【摘要】：古地震的年代確定是重建強震活動歷史、預測未來地震趨勢的重要依據(jù)(楊會麗,2014)。光釋光方法是測定古地震事件年代方法中的一種。由于古地震造成的是快速混雜堆積物,其信號的回零程度不一。所以對于光釋光運用于古地震測年的適應性引起過不少學者的爭論。2010年4月14日,位于甘孜-玉樹斷裂帶上的玉樹縣發(fā)生了Ms7.1級大地震,這提供了很好的研究地震裂縫充填物光釋光信號回零程度的機會。本文研究采集了在此次地震裂縫上的充填物及同深度的原生堆積層的樣品,采用光釋光對石英進行測年,并將得到的測年結(jié)果進行對比,分析充填物的曬退情況。并由此探討了光釋光測年在古地震測年中的適應性。從本次研究工作中得到以下結(jié)果和認識:1.隆寶湖西1號探槽充填物樣品LBHX1-4、LBHX1-5的年代結(jié)果分別是1.95±0.08ka、2.50±0.10ka,同深度的原生堆積層樣品LBHX1-2、LBHX1-6的年代結(jié)果分別是2.53±0.10ka、1.95±0.07ka。充填物年齡與同深度的原生堆積層的年齡在誤差范圍內(nèi)基本一致。探槽原生堆積層自上而下,LBHX1-1、LBHX1-2和LBHX1-3的年代結(jié)果分別為1.65±0.09ka、2.53±0.10ka、2.81±0.3ka,有明顯的層序性,年代結(jié)果從原生堆積層頂部越往下越老。2.隆寶湖西2號探槽的充填物從上到下依次為LBHX2-1、LBHX2-2、LBHX2-3,年代結(jié)果分別為1.29±0.07ka、2.83±0.1ka、4.15±0.3ka,充填物從上到下也有較好的層序性,年代結(jié)果從崩積楔頂部越往下越老。3.可能是母質(zhì)比較老的緣故,納利庫探槽和禪古水電站探槽的充填物年齡達到了4.68±0.3ka(NLK1-2)、和17.75±0.53Gy(CGSDZ1-2)。采集類似于納利庫和禪古水電站探槽的充填物樣品來限定60ka以內(nèi)的古地震年齡可能存在較大的誤差。4.隆寶湖西1、2號探槽、納利庫探槽及禪古水電站四個探槽樣品的測年結(jié)果均表明地震填充物等在2010年地震中曝光不充分。5.隆寶湖西1、2號探槽處于原生堆積狀態(tài),充填物及原生堆積層的年代結(jié)果小于2.53±0.1ka,在光釋光允許誤差范圍內(nèi)(5%-10%),采集充填物頂部或同深度原生堆積層的樣品來測定25ka以上的古地震年代是適用的。6.由于地震造成的快速沉積物可能存在個別礦物顆粒曝光充分的情況,接下來可以運用單顆粒的方法進行光釋光測年,檢測出沉積時曝光充分的顆粒,或許可以獲得地震發(fā)生的確切年齡。
[Abstract]:The dating of paleoearthquakes is an important basis for reconstructing the history of strong earthquakes and predicting the trend of earthquakes in the future (Yang Huili 2014). Photoluminescence method is one of the methods for dating paleoearthquake events. Since the paleoearthquakes caused by the rapid mixed deposits, the signal return to zero varying degrees. Therefore, the adaptability of the application of photoluminescence to paleoseismic dating has caused controversy among many scholars. On April 14, 2010, a large earthquake of magnitude Ms7.1 occurred in Yushu County, located on the Ganzi-Yushu fault zone. This provides a good opportunity to study the degree of return to zero of photoluminescence signal of seismic fracture filling. In this paper, samples of fillers and primary deposits of the same depth on the fractures of this earthquake have been collected, and the age of quartz has been measured by means of photoluminescence, and the results obtained have been compared to analyze the sunburn of the fillers. The adaptability of photoluminescence dating in paleoseismic dating is discussed. From this research work to get the following results and understanding: 1. The dating results of LBHX1-4 and LBHX1-5 in LBHX1-4 and LBHX1-5 of LBHX1-4 and LBHX1-6 in LBHX1-2 and LBHX1-6, respectively, are 1.95 鹵0.07ka and 2.53 鹵0.10ka1.95 鹵0.07ka, respectively. The age of the filling is basically the same as that of the primary deposit of the same depth within the error range. The age results of LBHX1-1 and LBHX1-3 are 1.65 鹵0.09ka/ 2.53 鹵0.10ka/ 2.81 鹵0.3ka. the age result is older and older from the top of the primary accumulation layer to that of LBHX1-2 and LBHX1-3, respectively, and the age result is 1.65 鹵0.09kaor 2.53 鹵0.10ka/ 2.81 鹵0.3ka. the age result is older and older from the top of the primary accumulation layer. LBHX2-1 and LBHX2-2 LBHX2-3 were used in LBHX2-1, LBHX2-2, LBHX2-3, and the results were 1.29 鹵0.07kaor 2.83 鹵0.1kaor 4.15 鹵0.3ka. the filling also had better sequence from top to bottom. It is possible that the filling ages of the Naliku and Chengu grooves are 4.68 鹵0.3ka (NLK1-2) and 17.75 鹵0.53Gy (CGSDZ1-2). It is possible that there is a large error in determining the paleoseismic age within 60ka by collecting the backfill samples similar to the trenches in Naliku and Zenggu Hydropower stations. The dating results of the first and second grooves in Longbao Lake, Naliku Prospecting Groove and four Prospecting channels in Zenggu Hydropower Station indicate that the seismic fillers were not fully exposed in the 2010 earthquake. The Prospecting trough No. 1 and No. 2 in the west of Longbao Lake is in the state of primary accumulation. The age results of the filling and primary deposits are less than 2.53 鹵0.1 ka. within the allowable error of photoluminescence (5-10%), it is suitable to measure the paleoearthquake age above 25ka by collecting samples from the top of the filling or the same depth of the primary accumulation. Because the rapid sediment caused by earthquake may have sufficient exposure of individual mineral particles, we can then use the method of single particle to carry out the photometric dating to detect the fully exposed particles at the time of deposition. It may be possible to obtain the exact age at which the earthquake occurred.
【學位授予單位】：青海師范大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：P315.6
，

本文編號：2154965