鄂尔多斯盆地东南缘白垩纪以来构造演化的裂变径迹证据  

Evidence from detrital zircon and apatite fission track for tectonic evolution since Cretaceous in southeastern margin of Ordos basin

作　　者：黄志刚[1] 任战利[2] 高龙刚 

机构地区：[1]太原理工大学地球科学系,太原030024 [2]西北大学地质学系,西安710069

出　　处：《地球物理学报》2016年第10期3753-3764,共12页Chinese Journal of Geophysics

基　　金：国家自然科学基金(41372128);国家重大专项(2011ZX05005-004-007HZ)资助

摘　　要：鄂尔多斯盆地东南缘处于渭北隆起、晋西挠褶带和东秦岭造山带的转折地带,构造位置独特,演化历史复杂.本文选取东缘韩城地区和南缘东秦岭洛南地区上三叠统延长组为研究对象,采集6件砂岩样品进行锆石、磷灰石裂变径迹分析,对关键构造-热事件提供热年代学约束,恢复盆地东南缘不同构造带的热演化史,深化对盆地东南部油气资源赋存条件的认识,以期实现油气勘探的新突破.研究表明韩城和洛南地区的抬升冷却史存在明显差异.磷灰石裂变径迹年龄表现为从南到北减小的趋势.东缘韩城剖面磷灰石裂变径迹记录51.6~66.3 Ma、33 Ma两次抬升冷却的峰值年龄.南缘洛南剖面锆石裂变径迹年龄和磷灰石裂变径迹年龄分别记录89~106 Ma和59~66 Ma的冷却抬升年龄.洛南地区抬升冷却时间较早,剥蚀速率（106m/Ma）大于韩城地区（68m/Ma）,且持续时间长.磷灰石裂变径迹（Apatite Fission Track,AFT）热史模拟显示,晚中生代,受燕山运动的影响,东秦岭地区发生强烈的构造岩浆事件,洛南地区热演化程度明显高于韩城地区.洛南剖面的热演化主要受岩浆活动的控制,韩城剖面为埋藏增温型.鄂尔多斯盆地东南缘的裂变径迹年龄格局基本受控于白垩纪以来的抬升冷却事件.The southeastern margin of Ordos basin is located in the transition zone among the Weibei uplift,Jinxi flexural fold and East Qinling orogenic zones.It is in a unique and important tectonic setting and has a complex evolution history.This article focuses on the study of the Yanchang Formation in Hancheng,which is in the east of Ordos,and in Luonan,which is in the south of Ordos.Six sandstone samples are collected and the key tectonic thermal event is constrained by thermochronology,using the methods of detrital zircon and apatite fission track.Thermal evolution histories are recovered for different structural belts of the southeast margin of the basin.The occurrence conditions of oil and gas arefurther studied which would add to open a new domain of petroleum exploration.Research shows that the uplift and cooling histories are obviously different in researched regions.The AFT dates show that ages decrease from south to north.The AFT ages of the Weibei uplift reduce from 110 Ma in south to 33 Ma in north,and those of the North Qinling also reduces from 80 Ma in south to 9.7Ma in north.In the Hancheng section,two tectonic uplifting events were recorded by apatite fission track,of which thermochronology ages are 51.6~66.3 Ma and 33 Ma,respectively.In the Luonan section,two thermochronology ages of zircon fission track were recorded,which reflect one tectonic event in 89~106 Ma.Apatite fission track dates reflect one tectonic event in 59~66Ma.Denudation and cooling histories were obviously different in the study areas.Rapid uplift of the Luonan region located in the East Qinling orogen is earlier than the Hancheng region,and lasted a long time.The uplift-denudation rate is 106m/Ma in the Luonan region,and 68 m/Ma in the Hancheng region,respectively.The modeled thermal history,which is based on apatite fission track data,exhibits fairly similar three-stage cooling,starting with an uplift-cooling event of the late period of early Cretaceous（100Ma）,followed by a period of relative thermal stability keeping the rocks

关 键 词：裂变径迹 抬升过程 热史模拟 延长组 鄂尔多斯盆地东南缘 

分 类 号：P314[天文地球—固体地球物理学] P541[天文地球—地球物理学]