【摘要】：內(nèi)蒙古河套盆地處于構(gòu)造沉降區(qū),第四紀(jì)以來河流沉積作用顯著,沉積物保存完好,是研究沉積環(huán)境的良好區(qū)域。由于平原區(qū)地勢(shì)平坦,受人類影響強(qiáng)烈,第四紀(jì)地質(zhì)調(diào)查工作存在填圖理論、方法、過程以及創(chuàng)新表達(dá)等方面的不足。地質(zhì)工作者面臨著填什么、怎么填、地質(zhì)圖件如何表達(dá)的棘手問題。通過遙感解譯獲取研究區(qū)表層地貌特征,應(yīng)用淺鉆揭露(槽型鉆、沖擊鉆)獲得淺層沉積物、沉積組合、沉積構(gòu)造的原始資料。結(jié)合測(cè)年數(shù)據(jù),確定不同期次河流的沉積亞相及沉積微相。將沉積相劃分引入到第四紀(jì)地質(zhì)調(diào)查工作,為其提供理論支撐和創(chuàng)新表達(dá)方法。經(jīng)過以上研究得出以下認(rèn)識(shí):1、通過對(duì)不同深度鉆孔中沉積物及沉積組合特征研究,結(jié)合測(cè)年數(shù)據(jù)依次確定全新世以來不同時(shí)期河流的河道亞相、堤壩亞相(天然堤微相)、泛濫平原亞相;建立了全新世以來河流沉積模式,為后期第四紀(jì)地質(zhì)調(diào)查提供理論指導(dǎo);通過對(duì)野外沉積相劃分工作的總結(jié),提出了研究區(qū)獨(dú)有的沉積相判斷標(biāo)準(zhǔn),為第四紀(jì)地質(zhì)調(diào)查工作中填圖單元的確定提供了依據(jù)。2、通過對(duì)研究區(qū)鉆孔FX1A和FX2A中樣品進(jìn)行光釋光和14C年代測(cè)試,得到地下1-2 m深度處沉積物年齡值為3.920±0.03 ka;7.14-7.5 m深度處沉積物年齡值為7.99±0.29 ka;7.79-7.99 m深度處沉積物年齡值為10.79±0.73 ka。為沉積亞相和沉積微相的確定及填圖工作的開展提供了精確的時(shí)間約束。3、通過遙感解譯、路線地質(zhì)調(diào)查、淺鉆揭露(槽型鉆、沖擊鉆)的手段,結(jié)合沉積相的劃分確定了研究區(qū)1:50000第四紀(jì)地質(zhì)圖填圖單元;采用“逐步逼近”原則確定地質(zhì)界線并以“時(shí)代(地層)+成因+沉積相”作為填圖單位的表達(dá)方式;將典型鉆孔柱狀圖表達(dá)于相應(yīng)沉積單元內(nèi),精確表達(dá)了地質(zhì)體信息,并豐富了地質(zhì)圖內(nèi)容。該方法為具有相似地質(zhì)條件的平原區(qū)第四紀(jì)地質(zhì)調(diào)查工作提供了示范,具有一定的推廣價(jià)值。為不同成因類型的盆地區(qū)第四紀(jì)地質(zhì)調(diào)查工作指出了新的方向。
[Abstract]:Hetao Basin in Inner Mongolia is located in the tectonic subsidence area. Since Quaternary, the fluvial sedimentation has been remarkable and the sediment is well preserved. It is a good area for the study of sedimentary environment. Because the plain area is flat and strongly influenced by human beings, there are some shortcomings in Quaternary geological survey, such as mapping theory, method, process and innovative expression. Geologists are faced with thorny questions about what to fill, how to fill it, and how to express geological maps. The surface geomorphological characteristics of the study area are obtained by remote sensing interpretation, and the original data of shallow sediment, sedimentary assemblage and sedimentary structure are obtained by shallow drilling exposure (trough drilling, impact drilling). Based on the dating data, the sedimentary subfacies and sedimentary microfacies of different stages of rivers are determined. The division of sedimentary facies is introduced into Quaternary geological survey to provide theoretical support and innovative expression method. Through the above research, the following understandings are obtained: 1. Through the study of the characteristics of sediments and sedimentary assemblages in different depths of drilling, combined with dating data, the river subfacies, dike subphase (natural embankment microphase) and flood plain subphase of rivers in different periods since Holocene are determined in turn, and the river sedimentary model since Holocene is established, which provides theoretical guidance for the late Quaternary geological survey. Based on the summary of the division of sedimentary facies in the field, the unique criteria for judging sedimentary facies in the study area are put forward, which provides the basis for the determination of the mapping unit in the Quaternary geological survey. 2. Through the photoluminescence and 14C dating tests of the samples in the drilling FX1A and FX2A in the study area, the age value of the sediment at the depth of 1 m and 2 m underground is 3.920 鹵0.03 ka;. The sediment age value at 7.14 鈮，

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