史时期经历过较缓慢的冷却退火过程。样品的热史模拟结果显示,所有样品在进入部分退火带(PAZ)以后没有再经历明显的沉降埋藏,均表现为持续的隆升,但不同地区进入隆升期的先后次序不同。盆地东南缘的隆升起始时间在95～60Ma左右,即晚白垩世—古近纪,向北到达盆地边缘的时间为40～35Ma,为古近纪晚期。几乎所有的样品都具有晚期快速抬升的特点,抬升时限均在10Ma以内,多数小于5Ma,部分小于2Ma。从油气地质的角度看,川东南地区喜山期的强烈隆升一方面可能造成已有的气藏破坏,另一方面也可能有利于形成新的具裂缝性储层的岩性气藏或者水溶气气藏。Viewed from sedimentary records,the uplift and deformation in the southeastern margin of Sichuan basin occurred later than late Jurassic.Prior to this event,there existed a favorable petroleum geological conditions resulting in large scale hydrocarbon accumulation in this area.However,hydrocarbon accumulation was destroyed and adjusted by uplift and deformation of the sedimentary sequence.It is of great significance to determine the time limit of uplift and analyze its effect on hydrocarbon accumulation.Based on apatite fission track analysis of eight samples from different strata in the southeastern margin of Sichuan basin,the authors confirmed the Mesozoic-Cenozoic uplifting time limit and discussed its tectonic and petroleum geological significance.The apatite track lengths are distributed mostly in the single peak form,with a few in the double-peak form.The mean track length is between 10 μm and 13 μm,and standard error is between 1.5 μm and 2.5 μm.The distribution characteristics of fission tracks suggest that the samples have experienced a slow cooling process.The thermal history simulation results show that all the samples have not experienced obvious subsidence since they entered the partial annealing zone.Almost all the samples have experienced three uplift periods,i.e.,fast uplift in the early period,gentle uplift in the middle period and fast uplift in the late period,with the uplift time being different in different areas.The first uplift period in the southeastern margin of Sichuan basin occurred at about 90～60 Ma,and the arrival at the margin of the basin occurred at 40～35 Ma after northward transmission.Almost all of the samples experienced fast uplift events in late Cenozoic,and the time limit of them are within 10 Ma,with most of them being younger than 5 Ma and a few of them younger than 2 Ma.From the angle of plate tectonics,the uplift of this area in Himalayan period was related to the uplift of Tibet.From the angel of petroleum geology,the intense uplifting in the southeastern margin

关 键 词：川东南 磷灰石裂变径迹 构造隆升 中新生代 

分 类 号：P597[天文地球—地球化学] P542.1[天文地球—地质学]