遼河三角洲ZK2孔晚更新世以來的沉積記錄及全新世海侵期古氣候研究
發(fā)布時間：2018-09-18 16:47
【摘要】：遼河三角洲是我國四大河口三角洲之一,地跨中溫帶和暖溫帶,溫帶季風(fēng)性氣候,是氣候變化敏感區(qū)。建立遼河三角洲晚更新世以來的地層格架和物源區(qū)劃分,有助于深入認(rèn)識晚更新世以來渤海的地質(zhì)演化歷史;重建遼河三角洲全新世海侵期古氣候及氣候事件的區(qū)域?qū)Ρ妊芯?可以能夠更好地“以古論今”,為分析和預(yù)測未來氣候環(huán)境變化提供科學(xué)依據(jù)。ZK2孔是遼河三角洲迄今巖芯長度較長(41.4m)、取芯完整(取芯率平均為90.22%)、研究程度較深的地質(zhì)研究鉆孔,其全新世海侵期沉積的地層厚度較大,地層連續(xù)完整、巖性均一、無缺失,是研究遼河三角洲地區(qū)全新世海侵期環(huán)境演變和氣候變化不可多得的良好材料。本文在對ZK2孔沉積物的巖性、粒度、有孔蟲豐度及分子標(biāo)志物等資料的基礎(chǔ)上,結(jié)合精確的測年數(shù)據(jù)、海面變化等資料,并與其它鉆孔資料分析對比,構(gòu)建了遼河三角洲晚更新世33kyrBP以來的地層年代框架,恢復(fù)了遼河三角洲的沉積環(huán)境變遷歷史,并運(yùn)用稀土元素地球化學(xué)方法分析了晚更新世以來ZK2孔沉積物物源區(qū)的劃分及母巖組合;通過提取ZK2孔U3段沉積物地球化學(xué)元素、有機(jī)碳氮、孢粉及分子標(biāo)志物等古氣候代用指標(biāo),重建了遼河三角洲全新世海侵以來古氣候的演變過程,并結(jié)合國內(nèi)外其它典型區(qū)域古氣候研究成果,對比探討了遼河三角洲古氣候變化對典型氣候事件的響應(yīng)。通過研究區(qū)ZK2孔巖芯剖面的沉積特征(巖性、粒度、微體古生物、BIT),結(jié)合該鉆孔年代學(xué)資料及臨近鉆孔的研究成果,可將ZK2孔自下而上劃分U1-U4四個沉積段,即U1陸相(河道相),U2陸相(河漫灘相),U3海相(全新世海侵)和U4陸相(上三角洲平原相),并將U3段海相沉積自下而上進(jìn)一步詳細(xì)劃分為U31、U32、U33、U34、U35五個沉積層,分別對應(yīng)了河口灣相-淺海相-前三角洲相-三角洲前緣相-下三角洲平原相(潮坪相)。其沉積物粒度、有孔蟲及生物標(biāo)志物BIT等指標(biāo)在不同沉積環(huán)境中出現(xiàn)了較為明顯的變化,且變化趨勢相似,揭示了遼河三角洲晚更新世33kyr BP以來的海平面變化的沉積歷史,其中U3段沉積物(15.75m-2.65m)沉積連續(xù)無缺失,地層完整,測年數(shù)據(jù)可靠,較完整地反映了遼河三角洲9100 cal yr BP以來全新世海侵期的沉積歷史。ZK2孔沉積物REE組成垂向變化比較復(fù)雜,存在明顯的階段性。REE含量主要受控于母巖組成和化學(xué)風(fēng)化作用,存在明顯的粒級效應(yīng),Fe-Mn氧化物、TOC對稀土元素組成產(chǎn)生一定的影響,而重礦物對其影響不明顯。REE分餾參數(shù)(La/Sm)UCC和(Gd/Yb)UCC能夠消除沉積物粒度、TOC、Fe-Mn氧化物和化學(xué)風(fēng)化作用的影響,與重礦物相關(guān)性也不明顯,較好地保存了母巖的REE特征,是ZK2孔沉積物物源區(qū)分析的有效指標(biāo)。分析結(jié)果表明:研究區(qū)晚更新世33ka以來23.75-41.4m段沉積物具有與現(xiàn)代周邊多條河流母巖源區(qū)一致的特征;15.75-23.75m段沉積物的母巖組合與來自遼河、大遼河的物源區(qū)母巖組合比較接近;0-15.75段是全新世海侵期形成的沉積物,其物質(zhì)來源比較穩(wěn)定,與現(xiàn)代大遼河和大凌河的物源區(qū)母巖組合最接近。運(yùn)用常微量元素地球化學(xué)指標(biāo)、有機(jī)碳/總氮、孢粉組合和生物標(biāo)志物GDGTs等不同的氣候代用指標(biāo),逐一分析了ZK2孔U3段(2.65-15.75m)全新世海侵期各指標(biāo)的垂向變化及環(huán)境意義,從中挑選了對于氣候變化比較敏感的元素地球化學(xué)CIA指標(biāo)和基于GDGTs的MAAT指標(biāo),重建了遼河三角洲全新世海侵期9100yr BP以來古氣候的變化過程,研究表明其經(jīng)歷了全新世早期快速升溫期、中全新世早期溫暖濕潤期、中全新世晚期寒冷干燥期和全新世晚期溫涼干燥期四個階段;在全新世氣候演化過程中,在孔深14.2m、12.25m、10.65m、9.35m、8.15m和5.65m處存在6次明顯的降溫變干事件。通過與國內(nèi)外已有研究成果的區(qū)域?qū)Ρ确治?發(fā)現(xiàn)遼河三角洲全新世以來古氣候變化過程與國內(nèi)外相關(guān)研究的氣候變化吻合較好,只是在氣候波動發(fā)生的年代、事件發(fā)生的強(qiáng)度上存在差異。各氣候代用指標(biāo)對比研究發(fā)現(xiàn)CIA指標(biāo)和MAAT指標(biāo)較敏感,可以作為重建古氣候的敏感代用指標(biāo),而MAAT指標(biāo)在中全新世前對氣候的響應(yīng)要好于CIA指標(biāo)。
[Abstract]:The Liaohe Delta is one of the four major estuarine deltas in China. It spans the middle and warm temperate zones and has a temperate monsoon climate. It is sensitive to climate change. The regional comparative study of paleoclimate and climatic events during transgression can provide a scientific basis for the analysis and prediction of future climate and environmental changes. The sedimentary strata of the Holocene transgression period are thick, continuous and intact, with uniform lithology and no defect. It is a rare good material for studying the environmental evolution and climate change during the Holocene transgression period in the Liaohe River Delta area. The stratigraphic chronological framework of the Liaohe River Delta since 33 kyrBP in the Late Pleistocene has been constructed, and the history of sedimentary environment changes in the Liaohe River Delta has been restored. The provenance zones of pore ZK2 sediments since the Late Pleistocene have been analyzed by using REE geochemical methods. The paleoclimate evolution of Liaohe Delta since Holocene transgression was reconstructed by extracting the geochemical elements, organic carbon and nitrogen, sporopollen and molecular markers from the sediments of U3 member of hole ZK2. According to the sedimentary characteristics (lithology, grain size, micropaleontology, BIT) of the core section of hole ZK2 in the study area, and the geochronological data of the borehole and the research results of the adjacent boreholes, the four sedimentary sections of hole ZK2 can be divided from bottom to top, namely, U1 continental facies (channel facies), U2 continental facies (floodplain facies), U3 marine facies (Holocene). The marine sediments of U3 member are further divided into five sedimentary layers: U31, U32, U33, U34 and U35, which correspond to estuarine-shallow-sea facies-front Delta facies-front Delta facies-lower delta plain facies (tidal flat facies). There are obvious changes in different sedimentary environments, and the trend of change is similar. It reveals the sedimentary history of sea level changes in the Liaohe River Delta since 33 kyr BP in Late Pleistocene. The deposits of the U 3 member (15.75 m-2.65 m) are continuous and intact, the strata are complete, and the dating data are reliable, which reflects the 9100 cal yr BP in the Liaohe River Delta more completely. The REE content in the sediments of hole ZK2 is mainly controlled by the composition of parent rocks and chemical weathering, and has obvious grain size effect. Fe-Mn oxides and TOC have certain influence on the REE composition, while heavy minerals have no obvious effect on it. The fractionation parameters (La/Sm) UCC and (Gd/Yb) UCC can eliminate the grain size of sediments, and the influence of TOC, Fe-Mn oxides and chemical weathering is not obvious, and the REE characteristics of parent rocks are well preserved. The results show that the sedimentation of 23.75-41.4m section of sediments in the study area since 33 Ka of Late Pleistocene is an effective indicator for provenance analysis. The sediments in the 15.75-23.75 m section are similar to those in the Liaohe and Daliaohe provenances, and the 0-15.75 section is formed during the Holocene transgression, and the sediments in the 0-15.75 section are of stable material source, and are similar to those in the Daliaohe and Daling provenances. The vertical variations and environmental significance of the indicators of the Holocene transgression in the U3 segment of hole ZK2 (2.65-15.75 m) were analyzed by using the geochemical indices of the trace elements, organic carbon/total nitrogen, SPOROPOLLEN ASSEMBLAGES AND biomarkers GDGTs. The elements which are sensitive to climate change were selected. CIA index and MAAT index based on GDGTs have reconstructed the paleoclimate change process since the Holocene transgression of 9100yrBP in the Liaohe River Delta. The study shows that the Liaohe River Delta experienced four stages: the rapid warming period in the early Holocene, the warm and humid period in the early Miocene, the cold and dry period in the late Miocene and the warm and dry period in the late Holocene. In the process of climate evolution, there are six obvious cooling and changing events at the depth of 14.2m, 12.25m, 10.65m, 9.35m, 8.15m and 5.65m. By comparing with the existing research results at home and abroad, it is found that the paleoclimate change process of the Liaohe River Delta since Holocene is in good agreement with the climate change of the relevant research at home and abroad, but in the climate fluctuation. The results show that the CIA and MAAT indices are more sensitive than the CIA indices, and they can be used as sensitive proxy indices for reconstructing palaeoclimate, while the MAAT indices are better than the CIA indices before the Miocene.
【學(xué)位授予單位】：中國科學(xué)院研究生院(海洋研究所)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：P534.631;P532
本文編號：2248521
[Abstract]:The Liaohe Delta is one of the four major estuarine deltas in China. It spans the middle and warm temperate zones and has a temperate monsoon climate. It is sensitive to climate change. The regional comparative study of paleoclimate and climatic events during transgression can provide a scientific basis for the analysis and prediction of future climate and environmental changes. The sedimentary strata of the Holocene transgression period are thick, continuous and intact, with uniform lithology and no defect. It is a rare good material for studying the environmental evolution and climate change during the Holocene transgression period in the Liaohe River Delta area. The stratigraphic chronological framework of the Liaohe River Delta since 33 kyrBP in the Late Pleistocene has been constructed, and the history of sedimentary environment changes in the Liaohe River Delta has been restored. The provenance zones of pore ZK2 sediments since the Late Pleistocene have been analyzed by using REE geochemical methods. The paleoclimate evolution of Liaohe Delta since Holocene transgression was reconstructed by extracting the geochemical elements, organic carbon and nitrogen, sporopollen and molecular markers from the sediments of U3 member of hole ZK2. According to the sedimentary characteristics (lithology, grain size, micropaleontology, BIT) of the core section of hole ZK2 in the study area, and the geochronological data of the borehole and the research results of the adjacent boreholes, the four sedimentary sections of hole ZK2 can be divided from bottom to top, namely, U1 continental facies (channel facies), U2 continental facies (floodplain facies), U3 marine facies (Holocene). The marine sediments of U3 member are further divided into five sedimentary layers: U31, U32, U33, U34 and U35, which correspond to estuarine-shallow-sea facies-front Delta facies-front Delta facies-lower delta plain facies (tidal flat facies). There are obvious changes in different sedimentary environments, and the trend of change is similar. It reveals the sedimentary history of sea level changes in the Liaohe River Delta since 33 kyr BP in Late Pleistocene. The deposits of the U 3 member (15.75 m-2.65 m) are continuous and intact, the strata are complete, and the dating data are reliable, which reflects the 9100 cal yr BP in the Liaohe River Delta more completely. The REE content in the sediments of hole ZK2 is mainly controlled by the composition of parent rocks and chemical weathering, and has obvious grain size effect. Fe-Mn oxides and TOC have certain influence on the REE composition, while heavy minerals have no obvious effect on it. The fractionation parameters (La/Sm) UCC and (Gd/Yb) UCC can eliminate the grain size of sediments, and the influence of TOC, Fe-Mn oxides and chemical weathering is not obvious, and the REE characteristics of parent rocks are well preserved. The results show that the sedimentation of 23.75-41.4m section of sediments in the study area since 33 Ka of Late Pleistocene is an effective indicator for provenance analysis. The sediments in the 15.75-23.75 m section are similar to those in the Liaohe and Daliaohe provenances, and the 0-15.75 section is formed during the Holocene transgression, and the sediments in the 0-15.75 section are of stable material source, and are similar to those in the Daliaohe and Daling provenances. The vertical variations and environmental significance of the indicators of the Holocene transgression in the U3 segment of hole ZK2 (2.65-15.75 m) were analyzed by using the geochemical indices of the trace elements, organic carbon/total nitrogen, SPOROPOLLEN ASSEMBLAGES AND biomarkers GDGTs. The elements which are sensitive to climate change were selected. CIA index and MAAT index based on GDGTs have reconstructed the paleoclimate change process since the Holocene transgression of 9100yrBP in the Liaohe River Delta. The study shows that the Liaohe River Delta experienced four stages: the rapid warming period in the early Holocene, the warm and humid period in the early Miocene, the cold and dry period in the late Miocene and the warm and dry period in the late Holocene. In the process of climate evolution, there are six obvious cooling and changing events at the depth of 14.2m, 12.25m, 10.65m, 9.35m, 8.15m and 5.65m. By comparing with the existing research results at home and abroad, it is found that the paleoclimate change process of the Liaohe River Delta since Holocene is in good agreement with the climate change of the relevant research at home and abroad, but in the climate fluctuation. The results show that the CIA and MAAT indices are more sensitive than the CIA indices, and they can be used as sensitive proxy indices for reconstructing palaeoclimate, while the MAAT indices are better than the CIA indices before the Miocene.
【學(xué)位授予單位】：中國科學(xué)院研究生院(海洋研究所)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：P534.631;P532
【參考文獻(xiàn)】
相關(guān)期刊論文 前10條
1 劉東生;劉敏厚;吳子榮;陳承惠;;氣候標(biāo)志及中國第四紀(jì)地層的劃分[J];中國地質(zhì);1962年06期
2 李元芳,何希賢;渤海灣北岸表層沉積中的有孔蟲群及其生態(tài)環(huán)境[J];地理研究;1983年01期
3 覃軍干,吳國tD,鄭洪波,李從先;從孢粉、藻類化石組合看長江三角洲第一硬質(zhì)粘土層的成因及其古環(huán)境意義[J];第四紀(jì)研究;2004年05期
4 吳立;王心源;張廣勝;肖霞云;;安徽巢湖湖泊沉積物孢粉—炭屑組合記錄的全新世以來植被與氣候演變[J];古地理學(xué)報;2008年02期
5 吳建政;孫洪光;亓發(fā)慶;許振強(qiáng);;遼東灣北部晚更新世中期以來的地層結(jié)構(gòu)及環(huán)境演化[J];海洋科學(xué)進(jìn)展;2005年04期
6 宋云香,張永華,鄭延英,符文俠;遼東灣岸帶沉積物中的礦物特征與物質(zhì)來源[J];海洋通報;1987年04期
7 李珍,王永吉,劉振夏,徐小薇;東海沉積物中全新世中晚期氣候變化的孢粉學(xué)證據(jù)[J];海洋通報;2001年05期
8 楊子賡;第四紀(jì)海洋沉積高分辨地層劃分[J];海洋地質(zhì)動態(tài);2000年02期
9 藍(lán)先洪;河口三角洲沉積地球化學(xué)研究[J];海洋地質(zhì)動態(tài);1994年09期
10 黃慶福,蒼樹溪;從動物群化石看渤海晚第四紀(jì)的古環(huán)境演變史[J];海洋地質(zhì)與第四紀(jì)地質(zhì);1985年01期
相關(guān)會議論文 前1條
1 黃小忠;陳發(fā)虎;;博斯騰湖全新世氣候環(huán)境演化的孢粉記錄[A];中國地理學(xué)會2006年學(xué)術(shù)年會論文摘要集[C];2006年
，本文編號：2248521
本文鏈接：http://sikaile.net/shoufeilunwen/jckxbs/2248521.html
最近更新
教材專著
