本文關(guān)鍵詞： 沉積記錄 礫石特征 孢粉組合 水合物鉆井 更新世　出處：《中國地質(zhì)大學(xué)(北京)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：本論文利用我國天然氣水合物勘查和開采專項2014年在北羌塘凍土區(qū)水合物鉆井QK-6第四系沉積物展開了沉積學(xué)研究,得到以下成果和認識:(1)綜合利用2個ESR測年和5個生物或沉積標志年代記錄,將該井246.4m巖心確定為中更新世1311±174 ka以來沉積,建立了該井的地層年代框架。(2)獲得該鉆孔中更新世-全新世凍土的粒徑及垂向變化記錄,在此基礎(chǔ)上嘗試建立了該套沉積序列的沉積相,指出該套沉積總體為湖相沉積的的濱湖和扇三角洲相,并進一步劃分為6個微相。(3)對該套沉積序列中礫石組分進行了進一步研究,發(fā)現(xiàn)礫石含量變化分為3段,下段(246.40-172.00m)極低含量段,中段(172.00-55.25m)含量逐增段,上段(55.25-0m)高含量段,其中下段礫石磨圓度比中段和上段好。初步分析了這三段礫石的巖石學(xué)和化學(xué)成分組成及垂向變化。(4)孢粉分析可識別出5個孢粉帶,指示了該區(qū)周邊陸地從中更新世由旱生草本為主的疏林草原,逐漸向旱生草原演化的過程。(5)研究表明,該套沉積序列礫石中段含量增加變化初期可能與青藏高原發(fā)生“昆侖-黃河運動”這一青藏高原構(gòu)造抬升事件(0.9~0.8Ma)對比。研究初步認為,盡管該次鉆探未發(fā)現(xiàn)水合物,從沉積條件角度來說,該井第四系凍土具有含松散的、礫粗粒徑組分含量高、沉積厚度大等特征屬于有利于水合物成藏的沉積條件。
[Abstract]:In this paper, the sedimentology of QK-6 Quaternary sediments of hydrate drilling in the frozen soil area of Qiangtang, North China, was carried out in 2014 by means of the exploration and exploitation of natural gas hydrate in China. Using 2 ESR dating and 5 biotic or sedimentary marker dating records, the 246.4 m core of the well is determined to have been deposited since the Middle Pleistocene period (1311 鹵174ka). The stratigraphic chronological framework of the well is established. (2) the records of the grain size and vertical variation of permafrost in this borehole during the Pleistocene to Holocene are obtained, and the sedimentary facies of the sedimentary sequence are attempted to be established on this basis. It is pointed out that this set of sediments is a lacustrine and fan delta facies, and further divided into 6 microfacies. (3) the gravel components in the sedimentary sequence are further studied. It is found that the variation of gravel content is divided into three sections. The lower segment (246.40-172.00 m), the middle segment (172.00-55.25m), the upper segment (55.25-0 m), the middle segment (172.00-55.25m), The gravel grinding roundness in the lower section is better than that in the middle and upper sections. The petrology and chemical composition and vertical variation of the gravel in these three sections are preliminarily analyzed. It is indicated that the study on the evolution process of the open forest steppe, which is dominated by xerophytic herbaceous in the middle Pleistocene, to the xerophytic steppe in the surrounding land, indicates that, In the initial stage of the increase in the content of gravel in this set of sedimentary sequences, it may be compared with the "Kunlun Yellow River Movement", a tectonic uplift event of the Qinghai-Xizang Plateau, which occurred in the Qinghai-Tibet Plateau at the initial stage. The preliminary study shows that although no hydrates were found during the drilling, From the point of view of sedimentary conditions, the Quaternary permafrost of the well has the characteristics of loose, high content of coarse gravel-size components and large deposition thickness, which are favorable to hydrate accumulation.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：P618.13;P512.2;P534.631
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本文編號：1517425