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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.
In order to clarify the evolution of various provenance systems in the context of complex provenance, the statistic analysis of sandstone components and heavy minerals in different intervals of 37 wells in the Upper Cretaceous Qing 3 Member-Yao 1, Changling Depression, According to the Q-type clustering method based on SPSS software, the single-well heavy minerals from different rock areas are distinguished on the plane. Based on the ZTR index and the flat distribution trend of percentage of sandstone, Distribution patterns finally revealed the evolvement course of the study area from dual-source supply (Qing 3 Member) to multi-source convergence (Yao 1) in the framework of Late Cretaceous tectonic movement and palaeoclimate transformation.The results show that in the vertical direction The percentage of Yao block over the underlying Q3 block increased by 8.14%, while the percentage of stable heavy minerals decreased by 9.25%, indicating the enhancement of denudation in the parent rock area. According to the influence of the Baokang and Tongyu systems distributed along the SW-NE, they are respectively developed in the order of “zircon_ (93.41%) + tourmaline (3.56%) + cassiterite (0.64%)” and “ Zircons (69.42%) + white titanium stone (22.89%) + tourmaline (5.6%) Characteristics of the heavy mineral assemblage belt, the parent rock are all the middle-acidic volcanic rock bedrocks exposed in the ancient Tiefa Ridge area.During the Yao period of deposition, the regional tectonic extrusion makes the ancient lake basin area rapidly shrink, the same period The climate is gradually dry and hot, the peripheral source areas are subject to a large number of erosion, for the ability to enhance the chip, in addition to the work area southwest of the Qinghai three deposition period of the source system, the northwest and northeast of the work area were also along the NW- SE and the Changcheng-Wilder sedimentary system spreading along the NE-SW direction. Both of them are developed in the order of ”zircon_ (58.72%) + tourmaline (28.73%) + pomegranate The heavy mineral assemblage zone characterized by the “zircon” (8.2%) “and” zircon “(51.04%) + garnet (28.95%) + tourmaline (7.2%)” Middle-acidic magmatic rocks, middle-high metamorphic rocks and paleocentric volcanic rocks exposed in the Gansu-Changqingcai area of the Daxinganling area.