【摘要】：海岸帶沖積扇作為海陸過渡帶中的重要沉積地貌單元,蘊(yùn)藏有豐富的"陸-海-氣"耦合作用及其古地理環(huán)境變化信息。本文選取福建海壇島北部的海岸帶沖積扇(大砂山)為研究對象,在大砂山表層布設(shè)6條累計長度約700m的探地雷達(dá)(GPR)測線,結(jié)合剖面觀察解譯以獲取大砂山內(nèi)部沉積構(gòu)造和沉積序列信息。結(jié)果顯示:GPR探測圖像很好地顯示約20m深度范圍內(nèi)的沉積構(gòu)造信息,可以識別出9種沉積構(gòu)造雷達(dá)相,這些雷達(dá)相總體上反映了海岸帶沖積扇以泥石流和溝谷洪流為主、并交替有海岸風(fēng)沙作用的沉積構(gòu)造特征。綜合三維沉積構(gòu)造信息可知,大砂山為兩個沖積扇側(cè)向連接而成的復(fù)合體。結(jié)合野外地質(zhì)地貌考察和砂樣粒度分析,認(rèn)為該沖積扇發(fā)育過程可分為四個階段:(1)晚更新世末次間冰期,海岸帶老紅砂堆積形成"紅色沙漠";(2)晚冰期時頻發(fā)的暴雨洪水,攜帶南部山區(qū)的風(fēng)化碎屑物質(zhì)堆積在海岸帶形成了沖積扇主體,并覆蓋在老紅砂剝蝕面上;(3)全新世早中期氣候濕潤,河流下切侵蝕沖積扇,形成大砂山基本形態(tài);(4)全新世晚期,全球氣候轉(zhuǎn)冷,海岸風(fēng)沙作用興起,塑造成為現(xiàn)代大砂山的地貌特征。
[Abstract]:Coastal alluvial fan, as an important sedimentary geomorphological unit in the sea-land transitional zone, contains abundant information of "land-sea-air" coupling and paleogeographic changes. In this paper, the coastal alluvial fan (Dashanshan) in the northern part of Haitan Island, Fujian Province, is chosen as the object of study. Six ground penetrating radar (GPR) lines with a cumulative length of about 700m are set up on the surface of Dashanshan. The information of sedimentary structure and sequence in Dashanshan mountain can be obtained by cross-section observation and interpretation. The results show that 9 kinds of sedimentary structural radar facies can be identified from GPR images, which reflect that debris flow and gully flood are dominant in alluvial fan of coastal zone, and that the sedimentary tectonic information in the depth of about 20m can be identified very well, and that 9 kinds of sedimentary structural radar facies can be identified in this paper. And alternately has the sedimentary structural characteristics of coastal aeolian action. According to the information of three-dimensional sedimentary structure, Dashanshan is a complex formed by lateral connection of two alluvial fans. Combined with the geological and geomorphological investigation in the field and the grain size analysis of sand samples, the development process of the alluvial fan can be divided into four stages: (1) the late Pleistocene interglacial period, the old red sand accumulation in the coastal zone formed the "red desert"; (2) the heavy rain and flood occurred frequently in the late glacial period, and the weathering debris from the southern mountain area accumulated in the coastal zone to form the main body of alluvial fan, which was covered on the eroded surface of the old red sand; (3) in the early and middle Holocene, the climate was moist, the rivers cut down and eroded alluvial fan, and formed the basic form of the big sand mountain; (4) in the late Holocene, the global climate turned cold and the coastal wind and sand action rose, which became the physiognomy characteristic of the modern big sand mountain.
【作者單位】： 福建師范大學(xué)地理科學(xué)學(xué)院;福建省濕潤亞熱帶山地生態(tài)重點實驗室;福建師范大學(xué)地理研究所;
【基金】：國家自然科學(xué)基金(編號:41271031和41301012) 國家自然科學(xué)基金委員會——福建省人民政府促進(jìn)海峽兩岸科技合作聯(lián)合基金(編號:U1405231) 福建省自然科學(xué)基金(編號:2017J01460)聯(lián)合資助的成果
【分類號】：P736.21
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本文編號：2463158