發(fā)布時(shí)間：2017-12-27 23:31

  本文關(guān)鍵詞：甘肅民樂地區(qū)晚更新世以來的氣候變遷　出處：《中國(guó)地質(zhì)大學(xué)(北京)》2016年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 民樂地區(qū) 粒度 磁化率 環(huán)境變遷

【摘要】：民樂地區(qū),居祁連山北麓,位于河西走廊的中段,屬于氣候變化的敏感區(qū),而黃土又是記錄第四紀(jì)時(shí)期氣候變化的一大載體,因此對(duì)該地區(qū)典型的黃土剖面進(jìn)行取樣,分析,對(duì)于揭示該區(qū)第四紀(jì)時(shí)期氣候特征的變化和預(yù)測(cè)未來環(huán)境變遷有一定的借鑒意義。論文是在榆木山活動(dòng)斷裂1:5萬活動(dòng)斷層填圖項(xiàng)目基礎(chǔ)上完成的,本研究對(duì)甘肅民樂地區(qū)的冰溝臺(tái)和董家莊剖面進(jìn)行了實(shí)測(cè),取樣,并對(duì)磁化率和粒度的特征進(jìn)行了分析,恢復(fù)了研究區(qū)晚更新世以來的氣候環(huán)境變化特征及演化歷程,并和古里雅冰芯氧同位素曲線進(jìn)行了對(duì)比。得到以下結(jié)論:1,冰溝臺(tái)剖面和董家莊剖面所取的粒度和磁化率數(shù)據(jù)基本合理,均表現(xiàn)出干冷的氣候條件下,冬季風(fēng)強(qiáng)盛,沉積物粒度普遍較大,分選較差,對(duì)應(yīng)的磁化率較低。而暖濕氣候背景下,冬季風(fēng)較弱,沉積物的粒度較小,對(duì)應(yīng)的磁化率顯示也較高。并且兩剖面沉積物都屬于風(fēng)成沉積。2,研究區(qū)晚更新世以來的氣候經(jīng)歷了大概五個(gè)階段的變遷,從古至今依次為:溫暖濕潤(rùn)的晚更新世末次間冰期(122.10kaB.P.-91.36kaB.P.);(晚更新世末次間冰期晚期至末次冰期早期即91.36kaB.P.至70.23kaB.P.部分的地層及其沉積環(huán)境特點(diǎn)因?yàn)榭陀^原因未能獲得。);較冷的晚更新世末次冰期早期(約70.23kaB.P.-55.99kaB.P.);較溫暖的晚更新世末次冰期中期(約55.99kaB.P.-23.60kaB.P.);最為干冷的晚更新世末次冰期晚期的盛冰期(約23.60kaB.P.-13.78kaB.P.);最為溫暖濕潤(rùn)的全新世(13.78kaB.P.至今)。3,將冰溝臺(tái)剖面和董家莊剖面與古里雅冰芯所記錄的氧同位素曲線進(jìn)行對(duì)比,發(fā)現(xiàn)其中存在很好的對(duì)應(yīng)關(guān)系,從古至今依次對(duì)應(yīng)于古里雅冰芯氧同位素的第5(e,d,c,b),4,3,2,1階段。并且各個(gè)階段內(nèi)的一些峰值谷值也對(duì)應(yīng)良好,與古里雅冰芯氧同位素曲線上反映出來的冷暖事件有著很好的響應(yīng),其中10.22kaB.P.附近出現(xiàn)的冷事件對(duì)應(yīng)于新仙女木事件。發(fā)生在12kaB.P.附近的暖事件是對(duì)Bolling事件的響應(yīng),進(jìn)一步論證了民樂地區(qū)氣候的敏感性。
[Abstract]:Minle area, in the north of Qilian Mountains, located in the middle of the Hexi Corridor belongs to sensitive area of climate change, and loess is a big carrier to record the changes of Quaternary climate, so the typical loess profile in the area of sampling, analysis, to reveal the characteristics of Quaternary period climate change and forecast area has certain reference significance the future environmental changes. This paper is in the Yumushan fault 1:5 million active fault mapping project on the basis of this research on ice furrow Gansu folk area and Dong Village section were measured, sampling, and characteristics of magnetic susceptibility and grain size analyses, recovery in the study area and the evolution characteristics of late Pleistocene to climate change come, and Guliya Ice core oxygen isotope curve comparison. Get the following conclusions: 1, particle size and magnetization ice furrow profile and the profile of the Dong Village rate data is basically reasonable, showed dry climates, winter monsoon, sediment grain size is generally big, bad sorting, corresponding to the low magnetic susceptibility. In the warm and wet climate background, the winter wind is weak, the grain size of the sediment is smaller, and the corresponding magnetic susceptibility is also higher. And the sediments of the two section are all aeolian. 2, the study area since late Pleistocene climate has experienced about five stages of change, since ancient times as follows: warm and humid in the late Pleistocene and the last interglacial (122.10kaB.P.-91.36kaB.P.); Late Pleistocene (the last interglacial period to the last glacial period in early stage of 91.36kaB.P. to 70.23kaB.P. part of the stratigraphy and sedimentary environment characteristics because of objective reasons failed to get. ); cold during the last glacial period of late Pleistocene early (about 70.23kaB.P.-55.99kaB.P.); the middle warmer during the last glacial period of late Pleistocene (about 55.99kaB.P.-23.60kaB.P.); the late Pleistocene and late glacial ice cold period (about 23.60kaB.P.-13.78kaB.P.); the Holocene warm humid (13.78kaB.P. now). 3, compare the oxygen isotope curve of ice furrow profile and Dong Village section and the Guliya ice core records, found that there is a good correspondence between them, which corresponds to the Guliya ice core oxygen isotope fifth times (E, D, C, B, 4,3,2,1). And some of the values in each stage of peak valley also corresponds well with good response and reflected the Guliya ice core oxygen isotope curve and events, which appear near the cold event 10.22kaB.P. corresponds to the Younger Dryas event. The warm event near 12kaB.P. is a response to the Bolling event and further demonstrates the sensitivity of the climate in the Minle area.
【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：P532

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本文編號(hào)：1343671