本文選題：礦物　切入點：物源　出處：《中國石油大學(xué)(華東)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：為探討東海內(nèi)陸架17.3Ka BP以來的重礦物含量變化特征及其對物源與環(huán)境的指示意義,對東海內(nèi)陸架南部泥質(zhì)沉積中心EC2005孔巖心沉積物不同粒級中的重礦物進(jìn)行了鑒定和分析。結(jié)果表明:(1)在0.031—0.063mm和0.063—0.25mm粒級的重礦物中,片狀礦物、磁鐵礦、角閃石族礦物、綠簾石族礦物、白云石、輝石族礦物、變質(zhì)礦物、蝕變礦物、巖屑和自生黃鐵礦占重礦物總數(shù)的96.00%以上,但其相對含量變化很大,重礦物含量較高的層位均出現(xiàn)在自生黃鐵礦含量較高的層段;(2)由于細(xì)粒物質(zhì)對水動力的變化更為敏感,且礦物本身的理化性質(zhì)對細(xì)粒級礦物搬運(yùn)和沉積作用的控制程度加大,使0.031—0.063mm粒級和0.063—0.25mm粒級中的重礦物無論在平均含量還是在垂向上的含量變化差別明顯;相對于0.063—0.25mm粒級中的重礦物含量變化特征,0.031—0.063mm粒級沉積物中含有較高含量的普通角閃石、電氣石、榍石、綠簾石、白云石、磷灰石、橄欖石和普通輝石,而片狀礦物和自生黃鐵礦含量較少,其他礦物含量區(qū)分不明顯;在0.25mm粒級的全巖樣組分中,自生黃鐵礦、自生石膏、生物碎屑和植物碎屑出現(xiàn)層段集中,含量變化明顯。根據(jù)不同粒級的各重礦物分布特征,將巖心劃分為Ⅰ—Ⅴ五個沉積層段。結(jié)合碎屑單礦物特征、粒度參數(shù)、地球化學(xué)、AMS14C年代及西太平洋海平面變化等數(shù)據(jù),對物源和水動力條件的分析表明:自末次冰消期以來,東海內(nèi)陸架EC2005孔巖心沉積物所反映的沉積水動力環(huán)境變化趨勢由弱(17.3—15.6Ka BP)—強(qiáng)(16.4—15.6Ka BP)—較強(qiáng)(15.6—13.5Ka BP)—極弱(13.5—13.1Ka BP)—強(qiáng)(13.1—12.3Ka BP)—弱(12.3—0Ka BP),其中在12.3—4.7Ka BP時期,上升流發(fā)育,而在4.7—0Ka BP時期,上升流強(qiáng)度減弱,沿岸流強(qiáng)度增強(qiáng);沉積物源的分析表明東海內(nèi)陸架EC2005孔巖心沉積物源主要為長江,其次還受到甌江等近源河流所攜帶物質(zhì)的影響,特別在陸相沉積時期(13.1—17.3Ka BP),巖心沉積礦物數(shù)據(jù)反映出強(qiáng)烈的長江物源信號。
[Abstract]:In order to study the variation characteristics of heavy mineral content since 17.3 Ka BP in the inland shelf of the East China Sea and its indicative significance to the provenance and environment, The heavy minerals in the EC2005 core sediments in the south of the East China Sea are identified and analyzed. The results show that in the grain-grade heavy minerals of 0.031-0.063mm and 0.063-0.25mm, there are flake minerals, magnetite minerals, hornblende family minerals. More than 96.00% of the total amount of heavy minerals are composed of green curtain group minerals, dolomite, pyroxene minerals, metamorphic minerals, altered minerals, cuttings and authigenic pyrite, but their relative contents vary greatly. The layers with higher content of heavy minerals appear in the strata with higher content of authigenic pyrite) because fine particles are more sensitive to hydrodynamic changes, and the physical and chemical properties of minerals have greater control over the transport and deposition of fine-grained minerals. The variation of heavy minerals in 0.031-0.063mm grain-grade and 0.063-0.25mm grain-grade is obviously different both in average content and in vertical direction, compared with 0.063-0.25mm grain-grade grain-grade sediment, 0.031-0.063mm grain-grade sediment contains relatively high content of common amphibole and tourmaline. Sphene, verdite, dolomite, apatite, olivine and ordinary pyroxene, while flake minerals and authigenic pyrite are less than other minerals. Bioclastic and phytoclastic layers are concentrated, and their contents change obviously. According to the distribution characteristics of various heavy minerals in different grain levels, the core is divided into five sedimentary layers 鈪，

本文編號：1581121