乌拉特后旗测老庙坳陷早白垩世古流向分析

发布时间：2018-04-22 21:01

本文选题：测老庙坳陷 + 早白垩世　；参考：《地质论评》2017年02期

【摘要】：位于狼山以北的测老庙地区是内蒙古西部巴音戈壁盆地群东部边缘的次级坳陷,面积850 km~2,沉积主体为白垩纪陆相碎屑岩。在目前能够搜集到的所有资料(包括内部资料)中,前人在该坳陷内的沉积相模式分析以及水文地质研究等工作均认为:测老庙坳陷下白垩统巴音戈壁组的物源区主要是坳陷东南侧的狼山,这意味着狼山在早白垩世就已经隆起。几十年内,这个模式一直作为指导思想影响着该地区找矿勘探方向,但找矿效果均不佳,造成了极大的财力、物力和人力资源的浪费。笔者等认为是这一模型存在问题,因为早白垩世巴音戈壁期狼山尚未隆起,无法充当测老庙坳陷的主要物源区。在沉积盆地分析中,利用古流向判别沉积岩的物源区方位是一种非常简便、有效的研究方法,然而笔者等未找到前人在本研究区进行该项工作的记录。笔者等在测老庙坳陷露头区对巴音戈壁组碎屑岩进行了大规模的古流向测量工作:寻找发育波痕和前积纹层等沉积构造为主的露头48处,并依46组前积纹层和5组波痕测得共计51组数据,利用野外现场恢复和室内赤平投影的方法恢复其原始古流向,最终用玫瑰花图和古流向分布图展示测老庙坳陷早白垩世古流向格局。分析结果表明,测老庙坳陷在早白垩世巴音戈壁期的古流向以自北向南为主,向SE、SW两个方向对称递减,集中分布在140°~210°的范围内,甚至在紧靠狼山的区域,古流向垂直指向狼山山脉延伸方向。据此可以判断:狼山不是巴音戈壁组碎屑岩的主要物源区,狼山最早也应在早白垩世巴音戈壁末期之后才可能隆起。这一研究结果为测老庙地区早白垩世沉积岩相关矿产的勘探开发提供了重要的科学依据,为狼山隆起时代的研究提供了重要的突破点,同时也为沉积岩的古流向测量、恢复与物源区分析提供了成功的范例。
[Abstract]:Located to the north of Langshan, the Zhaolaimiao area is a sub-depression on the eastern margin of the Bayingbi basin in western Inner Mongolia, with an area of 850 km2. The main sedimentary body is Cretaceous continental clastic rock. Of all the information currently available, including internal information, The analysis of sedimentary facies models and hydrogeological studies in the depression by predecessors all suggest that the source region of the lower Cretaceous Bayingobi formation in the Shilao depression is mainly Langshan in the southeast side of the depression, which means that Langshan has been uplifted in the early Cretaceous. For several decades, this model has been used as a guiding ideology to influence the prospecting and exploration direction in this area, but the prospecting effect is not good, resulting in a great waste of financial, material and human resources. The author thinks that this model has some problems because the Langshan in the early Cretaceous Bayingobi period has not been uplifted and can not be used as the main provenance of the Zhaolaomiao depression. In the analysis of sedimentary basins, it is a very simple and effective research method to use paleodirection to determine the source area of sedimentary rocks. However, the author has not found the previous records of this work in this research area. In the outcrop area of the Zhaolaimiao depression, the authors have carried out a large-scale paleodirection survey of the clastic rocks of the Bayingobi formation: 48 outcrops with mainly depositional structures such as ripples and foregrained layers have been found. A total of 51 groups of data were obtained from 46 groups of pre-grained layers and 5 groups of ripples. The original ancient direction was recovered by field restoration and indoor projection. Finally, the early Cretaceous paleo-direction pattern of the Zhaolao depression was demonstrated by using the rose chart and the paleo-direction distribution map. The results show that the paleodirection of the early Cretaceous Bayingobi period in the Zhaolaimiao depression is mainly from north to south, and decreases symmetrically toward SENW, and is concentrated in the range of 140 掳~ 210 掳, even in the area close to Langshan. The ancient direction points vertically to the extending direction of the Langshan Mountains. It can be concluded that Langshan is not the main source of the clastic rocks of the Bayingobi formation, and that Langshan should be uplifted at the earliest after the end of the early Cretaceous Bayingobi. The results provide an important scientific basis for the exploration and development of sedimentary rocks related to the early Cretaceous in the Zhaolaimiao area, provide an important breakthrough point for the study of the Langshan uplift, and also provide an important basis for the measurement of the paleodirection of sedimentary rocks. Recovery and provenance analysis provides a successful example.
【作者单位】：中国石油大学地学院;中国科学院南京地质古生物研究所;中国地质科学院地质研究所;香港大学地球科学系;中国石油长庆油田勘探开发研究院;
【基金】：中陕核工业集团委托的研究项目“测老庙盆地区域地质研究与铀矿有利区带预测”的成果
【分类号】：P534.53;P624

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