东海内陆架泥质沉积区EC2005孔碎屑矿物特征及其物源意义

发布时间：2018-03-07 21:52

  本文选题：矿物　切入点：物源　出处：《中国石油大学(华东)》2015年硕士论文　论文类型：学位论文

【摘要】：为探讨东海内陆架17.3Ka BP以来的重矿物含量变化特征及其对物源与环境的指示意义,对东海内陆架南部泥质沉积中心EC2005孔岩心沉积物不同粒级中的重矿物进行了鉴定和分析。结果表明:(1)在0.031—0.063mm和0.063—0.25mm粒级的重矿物中,片状矿物、磁铁矿、角闪石族矿物、绿帘石族矿物、白云石、辉石族矿物、变质矿物、蚀变矿物、岩屑和自生黄铁矿占重矿物总数的96.00%以上,但其相对含量变化很大,重矿物含量较高的层位均出现在自生黄铁矿含量较高的层段;(2)由于细粒物质对水动力的变化更为敏感,且矿物本身的理化性质对细粒级矿物搬运和沉积作用的控制程度加大,使0.031—0.063mm粒级和0.063—0.25mm粒级中的重矿物无论在平均含量还是在垂向上的含量变化差别明显;相对于0.063—0.25mm粒级中的重矿物含量变化特征,0.031—0.063mm粒级沉积物中含有较高含量的普通角闪石、电气石、榍石、绿帘石、白云石、磷灰石、橄榄石和普通辉石,而片状矿物和自生黄铁矿含量较少,其他矿物含量区分不明显;在0.25mm粒级的全岩样组分中,自生黄铁矿、自生石膏、生物碎屑和植物碎屑出现层段集中,含量变化明显。根据不同粒级的各重矿物分布特征,将岩心划分为Ⅰ—Ⅴ五个沉积层段。结合碎屑单矿物特征、粒度参数、地球化学、AMS14C年代及西太平洋海平面变化等数据,对物源和水动力条件的分析表明:自末次冰消期以来,东海内陆架EC2005孔岩心沉积物所反映的沉积水动力环境变化趋势由弱(17.3—15.6Ka BP)—强(16.4—15.6Ka BP)—较强(15.6—13.5Ka BP)—极弱(13.5—13.1Ka BP)—强(13.1—12.3Ka BP)—弱(12.3—0Ka BP),其中在12.3—4.7Ka BP时期,上升流发育,而在4.7—0Ka BP时期,上升流强度减弱,沿岸流强度增强;沉积物源的分析表明东海内陆架EC2005孔岩心沉积物源主要为长江,其次还受到瓯江等近源河流所携带物质的影响,特别在陆相沉积时期(13.1—17.3Ka BP),岩心沉积矿物数据反映出强烈的长江物源信号。
[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，

本文编号：1581121