碎屑重矿物差异与物源演化——以长岭凹陷乾北地区青三段—姚一段为例  

Detrital heavy mineral difference and its implication for provenance:A case study of the third member of Qingshankou formation and the first member of Yaojia formation in Qianbei area,Changling sag

作　　者：胡鹏[1] 鲍志东[2,3] 于兴河[1] 刘学超 华正秋[5] 刘俊玲 黄玉欣[5] 李勇[7] 

机构地区：[1]中国地质大学(北京)能源学院,北京100083 [2]中国石油大学(北京)地球科学学院,北京102249 [3]油气资源与探测国家重点实验室,北京102249 [4]盎亿泰地质微生物技术(北京)有限公司,北京102200 [5]中国石油吉林油田分公司勘探开发研究院,吉林松原138001 [6]中石化西北局塔河采油一厂,新疆轮台841600 [7]中国石油华北油田分公司地球物理勘探研究院,河北任丘062552

出　　处：《中国矿业大学学报》2017年第2期375-387,共13页Journal of China University of Mining & Technology

基　　金：国家油气重大专项(2011ZX05028);中石油天然气股份有限公司重大科技专项(2013E-0501)

摘　　要：为了厘清复杂物源供给背景下各物源体系演化规律,对长岭凹陷乾北地区上白垩统青三段—姚一段37口井不同层段内砂岩骨架组分与重矿物资料进行统计分析,并基于SPSS软件的Q型聚类法将源于不同母岩区的单井重矿物组合在平面上加以区分,再依据ZTR指数与砂岩百分比的平面分布趋势明确物源方向,进而结合古物源水系分布格局,最终揭示了晚白垩世区域构造动力体制与古气候转换背景下研究区由双物源供给(青三段)到多物源汇聚(姚一段)的演化历程.研究结果表明:纵向上姚一段较其下伏的青三段砂岩岩屑百分比整体增加8.14%,而稳定重矿物百分比降低9.25%,指示着母岩区剥蚀作用的增强.平面上青三段沉积时期研究区西南部受整体沿SW-NE展布的保康、通榆体系的影响,分别发育以"锆石_(93.41%)+电气石_(3.56%)+锡石_(0.64%)"和"锆石_(69.42%)+白钛石_(22.89%)+电气石_(5.6%)"为特征的重矿物组合带,其母岩均为古铁法岭地区出露的以中酸性火山岩为主的基岩.至姚一段沉积时期,区域构造挤压使得古湖盆面积迅速萎缩,同期古气候逐渐干热,周缘物源区均遭受大量剥蚀,供屑能力增强,除工区西南部整体继承青三段沉积时期的物源体系格局外,工区西北部、东北部还分别受到整体沿NW-SE展布的白城沉积体系和整体沿NE-SW方向展布的长春—怀德沉积体系的影响,二者分别发育以"锆石_(58.72%)+电气石_(28.73%)+石榴石_(8.2%)"与"锆石_(51.04%)+石榴石_(28.95%)+电气石_(7.2%)"为特征的重矿物组合带,其母岩分别为古大兴安岭地区出露的中酸性岩浆岩、中高级变质岩与古张广才岭地区出露的高级变质岩、中酸性火山岩.Qianbei area,located in the center of Changling sag,is controlled by multi sedimentsources in the span of the 3rd member of Qingshankou formation（K2qn^3）and the 1st member of Yaojia formation（K2y^1）.In order to sufficiently identify the evolution of each sedimentsource,detailed statistical analysis of clastic particles and heavy minerals from 37 cored wells was conducted.Based on Q-type clustering analysis of SPSS,wells with different heavy mineral assemblages were separated.Furthermore,with an integrated approach of ZTR index and percentage of sandstones,the provenance direction of K2qn3-K2y^1 was also determined.Combined with the background of paleodrainage systems of source areas,the provenance transformation from two sediment-sources during the period of K2qn^3 to four sediment-sources during the period of K2y^1 in Qianbei area was clarified,which is the result of a key transition of tectonic dynamic regime and paleoclimate of late Cretaceous.The result shows that the sandstone of K2y^1 contains 8.14% more rock fragments and 9.25%less stable heavy minerals than that of K2qn^3 in average percentage,suggesting a stronger erosion in parent-rock areas.During the period of K2qn^3,the southwest part of Qianbei area was controlled by Baokang and Tongyu sedimentary systems,both distributing along almost SW-NE direction.Their heavy mineral combinations are characterized by ＂Zircon93.41%＋Tourmaline3.56% ＋Cassiterite0.64% ＂and ＂Zircon69.42% ＋Leucoxene22.89% ＋ Tourmaline5.6% ＂,respectively.The types of parent rocks are mainly intermediate-felsic volcanic rocks of Paleo-Tiefa range situated in the southeast of Songliao basin.During the period of K2y^1,the scope of Pelae-Songliao lake decreases rapidly,as a result of regional compression tectonic events.Meanwhile,the paleoclimate becomes drier and hotter gradually.Source areas around the Southern Songliao basin suffer greater erosion and provide larger amounts of clastic materials driving to the center of the sag via different water systems.Apart fr

关 键 词：重矿物 聚类分析 青三段—姚一段 物源 乾北地区 长岭坳陷 

分 类 号：P512.2[天文地球—地质学]