南堡凹陷油田古近系碎屑重矿物的物源和构造意义  

Provenances and Tectonic Implications of Paleogene Terrigenous Heavy Minerals in Nanpu Rifted Trough,Eastern Hebei Province

作　　者：董月霞[1] 张宁[2] 周海民[3] 夏文臣[2] 

机构地区：[1]中国石油大学,北京102249 [2]中国地质大学地球科学学院,武汉430074 [3]中国石油天然气股份有限公司冀东油田公司,河北唐山063004

出　　处：《地质科技情报》2008年第5期7-13,共7页Geological Science and Technology Information

基　　金：中国石油天然气股份有限公司冀东油田公司科研项目"南堡凹陷东营组沉积体系;盆-源耦合及成藏贡献研究"

摘　　要：利用石油钻井岩心,在南堡凹陷古近纪地层中采集了52件砂砾岩样品并进行了重矿物定量分析。重矿物组合的垂向变化指示出了3个碎屑重矿物组合段,它充分展现了物源区多阶段隆升-剥蚀的历史:始新世的沙三至沙二组合段为凹陷基底岩石层圈(以花岗片麻岩为主)的隆升—剥蚀过程;始新世沙一至渐新世的东二组合段为更深层变质岩层圈的隆升-剥蚀过程;渐新世末的东一段为稳定和老化的变质层圈的隆升—剥蚀及物源区调整过程。在石油勘探井较密且分布较广的东一段,系统进行了各类碎屑扩散体系的重矿物分析,区分出了4个碎屑重矿物扩散体系,分别来自两种构造类型的物源区:①扇三角洲和辫状河三角洲前浊积扇体系物源区为燕辽古造山带,重矿物分布模式表现为主峰左偏、重矿物组分较少、稳定重矿物显示度偏低的特点;②两个河控三角洲体系物源区为华北古克拉通,重矿物分布模式表现为对称的主峰、重矿物组分较多、稳定组分显示度偏高的特点。Fifty and two samples were taken from various positions and strata levels of the Paleogene filling sequences in the Nanpu rifted trough by coring for oil exploration and quantitative analysis of terrigenous heavy minerals. Vertical changes of heavy mineral compositions reveal their three assemblage intervals in the Paleogene filling sequences which imply the uplifting and eroded history of provenances. Total heavy mineral compositions in the interval of lower and middle member of Shahejie Formation （Eocene） reveal the lifting and eroded process of metamorphic granite-gneiss-dominated provenance. Those of the interval from the upper member of Shahejie Formation （Eocene） to the middle member of Dongying Formatoin（Oligocene） exhibit the lifting and eroded process of the katazone in the paleo-orogenic provenance. Spatially- differential heavy mineral compositions in the interval of the upper member of Dongying Formation not only indicate the lifting and eroded process of the ageing and stable orogenic provenance but also imply the commutation of provenances. Four types of heavy minerals-dispersed systems were recognized by differentiation of heavy mineral compositions of spatially-spaced sample on the upper member of Dongying Formation both the Laoyemiao fan-delta system and the Beipu turbidity fan system front delta root in the Yanliao paleo-orogenic provenance. Within these systems the distribution patterns of terrigenous heavy minerals are consistently characterized by having left-deflection main apex of garnet and lower tokens of instable mineral. The Napu river-dominated deltaic system and the southern Beipu distal system of river-dominated delta originate in the cratonic provenance. Their distribution patterns of terrigenous heavy minerals are characterized by having a symmetric main apex of garnet and higher tokens of instable mineral.

关 键 词：碎屑重矿物 物源 古造山带 克拉通 南堡凹陷 

分 类 号：P571[天文地球—矿物学]