【摘要】：深水斜坡沉積是深水沉積理論的主要組成部分之一,開展深水斜坡沉積研究工作具有重要的科學(xué)理論意義和實(shí)際應(yīng)用價(jià)值。本文利用地震沉積學(xué)的方法對(duì)南海北部深水斜坡沉積體系進(jìn)行了系統(tǒng)的研究和分析。首先,根據(jù)深水斜坡不同的物源供給背景將深水斜坡劃分為陸架斜坡、臺(tái)緣斜坡和火山斜坡。其次,根據(jù)深水斜坡與其它地貌單元的空間分布關(guān)系,將其進(jìn)一步劃分為不同的階次。最后,分別對(duì)不同背景下的深水斜坡體系沉積特征和演化模式分別進(jìn)行了系統(tǒng)的研究。結(jié)果表明,陸架斜坡具有多階次性,表現(xiàn)為階梯式沉積物輸送模式。一階陸架斜坡之上發(fā)育峽谷群體系和蠕變皺痕群體系,二階陸架斜坡主要發(fā)育單條大型海底峽谷體系。不同階次的斜坡侵蝕性表現(xiàn)出相似的先變強(qiáng)后變?nèi)醯奶攸c(diǎn),導(dǎo)致沉積物在不同階次斜坡上部以沉積物過路為主,下部以沉積為主。上一階次斜坡的下部沉積物聚集區(qū)是下一階次斜坡沉積物的主要供給區(qū),這是一種典型的階梯式搬運(yùn)過程。陸架斜坡的多階次性與階梯式沉積模式是由構(gòu)造基底格局和沉積物輸入共同決定的,并受到海平面變化的影響。陸架斜坡的階梯式沉積模式首次揭示了陸架斜坡沉積過程的宏觀分布規(guī)律,不僅具有重要的科學(xué)意義,而且對(duì)深水油氣勘探和海底工程建設(shè)具有重要的指導(dǎo)意義。本文揭示了碳酸鹽臺(tái)地臺(tái)緣沉積過程和斜坡沉積體系沉積模式。臺(tái)緣存在四種混合沉積機(jī)制,即原位混合、間斷混合、相緣混合以及與火山活動(dòng)相關(guān)的混合。在流花碳酸鹽臺(tái)地臺(tái)緣斜坡發(fā)育大型水道體系,水道充填沉積以灰?guī)r和泥巖組成的交互層為主,表現(xiàn)出間斷混合沉積的特征。進(jìn)一步研究表明水道混合沉積旋回受控于海平面變化,水道碳酸鹽巖充填發(fā)生在臺(tái)地生產(chǎn)力較高的高位期。西沙海域現(xiàn)代島礁碳酸鹽臺(tái)地臺(tái)緣斜坡發(fā)育由“沖溝群-滑坡凹槽-(等深流)水道-大型峽谷”組成的沉積物輸送網(wǎng)體系,將淺水島礁碳酸鹽臺(tái)地與深海盆地連接起來。該輸送體系是臺(tái)緣源匯過程中最為核心的輸送路徑,其揭示了臺(tái)緣斜坡存在復(fù)雜的由碳酸鹽巖碎屑組成的面狀濁流、塊體流、底流及其線狀濁流等沉積物輸送方式。臺(tái)前斜坡沉積物輸送過程揭示了島礁臺(tái)前蘊(yùn)含著頻發(fā)的沉積地質(zhì)災(zāi)害,這對(duì)于島礁建設(shè)決策具有一定的理論參考價(jià)值。此外,通過分析火山周緣層序地層,揭示了火山周緣斜坡沉積過程異于正常盆地沉積,主要原因是火山活動(dòng)改變了原有的源匯體系、可容納空間以及水動(dòng)力環(huán)境。根據(jù)巖石學(xué)特征和地震相分析,建立了火山周緣沉積演化模式,對(duì)火山周緣沉積歷史劃分為前火山丘階段、同火山噴發(fā)階段、間火山噴發(fā)階段、后火山丘階段等演化階段。該研究還揭示了火山作用大大改變了原有的盆地充填過程,這對(duì)盆地演化以及油氣成藏具有重要的影響�；鹕角鸺捌渲芫壭逼聦有蜓莼Ｊ骄哂兄匾某练e學(xué)意義和實(shí)際應(yīng)用價(jià)值。
[Abstract]:The deep-water slope deposition is one of the main components of the deep-water sedimentary theory, and it is of great theoretical and practical value to carry out the research of deep-water slope deposition. This paper studies and analyzes the deep-water slope deposition system in the north of the South China Sea by means of the method of seismic sedimentology. First, the deep-water slope is divided into a shelf slope, a stage edge slope, and a volcanic slope according to the different source supply background of the deep water slope. Secondly, according to the spatial distribution of the deep-water slope and other geomorphic units, it is further divided into different order times. Finally, the sedimentary characteristics and the evolution model of the deep-water slope system under different background are studied respectively. The results show that the slope of the continental shelf is of multi-order and is represented as a step-type sediment transport mode. The system of the canyon group and the creep-creping group system are developed on the slope of a step-order continental shelf, and the second-order shelf slope mainly develops a single large-scale submarine canyon system. The slope erosion of different order times shows the characteristics of similar first and weak first, leading to the sediment passing mainly at the upper part of the lower slope of the different order, and the lower part is dominated by the deposition. The lower sediment accumulation region of the next-order secondary slope is the main supply area of the next-order secondary-slope sediment, which is a typical step-by-step process. The multi-order and step-step sedimentary mode of the shelf slope is determined by the structure base pattern and the sediment input, and is affected by the sea level change. The step-step sedimentary model of the shelf slope is the first time to reveal the macro-distribution of the sedimentary process of the continental shelf, which not only has important scientific significance, but also has important guiding significance to the deep-water oil and gas exploration and the submarine engineering construction. The deposition process of the carbonate platform and the deposition mode of the slope deposition system are described in this paper. There are four mixed deposition mechanisms at the edge of the stage, namely, in-situ mixing, intermittent mixing, phase-edge mixing, and mixing associated with volcanic activity. A large-scale water channel system is developed on the slope of the platform edge of the flow-flower-carbonate platform, and the filling and deposition of the water channel is dominated by the interaction layer composed of the limestone and the mudstone, and the characteristics of the discontinuous mixed deposition are shown. Further research shows that the mixed sedimentary cycle of the water channel is controlled by the sea level change, and the carbonate filling of the water channel takes place in the high-order period with high platform productivity. The sediment transport network system, which is composed of the 鈥済ully group-landslide groove-(deep-flow) water channel-large-scale canyon鈥，

本文編號(hào)：2417717