發(fā)布時(shí)間：2018-05-05 15:11

  本文選題：柴達(dá)木盆地 + 風(fēng)成沉積　； 參考：《中國(guó)科學(xué)院研究生院(地球環(huán)境研究所)》2015年碩士論文

【摘要】：柴達(dá)木盆地位于青藏高原東北部,為祁連山、阿爾金山和昆侖山所環(huán)繞,盆地西北部緊鄰極端干旱的塔里木盆地,東南部位于西風(fēng)環(huán)流和東亞季風(fēng)的結(jié)合處。盆地的東南部、西南緣和中部的三湖地區(qū)風(fēng)成沉積和風(fēng)蝕地貌十分發(fā)育,這些風(fēng)成沉積記錄了柴達(dá)木盆地風(fēng)沙活動(dòng)歷史與氣候演化信息。研究柴達(dá)木盆地風(fēng)成沉積有助于研究西北內(nèi)陸風(fēng)沙活動(dòng)與西風(fēng)、季風(fēng)環(huán)流系統(tǒng)及全球氣候變化的關(guān)系和驅(qū)動(dòng)機(jī)制。本文以前人在柴達(dá)木盆地東部風(fēng)成沉積剖面的研究資料為基礎(chǔ),對(duì)盆地東南部都蘭縣的香日德(XRD)和夏日哈(XRH)風(fēng)成沉積剖面開(kāi)展詳細(xì)的年代學(xué)、粒度、色度、地球化學(xué)等氣候代用指標(biāo)的分析,并與古里雅冰芯、西風(fēng)區(qū)湖泊等記錄進(jìn)行對(duì)比,初步得出以下結(jié)論:(1)光釋光(OSL)和加速器質(zhì)譜儀(AMS)14C測(cè)年結(jié)果表明,XRD剖面形成于6.25~1.33 ka,XRH剖面形成于14.13~5.83 ka,構(gòu)成末次冰消期以來(lái)的時(shí)間序列。(2)粒度分析表明XRD剖面平均粒徑值為32.48μm,砂質(zhì)古土壤和砂質(zhì)黃土的分選要優(yōu)于風(fēng)成砂;XRH剖面平均值194.80μm,風(fēng)成砂分選優(yōu)于砂質(zhì)古土壤。兩個(gè)剖面的物源均表現(xiàn)出近源和遠(yuǎn)源疊加形成,為典型風(fēng)成沉積。其中63μm粗顆粒組分含量可以與古里雅冰芯和西風(fēng)區(qū)湖泊進(jìn)行對(duì)比,揭示盆地東部末次冰消期以來(lái)的氣候演化與全球氣候記錄具有一致性。(3)地球化學(xué)數(shù)據(jù)顯示XRD剖面處于低等化學(xué)風(fēng)化和中等化學(xué)風(fēng)化之間,部分砂質(zhì)古土壤的CIA值高于洛川古土壤平均值;XRH剖面處于低等化學(xué)風(fēng)化階段,砂質(zhì)古土壤的CIA平均值低于洛川黃土平均值。(4)柴達(dá)木盆地風(fēng)成沉積記錄顯示盆地東部14.13~10.62 ka期間,濕度較大,風(fēng)沙活動(dòng)較弱;10.62~7.16 ka階段,濕度和溫度均降低,風(fēng)砂活動(dòng)強(qiáng)烈;7.16~5.83 ka期間,快速增溫增濕,成壤作用加強(qiáng),風(fēng)沙活動(dòng)迅速減弱;5.83~1.33ka階段,處于較高溫度和濕度的適宜期,風(fēng)成砂固定成壤�！�4.2 ka”事件在柴達(dá)木盆地東部風(fēng)成沉積記錄中表現(xiàn)突出,4.16~3.8 ka階段地層中石英微形態(tài)主要呈擦痕和“V”形坑,指示這次突變事件為洪泛事件,并非風(fēng)沙強(qiáng)烈活動(dòng)事件,這對(duì)于理解晚全新世氣候不穩(wěn)定性和古人類(lèi)文化興衰具有重要意義。(5)柴達(dá)木盆地東部風(fēng)成沉積記錄的氣候變化不同于石筍和太陽(yáng)輻射強(qiáng)度曲線(xiàn)的變化趨勢(shì),與古里雅冰芯氧同位素、博斯騰湖的有效濕度以及克魯克湖的孢粉記錄變化趨勢(shì)相一致。氣候變化呈現(xiàn)出早全新世干旱,中晚全新世濕潤(rùn)的特點(diǎn),揭示盆地東部末次冰消期以來(lái)氣候變化模式更符合“西風(fēng)模式”,而非季風(fēng)區(qū)氣候變化特征。
[Abstract]:The Qaidam Basin is located in the northeast of the Qinghai-Xizang Plateau, surrounded by the Qilian Mountains, the Aljin Mountain and the Kunlun Mountains. The northwestern part of the basin is adjacent to the extremely arid Tarim Basin, and the southeast is located at the junction of the westerly circulation and the East Asian monsoon. The aeolian deposits and wind-eroded landforms are well developed in the southeastern part of the basin, the southwest margin and the three lakes in the central part of the basin. These aeolian deposits record the historical and climatic evolution information of the aeolian sand activity in the Qaidam Basin. The study of eolian deposition in Qaidam Basin is helpful to study the relationship and driving mechanism between the eolian sand activity in northwest China and the westerly monsoon circulation system and global climate change. Based on previous studies on the eolian sedimentary profiles in the eastern Qaidam Basin, detailed chronology, granularity, chromaticity of the XRD and XRH) sections of Dulan County, southeastern Qaidam Basin, have been carried out in this paper. Analysis of climate proxy indicators such as geochemistry, and comparison with the records of the Guliya ice core and lakes in the westerly region, The preliminary conclusions are as follows: (1) OSL) and AMS / 14C dating results show that the XRD profile was formed in 6.25 ~ 1.33 ka- XRH section at 14.135.83 ka. the particle size analysis shows that the average particle size of XRD profile is the same as that of the time series since the last ice depletion period. The value is 32.48 渭 m. The separation of sandy paleosol and sandy loess is better than the average value of XRH profile of aeolian sand (194.80 渭 m), and that of aeolian sand is better than that of sandy paleosol. The provenance of the two sections is characterized by near-source and far-source stacking, which is a typical aeolian deposit. The contents of 63 渭 m coarse particles can be compared with those of the Guliya ice core and the lakes in the westerly region. It is revealed that the climatic evolution in the eastern part of the basin is consistent with the global climate record. The geochemical data show that the XRD profile is between low chemical weathering and moderate chemical weathering. The CIA value of some sandy paleosols is higher than the average value of Luochuan paleosol. The CIA average of sandy paleosol is lower than that of Luochuan loess. During the period of higher humidity and weaker wind sand activity, both humidity and temperature decreased. During the period of 7.165.83 ka, the rapid warming and humidification, the strengthening of earth-forming process, the rapid weakening of wind-sand activity at 5.83 ~ 1.33ka, and the suitable period of higher temperature and humidity were observed. The "4.2 ka" event in the aeolian sedimentary records of the eastern Qaidam Basin shows that the quartz micromorphology in the strata of stage 4.16 ~ 3.8 ka is mainly grazed and "V" shaped, indicating that this sudden event is a flood event. It is not a violent event of wind and sand, This is of great significance for understanding the climatic instability of the late Holocene and the rise and fall of paleo-human culture.) the climatic changes recorded in the east-Qaidam basin are different from those of stalagmite and solar radiation intensity curves. It is consistent with the oxygen isotopes of Guliya ice core, the available humidity of Bosten Lake and the change trend of pollen records of Lake Kruke. The climate change shows the characteristics of early Holocene drought and middle and late Holocene wetness, which reveals that the climate change model in the eastern part of the basin is more in line with the "westerly model" than in the monsoon region.
【學(xué)位授予單位】：中國(guó)科學(xué)院研究生院(地球環(huán)境研究所)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：P532;P534.63

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