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1.
东海陆架北部表层细粒级沉积物的级配及意义 总被引:3,自引:3,他引:3
本文依据东海陆架北部 2 3个表层沉积物样品的粒度分析资料 ,就东海陆架北部表层细粒级沉积物的级配及意义进行了研究。结果表明 ,研究区表层沉积物中细粒级部分以 <0 .0 16 mm为优势粒级 ,可占到总细粒级沉积物的 75 %以上。济州岛西南泥质区以细于 0 .0 0 8mm粒级的沉积物占据优势 ,长江口泥质区则以 <0 .0 16 mm粒级的沉积物为主 ,两泥质区细粒级沉积物的级配很不相同 相似文献
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利用浸出试验方法,对火电厂粉煤灰进行浸出特性的测定,对其有害特性进行鉴别并分析其浸出规律,从而为地下水受粉煤灰排水影响后的水质预测、堆灰场选址、环境影响评价提供依据. 相似文献
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粘粒含量对南京粉细砂液化影响的试验研究 总被引:16,自引:1,他引:16
南京粉细砂是一种以片状颗粒成分为主的粉细砂,与通常的圆形颗粒石英砂有一定区别,片状颗粒成分使得南京粉细砂具有各向异性的性质。通过对不同粘粒含量的南京粉细砂进行液化试验,分析其试验结果发现:对于粘粒含量ρc=5%、10%和15%三种情况,在均压固结情况下,当南京粉细砂达到初始液化时,采用变形标准和孔压标准是一致的;而偏压固结时,只能采用变形标准作为南京粉细砂达到初始液化的标准,此时振动孔压仅达到围压的50%-70%。粘粒含量对南京粉细砂的抗液化强度影响很大,随粘粒含量增加,在不同固结比时,其抗液化强度并不是单调变化,而是在粘粒含量ρc=10%左右处于一个低谷,其抗液化强度最低。 相似文献
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广西金牙金矿床百逢组沉积特征及其与金矿的关系 总被引:2,自引:2,他引:2
广西金牙金矿产于中三叠统百逢组中 ,矿区的百逢组为一套陆源碎屑浊积岩 ,既有阵发性高密度浊流引起的浊积扇体系 ,又有稳定低密度浊流引起的鲍马序列。百逢组下段为浊积扇体系 ,中段及上段为鲍马序列 ,一般不全 ,其中d、e段最发育 ,其次为c、b段。金矿化出现在砂泥混积的百逢组中段。矿体位于鲍马序列段 ,尤其是de和cde组合段 ,岩石为富含有机质的泥质与粉砂的混积岩 ,属远端浊积岩。其中 ,钙质泥岩和粉砂质泥岩是最有利的矿化围岩。主要载金矿物毒砂和黄铁矿呈自形晶出现。矿体的有机碳含量高于相邻围岩的有机碳含量 ,与运移烃类的叠加有关。金品位随有机碳含量的增加而增加 ,有机质也是有用的金的载体。富含有机质的浊积岩是浊积岩型金矿床形成的有利条件。 相似文献
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The alluvial architecture of a suspended sediment dominated meandering river: the Río Bermejo,Argentina 下载免费PDF全文
Gregory H. Sambrook Smith James L. Best Jessica Z. Leroy Oscar Orfeo 《Sedimentology》2016,63(5):1187-1208
The alluvial architecture of fine‐grained (silt‐bed) meandering rivers remains poorly understood in comparison to the extensive study given to sand‐bed and gravel‐bed channels. This paucity of knowledge stems, in part, from the difficulty of studying such modern rivers and deriving analogue information from which to inform facies models for ancient sediments. This paper employs a new technique, the parametric echosounder, to quantify the subsurface structure of the Río Bermejo, Argentina, which is a predominantly silt‐bed river with a large suspended sediment load. These results show that the parametric echosounder can provide high‐resolution (decimetre) subsurface imaging from fine‐grained rivers that is equivalent to the more commonly used ground‐penetrating radar that has been shown to work well in coarser‐grained rivers. Analysis of the data reveals that the alluvial architecture of the Río Bermejo is characterized by large‐scale inclined heterolithic stratification generated by point‐bar evolution, and associated large‐scale scour surfaces that result from channel migration. The small‐scale and medium‐scale structure of the sedimentary architecture is generated by vertical accretion deposits, bed sets associated with small bars, dunes and climbing ripples and the cut and fill from small cross‐bar channels. This style of alluvial architecture is very different from other modern fine‐grained rivers reported in the literature that emphasize the presence of oblique accretion. The Río Bermejo differs from these other rivers because it is much more active, with very high rates of bank erosion and channel migration. Modern examples of this type of highly active fine‐grained river have been reported rarely in the literature, although ancient examples are more prevalent and show similarities with the alluvial architecture of the Río Bermejo, which thus represents a useful analogue for their identification and interpretation. Although the full spectrum of the sedimentology of fine‐grained rivers has yet to be revealed, meandering rivers dominated by lateral or oblique accretion probably represent end members of such channels, with the specific style of sedimentation being controlled by grain size and sediment load characteristics. 相似文献
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Importance of wave-induced bed liquefaction in the fine sediment budget of Cleveland Bay,Great Barrier Reef 总被引:3,自引:0,他引:3
J. Lambrechts C. Humphrey L. McKinna O. Gourge K.E. Fabricius A.J. Mehta S. Lewis E. Wolanski 《Estuarine, Coastal and Shelf Science》2010
Data from a three-year long field study of fine sediment dynamics in Cleveland Bay show that wave-induced liquefaction of the fine sediment bed on the seafloor in shallow water was the main process causing bed erosion under small waves during tradewinds, and that shear-induced erosion prevailed during cyclonic conditions. These data were used to verify a model of fine sediment dynamics that calculates sediment resuspension by both excess shear stress and wave-induced liquefaction of the bed. For present land-use conditions, the amount of riverine sediments settling on the bay may exceed by 50–75% the amount of sediment exported from the bay. Sediment is thus accumulating in the bay on an annual basis, which in turn may degrade the fringing coral reefs. For those years when a tropical cyclone impacted the bay there may be a net sediment outflow from the bay. During the dry, tradewind season, fine sediment was progressively winnowed out of the shallow, reefal waters. 相似文献
8.
川西北地区微细粒浸染型金矿成矿的区域地质、地球物理、地球化学特征 总被引:4,自引:1,他引:4
总结了川西北金三角地区的区域地质和矿床地质特征,研究了区域重力场和金矿发育的关系,详细论述了本区金矿发育的区域地球化学背景、区化异常特征及东北寨金矿的地球化学特征。从地球化学方面进行了成矿预测,指明本区尚有较好的找矿前景,应进一步加强工作。 相似文献
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