冀北宣化盆地沉积充填及对盆地性质的指示

发布时间：2018-04-29 13:41

本文选题：宣化盆地 + 九龙山组　；参考：《中国地质大学(北京)》2017年硕士论文

【摘要】：宣化盆地位于燕山褶皱带西段和太行山褶皱北段的交汇部位,中生代燕山褶皱带遭受褶皱变形,发育了大量的挠曲盆地,宣化盆地在中生代断裂的控制下发育了特征性的盆地充填序列和沉积模式,尤以九龙山组和土城子组两套粗粒陆源碎屑沉积为典型代表。通过对盆地沉积和盆地沉积与盆缘构造关系的研究,可以恢复宣化盆地在晚侏罗世至早白垩世的沉积环境,探讨盆地充填的构造背景,进而对该时期燕山褶皱带的构造体制的讨论也有启示意义。论文依据对宣化盆地野外露头的实地勘测,对九龙山组和土城子组进行了详细的沉积岩相的划分,主要观察内容包括沉积层厚度、沉积层间的接触关系、沉积层内碎屑颗粒的结构及分布特征等,将九龙山组和土城子组划分出13种岩相类型。通过对岩相的识别和鉴定,解释不同的岩相和岩相组合所代表的成因相和沉积相,进而通过沉积相组合推断出九龙山组和土城子组沉积环境和沉积体系。由此得到九龙山组为扇三角洲沉积体系,土城子组为湖泊-辫状河三角洲-冲积扇的沉积体系组合。盆地的沉积充填是盆地发育过程的表现和产物,而盆地的发育过程受控盆断层和区域构造背景的控制。九龙山组扇三角洲和土城子组冲积扇的发育都是盆缘造山作用控制的突出表现,但真正能够反映盆地构造性质的关键证据是盆地内发育的两套生长地层。这两套生长地层分别位于立石村和谷峪口,均由下花园逆冲断裂的前展次级逆冲断层控制,立石村生长地层发育于髫髻山期,在土城子组沉积前就已停止生长;谷峪口生长地层发育于土城子期,并且谷峪口生长断层的发育还改变了盆地的沉积格局。逆冲断层控制的生长地层反映了挤压作用控制的沉积盆地。综合盆地的沉积充填特征及生长地层性质,晚侏罗世至早白垩世宣化盆地是区域挤压背景下的产物,这种区域挤压背景与整个中国东部所处的大地构造背景相关。
[Abstract]:The Xuanhua Basin is located at the intersection of the west segment of the Yanshan fold belt and the northern segment of the Taihang fold. The Mesozoic Yanshanian fold belt suffered fold deformation and developed a large number of flexural basins. Under the control of Mesozoic faults, the Xuanhua Basin has developed a typical filling sequence and sedimentary model, especially two sets of coarse continental clastic deposits of Jiulongshan formation and Tuchengzi formation. The sedimentary environment of Xuanhua Basin from late Jurassic to early Cretaceous can be restored and the tectonic background of basin filling can be discussed by studying the relationship between basin sedimentation and basin margin tectonics. The discussion on the tectonic system of Yanshanian fold belt in this period is also instructive. Based on the field survey of outcrop in Xuanhua Basin, the paper divides the sedimentary lithofacies of Jiulongshan formation and Tuchengzi formation in detail. The main observation contents include the thickness of sediment layer and the contact relationship between sedimentary layers. The structure and distribution characteristics of detrital particles in the sedimentary layer are divided into 13 lithofacies types of Jiulongshan formation and Tuchengzi formation. The genetic facies and sedimentary facies represented by different lithofacies and lithofacies combination are explained by identifying and identifying lithofacies, and the sedimentary environment and sedimentary system of Jiulongshan formation and Tuchengzi formation are inferred through sedimentary facies combination. Therefore, the Jiulongshan formation is a fan delta sedimentary system, and the Tuchengzi formation is a lacustrine braided river delta alluvial fan sedimentary system. The sedimentary filling of the basin is the manifestation and product of the development of the basin, while the development of the basin controls the fault of the basin and the control of the regional tectonic setting. The development of fan delta of Jiulongshan formation and alluvial fan of Tuchengzi formation is a prominent manifestation of basin margin orogeny control, but the key evidence to reflect the tectonic properties of the basin is the two sets of growth strata developed in the basin. The two sets of growth strata are located in Lishicun and Guyukou, respectively, and are controlled by the secondary thrust fault of Xiayuan thrust fault. The growth strata of Lishicun developed in Tiaojishan period and stopped growing before Tuchengzi formation was deposited. The growth strata of Guyukou developed in Tuchengzi period, and the development of Guyukou growth fault also changed the sedimentary pattern of the basin. The growth strata controlled by thrust faults reflect the sedimentary basins controlled by compressibility. From late Jurassic to early Cretaceous Xuanhua basin is the product of regional compression background which is related to the tectonic setting of the whole eastern China.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P512.2

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