湖相深水細(xì)粒物質(zhì)的混合沉積作用探討
發(fā)布時(shí)間:2018-05-30 23:28
本文選題:細(xì)粒物質(zhì) + 混合沉積; 參考:《古地理學(xué)報(bào)》2017年02期
【摘要】:沉積物的混合是自然界的普遍現(xiàn)象,湖盆中廣泛發(fā)育的深水細(xì)粒沉積巖本身就是一類混積巖。以東營凹陷古近系沙河街組三段下亞段—沙河街組四段上亞段細(xì)粒沉積巖為研究對(duì)象,通過厘米級(jí)巖心觀察描述、小型沉積構(gòu)造解剖、巖石薄片觀察、X射線衍射全巖礦物分析及微量元素測試等方法,研究細(xì)粒物質(zhì)的產(chǎn)出狀態(tài)和混合方式;分析湖盆流體、氣候及水體性質(zhì)對(duì)細(xì)粒物質(zhì)遷移、混合、沉積的控制作用,嘗試探討細(xì)粒物質(zhì)的混合沉積機(jī)制。結(jié)果表明,湖相深水細(xì)粒沉積巖既有物質(zhì)成分上的混合,也有結(jié)構(gòu)的混合,且在宏觀與微觀的不同尺度均存在混合;混合沉積作用有均勻混合、紋層疊置混合、不均勻團(tuán)塊狀混合等類型。紋層疊置混合沉積是最主要的混合沉積方式,依據(jù)紋層接觸關(guān)系、所占比例及礦物產(chǎn)出狀態(tài)可分為泥砂—灰紋層疊置混合型、泥—灰紋層疊置混合型、泥砂粒序—灰紋層疊置混合型、灰—泥—云紋層疊置混合型等。湖相深水細(xì)粒物質(zhì)的混合沉積作用類型多且往往受多個(gè)因素同時(shí)控制,氣候及水動(dòng)力條件是控制細(xì);旌铣练e巖發(fā)育的最主要因素,不同流體(濁流和底流)作用下的細(xì)粒沉積物混合作用存在差異。氣候引起湖水性質(zhì)變化及水體分層,從而控制不同類型細(xì)粒物質(zhì)的絮凝沉降及化學(xué)沉積。不同構(gòu)造部位、不同水體深度的混合作用不同;相同構(gòu)造部位在垂向上也存在混合沉積方式的差異。
[Abstract]:Sediment mixing is a common phenomenon in nature. Deep-water fine-grained sedimentary rocks, which are widely developed in the lake basin, are a kind of migmatite. The fine sedimentary rocks of the lower submember of the third member of the Shahejie formation of Paleogene and the upper submember of the fourth member of the Shahejie formation in Dongying Sag are taken as the research object. The observation and description of the centimeter core are used to dissect the small sedimentary structure. X-ray diffraction analysis of whole rock minerals and trace element measurement were used to study the state and mixing of fine particles, and to analyze the migration and mixing of fine-grained materials by the fluid, climate and water properties of the lake basin. The mechanism of mixed deposition of fine-grained materials is discussed. The results show that the lacustrine deep-water fine-grained sedimentary rocks are mixed in both material composition and structure, and are mixed at different scales of macroscopical and microcosmic. Heterogeneous lumps, block mixing, etc. According to the contact relation of grain layer, the proportion and the state of mineral production can be divided into mud sand and gray grain superposition mixed type, mud and gray grain stacking mixed type, according to the contact relation of grain layer, it is the most important mixed deposition method. The mud-sand sequence-gray-grain stacked mixed type, the gray-mud-moire stacked mixed type, etc. There are many types of mixed sedimentary processes of lacustrine deep-water fine-grained materials and are often controlled by multiple factors at the same time. Climate and hydrodynamic conditions are the main factors controlling the development of fine-grained mixed sedimentary rocks. There are differences in the mixing of fine sediments under the action of different fluids (turbidity current and bottom current). Climatic changes of lake water properties and water stratification control the flocculation sedimentation and chemical deposition of different types of fine particles. The mixing processes of different structures and different water depths are different, and the mixing and deposition patterns of the same structures are also different in vertical direction.
【作者單位】: 中國石油大學(xué)(華東)地球科學(xué)與技術(shù)學(xué)院;中國石化勝利油田公司勘探開發(fā)研究院;中國石化勝利油田博士后流動(dòng)工作站;
【基金】:國家自然科學(xué)基金項(xiàng)目(編號(hào):41372107) 國家重點(diǎn)基礎(chǔ)研究發(fā)展計(jì)劃(973)項(xiàng)目(編號(hào):2014CB239102)資助~~
【分類號(hào)】:P512.2
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本文編號(hào):1957306
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